FISHERIES, GAME AND FORESTS. 1 79 



anchor-like enlargement at the extremity of the anterior appendages. The mouth 

 is adapted for sucking and the parasite is nourished by the blood obtained 

 from the gills. 



None of these parasites were numerous enough to account for the trouble, and, 

 although an occasional intra-cellular sporozoan parasite was found, they were not 

 abundant enough to warrant continued search, for in fish with the most noticeable 

 external indications of the disease, the organs within were apparently normal and cysts 

 or other usual indications of Sporozoa were not forthcoming. In every section that 

 was cut, however, a variable number of minute foreign bodies, which were so small 

 that they were at first taken for bacteria, were found especially abundant in the lymph 

 spaces surrounding the various organs and in the testis. These were so minute that 

 it seemed hardly possible that they could be the cause of the disease and yet their 

 numbers were so constant and they were so widely distributed throughout the entire 

 body that I was forced to the belief that they were the cause of the epidemic. They 

 were found in the body cavity surrounding the intestine and other visceral organs, in 

 the ■ lymph spaces, in many of the organs themselves, in the blood vessels including 

 capillaries and veins, and in the gills, muscles, and connective tissue of the diseased 

 fish. In short, they were found wherever there was a cavity, sometimes only occasion- 

 ally, again in great multitudes. 



As there were no satisfactory experiments in inoculating normal fish to show that 

 this organism is the cause of the disease, I will give a brief description of each of the 

 important organs of the body showing the appearance of the sporozoan in question 

 and its wide distribution. The organs chosen are the intestine, including the pyloric 

 cceca, the liver, kidney, gall bladder, blood vessels, testis, and muscles, especially those 

 around the ulcers in the body wail. All of the organs were taken from young fish of 

 not more than five inches in length, and all of the fish showed external evidences of 

 the disease. 



The stomach and pyloric cceca had only an occasional spore of the parasite but 

 the intestine (Plate II-I) had many of them mixed in with the bacteria. Here, too, 

 they were in reproductive stages and it was plainly evident that they had been taken 

 in from the outside through the mouth. There is little doubt that this is the means 

 of infection from fish to fish. 



The liver showed no traces of disease either macroscopically or microscopically, 

 the cells being perfectly normal and with no parasites among them. The kidney, on 

 the other hand, frequently appeared swollen and discolored while numerous scattered 

 parasites were seen in it, especially at the anterior end, where the tissue is more 

 lymphatic than in the posterior part and has no excreting function. Only a few 

 parasites were observed in the posterior region of the kidney and these at such rare 



