SUSCEPTIBILITY OF ANIMALS. 225 



there were found at necropsy abscesses measuring several milli- 

 meters in diameter in the subcutaneous tissues or in the abdo- 

 minal muscles, near the point of inoculation, and swelling of the 

 inguinal glands, while the liver and spleen showed indurated, 

 yellowish nodules also measuring several millimeters in diameter. 

 (See Plate XII, fig. 2.) Plague bacilli were present in small 

 numbers in the abscesses and in the nodules in the spleen and 

 liver. These animals, judging from their condition at the time 

 they were killed, would probably have lived at least several 

 weeks longer. The lesions present were similar to those which 

 have been described in rats which have succumbed to chronic 

 plague infection. We have also shown that the tarbagan is also 

 susceptible to primary pneumonic plague when infection has 

 taken place by inhalation. Death then occurs three or four days 

 after infection from primary pneumonia and secondary septi- 

 caemia. These experiments were performed with the species 

 Arctomys bobac Schreb.- We also showed that another species 

 of marmot (Spermophilus citillus Linn.), very common about 

 Mukden and the vicinity, was susceptible to acute plague in- 

 fection, these animals dying in from three to seven days after 

 cutaneous or subcutaneous inoculation of small doses of the 

 pneumonic strain and exhibiting at necropsy haemorrhages about 

 the point of inoculation, typical buboes, and acute, splenic tumor.'' 



DONKEYS. 



Some evidence was introduced at the International Plague 

 Conference to show that donkeys became infected with pneu- 

 monic plague during the epidemic. Dr. W. S. Yang reported to 

 the Conference ^ the death of 10 donkeys, the first of which died 

 with cough and expectoration of blood. In the case of one of 

 these animals, a necropsy was performed and cultures were made 

 from the heart, spleen, lungs, and liver. All of these cultures 

 were said to show plague bacilli. It was also announced that 

 Doctor Otsuki in Fushun had observed at necropsy 2 donkeys in 

 which there was hepatization of the lungs, in one in the right 

 and in the other in the left caudal lobe. The pathological 



' Petrie has shown (Report of the International Plague Conference, 

 p. 235) that Arctomys bobac Schreb. found in Manchuria may be infected 

 with the flea, Ceratophylliis silantievi Wagner, and that this flea will bite 

 man. Tiraboschi and D-Kolbasenko have also described fleas on the tar- 

 bagan in Russia. 



' For the details of these experiments, see Report of the International 

 Plague Conference, pp. 237 and 385. 



*Ibicl., p. 440. 



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