ON THE BACTERIA. 155 



OX, or in other suitable organic fluids, kept at a temperature of 

 nearly blood-heat. At first the rods appear to be simple tubes, 

 divided by transverse partitions, but after a time minute dots are 

 seen, which develop into ovoid bodies, lying in rows within the 

 tubes ; until at last the rod falls to pieces, liberating the germs, 

 and the minutest drop of fluid containing the spores starts the 

 process of growth and reproduction in other organic fluid, or 

 developes the disease in the bodies of healthy animals inoculated 

 with it ; and this may be repeated many times without impairing 

 its potency. Koch also showed that the blood may even be 

 dried, kept for years, and reduced to powder, without losing its 

 power. 



Pasteur next examined outbreaks of Charbon among sheep. 

 For a long time he was unable to account for the appearance of 

 the disease among flocks apparently free from any chance of 

 contagion ; but he ultimately found that it was customary to bury 

 the dead bodies deep in the soil. It might be as many as ten or 

 twelve years before a fresh outbreak, and he divined that earth- 

 worms might possibly be the cause of communicating the disease, 

 and on inoculating rabbits and guinea-pigs with an extract of the 

 alimentary canal of these worms, he found that they were attacked 

 with the severest form of Charbon, and their blood was found to 

 be loaded with the deadly Bacillus Aiithracis. 



Among other experiments on Anthrax, Pasteur found that 

 birds were insusceptible of the disease ; knowing that the tem- 

 perature of the mammalia (about 99° F.) was most favourable to 

 the development of the Bacillus^ but that the temperature of birds 

 was higher (namely, 107° F.), he supposed that this might be the 

 reason of their insusceptibility, and it struck him that if he could 

 reduce the temperature of birds to that of mammals, he might be 

 able to inoculate them with the disease ; this he succeeded in 

 doing by keeping their feet in cold water, when he found that they 

 could be made to take the disease. Frogs, on the other hand, 

 whose temperature is lower than that of mammals, could be made 

 susceptible by keeping them in water at about 99° F. 



Further researches on Anthrax have been made by Dr. 

 Greenfield in our own country, while similar experiments have 

 been made by Klein on the typhoid fever of swine, which he 



