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PLACENTA PREVIA.

BY J. E. L. DAVIS, M. D., NYACK.

October 6, 1879, was called to see Mrs. R., et. 21. Found her having slight labor pains, and somewhat alarmed at the bleeding, which she termed "a show." It was of a bright red character; the patient complaining of nausea and dizziness.

I learned from one of her associates that she, the patient, had slight hemorrhages, from time to time, previous to this, but, as she was desirous of having a miscarriage, did not consult a physician.

Also learned that this was her eighth month of

pregnancy.

!

She had two children previous to this, and with each child long and tedious labors.

Upon examination, found the os uteri soft and slightly dilatable. Having the above symptoms, I 1. prescribed Ipecacuanha, and directed her to keep very quiet, hoping she might be delivered at term without further difficulty.

10

October 7, found her comparatively comfortable; an occasional slight pain and no hemorrhage.

October 8, A. M., labor pains frequent, but not strong or lasting very long; some hemorrhage. By examination, found the os uteri soft and easily dilata ble. The placenta presenting itself in the form of a soft spongy mass, I concluded to partially separate the placenta, finding, if possible, the side to which it was the least attached. This, I soon determined, was on the left side, to the extent of about an inch and a half. I entirely separated it on that side; the hemorrhage not being very profuse, and easily controlled,

I now found an arm presentation, which, by conjoined manipulation, was changed to the cephalic. I then made a slight puncture in the membrane, thinking I was doing a very good thing, but the discharge of liquor amnii was very copious, and although the presentation was good and the haemorrhage slight, yet there seemed to be atony of the uterus, from too

sudden relief.

She did not have another pain for nearly twenty hours; then they began to come again, spasmodically. I now administered Secale corn., the only result being that the pains were more frequent, not strong or last ing long. The hand again seemed to be presenting and the head retracting. I concluded to turn and deliver at once, for my patient was growing weaker.

The liquor amnii had nearly al escaped, and my endeavors only resulted in bringing down the other

arm,

This was returned with some difficulty, and the head again brought down, I then applied the forceps and delivered the patient. The child was still born, the mother is making a rapid recovery. Considerable force was necessary in the delivery of the child; the head, arms, and shoulders were large; other parts of the body's nall. There was a slight rupture of the perineum, but, with Calendula dressing, healed very Kindly

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RULES FOR SENDING CONSUMPTIVES TO TRAVEL.— The following rules are those laid down by Dr. James Edward Pollock in a recent lecture:

1. Never permit any patient to travel who is not in the quiescent stage of disease, or who, in other words, is feverish, with high evening temperature, and the physical signs and conditions already described to you, indicating the continuous form of phthisis. Observe this rule, and you will be successful; break it, and your patient and his friends will not thank you.

2. None of the secondary complications should be present; as, continuous or frequent diarrhoea, serious gastric disorder, or laryngeal irritation.

3. Chronic single cavity, with retraction of walls, accomplished or proceeding, is favorable for removal to a dry, bracing locality, if the hæmophysical element is wanting in the case.

4. That form of disease described as diffused deposit in one lung, without much dullness or signs of massing of disesse, with pretty large chest, and with more moderate emaciation, generally does well on a sea

Voyage.

