HISTOLOGY AND DEVELOPMENT OF MYRIOTHELA PHRYGTA. 531 



spherules of the ripe egg, and they are also found in some 

 abundance in the young buds. I can throw no light either on 

 their special significance or on their relation to the small nutri- 

 tive spheres. I might finally add that they are rarely widely 

 distributed throughout the endoderra, but usually occur in 

 localised patches as though they were related to some localised 

 and special metabolic process. They are perhaps never com- 

 pletely absent. 



Though the term nutritive sphere can, I think, be applied 

 with justice to both the preceding bodies, its application to 

 the third class of endodermal products would be misleading, 

 since they are merely a specialised product of the endoderm 

 of the tentacles. 



When abundant, each cell of the endoderm of a tentacle 

 may contain one of these bodies, and then they doubtless give 

 rise to that opacity which was noted by Allmann. They form, 

 however, a very variable element, for while one tentacle may 

 be fully charged with them its neighbour may contain few or 

 none. Each of these bodies is, when fully formed, 10 m in 

 diameter, and consists of a sphere which stains intensely 

 with picro-carmine (fig. 26), and is embraced by a cup-shaped 

 capsule with expanded edge. 



That these bodies play any great part or are at all concerned 

 in the general nutrition is extremely improbable. Under 

 certain circumstances they are discharged from the endoderm- 

 cells of the tentacles and find their way into the enteric space, 

 and are ingested and digested by the apical cells of the 

 adjacent villi. 



In what I have to say concerning the formation and fate of 

 the nutritive spheres in the following pages, I shall refer ex- 

 clusively under that title to the small nutritive spheres which 

 are so abundant and numerous. The method of formation of 

 these bodies has been already described, and it was seen that 

 they develop in vacuoles formed in the protoplasm of the 

 vacuolate cells ; and I see no reason to doubt, but rather every 

 reason for agreeing with Miss Greenwood's view, that these 

 bodies are formed from material absorbed in the fluid form 



