E. MAESHALLI. — DEVELOPMENT OF HEXASTEES. 195 



case of graphiocomes, somewhat less so in that of floricomes, and 

 least of all in that of certain oxyhexasters (see anon, p. 199). 



The scleroblast-mass remains in its position, unchanged in 

 essential points of appearance, until the development of the 

 terminals is completed. Sooner or later after that, the mass 

 disappears, but whether by atrophy or by dispersal, I have no 

 more means of knowing than I have respecting the source from 

 which it is derived. If it be justifiable to judge from what be- 

 came known through Minchin in the Calcarea, the mass may 

 be referred genetically to the trabecular tissue ; and its return to 

 the same after the comj)letion of its special formative function 

 is probably to be assumed. 



Certain it seems that during the growth of the terminals no 

 nucleus moves away from its group around the spicular center. 

 At least I could gather no evidence pointing to such a move- 

 ment. It is true that after a certain period in the growth of 

 terminals, a variable number of nuclei is met with right among,, 

 or in close proximity to, these (figs. 31, 33-35). However, they 

 are altogether so inconstant in number and indefinite in position 

 that it is exceedingly questionable if they have anything to do 

 with the building up of the terminals. The nuclei, together 

 with the more or less cobweb-like protoplasm in connection there- 

 with, are probably to be considered, for the greater part at least, 

 as representing the ordinary trabecule which have come into a 

 secondary relation with the hexasters. 



The terminals in their minute inceptional state (figs. 30, 

 32) are evidently inclosed quite within the protoplasm of the 

 scleroblast-mass, and are entirely independent of the general 

 trabecular system. It is then a matter of great probability that 

 essentially the same condition persists throughout all the later 



