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exceedingly numerous and all gradations in size are met with, so that 
it is often impossible to separate sharply the small from the lai’ge 
variety. 
In the blood of one eel I saw a very large number of leucocytes 
containing round structures, and Prof. Laveran, to whom I sent a film, 
suggested that these might represent the remains of phagocyted red 
corpuscles. 
T. percae in the perch {Perea fluvialis). Next to the eel this is 
probably the commonest fish containing parasites. I have found 
trypanosomes especially in the smaller fish. The size of the parasite 
varies considerably but the large forms with short flagella are more 
commonly met with than the small forms in which the flagella are 
longer. 
T. reiiiaki in the pike {Esox lucius). Two forms were found, var. 
parva and magna, which can be distinguished by the characters which 
Minchin (1909) has pointed out. 
T. remaki parva, is clearer, has a few coarse granules, the undulating 
membrane is shallow and does not stand out sharply from the body, 
the flagellum is longer relatively and absolutely. 
T. remaki magna, larger size, opaque protoplasm full of coarse 
granules staining reddish with Giemsa, the undulating membrane is 
very prominent. The kinetonucleus is slightly larger in parva than 
in magna (Minchin). I have only found these parasites in small 
numbers. 
T. leucisci in the roach {Leuciscus rutilus) was very infrequent. 
In the blood of sea-fish I have met the following trypanosomes; 
T. solae in Solea vulgaris —the sole, 
T. raiae in Raia hatis —the skate, 
T. scylii in Scyllium catulus —dogfish. 
In many cases the trypanosomes were associated with Haemogre- 
garina. I found haemogregarines in the sole, flounder, dogfish, skate 
and in the weaver {Trachinus vipera). 
Haemogregarines or Leucocytogregarines 
(Haemogregarina microti sp. n. ?) in Field Vole. 
In the blood of two field voles {Microtus agrestis), sent from 
Reading, June 24 and July 4, 1913, I found haemogregarines. I had 
previously examined from time to time several field voles caught in 
this locality but bad not met with these parasites, whilst in the only 