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5. A first stage case, already chronic, does best for traveling about, with frequent change of residence. The complication with bronchitis or asthma is generally much benefited by change eit a to emw 6. Persons ought not to travel at all with feverish symptoms, with secondary complications, with a large amount of local disease in any stage; with both lungs diseased, with poor digestion and greatly lowered nutrition; or in such a state of weakness or emaciation us to require home comforts, peculiar beds or chairs, or Varieties of invalid cookery. --Medical and Surgical Reporterson bat das „9ile ng 9df dod Fired Ja nt Row How fal PCR o PICRATE OF AMMONIA IN WHOOPING COUGH AND DIPHTHERIA.-Dr. Z S. Dellenbaugh reports, ten or twelve cases of whooping cough he has treated with pierate of ainmonia with the most satisfactory results. Indeed, some of the cases were cured in the marvelously short time of from twenty-four to seventytwo hours." In view of this experience, together with some fifteen or twenty cases reported by him within the past few days, Dr. Dellenbaugh thinks he can most safely affirm that, if properly administered, the picrate of ammonia is a specific for the cure of whooping cough. He gives to babies from one-sixteenth to * MESSRS. EDITORS-It may interest you, and your one twelfth grain, and to children from one twelfth to many readers, to learn that this eminently conservative one-eighth grain, every three hours. In one case of bercity has at last roused itself sufficiently to comprehend diphtheria, he has also used picrate of ammonia as a that homœopathy is an established fact. With ample gargle (gr. viij to oj), and by atomization. The soluhospital privileges for the elect, our practitioners have tion of picrate produced a yellowish staining of the hitherto been without representatation on any of the parts in such a way that he was inclined to believe a domedical boards of any of our numerous charities. A destruction of the micrococci ensued, and a speedy "-little band of self-denying women who have been concure of the disease was the results (in) out no

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MEDICAL ITEMS AND NEWS

ARK HOMOEOPATHIG HOSPITAL IN DETROIT. •onezi ad of trods 0.4 11. T

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Month ending N. Y. OPHTHALMIC HOSPITAL. BUREAU OF MATERIA MEDICA, PHARMACY, AND Sept. 30, 1879: Prescriptions, 3.276; new patients, PROVINGS, IN THE AMERICAN INSTITUTE OF HOMEO-488; resident, 26; average daily, 126; largest, 182. PATHY.-Special subject to be reported on and discussed at the meeting in Milwaukee, June, 1880: “ The Limits of Drug Attenuation and of Medicinal Power in Homœopathic Posology:"

I. The proofs of drug presence and power in attenuations fabove the sixth decimal: (a). As furnished by the tests of chemistry-W. L. Breyfogle, M.D.; (b). As furnished by the spectroscope and microscope-C. Wesselhoeft, M D., J. Edwards Smith, M. D.; (c). As furnished by the tests of physiology-T. F. Allen, M. D., Lewis Sherman, M. D.; (d). As furnished by analogy from the field of impalpable morbific agencies -J. P. Dake, M. DI

J. H. BUFFUM, M.D., Resident Surgeon. WANTED -A Junior Resident for the Brooklyn Homœopathic Hospital and Dispensary. Apply either in person or by letter to to S. E. Stiles, M.D., Resident Physician, 109 Cumberland Street, or J. G. Atkinson, M.D., Supt. of Dispensary, 304 Adelphi Street, Brooklyn.

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VOMITING IN PREGNANCY.-Dr. J F. Baldwin, of Copeman's method" of Columbus, O., has found thoroughly dilating the external os and cervical canal with the finger successful in three desperate cases of vomiting.

REMOVALS-Dr, A. R. Thomas, to 1,733 Chestnut Street, Phila; Dr. E. B Britton, to 30 South Broadway, Baltimore; Dr. Mary W. Noxon, to 531 Fifth Avenue, NY; Dr. Clara C. Plimpton, to Nashville, Tenn. Dr. Thos Wildes to 35 West 31st Street, N.Y. Dr St. Clair Smith to 11 East 38th Street, N. Y

