.500 ON TWO REMARKABLE SPOROCYSTS, 



doubtedly, by the cells of the germinal epithelium through the 

 pores of the cuticle, and most of it must be given off in a state of 

 solution into the fluid in which the developing embrj^os, in all but 

 their earliest stages, float freely. The special part played by the 

 nutriment provided in the form of globules is that it supplies a 

 store of sustenance which the Cercaria takes with it when it 

 leaves the Sporocyst and sets out in search of a second host. 



I can find no mention in the literature accessible to me of this 

 giving off of globules by the cells of the germinal epithelium. 

 That the case is not an altogether isolated one, however, is shewn 

 by the fact that Reuss in a recently published preliminary 

 notice (H) mentions the presence in the Sporocysts of DidcnmLm 

 duplicatum of many "fat drops." It is at least possible that the 

 phenomenon is a general one, and that it is only owing to the 

 colourless character of the globules in most instances that it has 

 hitherto escaped notice. On the other hand, it has to be borne 

 in mind that in many Cercariie the digesti^ e canal does not become 

 suflicientiy well developed to be functional until after the larva 

 has escaped from the Redia or Sporocj^st. In such cases the 

 formation of the globules, except merely in order to be subsequently 

 dissolved in the nutrient fluid of the cyst, would evidentl}^ be 

 superfluous. 



The occurrence of a pigment in the germinal epithelium appears 

 to be exceptional. I have met with only three recorded cases of 

 such a thing — by Wagener (14) in the Sporocyst of Cercaria cysto- 

 phora, by Pagenstecher (10) in the case of the Sporocyst of Cercaria 

 cotylocerca, and by Heckert (4) in that of Lencochhridnwi para- 

 doxiim. 



The embryos are developed from a mass of specialised cells of 

 the germinal epithelium — the ovary (figs. 5-7). This is constant 

 in position, at the posterior end, and there is never more than 

 one. It projects as a free process into the cavity of the Sporo. 

 cyst. At its base every gradation is to be observed between the 

 ordinary cells of the posterior thickening of the germinal epithe- 

 lium and the cells destined to give rise to embryos. Towards its 

 free extremity the ova undergo segmentation which results in 



