FISHERIES, GAME AND FORESTS. l8l 



Description and Life History of tl)e Parasite. 



In all Sporozoa where the life history is fully known, the adult individuals give 

 rise to a definite number of spores. Instead of developing at once into new organisms, 

 these spores in turn give rise to progeny by dividing into a definite number of parts. 

 The germs formed by this second division are called sporozoites and each is capable 

 of developing into a new adult, and of repeating the cycle. The parasites in the spore 

 stage are frequently taken into the stomach with the food. Here the digestive 

 fluids dissolve the spore cyst and liberate the sporozoites which penetrate the 

 epithelial cells and grow to full size. After a certain number of such cycles, however, 

 there is a period of conjugation in which two individuals fuse together. In some 

 unknown way the fusion leads to a renewal of vitality and, indirectly, to reproduction 

 by spore-formation for a number of generations. 



In the present investigation I have been able to follow the life history of the 

 parasite which, I believe, is the cause of the present epidemic, and to which I have 

 given the name LympJiosporidium truttce, from the sporozoite stage, until sporozoites 

 were again formed. But I have seen no trace of conjugating individuals and this 

 page of its life history, for the present, at least, must remain closed. 



I will begin the description of the life history with the spore stage. The spores 

 are pyriform in shape but flattened upon the broader end. Under ordinary conditions 

 of fixation and staining they appear homogeneous and without internal structures of 

 any kind; they always stain intensely with the nuclear stains (basic stains). I was 

 unable to determine whether the homogeneous appearance indicates a similar condition 

 throughout the entire cell or whether it was due to incomplete extraction of the stain. 

 In many cases,, however, preparations were obtained in which the organism was 

 differentiated into a peripheral deeply staining portion and a less stained part with a 

 central, nucleus-like body. This condition, however, marks a stage in the life history 

 and indicates the preparation for sporozoite-formation, while the intense homogeneous 

 appearance indicates a young form or an unripe spore. In size the spores are never 

 larger than 2.5 microns (.0025 mm., or .0001 inches) and never smaller than 2 

 microns. In some conditions, especially during and before sporozoite-formation they 

 lose their pyriform shape and become circular in outline. 



Great bunches of spores, as described above, are found in the intestine, and in 

 such groups there are, here and there, certain individuals in which the body is divided 

 up into eight parts. These parts are the sporozoites and in some cases, in certain 

 divisions of the intestine, all of the individuals of a group are in some stage of 

 sporozoite-formation. The first indication of the process is a noticeable cleft begin- 

 ning at the broad end of the spore, while the entire periphery appears irregular 