II. The proofs of medicinal presence and efficacy in attenuations above the sixth decimal: (a). As furnished by the tests of clinical experience, in the use of attenuations, ranging from the sixth to the fifteenth decimal-J. F. Cooper, M. D.; (b). As furnished by clinical experience, in the use of attenuations, ranging from the fifteenth to the thirtieth decimal-A. C. Cow perthwaite, M. D.; (c). As furnished by clinical exDANGER OF OPIUM IN CHRONIC BRIGHT'S DISEASE. perience, in the use of attenuations above the thirtieth -The possibly dangerous effect of even small doses of decimal-C. H. Lawton, M. D.; H. M. Paine, M. D. At the last meeting of the Institute this Bureau re-morphia in chronic Bright's disease, although alluded ported upon the "History, Methods and weans of to by several writers of authority, is not so widely and The thoroughly known as it should be by the profession. Drug Attenuation," in an exhaustive manner. reports of the current year, passing from the domain Intolerance of this drug is one of the peculiarities of of Pharmacy somewhat into that of Posology, will the disease; doses so small as to be looked upon as safe complete a work of vast importance for Homoeopathy. under any circumstances will sometimes have a poisonThe Bureau will be pleased to receive items of ous effect.-Phil. Medical imes. GRAAFIAN VESICLE DURING PREGNANCY.-Dr. Slavinformation and experimental aid from members of the profession, and, also, from scientific persons out-insky reports the case of a woman, aged 24 years, who side, who may be interested in any division of our subject. J. P. DAKE, M. D., CHAIRMAN.

NASHVILLE, TENN.

AT LAST.-A question of nearly ten years' standing It is the has at last been disposed of in Boston. woman question which has so long obtruded itself into the deliberations of the State Medical society. Attempts have repeatedly been made to secure the admission of women to membership, but conservatism, always of a rigid type in this organization, turned coldly away each time from the proposed innovation. Year by year a progressive spirit has gained ground among the ranks of younger members, and at a recent meeting of the Council the Board of Censors were very quietly directed to examine all female applicants for admission. The young members are very happy over their victory; the older ones accept it with what good nature they can, but insist that it does not concern the public, and the less that is said about it the better It is believed that very few female members will result from this decision.

Messrs. Editors :

In Guernsey's Obstetrics, p. 979, "Glossary," we

read :

died in the third month of gestation, and the post mortem showed ovarian follicles which were on the point of bursting, as well as recent corpora lutea. This confirms the opinion enunciated by the late Prof. Charles D. Meigs, that the development of the graafian follicles continued during pregnancy.-Med. Central Zeitung.

DR. S. H. QUINT of the New Jersey Homeopathic Medical Society has been appointed Medical Superintndent of the Camden Co. Insane Asylum at Blackwoodtown. The asylum has about seventy patients.

HEALTH BOARD, KENTUCKY.-A petition signed by eighty of the most prominent citizens of Louisville, for the appointment of a homeopathic member of the board has been refused by Gov. Blackburn on the ground that a homœopathic physician is not "regular." The proper wisdom of the governor's decision will be more apparent when it is understood that it comes from an allopathic physician.

WHAT IS A TEAR ?-Rev. Dr. Talmage says in one of his sermons, "if you should ask a chemist what a tear is he would tell you it is composed of salt and lime and has other component parts, but he would miss the chief ingredients: the acid of a soured life, the viper's sting of a bitter memory, the payment of a It is The authority for this bit of descriptive anatomy is broken heart. I will tell you what a tear is. agony in solution.

46

Cornea-Horney, transparent coat of front part

eye-lid."

not given.

of

We should think this "Glossary" might be omitted CRITIQUE. from the next edition as superfluous.

PILOCARPIN IN ALBUMINURIA.-Dr. T. G. Thomas regards it as a serious error when a physician thinks it necessary to produce premature labor in every case of albuminuria. In the treatment of these cases he regards it as important to keep up the excessive action of the skin, and for that purpose pilocarpin was suggested as a most reliable diaphoretic. Prof. Barker, on the contrary, says in the majority of cases in which he has seen this drug used the patient has died.

Dr. J. G. Gilchrist is preparing a work on Surgery, to be issued in four volumes, making in all over 2,000 pp. The first volume, about to be issued by Duncan Bros., covers Surgical Therapeutics and Institutes of Surgery; the second will cover Surgical Emergencies and Accidents; the third, which will really be the first, Surgical Principles and Minor Surgery); the fourth, Surgical Operations.

Dr, Bukk G. Carleton has been appointed Demonstrator of Anatomy in the N. Y. Hom. Med. College.

THE

HOMEOPATHIC TIMES.

A MONTHLY JOURNAL

Of Medicine, Surgery, and the Collateral Sciences.

