and Dalton studied his own defect for many years; neither of these persons were able to improve their condition. It seems unnecessary to mention the paint er's apprentice, who, after three years' practice in colors, gave up his calling on account of his color blindness. "Therefore a systematic exercise of the color sensations of the color-blind is a perfectly useless undertaking." (Magnus.) Color-blindness is congenital, and, in some degree, hereditary, as demonstrated by numerous examples, and affects almost exclusively the male gender. The example of the shoemaker, Harris, shows that colorblindness is a family failing, though rarely affecting all members. Harris had two brothers, who, like himself, were color-blind; however, besides, there was one brother and a sister with a normal color sense. Horner contributes two interesting pedigrees, extend ing over several generations. From the one it is seen that five daughters of a color-blind individual did not suffer from color-blindness; it affected, however, their collective male descendants, with two exceptions, in the five following generations, while all the females remained free. The other, the pedigree of a color-blind individual born in 1642, showed only male color-blind descendants to the seventh generation, and always so that the color-blindness was transmitted through a normal seeing female member to her male descendants. Color-blind individuals are naturally incapacitated for many callings in life, and their employment in positions where colored signals are to be recognized, as in the railroad service and the marine, is positively dangerous, and has probably occasioned both loss of life and property. Therefore, the necessity of a careful, uniform, and repeated examination of the color sense of the employés of railroads and marine is self-appar ent. Although color-blind persons have served in the capacity of railroad engineers without coming to grief, being able to distinguish between the different signals by their acute perception for different light effects, yet the conditions modifying light are so numerous and variable as to render this a very uncertain and hazardous method of deciding. To Dr. Favre belongs the honor of having first directed special attention to the importance of repeating the examinations at regular intervals, in order to detect cases of acquired color-blindness arising among employès from bodily causes. The color scale of the color-blind is much more penurious and poorer than that of the normal sighted. A considerable number of colors which appear to the normal color sense as entirely different, and belonging to different groups, and to which different names are applied, have for the color-blind no distinction. They appear to the color-blind as identical, or as so similar that he is unable to make a specific distinction between them. Therefore, the system of colors in use by the normal-sighted is useless to the color-blind, and not understood by them, and they can never learn to understand the color designations in use by the normal-sighted, or apply them to their abnormal color sensations. The first test I shall describe is that of the colored shadows, or simultaneous contrast, of which Dr. J. Stilling is the most enthusiastic supporter. If a white surface is illuminated by two lights, one of which is colored, and some object, such as a pencil, be brought between the lights and the illuminated surface, two shadows will be cast on the surface, one of which will be of the same color as the colored light; the other will appear in its antagonistic or complementary color. This appearance has never been satisfactorily explained as yet. Stilling says: "All that can be said is that, under certain circumstances, a colored illumination forces the normal eye to produce subjectively upon the shadow the opposite or antagonistic color. By presenting to the eye lights of all the different colors, it can be forced to produce subjectively all the colors it is capable of appreciating. An eye insensible to any given color will not produce upon the shadow its complementary color, and instead of appearing colored, as to the normal eye, the shadow will appear dark, provided the inducing color act alone. produce shadows for this purpose, allow the light of a lamp to shine through a colored plate of glass upon a sheet of white paper fastened to the wall; then interpose an ordinary lead pencil, which will throw a single shadow in the complementary color. For ordinary purposes, two lamps are unnecessary, as, in case the room is papered with light paper, sufficient light for the purpose will be reflected. If the wall paper is dark, a second white sheet of paper may be used for reflecting light upon the first, or ordinary daylight can be admitted to the room. For the inducing illumination, four large plates of glass are used, which transmit simply and unmixed the four principal colors. Το The large number of experiments on the color blind made in accordance with this method has produced uniform results. "The shadows either appear colorless and dark by red and green illumination, and colored by blue and yellow, or, on the other hand, colorless by blue and yellow illumination, and colored by red and green. In some cases no color would be perceived in any of the shadows." When two lights are used, forming two well defined shadows at the same time, either the objective red and the subjective green, or the objective blue and the subjective yellow appear colorless, or vice versa. According to these experiments, the sensations red and green, or