LIFR-OYOLE OF " CYSTOBIA " IRREGULARfS (MfNfH.). 17 



wlien about to encyst. They are probably able to induce 

 proliferation of the surrounding tissue to a considerable 

 extent. Nor do I think that they usually break through 

 the epithelial layer which they first invaginate, for in sections 

 of encysted stages this is always present next to the body 

 of the animalj and completely enclosing it. 



Situation in which the parasites encyst. — The re- 

 maining position in which I found the parasites bears out 

 these suppositions. Encysted Cystobias often occurred 

 firmly attached to — sometimes, indeed, almost in — the strong 

 retractor muscles which work the buccal mass. PI. 1, fig. 11, 

 shows three so attached, m. being a piece of the retractor 

 muscle. The two larger ones are fairly separate from the 

 muscle, connected to it by the short thick stalk (.9^.), but 

 the smaller one is more completely imbedded. Fig. 16 is a 

 section through a portion of the muscle with a Gregarine 

 firmly enclosed in the proliferated epithelium and connective 

 tissue lying external to the muscle-fibres. A is the originally 

 invaginated epithelium equivalent to that seen at h, figs. 9, 

 10, and 12. E^)' is the normal coelomic epithelium, which 

 at ep' is flattened out and in some places wanting, evidently 

 having been unable to keep pace with the proliferation of 

 connective tissue, C, c. are concentric layers of connective- 

 tissue around the parasite, and m., m. are the muscle-fibres. 

 Fig. 15 shows another one so encysted in section; it is more 

 separate from the muscle, which in this case is cut trans- 

 versely ; nevertheless the parasite is firmly enough attached. 

 A thick layer of connective tissue (c.) surrounds it, especially 

 fibrous nearest to the inner epithelial cells, which are here a 

 little disorganised. The nuclei (n.) of the outer epithelial 

 layer can be seen in places, extending over the surface. 



Conclusions. 



It will, perhaps, be suggested, may not these Cystobite 

 in the connective tissue surrounding the muscle have arrived 

 in this situation by passing along a blood-capillary as sporo- 



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