3 j6 ' REPORT OF THE COMMISSIONERS OF 



I have obtained enough evidence to lead me to the conclusion that the epidemic at 

 Cold Spring was quite similar to the present one and if my surmise is correct, it is a 

 significant fact that the same trouble should have occurred in two hatcheries in the 

 same region. 



Parasitic diseases are not uncommon among fish and the so-called psorosperms, in 

 particular, have been recognized as disease-causing organisms since 1841, when 

 Johannes Miiller first called attention co them. These have since been called the 

 Myxosporidia by Biitschli and other students of the Protozoa, and are now known 

 to be minute unicellular animals which by the accumulation of spores, form great 

 cysts in the muscles and connective tissues of fish. These are the most destructive 

 parasites known to the fish-breeder, and in some cases great epidemics are due 

 to them. During an epidemic among the barbels of the Meuse, in 1883 to 1885, 

 hundreds of fish died every day from this cause. The Myxosporidia are such frequent 

 parasites and so often the cause of fatal diseases in fish that it is not remarkable 

 that I confidently expected to locate the cause of the epidemic in some organism 

 belonging to this group. In this, however, I was disappointed, for the first glance at 

 the diseased fish showed a complete absence of cysts or tumors which characterize 

 many of the more common parasites. Although tumors were absent, the body was 

 frequently ulcerated and great holes in the body walls were often present, while 

 smaller holes were quite characteristic. As this condition frequently accompanies 

 Myxosporidiosis, I was still confident that the organism could be readily determined 

 upon sectioning some of the ulcerated spots. When this was done there were still 

 no traces of Myxosporidia, but instead of them, I found myriads of minute forms 

 belonging to the same group as the Myxosporida, i. c, to the Sporozoa, but which 

 cannot be classified among the usual fish parasites. This parasite, which has never 

 been described, I shall name LympJiosporidium truttce, and in the following report I 

 will give as much of its life history as could be made out. 



Characteristic 5^ m pt° m s °f tl)e Disease. 



The epidemic was equally fatal to fish of all ages. Mr. Thompson estimates that 

 2,000 yearlings, 1,000 two and three year old fish, and some 10,000 "fingerlings " 

 (from four to six inches long), were lost. They died as rapidly during the cold days 

 of November as in the hot days of July and August; indeed, the ponds are fed by 

 springs and Mr. Thompson asserts that the temperature of the water never rises above 

 sixty degrees F. 



The fish, especially the yearlings, were characterized by sluggish motion and 

 inability to withstand rough treatment of any kind, most of them dying within a few 

 minutes after removal from the waters of the runways to a pail. In the water the 