VOL. VII.

NEW YORK, DECEMBER, 1879.

ORIGINAL ARTICLES

THE COLOR-SENSE AND COLOR-BLIND

NESS.

BY ALFRED WANSTALL, M.D, BALTIMORE,

[Written for the Bureau of Miscellany, including Anatomy, Chemistry and Physiology, of the Homœopathic Medical society of the State of Maryland.]

Personally, except in a very limited degree, I possess no practical knowledge of this subject. For the past two years the scientific world has been so agitated about it, and the results of the investigations have become so numerous and interesting, that I feel no hesitation in bringing it before this society even at this somewhat late day.

Color-blindness possesses a history. The first officially known case was related by Joseph Huddart, of London, in a letter to Joseph Priestly, in January, 1777, now more than a hundred years ago. It referred to a shoemaker by the name of Harris, of Cumberland, Eng., and his brother, the captain of a merchant

vessel.

The first accurately described case is that of John Dalton, the celebrated English chemist and physicist. Red blind himself, he studied this defect on his own person, and published in 1794 an exact description of it. After him color blindness received the name Daltonismus. People were astonished to hear, from the communication of this celebrated man, that to him the red of the rose and the blue of the sky appeared as the same color, and that no distinction existed between the bright red of the sealing wax and the green of the

turf.

No. 9.

ber of persons, such as soldiers, students, police, etc., and found, among 1,154 persons, 56 color blind; i. e., 5.6 per cent., or one color-blind among 17.7 persons.

Wilson used tinted papers for testing, and depended upon the name of the color given to the pigment by the person being examined; only those who hesitated in distinguishing red and green were challenged and tested according to the method of Seebeck. According to Wilson, the color blind must renounce painting, weaving, tailoring, chemistry, botany, geology, medicine, etc., and especially, their employment on railroads and in the marine is dangerous, and may occasion loss of life. Wilson did not content himself with calling attention to these dangers alone, but he also endeavored to establish rules for prevention, and proposed that the colored signals in use be retained, and all color blind persons be excluded from the service; or that all persons be retained in the service without regard to their color-sense, and the signals be changed.

The single practical result given by Wilson as the result of his work is the decree of the Great Northern Central Railway Company that their collective employés must possess a normal color sense before their admission to the service.

Dr. A Favre, of Lyons, France, consulting physician of the Paris Lyon-Mediterranean Railway, has for a long time busied himself with the practical side of the question. He examined for color blindness the em. ployés of the above railroad, also soldiers, sailors, and scholars. The work of Dr. Favre has called forth two new ideas. He directs special attention to acquired color blindness, which, according to him, is of tolerably frequent occurrence, and asserts that congenital color-blindness is not incurable, and can be remedied by the systematic and continued practice of the colorsense.

Still later, this subject has been much discussed in Germany, Sweden, and other European countries by Stilling, Holingrew, Magnus, Cohen, Daae, Donders, and others.

THEORY. It is well known that a luminous body sets the smallest particles of the surrounding ether in wave like vibrations, which extend from it in all directions.

Seebeck was the first to examine a relatively large number of persons, and compare them with one another. As early as 1837 he had collected twelve cases of complete color-blindness, and mentioned, besides, a small number of more or less incomplete cases which formed the transition to typical color- When these vibrations come in contact with our blindness. He saw already how deceivable and un-sensory organs, whether in a direct line from the certain it was to estimate the nature of color-blindness luminous body, or reflected by another body, they from the name of the color which the color blind produce certain changes which are interpreted in give to the object. He used principally tinted papers, our nervous centres into definite sensations. If they about three hundred in number, and tested by comcome in contact with our skin, they are interpreted parison. as heat; if with our retina, we experience them as light. So it is our brain which, as the result of certain changes in our sensory organs, generates light and heat; although we designate the external origin by these names, and say that light and heat rays proceed from the glowing body, yet we must distinguish light and heat in an objective sense-which are one and the same thing, namely, vibrations of ether—from

George Wilson, professor of technology in the University of Edinburg, was the first to study color-blindness in its relation to the different occupations of life, and to call attention to the danger of employing color blind persons in the railroad service and in the marine, as well as in other positions where colored signals must be recognized. Wilson examined a great num

light and heat in a subjective sense, which are sensa tions of a totally different nature.