blue and yellow are at the same time wanting, or in some cases all color perceptions are absent, or very slightly developed. The contrasts can be made weaker or stronger according to the intensity of the lights, or the more or less marked prominence of the inducing color. This test could be further amplified, but sufficient has been said to show the principle upon which it is based. It is scarcely necessary to add that it is not adapted for examining large numbers of people when rapidity is of paramount importance. Holingren's test, which is simple, complete, and easily and rapidly executed, depends upon the principle of comparison. A supply of colored worsteds in the colors red, orange, yellow, yellow-green, green, blueFor these and other reasons in testing for color-green, blue, violet, purple, rose, brown and gray, sevblindness, methods which are based or depend on the eral shades of each color, and at least five degrees of subjective statements of the person to be examined saturation, is necessary. Green and grays of several must be avoided. In naming colors, the color-blind by kinds, red, blue, and violet, and shades of light brown, practice may acquire much dexterity, and thus avoid yellow, red and rose must be especially present. detection; and the unpracticed, yet normal, color sense can, by the subjective statements be classed as abnor mal. Tests for color blindness. The tests for color blindness are numerous; some of them time-consuming and difficult of conducting, while the necessary apparatus is complicated and expensive. I shall limit the remarks to three tests which are characterized by their simplicity, effectiveness, ease of performance, and-at least, two of them-by their adaptability to testing large bodies of persons. The collection of worsteds is spread upon a table, and the examiner selects the color he will use for the test from the collection, and lays it on one side; he then requests the subject to select from the collection those colors which seem to him to come nearest the test, and lay them by its side. According to the kind of colors, and the manner they are selected, the color sense is exposed. For diagnosing a deficient color sense, green is selected as the test color, because green is the lightest of the spectral colors, and therefore is the easiest confounded with gray. For diagnosing different kinds of complete partial color-blindness, purple (rose) is selected, i. e., the entire group of colors in which red (orange) and violet (blue) unite, and in which neither of these colors preponderate. Although purple is a compound color, it is completely saturated, and on this account it has been called the eighth spectra! color. For the examination of the color blind, purple is of great importance, because it is formed by the union of the two colors found at the extreme ends of the spectrum, and which are never confounded with one another. On this account, and according to the theory of Young Helmholtz, purple with the color blind either excites only one of the color sensitive organs, or it excites both simultaneously. Accordingly, it appears only as a simple color, i. e., as one of the two of which it is composed, or as white (gray). Test 1. The examiner lays before the subject a pure, light green bundle of worsted. The examination must be continued until the subject has laid beside the test all the bundles of worsted of the same color; or, until with these, also gray, reddish, and rose colored worsteds. Those who lay beside green, also reddish, gray, and rose colored worste with the test, are color blind; those who, without being guilty of this error, show a decided inclination to it, have a weak color sense. Test 2. A purple (rose) colored worsted, in a shade midway between the lightest and the darkest, is placed before the subject. 1. Those who are found color blind according to test 1, and who with this test select only purple col ored worsteds, are incompletely color blind. 2. Those who with test 2 select entirely, or with purple medium and dark blue and violet, or one of these two colors, are completely red blind. 3. Those who with test 2 select exclusively, or with purple, green and gray, or one of these colors, are completely green blind. Test 3. A bright red bundle of worsted is laid before the subject. The red blind select, besides the red, green and brown, shades which to the normal eye appear darker than the red, The green blind, on the contrary, select such shades of green and brown as to the normal eye appear lighter than red. Violet-blindness is betrayed by the confounding of red and orange with the purple of test 2 Holmgren has since simplified his test as follows: 1. With test 1 all the green tones are removed from the collection, with the single exception of those to which test 1 belongs, and which shall consist of five different shades. 2. When test 2 is to be used, the blue greens of Cif ferent shades are to be added to the collection. 3. Before commencing the examination, the subjects are to be stood in a circle around the table on which the collection of worsteds lies, so they can all see what occurs. 