l8o REPORT OF THE COMMISSIONERS OF 



intervals that the organ could scarcely be said to be diseased. I regard the dis- 

 coloration of this organ as due to the general morbid condition of the fish rather than 

 to a specific cause. 



♦ The spleen, unlike the liver, contained a varying number of parasites although 

 they were never abundant enough to cause distortion of the organ nor to give to it 

 a pathological appearance. They never appeared here in groups as in the intestine 

 and their presence in this organ is probably accidental. The gall bladder contained a 

 great number of spore-forming individuals but only a few of the free spores. Unlike 

 the other organs, the testis contained countless numbers of the parasites and thick 

 masses were formed, in some cases completely filling up the lobes of this organ, which 

 thus appears to be the main seat of the disease. It was greatly enlarged, while the 

 gonadel cells were abnormal and for the most part degenerate (Plate IV). 



Among these various organs of the body, therefore, the only one which was found 

 to harbor enough parasites to do injury was the testis, while, with the exception of 

 the intestine, no other organ contained more than a few scattered ones. The outsides 

 of all of the organs, however, that is, the surfaces which are exposed to the body 

 cavity and its fluids, were in all cases covered with the parasites which, especially in 

 the lymph spaces, frequently formed thick masses (Plates V, VI and VII). 

 ( The immense numbers of parasites in the testis, the body cavity, and in the lymph 

 spaces, show that these are the principal seats of the organism. They are never 

 absent from the body cavity and they settle upon all of the organs within it including 

 the mesentaries, the fat bodies, and blood vessels as well as all of the organs 

 mentioned above. From here, also, they are carried to all parts of the body and 

 especially to the muscles of the body wall which are bathed in lymph. Here they 

 penetrate the muscle bundles and accumulate in the spaces between them until the 

 cavities are entirely blocked up (Plate VIII). This is, I believe, the cause of the ulcers 

 and ultimate perforations in the body wall, the trouble being brought about by 

 stoppage of the food supply, and the tissues finally disintegrate because of the lack of 

 nutrition. The early stages of the localized trouble are always characterized by con- 

 gestion of the region about an ulcer, the blood vessels at such places being gorged 

 with blood. Not only the muscles but the cartilages also are apparently affected by 

 the same conditions as seen in the loss of certain bones in the head of some fish 

 (Plate I). The disease can be compared with leprosy in man where the bacteria 

 which cause this disease are known to accumulate in the blood vessels and block 

 up the normal food channels, causing abnormal growths or atrophy of the existing 

 tissues through lack of nourishment, and so leading to ulcers and other external 

 evidences of the disease, and even to the loss of bones. 



