96 OMENTAL PLAGUE chap. 



Dr. Edington, it was possessed of a considerably 

 diminished virulence. Nevertheless, it was endowed in 

 various cultures and under other conditions, presently to 

 be described, with characters which I think can leave no 

 doubt about its being the true B. pestis. In the stained 

 cover film specimens sent by Dr. Edington there were to 

 be seen numerous bacilli which were undergoing changes 

 that are generally and justly considered as indicating 

 degenerative forms ; all gradations from oval rods showing 

 something of a polar staining to large and small globular 

 or irregular bodies deeply stained could be observed. 

 These same kinds of degenerative forms are to be seen in 

 some old agar cultures of the plague bacillus, and especi- 

 ally in the tissues of animals in which the result of plague 

 infection is on the point of aborting ; that is to say, in 

 animals — guinea-pig or rat — which, having been infected 

 with a weakened plague culture, or having been previously 

 partially protected, are inoculated with virulent plague 

 culture. In such case, although there exists some indica- 

 tion, e.g. some swelling at the seat of inoculation and 

 bubo, that the infection has taken some slight effect, it 

 nevertheless appears probable that the animal will recover. 

 When such an animal is killed, and the swelling at or 

 about the seat of inoculation (likewise the spleen) is 

 examined in stained film specimens, large and small 

 distorted and globular stained bodies will be found, as to 

 which there can be little doubt that they are derivations 

 of plague bacilli : some few bipolar bacilli may still be 

 found, and between these two extremes some intermediate 

 forms. 



Such observations I have, in common with other 

 observers, repeatedly recorded in regard of both guinea- 



