As control. a similar quantity of the same culture is mixed with ft cubic centi metre of bullion as before, an amount of ordinary guinea-pig serum equal to the amount of immunizing serum made use of in the original test is added, and the whole is inoculated into another guinea-pig.
In twenty minutes some of the peri toneal contents in each ease is with drawn by means of glass pipettes. and is examined. If the bacteria are the spe cific germs of eholera they present a very different appearance in the two cases. Those obtained from the co»trol animal are well formed, active, and seem to have multiplied. Those which were exposed to the action of the immunizing serum are small, misshapen, immobile for the most part, and apparently dead.
Unless a distinct difference is observ able between the bacteria in the two ex periments the micro-organism under ex amination must be regarded as probably not the eholcra vibrio. since the change described is very constant in the ease of the eholera ET,C1'111, and has not been observed to occur with any other under similar conditions. Pfeiffer (Zeit. f. Hy giene it. Infectionskr., vol. xix, p. 75, '95).
Serum diagnosis; When the blood serum of an animal gives a good reaction in the fresh state, the reaction may also be obtained by moistening a drop of the dried blood with water and mixing it with an actively motile choleraic cul ture. Wyatt Johnston and E. W. Ham mond (.N. Y. Med. Jour., Nov. 28, '96).
According to Blaehstein, elfrysoidin prodnces agglutination in cholera cul tures in exactly the same manner as the diseased serum of immune animals, and does not produce agglutination in any other form of vibrio. Personal experi ments showing that the chrysoidin reac tion was not specific for cholera. Several vibrios are affected. and among them is inelttded the vibrio of Asiatic cholera, and it is not the most sensitive. Walter Engles (C'entralb. f. Bakt., Parasit., lufeetionskr., Jan. 20. '97).
In Il eases examined the agglutina tion of the cultnres of the cholera vibrio was ShOW11 10 times by the .sernm; twice on the first day of the disease, 4 times on the seeond day, 3 times on the third day, and once on the fourth day. The reltetion was particularly distinct in 2 of the patients from whom the blood was taken on the third day. The phe nomenon of agglutination ascertained by them was absolutely typical. Aebard
and Bensande (Presse .)1k1., Sept. 26, '97).
Bacteriology.—The specific germ of cholera Asiatica is now—thanks to the researches of Koch and of many other authors—perfectly known. It is found especially in the mucous flakes of the stools (and in the vomited matter). When these are spread upon an object glass, dried, and stained with one drop of methyl-blue, it appears in the shape of rods, measuring 1.5 to 2.5 microns in length, and 0.5 to 0.6 micron in width, and being generally curved, whence the name of "comma bacilli" or "bacilli virgule given to them. Sometimes, when two of them are joined at their extremities, in a direction opposed to their concavity, the resulting form is that of an italic S, and when several bacilli are joined to each other, their sbape becomes that of a spiral (choleraic "spirilla"). Cholera bacilli are very movable and endowed with oscillatory movements resembling those of sperma tozoa, and also with progressive move ments. They are easily cultivated in several culture-media, as in broth and upon agar-agar at the temperature of the human body, upon gelatin plates, which become slowly liquefied, and upon pota toes, meat, eggs, milk, and several other kinds of food. The broth-cultures pro duce indol and nitric acid (indol-nitrous reaction) and give rise to a peculiar re action with hydrochloric acid, assuming a violet-pink color, whose intensity rapidly increases during half an hour. This reaction, to which the name of "cholera red" was given, is a valuable diagnostic sign of cholera vibrios.
Cholera vibrios can live only for a short time in fmcal matter, seldom longer than two or three days; so that the advisability of immediate examina tion of the dejecta is. evident. They live, on the contrary, very long in the soil, especially when they find in it a proper nutritious material; it seems rather that their virulence is then heightened, the elaboration of their poison becoming more rapid and intense. They can live, also, on the outer surface of fruits and vegetables (the duration of their life be ing then from one to six days) and even on the cut-surface of these, where their life may last for a time ranging from one hour (on very acid fruits) to two weeks.