PRACTICAL RESULTS OF BACTERIOLOGY. 739 



domestic animals may usually be arrested. But it may happen 

 that the extent of the epidemic prevalence and the number of 

 animals already exposed to infection make these measures in- 

 adequate or difficult of execution. In this case we have, for cer- 

 tain diseases, another method of prophylaxis which has been 

 extensively employed with excellent results. I refer to the 

 method of protective inoculations, which we owe largely to the 

 genius and patient researches of the distinguished French chem- 

 ist Pasteur and his pupils. 



Toussaint, a pioneer in researches relating to protective in- 

 oculations, has a short paper in the Comptes-Rendus of the 

 French Academy of Sciences of July 12, 1880, entitled Immunity 

 from Anthrax {charhon) acquired as a Result of Protective Inoc- 

 ulations. 



In this paper he announces his discovery of the important fact 

 that the anthrax bacillus does not form spores in the tissues or 

 liquids of the body of an infected animal, but multiplies alone by 

 binary division: " Sa multiiilication sefait tovjours par une divi- 

 sion du mijcelium." 



In the same communication he reports his success in con- 

 ferring immunity upon five sheep by means of protective in- 

 oculations, and also upon four young dogs. We must therefore 

 accord him the priority in the publication of experimental data 

 demonstrating the practicability of accomplishing this result. 



In a communication made to the French Academy of Sciences, 

 September 27, 1880, Pasteur gave an account of an experiment 

 made July 14, 1879, upon two cows, which, in connection with a 

 subsequent experiment, made August 6, 1880, upon four cows, led 

 him to the conclusion that a single attack of anthrax protects 

 from subsequent attacks. 



The next important steps in the line of experimental research 

 leading to protective inoculations in the disease under consid- 

 eration were reported by Pasteur in his communication to the 

 French Academy made at the seance of February 28, 1881 (with 

 the collaboration of Chamberland and Roux), entitled De V At- 

 tenuation des Virus ei de leur Retour a la Virulence. In this 

 connection Pasteur announces his discovery of the fact that 

 when cultivated at a temperature of 42 to 43 C. the anthrax 

 bacillus no longer forms spores and rapidly loses its virulence. 



In a later communication (March 21, 1881) Pasteur says that 

 he has found by experiment that when attenuated varieties of the 

 anthrax bacillus form spores, these again reproduce the same 

 pathogenic variety, so that cultures of each degree of attenua- 

 tion can be maintained indefinitely. 



On June 13, 1881, Pasteur communicated the results of his 

 famous experiment at Pouilly-le-Fort, near Melun. He says : 