:

If all vibrations of ether were of a similar nature, or if all the elements of our optic apparatus reached in the same way to all vibrations of ether, we would scarcely appreciate different kinds of light every specific irritation of our optic apparatus would produce a sensation of light whose intensity would depend upon the strength of the illumination, but not its nature. A quantitative difference could be appreciated, but not a qualitative; in other words, differ nt kinds of light, i. e., colors. Physics teach that the vibrations of ether are of differ nt kinds, and that they are distinguished from one another by the rapidity of the vibrations, and the length of the waves. It is owing to these differences that we appreciate differences in quality, i. e., colors.

All quality of light must necessarily depend upon a difference of function of the elements of our optic apparatus. There are two possibilities: Our optic apparatus possesses only one kind of elements, and these are set in different functional activity by the different kinds of vibrations; or there exists in the retina or brain different terminal apparatus, of which each always reacts in the same way, while they are different from each other.

The principle upon which the sensation of quality of light-i. e, color-is explained, is as follows: If one element is excited alone, or if all are simultaneously excited, but one more than the others, we experience the excitation of this one element as quality of light, as colored light, or as color, and call primitive or fundamental color that which corresponds to the element excited. If two elements are excited, or if they are preferably excited, we see colored light, but in a color which corresponds to the mixed color of the two elements excited. This principle permits of the assumption of many fundamental elements and primitive colors. Likewise, from the simultaneous and similarly strong excitation of all the elements no color sensation can originate. We then see light in general, in contradistinction to absence of light, i. e., dark

ness.

It is evident that when one element is principally excited, while the others are excited to a less degree, the sensation of the specific quality of light will be weaker accordingly as the excitation of the other elements is stronger, because the sensory effect of the irritation corresponds to a mixing of colorless or white light with the specific color of the principally excited element.

The approximate representation of all colors can be produced by the use of three pigments or colored powders: red, yellow, and blue; red and yellow forming the different shades of orange and orange-yellow, blue and yellow giving a variety of shades of green, blue and red all the purple and violet hues. These facts furnished the foundation for the theory of the three primary colors, of which David Brewster was the most ardent defender. He maintained that there are three fundamental kinds of light-red, yellow, and blue-by the mixture of which all kinds of colored light can be produced, as is the case with the pig

ments.

This theory has been shown to be entirely without foundation. The results of mixing different kinds of light, by Maxwell's disks, is entirely fatal to the theory of Brewster. Color is a subjective sensation, and its laws can be studied only by considering the subjective sensations produced by mixing different kinds of ligat. The color of any object is due to its property of absorbing some kinds of light and reflecting others. We can see why the result of physically mixing a yellow and a green pigment may be entirely different from mixing yellow and green light reflected from two surfaces, as is done in the case of Maxwell's disks, when the mixing or union takes place in the nervous

centres. By mingling two pigments, white light is twice subjected to the process of absorption, and what remains over is the colored light reflected from the painted surfaces; while, on the other hand, the process of mixing colored light is one of addition. This will be sufficient to show why our color sensations cannot be studied with the palette. The following is the color theory of Herring: Red, green, yellow, and blue are the simple or principal colors. Pure red and pure green (subjectively) mixed give a colorless sensation of gray; likewise, pure yellow and pure blue. Pure red, on the one hand, forms all conceivable tones of color through yellowish red and blue red, in which we have the sensation of both colors, or recognize them; pure green, on the other hand, forms all conceivable tones of color through yellowish green and blue green, with which both colors are likewise recognizable. Herring indicates red and green, not as complementary, but as antagonistic colors; they work against or destroy each other in the act of exciting the sensation of color, as is also the case with yellow and blue.

