1896.] MICROSCOPICAL JOURNAL 125 



of experimental data demonstrating the practicability of 

 accomplishing this result. 



In a communication made to the French Academy 

 of Sciences, September 2Y, 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, upon four cows, led him to the conclu- 

 sion that a single attack of anthrax protects from subse- 

 quent attacks. 



The next important steps in the line of experimental 

 research leading to protective inoculations in the disease 

 under consideration were reported by Pasteur in his com- 

 munication to the French Academy made at the searice 

 of February 28, 1881 (with the collaboration of chamber- 

 land and Roux), entitled De I' Attenuation des Virus et de 

 leur Retour a la Viridence. 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 atten- 

 uated varieties of the anthrax bacillus form spores, these 

 again reproduce the same pathogenic variety, so cultures 

 of each degree of attenuation can be maintained indefi- 

 nitely. 



On June 13, 1881, Pasteur communicated the results 

 of his famous experiment at Pouilly-le-Fort, near Melum. 

 He says : 



"On the 5th of May, 1881, we inoculated, by means of 

 a Pravaz syringe, twenty-four sheep, one goat, and six 

 cows, each animals with five drops of an attenuated cul- 

 ture of the anthrax bacillus. On the 17th of May we re- 

 inoculated these animals with a second virus, also atten- 

 uated, but more virulent than the first. 



"On the 31st of May we proceeded to make a very vir- 

 ulent inoculation in order to test the efficacy of the pre- 



