94 THE ZOOLOGIST. 



germs in it were destroyed, and a drop of the diseased blood was 

 then placed in it. After a day or two it was full of the microbic 

 growth, and a single drop let fall into a fresh quantity of yeast- 

 water produced a second crop, and so on. Of course the latter 

 cultivations give the microbe free from any foreign matter, and it 

 is from these that its form is best studied. Over fifty successive 

 cultivations of the anthrax microbe have been made, and the last 

 one was as virulent as the first. I spoke of the spores of the 

 microbe. While the active form is very sensitive to degrees of 

 heat (the typhoid microbe being very inactive at low tempera- 

 tures, and the anthrax microbe inactive at high ones), the spores, 

 the seeds as one might call them, which form when the proto- 

 plasm of the active plant is drying up, can endure the greatest 

 heat and cold, and could be swept in dust-storms from one end 

 of the colony to another, carrying disease and death for 

 thousands of miles. 



" This should be borne in mind when we consider the pro- 

 posal to carry on the experiments ' safely ' here within walled 

 paddocks. We might as well build a post and rail fence to keep 

 out the cholera, or attempt to enclose smallpox within open wire 

 network. Even an island would not secure safety, for the germs 

 might be blown across, or be carried on a boat, or on the clothes 

 and hair of the experimenters. This is one of the great dangers 

 — once admitted, the disease is practically uncontrollable. 



" There is another point that I will ask you to bear in mind, 

 as upon it hinges all the value of the experiments held on 

 Sheep that we have received by a recent mail, and which are to 

 prove that they could not be attacked by the disease. I quote 

 the words of M. Valery Radot, M. Pasteur's son-in-law, and his 

 recognised organ : — ' Easily inoculable and fatal to the Ox, the 

 Sheep, the Rabbit, and the Guinea-pig, splenic fever is very rare 

 in the Dog and Pig. These must be inoculated several times 

 before they contract the disease, and even then it is not always 

 possible to produce it.' He proceeds to state that fowls never 

 take it, but that if they are artificially chilled they do take it 

 easily — (the logic is not mine) — and it proves exceedingly fatal to 

 them. Now all this simply shows that, under varying circum- 

 stances of temperature, and of intensity of the contagion, the 

 microbe affects different animals, including those rarely susceptible, 

 and those supposed to be never susceptible to its influence. 



