LIFE-CYCLE OF " CYSTOBIA " IRREGULARIS (mINCH.). 25 



in Cystobia is fairly simple, and practically similar iu the 

 case of both the species I examined. The body is always 

 limited by a very delicate membrane or cuticle, in which I 

 could never see any striations. When, as sometimes happened, 

 tlie fixative employed has caused the cytoplasm to shrink 

 away slightly from the membrane, the latter is easily seen 

 (fig. 12, l.m.). 



The parasites do not show any obvious differentiation of 

 the cytoplasm into ecto- and endoplasm. I could never 

 assure myself, by any method of fixation, of a well-marked 

 peripheral layer constituting a definite ectoplasm. The some- 

 what clearer border round tlie Gregarine depicted in fig. 2 is 

 simply due to the lessening thickness of the body approaching 

 the edge (the specimen, it should be remembered, was drawn 

 when living). Correlated with this absence of any ectoplasmic 

 supporting layer to the body is the extreme delicacy of the 

 latter, and the readiness with Avhich I found it became 

 irregular or distorted in shape if touched or placed in an 

 uncongenial environment. In two instances, I should add, 

 in sections of a couple of Gregarines which were fixed with 

 Flemming and stained Avith iron-hsematoxylin and orange, a 

 more finely granular, compactor structure of the cytoplasm 

 can be discerned near the margin (fig. 87 b) denoting a slight 

 alteration in its character, but hardly amounting to a distinct 

 layer. I only observed it in these two examples of C. irregu- 

 laris, and never in C. minchinii. A strong contrast is 

 afforded by the distinctness of the ectoplasm in Diplocystis 

 Schneider i, where it forms a thick, well-marked layer, 

 finely granular in character (fig. 27). 



A word or two with regard to the composition of the septal 

 plane. The septum is constituted by an extremely thin and 

 delicate membrane, which is, howevei*, remarkably persistent. 

 This runs straight to the limiting membrane at the periphery 

 (figs. 37, 39), with which, indeed, it corresponds. There is no 

 sign oE anything in the nature of ectoplasm in the dividing 

 partition, and, moreover, where the marginal cytoplasm shows 

 the slight alteration just mentioned, this is not continued into 



