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Tryp anoso mias is 
Leech-transmitted Trypanosomes of Fish, Reptilia and Amphibia. 
Trypanosoma granulosum, occurring in the eel, developes in a leech, 
Hemiclepsis marginata. The flagellates at first multiply actively in the 
leech’s stomach and afterwards in the intestine, where crithidial forms 
occur. Finally, the flagellates reassume the trypanosome form and 
appear in the proboscis-sheath of the leech. The latter only becomes 
infective when the flagellates appear in this situation. 
The Trypanosomes of the gold-fish, bream, perch and rudd all develope 
in Hemiclepsis marginata. They multiply enormously in the crop, 
undergoing a great change in appearance, being tadpole-like in form 
and having a crithidia-like arrangement of the nuclei. After the 8th 
day, slender trypanosomes appear, and after the 10th day they gather 
progressively in the leech’s proboscis-sheath, where they cease to divide. 
The leech’s bite is now infective and the flagellates are cleaned out of 
the sheath during the process of biting. The time when the leech 
becomes infective depends entirely upon the rate of the leech’s digestive 
processes, it may be delayed to the 35th day, or longer. The leech 
still continues to harbour the trypanosomes; others present in the gut 
succeed those that disappear from the pi’oboscis after each feed. 
This leech may produce a 'mixed infection in fish for it also 
transmits Trypanoplasma cyprini which occurs in gold-fish and tench. 
This parasite divides rapidly in the crop, slender forms appearing on 
the 2nd day and advancing on the 6th day so as to accumulate in 
the leech’s proboscis-sheath in vast numbers. The flagellates attach 
themselves in this situation by their flagella and tend to crowd forward 
as the leech’s digestion approaches completion, with the result that the 
leech may completely clean itself of parasites at a single feed. It is 
worthy of note that the trypanoplasm does not materially alter its 
morphology in the leech. 
Trypanoplasms have also been transmitted by the leech, Piscicola 
geometra, and a number of trypanosomes occurring in fresh and salt 
water fish (T. danieleivskyi, T. soleae, T. I'ajae, T. cotti) have been 
transmitted experimentally by different species of leeches {Hemiclepsis, 
Pontobdella, etc.). 
Trypanosoma inopinatum, which occurs in the green frog, is similarly 
conveyed by a leech. In this case, according to Brumpt, the flagellates 
are transmitted hereditarily to young leeches, thus offering a marked 
exception to what takes place in all other trypanosomes whose vectors 
have been determined. The leech concerned is Helobdella algira, and 
