PORIFERA OF THE L.M.B.C. DISTRICT. 211 



to them. Their chief character is : they are filled up by 

 strongly light-refracting clear granules, the diameter of 

 which I estimate to be 00006 mm. From their position 

 and appearance I scarcely doubt that those cells are the 

 skeleton-forming elements (scleroblasts), and the appear- 

 ance suggests that these granules represent anabolic stages 

 in the formation of the siliceous material for building up 

 the spicules. However, developing spicules were never 

 seen inside those cells. 



Apparently the same structures have been figured by 

 Oscar Schmidt* in HaUsarca giittuhi, S., Spongia adrl- 

 atica, S., and Spongelia elegans, S. He describes them as 

 irregular, mostly spindle-shaped bands of sarcode, with 

 delicate processes, full of molecular granules, but without 

 cell membrane, nucleus or nucleolus. He gives the fol- 

 lowing resume about the nature of these structures : *' Die 

 sehr allgemein bei den Spongien vorkommenden Koi-ner- 

 ballen, welche oft regelmassig und dicht gescliichtet er- 

 scheinen und nicht selten mit einem helleren Centralfleck 

 versehen sind, sind weder nach ihrer Entstehung noch 

 nach ihren Bestandtheilen als gemeine Zellen aufzufassen. 

 8ie sind ein Product oder Derivat der Sarcode, und da 

 ich die Kornchen bei keinem Schwamme vermisste, ein 

 mehr oder weniger wesentlicher Bestandtheil dieser Sub- 

 stanz." Notwithstanding Schmidt's views I cannot help 

 regarding those structures as true cells. To call them 

 *' Product oder Derivat der Sarcode" is no satisfactory 

 explanation from the standpoint of modern histology. 



Similar cells have been figured by Ridley and Dendy + 

 in Ad'hiella (?) ijarado.ca, which in the explanation of the 



* Oscar Schmidt, " Supplement der Spongien de.s Adriati.sclien Meere 

 enthaltend Histologic," &c,, p 3, pi. i., figs. 6 — 11. 



t Ridley and Dendy, "Report on the Monaxonida, collected by H.M.S 

 * Challenger,' " pi. xlix., tig. 2a. 



