418 The Philippine Journal of Science 1913 



Numerous severe bites were detected back of the ears and 

 on the neck of the dead animal. The post-mortem findings 

 were identical with those described in rat 1; that is, cervical 

 buboes, pleural effusion, and slightly enlarged spleen. 



It is well to remark that both rats had been kept in the same 

 room for about six months. Fleas had never been noticed on 

 our guinea pigs. During the time the rats had been kept in 

 the plague house no irregular results were noticed in plague- 

 inoculated animals. At the time the first rat was inoculated 

 no other plague-infected animals were in the plague house, and 

 since that time another building has been used for plague- 

 infected animals. 



The attached plan of the plague house shows the location and 

 time of death of these and the other animals in this outbreak. 



Two days after the death of rat 2 three guinea pigs, which 

 were kept in separate cages in the same room, were found dead 

 of plague (smears and cultures were both positive). Several 

 fleas (Lcemopsylla cheopis) were found on the necks of these 

 animals. They were collected and inoculated in the same way 

 as the fleas from the first rat. The experimental animal, which 

 was inoculated with the fleas, was killed and found to be infected 

 with plague. The findings were local reaction, inguinal buboes, 

 and typical spleen. Smears and cultures were positive for 

 Bacillus pestis. 



Although numerous healthy guinea pigs were examined in 

 the same plague house, no fleas could be found at that time, 

 only the 2 rats and the first 3 guinea pigs are positively known 

 to have harbored fleas, the latter after the death of the rats and 

 not before. 



The gross lesions in these naturally infected guinea pigs 

 Avere somewhat unlike those found in guinea pigs infected either 

 by vaccination or by intraperitoneal or subcutaneous inoculation. 

 All except one showed primary buboes on the neck with more 

 or less extensive hsemorrhagic oedema extending in some cases 

 over the thorax. There was little pleural effusion present; the 

 spleen always showed typical changes of necrotic foci varying 

 in size and number. In one instance similar foci were found 

 also in the liver, large enough to be visible macroscopically. This 

 was in a case where like changes were found in the lungs. 



Only one of the guinea pigs showed an exception, in that the 

 primary buboes were located in the inguinal region, with pelvic 

 and axillary glands secondarily involved. These are the findings 

 usually met with in guinea pigs artificially infected with plague 



