SPONGE WEAVERS. 123 



repeated process of cleavage, by which means it 

 quickly multiplies itself, though still more rapidly by 

 the subsequent encystment and breaking up of the 

 monads into spores." 



It is quite unnecessary to recapitulate the varied 

 phases of the controversy, which has become volumi- 

 nous, on behalf of the theory advanced by Haeckel 

 on the one hand and Professor Clarke on the other, 1 

 since this would scarce possess interest for the general 

 reader ; but should any one feel desirous of investi- 

 gating the subject, he will find an admirable summary 

 in the chapter, " On the Nature and Affinities of the 

 Sponges," in Mr. Saville Kent's " Manual." 



According to those who accept the affinity of the 

 sponge animal to the flagellate infusoria, first dis- 

 tinctly propounded by Professor Clarke, and further 

 developed since his death, the essential sponge- 

 structure consists of three elements, namely, the 

 collared flagellate monads, the hyaline mucous-like 

 stratum (cytoblastema), and the amoeboid bodies, or 

 cells, to which is added the skeleton or framework 

 already alluded to. It is claimed, on behalf of the 

 flagellate monads, that they should hold the foremost 

 position in the economy of the sponge, to which the 

 mucous stratum and amoeboid bodies are subsidiary. 



1 See " Nature of Sponges," by Henry Slack, in Popular 

 Science Review, vol. xi. p. 167. 1872. 



