Notes on certain Blood- Inhabiting Protozoa. 



241 



60 fj- in length (Text-Fig. 4). It has a narrow, undulating mem- 

 brane, produced at one end into a llagellum. The movement of 

 this creature is particularly beautiful ; it sometimes proceeds 

 forwards with a graceful eel-like motion, at other times roll- 

 ing itself up into a wheel and whirling round in a circle. 



Text-Fig. 4. — Trypanosoma from Pleuronectes. 



I would like here to emphasise the uncertainty of a nega- 

 tive diagnosis in the case of the blood flagellates of fishes ; 

 the flagellates are usually so scarce in positive cases that it 

 is impossible to conclude that they are absent merely because 

 a careful search has failed to reveal their presence. Thus in 

 one case where two live specimens were observed, no speci- 

 mens at all were found in the prepared films. The most 

 severe of the three infections showed only four or five speci- 

 mens in a 2 by 1 inch dry film. The endocorpuscular forms 

 are usually present in greater numbers, and a negative result 

 is apparently more trustworthy. 



I am not yet in a position to describe the details of the 

 nuclear apparatus of this creature, on account of technical 

 difficulties in staining. There is, however, a large nucleus 

 lying at the centre of the creature, or slightly anterior to it, 

 and there is a complicated blepharoplast present which takes 

 on a brilliant red colour when stained with polychrome 

 methylene blue or with Giemsa. This blepharoplast varies 

 in position, but is always near the vacuole, which lies a little 

 in front of the slightly truncated posterior end of the animal ; 

 the blepharoplast may form a single compact body, or may 

 be composed of several separate elements. A number of 

 well-marked striations are to be seen passing longitudinally 



