324 INFECTIVE DISEASES. 



vaccinia, can be kept up in this comparatively mild form. But 

 under certain conditions, such as a peculiarity in the subject inocu- 

 lated, or if lymph be taken too late, there will be, just as in variolation, 

 tendency to revert to the full intensity of the natural virus. 



Bacteria in Vaccine Lymph. Cohn, Sanderson, and Godlee 

 described micrococci in vaccinal vesicles. Quist and Ferre in 1883 

 investigated the same subject. Yoigt in 1885 distinguished three 

 species of micrococcus a diplococcus, a large coccus, and a third form. 

 Bauer in the same year described the presence of bacilli and sphsero- 

 cocci. Marotta in 1886 regarded a tetracoccus as the specific micro- 

 organism, and Tenhot in 1887 distinguished a dozen micrococci, two 

 bacilli, and two yeasts. In the same year Garre isolated a micrococcus 

 which appeared to him to be the contagium, but inoculated on a child 

 it neither produced local vesicles nor immunity ; while Guttmann 

 pointed out three micro-organisms which appeared to be rather more 

 constantly present than others. Pfeiffer much more fully investigated 

 the bacteriology of vaccine lymph, and found Saccharomyces vaccinse, 

 which was seldom present in human lymph but constantly found in 

 calf lymph ; sarcinse, both in human and calf lymph, including Sarcina 

 lutea, Sarcina tetragonus, Sarcina aurantiaca, Sarcina muscopus ; 

 bacteria and bacilli were found only exceptionally in human lymph, 

 but frequently in calf lymph. These included a bacterium corre- 

 sponding with Proteus vulgaris. 



Three mice were inoculated subcutaneously with a drop of the 

 liquefied gelatine, but the result was negative. The injection of a 

 considerable quantity proved fatal to guinea-pigs and rabbits, a 

 result which was probably due to ptomaine poisoning. 



There were also several bacilli which did not liquefy gelatine ; 

 these were not investigated. 



Staphylococcus cereus albus was found very frequently, and 

 Staphylococcus pyogenes aureus occasionally. Pure- cultivations of 

 these micrococci inoculated on the skin of calves produced a rapid 

 local irritation, followed by vesiculation, but without the classical 

 characters of the vaccine vesicle. The inoculated part was com- 

 pletely healed in three to five days. According to Pfeiffer they 

 explain the so-called false vaccine. 



Micrococcus pyogenes albus was almost constantly present. 

 Numerous other micrococci were found, but not constantly present ; 

 vaccine lymph being a splendid medium for the growth of micrococci. 

 Pfeiffer pointed out that the effects of Staphylococcus pyogenes aureus, 

 albus, and citreus, and of Streptococcus pyogenes on rabbits had an 

 important bearing upon the practice of vaccination, and he recom- 



