PHYLUM PORIFERA 



87 



originally simple cylinder or vase, may be looked upon as 

 an asexual mode of reproduction by budding. Asexual 



B.Pachychalina 



Fig. 39. — Microscopic structure of the skeleton in various sponges. A, Euspongia, 

 network of spongin fibres; B, Pachychalina, spongin strengthened by siliceous 

 spicules; C, Spongelia, spongin strengthened by various foreign siliceous 

 bodies, fragments of spicules of other sponges, etc. (After Vosmaer.J 



