238 GEOFFREY SMITH. 



appearance of the bird was changed : the comb and wattles 

 wei-e greatly shrunken, and instead of being bright red were 

 unhealthy pink patched with grey ; the skin round the eyes 

 was bloodless; the tail was carried drooping, and the bird 

 never crowed. The bird was isolated and treated with 

 purgatives, but the illness continued, the comb and wattles 

 having withered by the middle of April to about half their 

 original size. The spurs and plumage were unchanged, save 

 for the fact that the tail was always drooped. The bird was 

 killed and dissected on April 8th. 



The post-mortem examination showed that it was suffering 

 from very acute avian tuberculosis. The liver was inter- 

 penetrated with whitish calcai-eous nodules swarming with 

 the characteristic tubercle bacillus, while the whole course of 

 the alimentary canal, pancreas and spleen was covered with 

 similar swellings, some of them of the size of a pea, also full 

 of living bacteria. Only the alimentary and lymphatic organs 

 were infected, the lungs, kidneys, and testes being entirely 

 free of infection. 



Althousrh the testes were uninfected, it was at once 

 apparent that they were very remarkably reduced in size, 

 measuring only 10 mm. in length by 5 mm. in breadth, 

 whereas in a normal cockerel of the same breed and age, at 

 the same time of year, they measured 40 mm. in length by 

 25 mm. in breadth. The vasa deferentia were also reduced 

 in size, and this was especially noticeable in the coiled lower 

 part of the tubes where they pass into the vesiculte seminales: 

 no spermatozoa were present. 



Sections of the testes showed the testicular tubes intact, 

 with a regular lining of germinal epithelium cells with nuclei 

 in a resting condition. There was no sign of any mitosis or 

 of any other stages in the process of spermogenesis. The 

 testicular tubes, in fact, presented the appearance charac- 

 teristic of immature birds of a few weeks old. 



In a certain number of the tubes degenerating germinal 

 cells with abnormal nuclei could be seen. 



In contrast to this extreme reduction and arrest of develop- 