4. The examiner holds the five green tests before them, and requests them to impress the colors so they will be able to find them with certainty and rapidity when they are mixed with the other colors. Then the examiner lays the first test color, i. e., the lightest of the five green shades, on one side, and mixes the remaining four with the collection. He then immediately selects them from the collection, and lays them with the test; i. e., he executes the test before the eyes of the subjects as they shall execute it, This can be repeated as often as seems necessary for the proper understanding of the test. test 1, he is immediately subjected to test 2, for the differential diagnosis. Test 3 need not be made. 7. As the test in general, according to the above, proceeds very rapidly, the weak color sense is made known by the slowness of the manipulation. With this method, more than one hunc red disciplined persons can be examined in an hour. The third method of examining is that with the socalled pseudo-isochromatic plates of Dr. J. Stilling. It consists of a number of plates, principally for the discovery of red-green blindness; several are exclusively intended for the finer examination of discovering a decreased color sense for red and green. There are also similar plates for discovering blue-yellow blindness. The pseudo-isochromatic plates are constructed as follows: The different shades of both interchangeable colors are intermixed in smaller or larger squares in such a manner that the squares of the one color form letters and figures, and those of the other the ground work, so that the different intensities alternate in ground and letter. In this way every distinction is rendered impossible, and the question as to the judgment of colors is rendered unnecessary, the inquiry being merely about letters, numbers, figures. By means of these plates, reduced color sense, as well as color-blindness, may be diagnosticated, and it is immaterial whether daylight or lamplight be used, as the hue will suffer no change by the latter. Stilling says: "I believe I am justified in asserting the conviction that, for the estimation of the sensitiveness for red and green, the practitioner posseses in the present plates an apparatus so complete that he has no necessity to use other means of help; at least in the sorting of colored bundles of worsteds, in which the color-blind can become quite expert, and which, on this account, is not certain." The manner of using the plates and forming the diagnosis consists in holding them before the subject, or giving them into his hands, and requesting him to form (rose or red colored) letters out of the quadrants. According to their ability or inability to decipher the plates, their color sense is revealed. The author believes he has so far improved these plates in relation to lustre, etc., that they can be used by the unpracticed, without any preparatory rules, in any kind of light. These tests have respectively active opponents, as well as warm admirers, and the final value of each is yet to be determined. given by the different examiners, varies very much; STATISTICS. The per centage of color-blindness, as while one gives it between three and four per cent., another gives it as ten per cent, and over. The cause of this great difference may be sought in different factors. A pure objective method of examining will give a less per centage than when the subjective statements are considered. Again, the transition of colorblindness to a normal color sense is so gradual that no absolute line of demarkation can be drawn. One examiner may include an individual as color-blind to whom another would attribute a normal color sense. Finally, the material itself is subject to many variations in relation to race, social position, gender, etc. He gives the per centage as 3.25, supported by a The statistics of Holmgren have the greatest value. material of 32,165 persons examined. .. 8.18 .. 9 33 "Kragero, Norw'y ..10.24 This material includes persons in different conditions of life, such as railroad employés, soldiers, sailors, police, students, etc. education in colors-than would be the case with the cultivated; while the culture itself would assist the higher classes in hiding true color blindness. Again, as color blindness is congenital and in some degree hereditary, any social condition which could exert an influence on it must exist for a very long the state of society is continually changing; the ancestime; generations, perhaps. It is well known that tors of many who are to-day in the higher classes beEven with the longed to the lower, and the reverse. Dr. Magnus has studied color-blindness in relation to different grades of society with the following results: Among 2,002 scholars of gymnasia and higher pre-extremely low, the conclusions of Magnus could hardparatory schools, examined by him, were 53 color-ly hold good, as their ranks are continually recruited blind. This gives 2.65 per cent. Among 1,055 scholars from the other classes, to which their children in turn return. And here the factor of doubtful parentage is of grammar and elementary schools were 46 colorblind. This gives 4.36 per cent. greater than elsewhere. Prof. Cohen found among 1,424 scholars of gymnasia and higher schools, 47 color-blind. This gives about 3.35 per cent. Among 1,005 scholars of grammar and elementary schools, 48 color-blind. This gives about 4.8 per cent. The following table, given by Prof. Holmgren, is of special value in this relation: Per The opportunities for the color education, as here understood, of the children of the middle classes is not surpassed by any. Colored toys and the like are their ployed with colors in the arts for gererations, as they Constant companions; their parents have been em in their turn are. The fact that the higher classes and more cultivated give the preference to less pronounced and paler colors, while the lower classes love the more brilliant shades, would show that the color sense of the lower classes is less refined, but not that they incline more to color blindness, as assumed by Magnus. In fact, Dr. Burnet, of D. C., has found the percentage of color blindness strikingly small with the negroes, and their preference for loud, bright colors is well known. It has been generally stated that the Germens are much addicted to bright and inharmonious colors, nor have 4.50 they been shown to possess more color blindness than 2.15 other people. 