32 OMENTAL PLAGUE chap. 



tion even of large doses is extremely rare. Death after 

 three or even four days would not necessarily indicate 

 virulence greatly inferior than normal. Cutaneous inocu- 

 lation of guinea-pigs with virulent and moderately virulent 

 material is followed by death after four days up to seven, 

 nine, or even more days ; and this mode of inoculation 

 distinguishes in a marked manner the guinea-pig from the 

 rat, for in this latter animal the result of cutaneous 

 inoculation with plague material of great or moderate 

 virulence always causes acute fatal illness. In the guinea- 

 pig, on the other hand, material which on subcutaneous 

 injection in moderate doses causes death in two to three 

 days, and which material is therefore of normal virulence, 

 when administered cutaneously causes fatal issue always 

 much later, and with pathological symptoms different 

 from those found in animals dead in two or three days. 

 When death ensues later (four to seven days or more) the 

 bubo and spleen, also the liver and lungs, exhibit more or 

 less necrotic changes in the form of nodules and patches of 

 various sizes and in varying numbers. Such is generally 

 the case with guinea-pigs inoculated cutaneously even 

 with virulent material ; it is the same also in guinea-pigs 

 injected subcutaneously with material of less than normal 

 virulence. Cutaneous inoculation of guinea-pigs with ex- 

 ceptionally virulent material may cause death occasionally, 

 but not invariably, in two to three days with symptoms 

 of acute plague — that is to say, before necrotic changes 

 in the bubo or spleen or lung had had time to develop 

 and to make their appearance. The necrotic changes — 

 viz. whitish nodules in bubo, spleen, liver, and lung, — 

 which require at least four days for their development, 

 follow cutaneous inoculation of the guinea - pig with 



