33 



and in each case there was associated with it a small discharging sub- 

 cutaneous abscess. There were no other lesions in either case and the 

 pus from these abscesses failed to produce plague in guinea pigs. 



In a series of 61 consecutive plague rats in San Fransicso, injection 

 was present fifty-two times, it was confined to the region of the 

 bubo twice, it was unilateral twice, and was general in distribution 

 forty-eight times. It was slight thirteen times, moderate fifteen 

 times, marked sixteen times, intense eight times. 



THE BUBO. 



This is the most reliable single sign of plague infection, and when 

 present in typical form is enough on which to base a diagnosis which 

 rarely proves erroneous. 



The gland involved is usually surrounded by a more marked injec- 

 tion than is present elsewhere, and an infiltration which at times is 

 hemorrhagic. This surrounding hemorrhage which was common in 

 the plague rats described by the Indian Plague Commission was met 

 with very rarely in San Francisco. The gland proper is usually case- 

 ous. The contents may be shelled out very readily, though' prior 

 to section the gland feels very firm. In the cases seen at the federal 

 laboratory in San Francisco, the contents of the buboes were recorded 

 as being hemorrhagic four times and as caseous twenty-nine times. 

 Pest-like bacilli were noted as present in 18 cases, in 6 of which the 

 "coccoid" form predominated. They were recorded as absent five 

 times. 



Indolent enlargement of the lymph glands is very commonly en- 

 countered in rats that are not infected with plague. Among old rats 

 probably 15 per cent will show this. Such glands, however, are tough, 

 elastic, and not surrounded by infiltration. They are not likely to be 

 mistaken for the plague buboes. In the leprosy-like disease of rats, 

 the glands may reach an enormous size. 



Observers differ as to the location of the primary bubo. Skschivan 

 (1) states definitely the location of five primary buboes in plague rats 

 seen in Odessa in 1901. Two were in the axilla, two in the inguinal 

 region, and one in the neck. Kitasato (5) says: "To judge from the 

 experience of the past it can be suggested that in examining rats par- 

 ticular attention should be paid to their submaxillary and cervical 

 glands and to the spleen. These organs in most cases show the evi- 

 dence of infection, if there be any." From this it would appear that 

 he regarded the neck glands as the most frequent seat of the bubo. 

 It may be remarked here that his experience was derived from plague 

 rats seen in Asia. 



We find a marked difference between the experience in San Fran- 

 cisco and that in Bombay. This is demonstrated in the following 

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