iv MICEOBES SIMULATING THE B. PESTIS 77 



The first and second source can, I think, be left out as being 

 highly improbable; the third appears the more probable source — 

 viz. that this microbe inhabited the skin of the mouse, and under 

 conditions of inflammation is capable of rapidly multiplying. 

 Diphtheroid bacilli of the skin in and over inflamed and patho- 

 logical areas occur both in man and the rat, but they are without 

 any pathogenic action — are, in fact, B. xerosis. I have mentioned the 

 occurrence of B. xerosis in the skin over the inflamed bubos ; Dr. 

 Dean has described this microbe (Journal of Hygiene, 1905) in 

 connection with the lepra - like nodules in rats ; but in all these 

 latter instances the microbe was quite without any pathogenic 

 action. 



As regards the B. muris of the rat, on account of its being 

 associated generally with the natural lung disease, it appears feasible 

 to assume that in this animal it enters by way of the respiratory 

 organs, and causes here the local inflammation and necrotic change 

 of the lungs. 



7. B. Danysz and B. Gaertner. — The B. Danysz, first isolated by 

 Danysz, is a microbe which belongs to the coli-typhoid group. As 

 I have previously shown {Transactions of the Pathological Society, 

 London, 1902, p. 342), and as I have recently been able to confirm, 

 the B. Danysz is in all and every respect identical with the 

 B. enteritidis Gaertner. 



According to Danysz, the microbe causes acute septicemic 

 infection and death of rats by subcutaneous or intraperitoneal 

 injection, as also in a certain percentage of the animals by feeding, 

 and therefore, says Danysz, cultures of this microbe, if of the 

 proper virulence, can be used with good effect in the destruction 

 of rats, for the rat dead after feeding serves as infective material 

 for rats eating its body. That the Danysz bacillus causes acute 

 septicemic infection of the rat after subcutaneous and intraperitoneal 

 injection with copious distribution of the bacilli in the blood and 

 in the viscera, is a matter easy of demonstration ; but it is more 

 difficult to confirm the statement that the B. Danysz does not act on 

 other rodents, or that it can be relied upon to infect an appreciable 

 number of rats with the fatal disease by feeding them either on 

 culture or on animals dead of the disease. In the first place, the 

 microbe injected subcutaneously or intraperitoneally is as virulent 

 to the guinea-pig and the mouse as it is to the rat, and, in the 

 second place, its efficacy by feeding is somewhat uncertain. Dr. 



