(Read before the San Francisco Clinical Society, January 27, 1904.) Its Purpose.-Though the microscope, the chemical tests for hemoglobin and hematin, and the hematoporphyrin spectrum serve to identify blood from pigments, etc., only the biologic test will identify it as blood of a given species.

The Technique.-Certain European biologists, Bordet, Uhlenhuth and others, while studying the hemolytic and agglutinating power of sera discovered that the hemolytic power was greatly increased toward the corpuscles of a given species when the animals from which the sera were drawn had been injected with the serum or albuminous body fluids of the species whose blood was acted upon. This led to the discovery that any animal when injected successively with serum or fluids containing its products, developed in its own blood serum an anti-body or substance which caused a precipitate to form when added to the serum of the species from which the injected or immunizing fluid was drawn.

The technique is briefly as follows.--The test animal, usually a rabbit or guinea pig, is humanized by receiving 10 cc. of defibrinated blood serum, ascitic, pleural, or hydrocele fluid, either subcutaneously or intraperitoneally, daily, on alternate or third days till 30-60 cc. have been injected, the experiments being governed by the health and reaction of the rabbit. The blood is drawn, its serum separated and kept for test purposes, if not used at once, by adding 0.5 per cent acid carbolic, drawing it up into sterile pipettes and sealing. The suspected blood to be tested may be in contaminating fluids, mixed with other blood, or more commonly in stains on cloth, wood, metal, earth, etc., solutions must be filtered and cleared, stains are dissolved in distilled water and filtered; a dilution of

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1:500 is not excessive, and 1:4000 may give positive results. To the solution of suspected blood may be added the immunized test serum, either prove a few gtt., or diluted with normal salt in volume equal to diluted test blood. The specific result is a cloudiness succeeded by a flocculent precipitate, the result being apparent at once or after some hours according to the dilution and the temperature, for it is more rapid in a temperature of 37° C. Very dilute tests must be incubated. Of course control tests must be made with normal rabbit serum. In distinguishing the blood of kindred species, e. g., monkey and man, greater dilutions increase the accuracy, e. g., a dilution of 1:500 incubated.

E. N. Layton' of Chicago reviews the history of the test. It was developed in Europe in 1898-1900, and since then, especially the last two years, has been rigidly tested and perfected in America. The technique was carefully given by Whitney2 of Boston in April, 1902, who injected the peritoneal cavity, while the subcutaneous method is that of Uhlenhuth.

The conclusions of Layton are as follows:

Sources of Error.-1. Contamination by monkey's blood. 2. Contamination with precipitants, e. g., Cu So,, of albumin. 3. Too prolonged incubation and clouding from bacterial growth. The above errors are excluded by control tests with normal rabbit serum.

Further Conclusions.-1. The reaction is due to the development of an antibody in the injected animal that reacts with homologous serum. 2. The reaction does not occur when normal serum is used. 3. The reaction is more rapid at 37° C, but will occur at room temperature. 4. An immediate result can be obtained at room temperature, by diluting only the blood tested, and not the test serum. 5. The reaction is possible when the blood tested is diluted 1:1000, or the test serum 1:20000. 6. The delicacy is not impaired by the admixture of other blood or substances except the albumin precipitants. 7. The presence or absence of mineral salts, e. g., Cu So,, can be determined by the control tests. 8. The delicacy of the test is not materially altered by the age of the stain. 9. Human blood can be differentiated from monkey blood.

by dilution and incubation but not negro blood from Caucasian.

Here are appended my own experiments carried on in the physiological laboratory of the College of Physicians and Surgeons of San Francisco. The results are imperfect, because of inexperience and lack of time during certain periods. Group I, Nov. 27, '02 to Jan. 31, '03. Ascitic fluid was used previously subjected to fractional sterilization at 65°, and was injected into the peritoneal cavity. Nov. 27th, rabbit 1 injected with 10cc fluid, injection repeated Nov. 29, Dec. 4, Dec. 10, emaciation extreme, death occurred Dec. 13. Attendant destroyed rabbit in my absence, no tests. Dec. 20th, rabbits 2 and 3 injected with 5 cc fluid; initial rise of temperature, 0.5° and 1o respectively; injections repeated Dec. 27 and Jan. 8, '03. Jan. 17, rabbit 2 killed to fulfill another experiment; blood tests negative. Jan. 19 and 22, rabbits 3 and 4 injected. Jan. 24, rabbit 3 killed, the blood tests developed a p.p. slowly, human blood from a sponge dried and kept being used. Rabbit 4 was further injected Jan. 26, 28, 29, 30, 6 times in all, and killed Jan. 31st. The serum gave positive results when a few drops were added to low dilutions, 1:200. Group II, Dec. 31, '03, to Jan. 24, '04. Rabbit 5 and guinea pig 1 were injected Dec. 31 with 10 and 7 ce ascitic fluid once subjected to 65° C three quarters of an hour. Ten injections were given intraperitoneal and blood withdrawn, under chloroform anesthesia, for test serum on Jan. 22. The tests have been negative or slow in development. Guinea pig 2 was injected Jan. 6th, '04, with unsterilized ascitic fluid from a case of hepatic cirrhosis. Six injections were given and blood withdrawn Jan. 22d as in rabbit 5 and pig 1. The results with this serum when used undiluted 12 gtt in diluted fresh blood 1:200 (filtered) were positive, a flocculent precipitate occuning in 1 hours. Dog serum was added in equal quantities to different portions of the human blood dilution used as controls in all tests of group II. So far as the above experiments may be permitted to indicate anything they indicate:

