DOCTRINE OF A COXTAGIUM VIVUM. 33 



factor by which the struggle for life has kept down an excess. 

 We see their influence unchecked in the epidemics of the middle 

 ages, and cannot but wonder what new method will ultimately 

 prevail to prevent over-population when human knowledge and 

 ingenuity have enabled us to cope successfully with the destruc- 

 tive agencies of pathogenic germs. 



The specimens I have for your inspection are sections of 

 the lung of a chimpanzee, one of the last of a series of deaths 

 from what has appeared, clinically, to be an epidemic disease. The 

 immediate cause of death was gangrenous pneumonia, but on 

 post-7nortem examination it was found that the lungs contained an 

 abundance of miliary tubercle, and that almost every organ in the 

 body showed evidences of tuberculosis; the mesenteric glands were 

 much enlarged, and many of them had undergone suppuration ; 

 the spleen had numerous masses of caseous matter, some of which 

 had broken down, forming small abscesses. On microscopic 

 examination we found that the softened matter of the mesenteric 

 glands, that from the spleen, und that from the lung, all contained 

 abundant and large tubercle bacilli ; sections of the lung were 

 found to be crowded with them, and it is scarcely possible to look 

 at well-stained sections of tuberculous tissues, such as these, 

 without being at once convinced of the important part which the 

 bacillus tuberculosis plays in the pathological process of both local 

 and general tuberculosis. The case of this young, four-year-old 

 chimpanzee was clearly one of general tuberculosis, which appeared 

 to have commenced from the alimentary canal, and to have 

 affected the mesenteric glands, much as they are in tabes 

 rnesenterica of the human infant. 



This case has suggested certain reflections, bearing on the 

 subjects of tuberculosis and of contagious diseases in general, 

 which I shall now proceed to indicate. 



We assume that the bacillus, now so easily seen, since the 



method of staining it was discovered by Koch, is the virus, the 



particulate poison, the existence of which had been proved by 



Villemin, long anterior to the time when the stained bacillus was 



first seen. Whether the poison which gives rise to constitutional 



symptoms is a chemical or physiological one ; whether it be the 



living germ or the ptomaines produced by them, is immaterial, as 



Journal of Microscopy and Natural Science. 



New Series. Vol. III. 1890. d 