Our sight substance is composed of three different kinds of matter, namely: 1. The substance for the sensations from black to white; 2. The substance for the sensations from red to green; and 3. The substance for the sensations from yellow to blue; and are called the black-white, the red-green, and the yellow-blue substances. No color or tone of color can be experi enced in complete purity; and, also, the black-white substance is always affected by all the objective colors. If the sight substance is affected by objective yellow and blue in such proportions that the color sensations destroy each other, there remains of them their action on the black and white substance, and the resulting sensation is a colorless gray. The same is true of red and green. From the action of the collective rays of the spectrum, the sensations red and green, yellow and blue, are lost, and there remains only the action on the black white substance.

The red-green substance is affected, on the one hand, from the most external red of the spectrum to pure yellow; on the other hand, from greenish yellow to blue; and again, by the red contained in the violet of the spectrum; in pure yellow and in pure blue, not at all; in pure yellow, certainly not, because the action of red and the antagonistic action of green destroy each other; in complete blue not, because the action upon the green-red substance occurs with the opposite action of the violet upon the green-red substance. The yellow-blue substance is. excited, however, from red to green, and from blue green to the end of the spectrum. (Aubert. Physiologische Optik. FarbenSinro. Graefe und Saemisch, Bd. II.)

According to the above theory, color blindness must consist of an absence of or want of function of one or the other color-seeing substances; and color-blind persons must be either red-green or yellow-blue, or, finally, totally color-blind. With red-green blindness the color system consists only of yellow and blue. The spectrum appears only in these two colors. Colored stuffs appear yellow, blue, or gray, according to the quantity of the different kinds of reflected light. The spectrum is, in most cases, of normal length; in single cases, much shortened.

Blue-yellow blindness. The color system consists only of red and green. The spectrum appears only in these two colors. Colored stuffs appear green, red, or gray, according to the relative quantities of the refected kinds of light. The spectrum can be much shortened, and it can be of normal length.

In comparison with red-green blindness, blue yellow blindness is very rare. Total color-blindness is relatively very rare, and little understood. They see only black, white, and gray.

Early in the present century Thomas Young first propounded the theory of three fundamental colors.

1. Color blindness is divided into

a. Red-green blindness.

b. Blue-yellow

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About 1850 this theory was reviewed and advo- violet blindness; and b, a lower degree, which may be cated by Helmholtz, since which time it has received indicated as a weak color sense. many adherents, and is known as the Young-Helmholtz Stilling classifies color blindness, accordingly, as hypothesis. It assumes three fundamental colors; red, those color sensations which are indicated as simple, green, and violet, and, accordingly, three correspond are absent, and in harmony with the theory of Hering elements in the optic apparatus. If the red sensi-ring, of four principal or simple sensations. Since tive elements are alone excited, or more than the each two of these stand in a polar relation as positive others, we experience red, and so for the others. The and negative, so, when one color fails with a color different vibrations of ether excite the different ele-blind person, the other antagonistic color must also ments in a different degree, but always so that all are fail. Either the collective color sensations fail, or the set in a certain degree of excitement Homogeneous sensations of red and green, or yellow and blue, fail at red light irritates, from the outer end of the spectrum the same time. to its side of orange, the red sensitive elements in a high degree; much less the green, and still less the violet. In this way the sensation of red originates, which goes more and more into orange as the irritation of the green sensitive elements increases. Homogeneous yellow irritates strongly, and, in almost the same degree, the red and green sensitive elements, while it affects the violet sensitive elements only very weakly. On this account the sensation of yellow is a combination of red and green. Green light irritates the green sensitive elements strongly, the two others very weakly and in almost the same degree. Hence the sensation of green. Homogeneous blue irritates tolerably strong, and in almost the same degree, the green and violet sensitive elements; but the red in a less degree. Hence the sensation of blue is a mixture of green and violet. Violet light affects the violet sensitive elements actively, but the two others less. Hence the sensation of violet.

