CHAPTER IX 



rORIFERA {continued) : KEPEODUCTION, SEXUAL AND ASEXUAL 



PHYSIOLOGY DLSTPJBUTION FLINTS 



The reproductive processes of Sponges are of such great import- 

 ance in leading us to a true conception of the nature of a sponge 

 that we propose to treat them here in a special section. Both 

 sexual and asexual methods are common ; the multiplication of 

 oscula we do not regard as an act of reproduction (p. 174). 



\ 



X 





w 





c.s. 



Flc. 111. — A, ainphihlastuhi larva nf ^ijcon raphanns ; B, later .sta:je, showing invagina- 

 tion oi'tlie flagellated cells, c.s, Segmentation cavity ; fc, ectoderm ; en, endodenn. 

 (After F. E. Schulze, from Balfonr.) 



A cursory glance at a collection of sponge larvae from 

 different groups would suggest the conclusion that they are 

 divisible into two wholly distinct types. One of these is tlie 

 amphihlastula, and the other the parenchy inula. This was the 

 conclusion accepted by zoologists not long ago. We are indebted 

 to Delage, Maas, and Minchin for dispelling it, and showing that 

 226 



