314 E. C. POLLARD. 



use of which I am indebted to Mr. Willey, I have been 

 unable to find any trace of the parasite in the caecum ; and^ as 

 a matter of fact, I have never seen it so far anteriorly in the 

 digestive tract. 



Further, I regret to be obliged to state that I have not yet 

 succeeded in obtaining any other stage in the life history of 

 this form. 



Methods. 



From its differentiating properties cochineal is an extremely 

 useful stain for Amphioxus, and the parasites are easily seen 

 in sections prepared with this ; but the details of protoplasmic 

 and nuclear structure I have made out best in specimens 

 stained with a mixture of borax-carmine and picro-carmine as 

 prepared by BoUes Lee.^ 



The use of the homogeneous immersion lens was essential, 

 and figs. 6 — 9 were drawn under this with the aid of a Zeiss's 

 camera. 



In conclusion, my sincere thanks are due to Dr. G. H. 

 Fowler, who first drew my attention to an unusual appearance 

 in my sections of Amphioxus, which I investigated with the 

 results now published ; to Mr. Willey for the most kind loan 

 of his sections, and to Dr. Benham and Mr. Minchin for ever 

 ready advice and help. 



Oxford; October, 1892. 



Addendum. 

 In fig. 10 I have figured specimens of a ciliate parasite 

 which occurs in considerable numbers in the atrium of 

 Amphioxus. 



Professor Lankester noticed these years ago, and has recently 

 drawn my attention to them, with the suggestion that the cell 

 parasite described above might possibly be a stage in the life- 

 history of this ciliate form. 



> Bolles Lee, ' Vade Mccura,' p. 122. 



