ZOOUKiY FOR MEDICAL STUDENTS CHAP. 



d, small rounded chambers containing choanocytes 

 with two sets of tubular channels the one inhalent the 



lent. 



>picules are composed of silica and are either tetraxon with 

 - diverging from a point at equal angles or monaxon. The 



tour 



FIG. 60. 



Skrlrtnll (if E 



re lre<|ueiitly united into a continuous framework not however 



i.il lu>ion between the siliceous substance of the spicules as is the 



ith the llexactincllids but by the interposition of a peculiar 



Niihsiam-r allied to silk in its chemical composition and known 



as spongine. In various members of the group n,n interesting modifica- 



-kdrton has come about by the increase in amount of the 



' orresponding reduction of the siliceous spicules 