79 166 4.54 78 171 94 2.22 62 3.54 4.77 18 5.60 Magnus says: "Though these numbers are not sufficiently great to come to any final conclusion, still they show that color-blindness in general is greater with the lower classes than with the higher." He seeks the explanation as follows: With the lower classes a development of the color sense finds no consideration. The children frequently grow up without receiving any idea of the colors or their names. Even if, with the higher grades, the children receive no direct development of the color sense, yet their attention is turned to colors in a greater degree than is the case with the children of the lower classes. Colored toys, picture-books, paint boxes, and the like, are, to the children of the better classes, well known apparatus, and that these colored objects can exert a certain influence upon the development and sharpening of the color sense is generally conceded. The slight inclination to color-blindness shown by the female sex is, perhaps, due to a similar cause. He further says: "The preference given by the cultivated and better classes to the less pronounced and softer colors, while the lower classes love the brighter colors, tends to show that the lower classes have a less developed color sense, and tend more to color-blindness." There is no longer any doubt that the female sex possesses a more acute color sense than the male, and consequently inclines less to color blindness; a fact mentioned by ophthalmologists in the early part of this century, which then had more the character of a supposition than actual knowledge. At the present day the question is solved beyond doubt. Prof. Dor found in Berlin, among 611 girls, 5 color-blind.... .0.82 per cent. .0. .0. .0. Dr. Hansen found in Copenhagen, among .0.04 .0.11 ..0.26 The explanation of this extraordinarily small per cent. of color blindness among females, in comparison with males, is sought in the early education of the color-sense by the use of colored objects, stuffs, worsteds, etc., which is peculiar to the female world. Von Bezold says: "With women a difficult colorsense is less frequent than with men, so that we will I think it not out of place to attempt to show that in not be wrong when we ascribe to the female gender in some degree this argument is fallacious, and I think general a more completely developed color-sense. the greater inclination of the lower classes to color Shall the interest in the toilet, appearing so early with blindness, as shown by the statistics, is more apparent the female, contribute anything to the development of than real. Every one will concede that the color sense this color-sense?" Lederer remarks: "It is easy to of the lower classes is much less practiced than is the assume that females who are accustomed from childcase with the higher classes; this fact alone cannot hood to think of the much-colored decoration of their justify the assumption, even if apparently supported by toilet, in this way become and remain skilled in the statistics, that the lower classes incline more to color distinction of colors." Magnus appropriately adds: blindness, which is a congenital and incurable defect." Naturally a practice of this kind would never be able The lack of cultivation in general and want of practice to simply heal the one female individual of congenital in colors with the lower classes would render them physiological color-blindness. We dare not attribute very much more liable to be accidentally classed as to it more than a means of exercising the color-sense, color blind-when they lack only intelligence and an which gradually profits, and its influence does good not so much to the single individual as to the entire gender." The color sense of the single individual is gradually and imperceptibly strengthened and educated by early and continued practice. This development of the color sense, insignificant for the single individual, is transmitted from one generation' to the other, and becomes a pronounced sexual peculiarity of the female gender. Gradual practice and transmission are the two active factors which help the female to their peculiar preponderance of the color sense over the male. (Magnus) Holmgren also advances a similar theory: "If practice can have an influence upon this point (less occurrence of Daltonismus with females), according to our view, the single individual will not be healed so much as the entire gender, and in this manner the practice is transmitted unobserved to the coming gender. We know too little of the laws of transmission in order to speak upon such conjectures; however, we definitely know that good as well as bad peculiarities are transmitted. To the latter belongs color blindness, and we believe that practice, in one sense, in the way of transmission, may exert good results, even if we are unable to prove this." For the relief of color blindness Magnus proposes the early education of the color sense of the male gender by the systematic and methodical practice of this sense in the schools. As already mentioned, this was proposed by Dr. Favre, of France. He proceeded, however, from the supposition