204 THE HA E MO FLAGELLATES 



he noticed in Glossinae (sp. not given), one which from its entire 

 agreement with T. gambiense was to be identified with that form 

 occurred in two instances in the salivary glands. If this observation 

 be corroborated, its importance is, of course, very great. 



Several important facts have been lately brought forward by 

 Brumpt (10-12), which tend to show that the habitat of Piscine 

 Trypanosomes in leeches is also restricted to the alimentary canal. 1 

 Three types of behaviour can be distinguished, (a) The parasites 

 develop solely in the stomach and never pass into the intestine or 

 into the sheath of the proboscis. At the moment when the leech 

 sucks the blood of another fish, the Trypanosomes pass into the 

 latter directly, by way of the proboscis. This mode is exemplified 

 by T. remaki of the pike. (/>) The development begins in the 

 stomach and is continued in the intestine, where the parasites may 

 remain for a long while. From the intestine the Trypanosomes 

 pass back into the stomach, to gain at length the proboscis-sheath. 

 T. granulosum of the eel is an example of this type. In the third 

 variety (c) the development goes on in the stomach, but the para- 

 sites succeed in passing finally into the proboscis -sheath; ex.: 

 T. danilewskyi of the carp. In the case of certain marine forms 

 (T. raiae and T. scyllii), whose development goes on in Pontobdella, 

 Brumpt found the parasites in the stomach and intestine, but could 

 not ascertain how they got back into the fish. Miss Robertson, 

 however, has lately described (72) various developmental phases 

 of a Trypanosome which she regards as identical with T. raiae, and 

 states that small slender forms do migrate up into the proboscis : 

 it is probably these which serve to infect the Vertebrate. 



2. Relation to tlie Vertebrate Host. Once an entrance into the 

 blood is effected, the parasites pass rapidly into the general circula- 

 tion, and are thus carried to all parts of the body. In considering the 

 distribution and numerical abundance or otherwise of the Trypano- 

 somes in any given individual, it is necessary to bear in mind 

 whether they are in a tolerant host or in an unaccustomed one. 

 Dealing with the former case first, the trend of observation points 

 to their being usually rather scarce, sometimes very rare. The 

 reason for this scarcity is probably the fact that multiplicative 

 phases are very rarely met with, at all events in the general 

 circulation. Except for a short period at the beginning of the 

 infection, multiplication appears to be largely in abeyance ; this has 

 been well shown by Laveran and Mesnil (37) in the case of T. 

 lewisi of the rat. The parasites are often more numerous in the 

 spleen, bone-marrow, kidneys, and liver than elsewhere ; and it has 

 been found that multiplication goes on rather more actively in the 

 capillaries of these organs. One very important point may be 



1 Brumpt has recently noted (14), however, cases of hereditary infection of leeches, 

 with both Trypanosoma and Trypanoplasma. 



