238 BACTERIA IN INFECTIOUS DISEASES. 



scopical examination proved to be pervaded with the 

 identical micrococcus heretofore described and photo- 

 graphed (See Fig. 2, Plate IX.). A drop of culture 

 No. 7 was in like manner used to inoculate culture No. 

 8, and the next day, this being also pervaded by the 

 micrococcus, was used in the following experiment : 



" Exp. No. 4. September 14th. Injected ten 

 minims of culture No. 8 into a full-grown rabbit. Result : 

 This animal died at 9 A. M. September 15th, and a micro- 

 scopical examination made at once demonstrated the 

 presence of the micrococcus in great numbers in the 

 blood and in effused serum in the sub-cutaneous connec- 

 tive tissue. 



u Remarks. This experiment shows that the micro- 

 coccus retained its vitality and its full virulence at the 

 end of six weeks, and, very conclusively, that the viru- 

 lence of the culture-fluid is due to the presence of the 

 micrococcus, and not to a hypothetical chemical virus 

 found in the first instance in human saliva and subse- 

 quently in the blood of a rabbit inoculated with this 

 fluid. For the benefit of those who have not calculated 

 the degree of dilution which such a hypothetical chemi- 

 cal virus would undergo in such a series of culture ex- 

 periments, I submit the following simple calculation : 



" My culture-tubes contain about a fluidrachm of 

 sterilized bouillon. The amount of blood introduced 

 into culture No. 1, as seed, was considerably less than a 

 minim ; but for convenience I will suppose that one 

 minim is used each time to start a new culture, that is, 

 the original material is diluted 60 times in the first cul- 

 ture, 3,600 times in the second, 216,000 times in the 

 third, and in the eighth culture it will be present in the 

 proportion of one part in 1,679,611,600,000,000. Yet a 

 few minims of this eighth culture possesses all the viru- 

 lence of the first. 



