310 



of ether, and decapitated — its head and proboscis being immediately 

 introduced, with all possible cleanliness, into a tube of sterilized broth, 

 which is kept at a temperatcre of 37° C. The cultures generally germinate 

 at the end of twenty-four or forty-eight hours ; at times the broth remains 



sterile. 



Pathogenicity of the Tetracoccus versatilis 



In January of this year 1 determined to ascertain whether Dr. 

 Sternberg's assertion that the "Tetragenus versatilis is not pathogenic for 

 guinea-pigs or rabbits" was to be accepted in its absolute sense. My previous 

 experiments with 1 or 2 c. c. of live cultures injected under the skin or 

 into the peritoneum were in accordance with the statement of the 

 distinguished North American bacteriologist; and, last year, I had not 

 observed any pathogenous effects upon a rabbit after injecting 1 c. c. of 

 live culture into its jugular vein. The tetracoccus used in this instance, 

 however, had been obtained from blister serum of an immune subject 

 having suffered a severe attack of yellow fever a few weeks before ; it was 

 possible, therefore, that the germ, under such circumstances, should have 

 lost any virulence which it might originally have possessed, in which 

 case a variability in its pathogenic properties would have to be added to 

 the other versatile characters of our microbe. 



Tetracoccus v.r Mosquito. — In the first series of my new experiments 

 I employed the tetraccoecus obtained from contaminated mosquitoes. 



On January 17, I applied one of these insects to a yellow fever patient 

 (a fatal case), who occupied bed. N." 10 in the second ward of the Military 

 Hospital; on January 19, I made the same mosquito sting an unacclimated 

 person who demanded a preventive inoculation ; on January 22 I killed the 

 insect with a, little ether, and introduced its head and proboscis into a tube 

 of sterilized broth, which Dr. Davalos undertook to keep at 37° ('. in the 

 laboratory of the "Crónica Médico-Quirúrgica de la Habana." In the 

 afternoon of January 23 the broth was slightly turbid, and the following 

 day the presence of the "tetracoccus versatilis" was verified. It gave yellow 

 colonies in agar and slowly liquefied gelatine. No other micro-organism 

 developed in the original) broth. 



On the 26th of January Dr. Davalos, planted a balon of peptonized 

 broth with pure tetracoccus colonies, placing the balon in the hot chamber. 

 On March 11, having previously ascertained the purity of the culture, it 

 was passed through a Kitasato filter; we thus obtained several tubes of 

 transparent toxines, of a mahogany colour, and with the characteristic 

 odour of our microbe. These toxines, which we held to be sterile, contained, 

 however, some live tetracoccus germs, as we were able to determine at a 

 later period. 



<íuinea-pigs injected with 10 to 20 c. c. of this filtered culture showed 



