240 Proceedings of the Royal Physical Society. 



forms. This, however, is not surprising, as their absence 

 may be explained in a number of ways. The material, to 

 begin with, is very limited, and composed, so far as I am 

 aware, only of peripheral blood; the flagellate forms may 

 possibly be found in the deep-seated organs, such as the liver 

 or the spleen, or may only finally be developed in another host. 



In the light of Schaudinn's researches into the life-history of 

 Trypanosoma noctuce, and particularly in view of the presence 

 of a well-marked blepharoplast, it is pretty clear that the 

 parasite in question is really the intracorpuscular stage of a 

 trypanosome, and I propose to call it provisionally Trypano- 

 soma p>ythonis. 



This description is naturally of an incomplete nature, as 

 blood taken on a single occasion from an infected animal 

 rarely gives a sufficient number of different stages to form 

 anything like a complete series of the changes undergone by 

 the parasite during its sojourn in the blood. This criticism 

 is more particularly applicable to the parasite here discussed, 

 which very probably completes its life-cycle in another host. 



The two next forms to be considered were found in the 

 blood of specimens of Pleuronectes platessa and Pleuronectes 

 flesus, which were in the tanks of the Millport Biological 

 Station in January 1906. 



The first of these is a typical trypanosome, with blepharo- 

 plast, flagellum, and undulating membrane. The second is a 

 Hsemogregarine inhabiting the red blood-corpuscles, a point of 

 interest being that they were found associated in the same host. 



3. Trypanosoma from blood of P. flesns and P. platessa. 

 The trypanosome^ is a large creature, measuring from 50 /* to 



^ Since this paper was read, I have found that M, Lebailly has, in a short 

 note contributed to the C. R. Ac. Sci. Paris, T. 139, 1904, drawn attention 

 to parasites in the blood of PleiLronedes flesus and P. platessa, and has named 

 them respectively Trypanosoma flesi, T. pkitessce, Hcemogregarina flesi, and 

 H. platessce. While both tht^ Trypanosome and Hsemogregarine described by 

 M. Lebailly appear to correspond with those found by myself, there seems to 

 me to be only one species of Trypanosome and one species of Hsemogregarine. 

 That is to say, the Trypanosome I found in Pleuronectes platessa appeared to 

 me to be identical with the one present in the specimens of Pleuronectes flesus 

 which I examined, and similarly with the Hsemogregarine. 