1. That ascitic fluid subjected to 65° has its power to excite antibodies considerably lessened. This may be in line with the observations of Bordet, that serum heated to

55° lost its hemolytic power though it retained its agglutinating power.

2. That the peritoneum of animals injected was quite resistant to the bacteria abundantly present in the peritoneal fluid used; it was simply drawn into sterile bottles and kept cool in the case of pig 2, and the fractional sterilization resorted to for rabbit 5 and pig 1, failed to kill the bacteria. Yet the animals thrived during the injections in all instances of group II.

BIBLIOGRAPHY.

1. E. N. Layton, Am. Medicine, June 6, 1903, p. 913. Whitney, Boston Med. and Surg. Journal, April, 1902.

2.

A THERAPEUTIC CHAT.

By EMIL WESCHCKE, Ph. D., M. D.,

Lecturer on Materia Medica, College of Physicians and Surgeons of
San Francisco.

Inviting your attention to these ordinary cases that may fall to the observation of any general practitioner, allow me to impress upon you the necessity of constant logical thought in determining the why and wherefore of disease. It is not essential to be conversant with the latest remedies of a very active and forceful modern materia medica, nor the multitude of combinations of old therapeutic agents clad in recent fanciful garb and continually introduced into office and clinic, but it is absolutely necessary to analyze the action of any drug given for any symptom of disease or the latter itself.

Never administer a fraction of a grain or minim of anything, unless you quite know its exact action on the economy, and when you declare its necessity, give it boldly and abide by the results of your judgment. Think before you administer a drug, think while you are giving it, and think again after you have given it! Here lies the philosophy of physiological medication which will lead us from empiricism in medicine. We cannot all be surgeons, whose work is apparent at the finger's touch, but some of us can be, more should be, and others must be successfully thinking physicians.

CASE 1.-Here we have a well-nourished girl, not yet six years of age, frolicsome and hearty, yet experiencing at intervals symptoms of laryngeal and bronchial spasmodic

cough, highly distressing. During the paroxysm, after several attempts at expectoration, a little mucus is emitted, the labored breathing ceases, and the child returns unconcernedly to play.

Her general appearance is that of a healthy, wellnourished child, bright-eyed, the expression of the face vivacious and no symptoms of chorea or other nervous lesion apparent, nor anemia. Does she eat? Regularly and sufficiently. Does she cough at night, as she rests in bed? Her cough, in spells, seems looser then. Has she always been healthy? Did she have measles or whooping-cough? No; sometimes she breathes hard and gets very restless.

Physical examination revealed little. Some exaggerated bronchial breathing with suspicion of moist rales; no fever, no dullness. Diagnosis, what? A neurosis? What drugs has she had? Cod liver oil, pure, and in emulsion with hypophosphites; she likes both. Extract of malt and different cough mixtures. They said that she must be fortified against consumption.

Evidently, there is some obscure bronchial irritation, manifesting itself at uncertain intervals by spasmodic cough. Is it some incipient form of spasmodic asthma? The child looks well, eats well, thrives well, and evidently does not suffer from constitutional disease.

The indications are for a "loosening" expectorant, but why should medicine be administered repeatedly, as an expectorant should, to stimulate the laryngeal and bronchial mucosa, when these paroxysms of cough and distress occur only at long and uncertain intervals? May not emetic doses of an expectorant cut short an attack? Syrupus scillæ compositus in 15 minim doses, every 15 minutes, was ordered till vomiting freely resulted.

The expectorated mucus was saved for bacteriological examination, and what did we find? No bacillus tuberculosis, but the half digested and faded remnants, rather bleached, of a barley seed, that had probably been inhaled months before at the breakfast table while my little patient ate her dish of cereals, and had lodged in the bronchus. Since then I have sincerely appreciated tartarus stibiatus, that old, much abused, yet useful friend.

CASE 2.-Writhing in agony, of bilious countenance, and