According to this theory, color blindness must consist of red, green, violet, or total color blindness, ac cording as one, the other, or all of the color sensitive elements are absent, or are deficient in functional activity.

Red blindness originates from the absence of or want of functional activity of the red sensitive elements. The red blind possess two fundamental colors, namely, green and violet. To the red blind, spectral red ap pears as a saturated dark green; yellow, as a light saturated green; green, as a light but whitish gradation, of the same color as red and yellow; blue, as blue; and violet, as violet or dark blue.

Green blindness consists in the absence of or want of functional activity of the green sensitive elements. The green blind possess two fundamental colors, viz.: red and violet. The green blind see the spectral red as a dark but much saturated red; yellow, as a light red; green, as white or gray; blue, as a color similar to the indigo; and violet, as a much saturated violet.

Violet blindness consists in the absence of or want of functional activity of the violet sensitive elements. The violet blind possess two fundamental colors, red and green. They see the spectral red as red; yellow, as white or gray; green, as blue green; blue, as green; and violet, as dark green.

CLASSIFICATION OF COLOR-BLINDNESS.

Holmgren classifies color blindness as follows, in harmony with the color theory of young Helmholtz: I. Total color blindness; where the ability to see colors is totally wanting, and where the sense of sight is able to distinguish the difference between light and darkness, with their different grades of intensity.

II. Partial color blindness; where the ability to distinguish definite tones of color, not all, fails. It is divided into-1. Complete or typical color blindness; where one of the three fundamental color sensations, i. e., one of the three color sensitive organs, fails. This group includes three kinds, viz.: a, red blindness, b, green blindness, c, violet blindness." 2. Incomplete color blindness; where one or all three of the elements are weaker in irritability or number than the normal color sense. This group includes, a, a higher degree, which can be indicated as incomplete red, green, and

c. Total color

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2. Decreased color sensitiveness is divided into
a. That for red-green.

b. That for blue-yellow.
c. Total.

These different kinds of decreased sensibility of the color sense are not sharply separated. Not seldom true blindness for two antagonistic colors is united with a decreased sensibility for the two others, forming a transition between partial and total color blindness. Color blind persons possess a great sensitiveness toward light effects, which compensates them in some degree for their loss of color effects. It enables them to experience fine and delicate shades of light when a color-seeing eye would remark nothing. They also understand how to make their fine power of distinction for differences in light of practical value. It enables them to distinguish colors from one another, which, on account of their color blindness, seem alike. They discover that colors, which to them falsely appear identical, do not possess a like amount of light, and they use this difference in the amount of light to distinguish color tones from each other. This power is much developed by practice. Magnus mentions the case of a red-blind locomotive engineer who understood so well how to hide his color blindness, that, in a service of ten years, he did not once mistake the red signal, nor confound it with the green, and was supposed by his superiors, on this account, to be normal sighted. His defect was first brought to light by the obligatory examination of the color sense of the railroad employés. Magnus frequently convinced himself that this man did not confound the red and green signals, in spite of the fact that the examination of his color sense showed him to be in a high degree red-blind. He afterward gave this author to understand that he was aware of his color blindness for a long time, and in distinguishing between the red and green signals, he had been helped only by the amount of light possessed by the two colors. Magnus also relates an interesting case of a red-blind painter's apprentice, who had been taught by a master for three years, without the master having This individual had been able to strike the distinction any suspicion of the color blindness of his assistant. sensations of light effects. between the different colors only by his sharpened condition, and his anxiety that he would finally comHe was so agitated by his mit an error so frightened him, that he confessed his failing, and gave up his vocation as a painter. cian, that color blindness can be removed by a long The opinion of Dr. Favre, the French railroad physiand systematic practice of the color sense, has not been confirmed by experience; and, indeed, the evidence is that the condition of the congenitally colorblind cannot be improved. This is clearly evinced by numerous cases of color-blind individuals who, through long years of practice, were never able in any way to improve their condition. For example, the case of Harris, the shoemaker, and the celebrated John Dalton. Harris was aware of his defect from his fourth year,

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