290 DISCOVERY REPORTS 



The internal parts of the parasites were studied in sections. Six hosts with parasites were sectioned 

 transversely and two longitudinally. In one of the latter the host proved to be infested by two parasites. 

 The chief particulars of the various series of sections are given below. 



(i) The type specimen, on Euphaiisia vallentini from St. 963 (Fig. i). The section shows the external 

 part of the organ of fixation from which a number of trophomeres are branching off, and the internal 



Fig. I. AmaUocystis fagei Boschma on Euphausia vallentini Stebbing from St. 963 (type specimen). Transverse section of host. 

 After Boschma (1948, fig. 2). ch, chitin; e f, external part of organ of fixation;/, organ of fixation; h, hepatopancreas 

 of host; i, intestine of host; m, musculature of host; o, ovary of host; p, protoplasmatic excrescences; s, sieve plate; 

 t, trophomere. x 160. 



part of the organ of fixation embedded in the ovary of the host. The organ of fixation has a rather solid 

 cuticle which in many parts shows folds or wrinkles. At the lower surface of the organ of fixation there 

 is a region in which the cuticle is pierced by numerous holes, the sieve plate. Through the latter 

 a number of protoplasmatic excrescences are seen to protrude into the ovary. These excrescences form 

 the proximal part of the root system ; the more distal part of the latter is not distinctly visible in the 

 sections of this specimen. At the sides of the parasite there are a few irregular layers of chitinous 

 matter of a pronouncedly yellow colour. Probably these were formed by the host as a reaction against 