that color blindness is a curable defect, and that this was the most certain way of relieving it. Magnus proposes to educate, not so much individuals as the entire gender, and thus produce an improvement in the color sense of the male by transmission, as is supposed to be the case with the other sex. Magnus has made this point an object of study, and constructed a color system for the use of schools. It consists of a color map for the wall of the school containing in eight rows thirty-two different shades of color. The first color of each row is always a dark and much saturated tone, while the other three of the same row represent lighter shades of the same color. It contains in the first row brown, then follow purple, scarlet, yellow, green, blue, violet, and finally black. To this color map belongs a case containing colored worsteds-three bundles of worsted for each shade of color of the map. The map is used as follows, the method of instruction being divided into two divisions, one for the smaller (primary), the other for more developed children : With the first division the color map alone is used, the instruction beginning by the teacher naming the single colors of a row to the children, which they repeat. After which, the teacher points to any color field and requests the children to name the color. In this manner the children learn, not only the names of the characteristic saturated colors, but they will also be enabled to distinguish the lighter shades. When the children are sufficiently instructed in the first division, the second is brought into use. The teacher shows the scholar a color on the man, and requests him to select the corresponding color from the worsteds. It is best to begin with the more saturated characteristic colors and gradually proceed to the weaker shades. When the scholar has become expert in this procedure, the teacher names to him some colored object, as the violet, forget-me-not, rose, etc., and requests him to select its color from the worsteds, or point it out on the map. Magnus remarks: "The systematic education of the color sense of individuals who are born color blind is not considered; it only aims at gradually elevating the capacity of the color sense of one generation by systematic practice, and thereby transmitting to the coming gender a more capable color sense, and consequently limiting in this way the extension of colorblindness." In the earlier times color blindness was considered peculiar to the Germans; later statistics have shown the error of this supposition. It has been stated that a robust constitution and a bilious, melancholic temperament is especially predisposed to color blindness. Also that the color of the hair and eyes stood in some relation to the frequency of Daltonismus, and that blue eyes and blond hair were connected with a pre-disposition to color blindness. All of which theories have been dispelled by experience. Niementschek ten years ago examined tour color blind with a pupilary distance of 49.5 to 54 mm. In consequence of this short distance, he supposed there must exist a shortening of the parts between the orbita; the sensation of color lay in the anterior convolutions of the cerebrum ; and that it must be narrowed here. The investigations of Cohen show that "this theory is likewise absolutely false." The examinations of Magnus and Cohen, independently of one another, bave shown that with the Jews of Breslau the inclination to color blindness appears to be greater than with the Christians. Among 3,273 boys examined by Magnus, 2,509 were Christians and 764 Jews; among the 2,509 Christians he found 71 olor blind, -2.83 per cent.; among the 764 Jews he found 29 color blind, 3.79 per cent. With two exclusively religious Jewish schools he found, among 216 scholars, 11 color blind, about 5.09 per cent. This increased tendency to color blindness was confined to the males, no color blindness being found among the females. The results of Cohen's examinations completely confirm these of Magnus. The relation as given by Cohen is as 4.8: 36 per cent. Certain authors who believe that color sensations originate by a gradual development, regard the greater inclination of the Jews to color-blindness as indicative of a retarded development. Magnus, who is a believer in the theory of the gradual development of the color sense, seeks the explanation in another factor. As color-blindness is hereditary, and its propagation occurs through transmission, it is natural that the Jews, who for hundreds of years did not mix with the other races, and always marry among themselves, should incline more to the hereditary force of this defect than the Christians. Dr. Burnet, of D. C,, who examined 3,040 colored school children, found among 1,391 boy,22 color blind, -1.6 per cent. Among 1,691 girls, 2 color blind,-0.11 per cent. The smaller percentage of color-blindness as found among colored boys is certainly very remarkable. Cohen found an excellent color sense with eleven Nubians examined by him, with whom words for the designation of the colors failed, an interesting fact, as Geiger, Magnus, and Gladstone concluded, from the absence of certain color designations from the ancient Greek literature, that the color sense with these people was rudimentary. I shall close with the following recapitulation taken from Jeffries' article on The Dangers arising from Color-blindness." Certainly one in filty, much more probably, one in twenty in the community is color blind. Of this defect they may even themselves be wholly unconscious. This color-blindness