LTKK-CVOl.E OF " CYSTOBIA " TRT^EHULAinS (mINCH.). l-'^ 



connecting the posterior part of the gut witli the body-wall. 

 Fig". Ga shows two Cystobite, each attaciied to the body- 

 wall by an epithelial stalk, which itself is partially iuvaginated 

 by the parasite. Fig. 6 h represents one of the two drawn 

 with a lens; the slight constriction abont one third of the 

 length from the free end marks off the portion of the Gregarine 

 still left uncovered by the epithelium from that which is 

 already surrounded by it. There can be no doubt that they 

 are going in and not coming out; of this I have quite assured 

 myself. The process is exactly the opposite to that of 

 evagination which occurs in C. irregularis. One must 

 perforce suppose something like the following to take place : 

 After a successful infection some of the young parasites in 

 the trees, instead of becoming rounded off and growing 

 in situ, pass straight through the wall into the coelome, 

 assuming the typical ovoid form. (Unfortunately, I have 

 never observed any free in the body-cavity.) Probably the 

 parasites are not long carried about here and there by the 

 movements of the ccelomic fluid before touching a suitable 

 place. To this the Gregai-ine would at once adhere, doubtless 

 by means of a little secretion, which at the same time starts 

 the coBlomic epithelium at that point proliferating, with the 

 result that a stalk is formed into which the parasite is mean- 

 while pushing-. The process undoubtedly takes considerable 

 time before being completed, during which the Gregarine 

 continues growing, for I have seen parasites of very different 

 size in this position. 



A typical C. minchinii thus endeavouring to penetrate 

 the epithelium is seen in outline and optical section in fig. 9. 

 The stalk is, of course, broken off from its attachment to 

 the body-wall. The dotted lines represent the limit of the 

 epithelial investment, where it is reflexed internally. Fig. 10, 

 drawn in surface view, shows the covering of epithelium 

 more distinctly. The Gregarine drawn on a large scale in 

 fig. 12 was similarly attached to one of the more or less 

 vascular strands crossing the body-cavity. It is viewed 

 whole, in optical section, and the lumen of the stalk (in 



