8oz THE POPULAR SCIENCE MONTHLY. 



munication is vaccination in relation to chicken-cholera and splenic 

 fever, and a statement of the method by which we have arrived at 

 these results a method the fruitfulness of which inspires me with 

 boundless anticipations. Before discussing the question of splenic- 

 fever vaccine, which is the most important, permit me to recall the 

 results of my investigations of chicken-cholera. It is through this 

 inquiry that new and highly -important principles have been introduced 

 into science concerning the virus or contagious quality of transmissible 

 diseases. More than once, in what I am about to say, I shall employ 

 the expression virus-culture, as formerly, in my investigations on fer- 

 mentation, I used the expressions, the culture of milk-ferment, the 

 culture of the butyric vibrion, etc. Let us take, then, a fowl w T hich is 

 about to die of chicken-cholera, and let us dip the end of a delicate 

 glass rod in the blood of the fowl with the usual precautions, upon 

 which I need not here dwell. Let us then touch, with this charged 

 point, some bouillon depoide, very clear, but first of all rendered sterile 

 under a temperature of about 115 Centigrade, and under conditions 

 in which neither the outer air nor the vases employed can introduce 

 exterior germs those germs which are in the air, or on the surface of 

 all objects. In a short time, if the little culture-vase is placed in a 

 temperature of 25 to 35, you will see the liquid become turbid, and 

 full of tiny microbes, shaped like the figure 8, but often so small that, 

 under a high magnifying power, they appear like points. Take from 

 this vase a drop as small as you please no more than can be carried 

 on the point of a glass rod as sharp as a needle and touch with this 

 point a fresh quantity of sterilized bouillon de poide placed in a sec- 

 ond vase, and the same phenomenon is produced. You deal in the 

 same way with a third culture-vase, with a fourth, and so on to a hun- 

 dred, or even a thousand, and invariably, within a few hours, the cult- 

 ure-liquid becomes turbid and filled with the same minute organisms. 

 At the end of two or three days' exposure to a temperature of about 

 30 Cent., the thickness of the liquid disappears, and a sediment is 

 formed at the bottom of the vase. This signifies that the development 

 of the minute organism has ceased in other words, all the little 

 points which caused the turbid appearance of the liquid have fallen to 

 the bottom of the vase, and things will remain in this condition for a 

 longer or shorter time, for months even, without either the liquid or 

 the deposit undergoing any visible modification, inasmuch as we have 

 taken care to exclude the germs of the atmosphere. A little stopper 

 of cotton sifts the air which enters or issues from the vase through 

 changes of temperature. Let us take one of our series of culture 

 preparations the hundredth or the thousandth, for instance and 

 compare it, in respect to its virulence, with the blood of a fowl which 

 has died of cholera ; in other words, let us inoculate under the skin 

 ten fowls, for instance, each separately with a tiny drop of infectious 

 blood, and ten others with a similar quantity of the liquid in which 



