PHYLUM PORIFERA 



103 



FIG. 62. Venus' flower-basket. The skeleton of a sponge, Euplectella. 

 (From Weysse.) 



to appear." Sense cells are supposed to have developed next 

 as we find them in ccelenterates (p. 112), and finally a central 

 organ was added, completing the neuromuscular mechanism 

 as it exists in higher METAZOA. 



(3) Reproduction. Reproduction is either asexual or sexual. 

 By the asexual method there are produced buds and gemmules. 

 Buds may be set free to 

 take up a separate existence, 

 or may remain attached to 

 the parent sponge, aiding in 

 the formation of a complex 

 assemblage of individuals. 

 Gemmules are formed as de- 

 scribed in Spongilla (p. 99). 



In sexual reproduction the 

 eggs and spermatozoa are Fm 63 ._ The bath sponge> Euspmgia 



derived as in Sycon (p. 96) officinalis. (From Lankester, after Schulze.) 



