SEA-FISHERIES LABORATORY. 133 



Figure 5 is a section through a portion of a cyst. 

 The outer, ccelomic, side of the gut-wall lies to the right, 

 and the muscle-layers, though a little thin, perhaps, are 

 free from infection, and present no feature worth drawing. 

 At the left is a fold (endoth.) of the mucosa, also quite 

 normal, at the head of a furrow. At ect., ect. is seen the 

 thick, practically structureless external layer (ectoplasm) 

 of two adjacent cysts, which are separated by a 

 few delicate layers of connective-tissue (areol. tiss.). 

 Hagenmuller, who maintained that the cyst membrane 

 is formed of elements belonging to the host, was cer- 

 tainly referring to pseudocysts, which, however, he did 

 not recognise were intimately connected with diffuse 

 infiltration. He does not seem to have seen true cysts at 

 all. In these, there is no transition whatever visible 

 between the surrounding tissue and the firm "ectorind" (as 

 one may term the modified ectoplasm) of the parasite, nor 

 any signs in this latter of flattened-out nuclei or cells. 

 I entirely agree with Thelohan in thinking that the cyst 

 membrane is a modified ectoplasm, and for this reason 

 propose the term ectorind, to distinguish it from an ecto- 

 c}^st. Against its being an ectoplasmic secretion — com- 

 parable to the cyst-envelopes of Grregarines — I would say 

 there is no other layer which can be regarded as the ecto- 

 plasm. Immediately internal to the ectorind is a delicate 

 layer without any sign of spore-formation, but which is 

 structurally identical with the endoplasm into which, 

 indeed, it passes, and, therefore, I regard it also as such. 

 (In some sections through a Glugea anomala, from a 

 stickleback, which I possess, there is an equally distinct, 

 here finely-striated, ectorind, thus confirming Thelohan's 

 figs. 138 and 139, pi. 9). Internal to the ectorind, and ex- 

 tending all round, we see the typical Myxosporidian endo- 

 plasm (end.). It is a comparatively narrow layer, as by 



