THE BUBONIC PLAGUE. 67 



Exposure of the bacillus in thin layers to the direct action of 

 sunlight destroys it after from three to four hours, but to accom- 

 plish a like result from exposure to diffuse light as many days are 

 necessary. The germ is killed by an exposure to a temperature 

 of 80 C. for thirty minutes and at 100 C. within a few minutes. 

 Spore formation has not been observed. 



There is some reason for believing that there is a pseudo- 

 bacillus of the plague as there is one of diphtheria. In his studies 

 of the soil of the infected districts of Hong Kong, Yersin found a 

 bacillus that resembled that obtained from persons with the dis- 

 ease, both morphologically and in its growth on culture media, 

 but it was without effect upon mice and guinea pigs. He also 

 observed great differences in virulence in the germs obtained 

 from the sick ; some of these were without effect upon the above- 

 mentioned animals. There were, moreover, observable varia- 

 tions in the size of the bacilli found in the bodies of the sick 

 and dead. 



The studies of Yersin and Kitasato were interrupted by the 

 war between China and Japan, and a much more thorough knowl- 

 edge of the bacillus and the disease caused by it will probably 

 soon be in our possession. 



I will now consider some of the characteristic symptoms of the 

 disease. It is undoubtedly a septicemia, or form of blood-poi- 

 soning. As has been stated, the bacillus is found in the blood 

 and in all the organs. It is customary to describe the disease 

 under two forms. The milder epidemics are known under the 

 name of pestis minor. In this form the glands of the groins and 

 armpits swell and either suppurate or undergo resolution. There 

 is moderate fever, although in exceptional cases the temperature 

 may reach 104 F. The disease usually continues from ten to 

 twenty days, and may last for from four to eight weeks. Pestis 

 minor sometimes precedes and at other times follows the more 

 severe forms of the disease. The former was the case in the 

 epidemics in Mesopotamia in 1873 to 1878, and in Astrakhan 

 in 1878. 



Fodere*, as quoted by Cantline, makes the following statement 

 concerning pestis minor : " In the Levant and in the Marseilles epi- 

 demics of 1820, cases were to be seen which were not ushered in 

 by any alarming symptoms, and where the natural functions were 

 undisturbed, and where buboes and carbuncles appeared without 

 fever, or only with slight fever, or the buboes went on to a healthy 

 suppuration more or less prompt, or even disappeared and went 

 on to resolution without the help of art, without any inconven- 

 ience, and with a perfect integrity of all the functions. This state 

 is comparable to benign smallpox, during which children play to- 

 gether and walk in the streets without any precautions, no care 



