224 STRONG AND TEAGUE. 



neck, with secondary septicaemia and occasionally secondary 

 pneumonia or, in some cases, primary pneumonia with secondary 

 septicaemia. Very rarely does the spleen show miliary abscesses 

 in such cases, the animals dying before such lesions develop. 



In monkeys (Cynomolgus philippinensis Geoff.), also, the cuta- 

 neous or subcutaneous injection of the pneumonic cultures causes 

 typical bubonic infection. Monkeys infected by the same cul- 

 tures by inhalation develop primary pneumonic plague with 

 secondary septicaemia and without involvement of the glands of 

 the neck. 



Tarbagans. — There has been considerable evidence brought 

 forward during the past in support of the view that plague has 

 existed in epizootic form among a species of marmot, the tar- 

 bagan (Arctomys bobac Schreb.).^ (See Plate VI.) However, 

 there has been no direct bacteriological proof of this fact, and we 

 have known nothing definite before in regard to the susceptibility 

 of this animal to plague infection, though, according to Preble, 

 loc. cit., Tchaoushow showed these animals were susceptible to 

 plague infection. Our own experiments on tarbagans were car- 

 ried out in Mukden where, by the kindness of the Hon. Alfred 

 Sze, imperial commissioner to the Plague Conference, we were 

 supplied with these animals for experimental purposes. From 

 our experiments we were able to show for the first time that 

 cutaneous or subcutaneous infection of the tarbagan with viru- 

 lent cultures of the pneumonic strain gives rise in these animals 

 either to an acute bubonic or to subacute and chronic forms of 

 plague infection. In some instances we have shown by com- 

 parative experiments that the tarbagan seems as equally suscep- 

 tible to cutaneous or subcutaneous infection as the guinea pig, 

 these animals dying in about the same time (two and one-half 

 to five days after infection) and from the same doses of the 

 organism. In these instances there are haemorrhages about the 

 point of inoculation, typical buboes, and swelling of the spleen. 

 In other instances, after infection with the same organism and 

 with the same doses, the tarbagans may suffer from subacute and 

 chronic forms of plague infection. In three of these animals 

 killed by chloroform from ten days to two weeks after infection, 



^ For evidence of this fact, see Report of the International Plague Con- 

 ference under Tarbagans. Also, The Tarbagan and Plague. By Paul 

 Preble. Reprint from the United States Public Health Reports (1912), 

 No. 68. This latter article entirely omits our own experiments on tarbagans 

 while giving other observations on these animals reported at the Interna- 

 tional Plague Conference. 



