iv MICROBES SIMULATING THE B. PESTIS 67 



theless the microbe was on the whole very abundant, and it was 

 obvious from microscopic examination alone that the case was dis- 

 tinctly one of blood infection — infection due, that is, to a Diplococcus 

 capsulatus, the exact nature of which could, of course, only be deter- 

 mined by culture and by animal experiment. 



The agar surface plate made from the original blood showed next 

 day (but better still after forty-eight hours) an uncountable number 

 of translucent grey colonies, in many places confluent into a grey 

 filmy layer. These colonies in their general aspect were identical 

 with those of Diplococcus pneumonia, and, like the latter, were made 

 up of diplococci, either altogether wanting in capsule or possessed 

 only of an indication of it. So, too, they were chiefly arranged as 

 chains, some of these chains being composed of as many as eighteen 

 to twenty diplococci. A small amount of the growth, a few colonies 

 only, was used for making an emulsion, and with this emulsion mice 

 and guinea-pigs were injected subcutaneously. The result was 

 perfectly distinct and uniform j the guinea-pigs showed no illness, 

 while the mice died. The post-mortem appearances in the latter 

 case were those found in mice after infection with the Diplococcus 

 pneumonice ; the cedematous fluid of the seat of inoculation was 

 found crowded with the capsulated diplococcus, either as single 

 diplococci or as short chains of two elements. Fig. 57 is a char- 

 acteristic specimen of this kind, the capsules being shown with great 

 distinctness. 



There can, then, be no question as to the identity of this microbe. 

 It was the Diplococcus pneumonice, and it was present in the blood of 

 the patient T. in very large numbers. As already mentioned, this 

 patient had no pneumonia, while at the post-mortem examination 

 only a few petechia were found in the lung. The case, therefore, 

 was undoubtedly one of general blood infection with the Diplococcus 

 pneumoniae. That such a general infection — viz. copious presence 

 of the microbe in the blood — existed in this case ante mortem may be 

 taken as certain : cold weather prevailed at the time (December 9) ; 

 moreover, the blood was obtained within twelve hours of death. It 

 is altogether improbable, therefore, that an appreciable multiplication 

 of the microbe had taken place after death, since the Diplococcus 

 pneumonice requires for its growth and multiplication higher tempera- 

 tures than could have obtained here. Below 25° C. the growth 

 of this microbe in the laboratory is either nil or very delayed and 

 slow. 