may practically be regarded as red-green blindness and blue-yellow blindness. Total color blindness also exists. This defect is congenital. It exists in varying degrees. It is largely hereditary. It may also be permanently or temporarily caused by disease or injury. It is incurable when congenital. Exercising the eyes with colors, and the ears with their names, helps the color blind to supplement their names, but does not change or increase their color perception. Experiment and experience show that we are forced to use red and green marine lights to indicate a vessel's direction of motion and movements, and at least red light on railways to designate danger. Form instead of color cannot be used for these purposes. There are many peculiar conditions under which CROUP DIFFERENTIALLY CONSIDERED— employés and marines perform their duties which renCHLORAL HYDRATE, ETC. der colored siguals, especially colored lights, difficult to be correctly seen. These signals can never be correctly seen by the color blind. There is, therefore, great danger from color-blindness. Railway and marine accidents have occurred from it. There is no protection but the elimination from the personel of the railway, and the vessels, all persons whose positions require perfect perception, and who fail to possess this. This can now be readily and speedily done. Therefore, through the laws of the legislature, orders from State railroad commissioners, or by the rulers and regulators of the railroad corporations themselves, each and every employé should be carefully tested for color-blindness, and refused if he has it. BY ALLAN MOTT KING, M.D., ST. JOHN, NEW BRUNS- I would call attention to a very prevalent belief, Every employé who has had any severe illness, or who has been injured, should be tested again for colorblindness before he is allowed to resume his duties, The same examination should be carried out among pilots, masters of steamers and sailing vessels. These latter should be especially instructed how to detect color-blindness among the personel of their commands. In preparing this paper, the following authorities have been freely resorted to: Auburt. Physiologische Optik. Der Farbensinr. Hand-tion made of the discovery of a false membrane, such buch der Augenhulkunde Bd. II. Burnett, Swan M. Results of an examination of the color sense of 3,040 children of the colored Our opportunities for post mortem examinations in case of death from croup are very few in private practice, as the friends are naturally averse to having their little ones disturbed after death. But in searching through the few records at my command of post mortem examinations where death has ensued from croup, pure and simple, I have failed to find satisfactory menas I was led to believe formed in every case of croup. I will later on speak of cases where we invariably have the exudation, and it is to establish to some extent a more correct differential diagnosis between the two conditions that I am induced to pen this article. At this season of the year, in our northern climate, we are constantly meeting with cases of sporadic croup; or, in other words, an inflammation of the mucous membrane of the larynx and trachea. In the more severe cases we have considerable swelling caused by effusion into the sub-mucous areolar tissue, accompanied with secretion of stringy, often thick, tenacious mucus. The chink at the outlet of the larynx becomes smaller. The larynx and trachea are made narrower by the extremely congested state of the lining membrane. The same effusion into the sub-mucous tissue in other parts would produce no serious consequences; but occurring here, the danger becomes indeed imminent. Every moment, in fact, the case becomes more alarming; the breathing grows Farben-more and more difficult; respiration more and more Central-diaphragmatic; the lips assure a bluish hue; the face grows pallid and anxious; the lungs become congested Refe- by an insufficient supply of oxygen; the dyspnoea, which has been permanent, now becomes spasmodic; Color the child grows very restless; no sooner has he been Bos laid upon the bed than he begs to be taken up, immediately to be put down again; and thus the heart-rendBeing disease progresses, until death by suffocation closes a painful scene, alas, too familiar to all of us. This suffocation, Steiner to the contrary, has not been produced by the formation of a false membrane, but simply by the inflammatory swelling and effusion into the sub-mucous areolar tissue. Nor do we find the inflammatory process confined to the larynx and trachea alone, but sometimes extending to the larger bronchi, though the tendency of this disease is rather upward, thus making the chances of relief more doubtful where treatment has been delayed. Cohen, Hermann. Ueber Beobachtungen an 100 Far- And others. VANILLA BEAN is said to contain an essential oil liable to become rancid and poisonons. Several cases of severe gastro-intestinal disturbances, from eating food flavored with vanilla, are reported. A correct history of the attack should be carefully inquired into in every case, as this will greatly facilitate our diagnosis, and largely enable us to decide whether we have to deal with laryngeal croup or the diphtheritic form, in which the false membrane is always present. We generally find that, a few days previous to the attack, the patient had taken cold, but very little was thought of it, as he was able to play around There had been little or no lassitude and very slight lever. True, there has been a huskiness of the voice, and at |