519 



division of the granules as described by Schewiakoff (1893) in Achro- 

 matium 3 . When however the organisms prepare for spore-formation 

 these deeply staining granules disappear from the outer portions of 

 the protoplasm and apparently collect in several masses in the inte- 

 rior of the cell. These masses are the spores (fig. 6). 



Spore-forming individuals are frequently found in the lymph 

 surrounding the various organs, and are quite numerous in the cavity 

 of the gall-bladder and in the intestine. They are of relatively large 

 size (25 to 30 f.i) and may be formed from the union of two or more 

 individuals although save for the large size I have no evidence at all 

 to indicate that such is the case. 



The young spores at first consist of granules which stain intensely 

 like the distributed chromatin granules of the adult organism (fig. 6 A), 

 but as they grow older, they become more dense and, while still within 

 the body of the parent, they assume the homogeneous character 

 of the spores as described above (fig. 6 B) . The spores may be liber- 

 ated in the body cavity and so give rise to the large numbers which 

 are found distributed about the body, or in the intestine, where passing 

 to the outside with the faeces they may be one cause of the spread of 

 the disease. 



Briefly summarizing the above account of the life-history of the 

 parasite while within the body of the fish host, it appears that the 

 organism gets into the fish probably by means of the digestive tract 

 and while in the spore stage. In the intestine the spore completes its 

 development and forms sporozoites which penetrate the epithelial 

 tissues lining the wall of the gut, and get into the lymph. Here they 

 grow into amoeboid organisms which penetrate the muscle bundles 

 and live until maturity as inter-cellular or possibly as intra-cellular 

 parasites. When mature they withdraw from the muscles and form 

 spores, possibly after conjugation. The spores are liberated into the 

 body cavity or into the lymph and are carried to all parts of the body. 

 In the muscles of the body wall they may accumulate until the lymph 

 passages are fairly blocked with them, and the tissues are unable to 

 get sufficient nourishment, ultimately dying and falling out thus leav- 

 ing the sores and ulcers so characteristic of the diseased or dead fish. 



It is evident that, although closely analogous to the Myxospori- 

 diida in mode of life, these organisms cannot be classified with the 

 latter common fish parasites. Nor can they be grouped wits the Coc- 

 cidiida, or Sarcosporidiida. The Haemosporidiida are likewise entirely 

 different. 



3 Hab. Schrift. Heidelberg, Winter. 



