192 STRONG AND TEAGUE. 



even though an advanced bactersemia is present. This fact, also, 

 suggests that the lung tissue offers a more favorable location for 

 the growth and multiplication of the bacilli than does the spleen. 

 The bacteria are also present in far greater numbers in the lung 

 than they are ever found in the buboes or spleen in bubonic-plague 

 cases. It is, also, evident that in pneumonic plague the infected 

 lung (which may be said to correspond to the primary bubo of 

 bubonic plague) contains, by reason of the size of the infected 

 area, a far greater number of plague bacilli than the primary 

 bubo in bubonic plague. During epidemics of bubonic plague, 

 there are occasionally small epidemics of pneumonic plague in 

 which the same high mortality and acute course of the disease is 

 observed as occurred in the Manchurian epidemic of pneumonic 

 plague. This is another argument in favor of the fact that 

 during epidemics of bubonic plague the causative organism may 

 show the same high virulence. As examples may be cited the 

 epidemic of bubonic plague in Japan — in Kobe and in Osaka in 

 1899 to 1900 — in which 13 cases of primary pest pneumonia all 

 terminated fatally after a very rapid course, and the epidemic 

 of bubonic plague in 1898 in Bombay in which, toward its close, 

 11 cases of pneumonic plague also all quickly succumbed one 

 after the other. 



All this evidence is in favor of the supposition that the or- 

 ganism giving rise to the present epidemic is of no greater viru- 

 lence than in the case of many bubonic strains; furthermore, 

 definite proof of this fact has been obtained from comparative 

 inoculations made in animals with different pneumonic and bu- 

 bonic cultures. Many of our experiments have been reported 

 in the testimony of the Conference, and will not be given in detail 

 here;^ the results of others performed by us since that time are 

 recorded in Table I. 



The guinea pigs were all inoculated in the following manner: An area 

 of the abdomen, about 2 centimeters square, was shaved and scraped 

 with . the razor until petechial haemorrhages appeared in the skin. A 

 42-hour agar-slant-culture of each organism was suspended in 5 cubic 

 centimeters of peptone solution and 5 cesen of each suspension were rubbed 

 over the shaved area of the guinea pig's abdomen. At necropsy the animals 

 showed the usual lesions of bubonic plague. These guinea pigs were 

 inoculated on June 8. The pneumonic strains were isolated during the 

 month of March, the bubonic strain "Hongkong" on May 20, and the bubonic 

 strain "Mariveles" on May 27. The bubonic strain sent from Shanghai 

 had been on artificial media at least for several months. 



^ Report of the International Plague Conference held at Mukden, April, 

 1911. Manila (1912), 75, and Index under Virulence. 



