154 BRITISH SPONGES: 



cases it happens, however, that while even within the sphserula 

 the globules give origin to the formation of other sphaerulae, 

 just as they do when expelled from it. Thus Gervais has found 

 beneath the bases of some masses of Spongillse a great number 

 of these parent sphaerulae, which themselves contained two, thi*ee, 

 or even four others, having the same structure, the same com- 

 position, and the same yellowish colom*.* 



There appears reason to believe that the contained globules 

 are essentially the same as the gelatinous granules of the organic 

 mucus. The observations of Professor Grant are, it is true, op- 

 posed to this conclusion, for his description of the contained globules 

 diifers from that which he has given of the granules ;-f- nor did 

 he find that either thev or the entire sporidia suffered any change, 

 or showed any sign of germinating, during the six weeks they 



* According to Meyen these spliEerulae, sporidia or sporangia (for all 

 these terms are applied to them) of Spongilla are essentially distinct from 

 the sporangia of Algoe, and are similar to what are denominated the winter 

 eggs of polypes. " They consist of a coriaceous skin, which is covered 

 over with a thick crust, except at a small circular spot. This crust is 

 composed of minute and delicate siliceous particles of the 3-50th of a 

 millimetre in length, which particles are composed of vertically placed 

 spicula of 1-250 to l-200th of a Mm. broad, at whose extremities near 

 the circumference, more or less toothed, little disks are found. At an 

 after period from 4 — 5, or more generally 7 — 8 of the teeth elongate, 

 becoming uncinate and curved rays. Between the spicula exists carbo- 

 nate of lime, having a cellular structure. Within the eggs are delicate 

 cells filled with various granular matters. Besides the larger siliceous 

 spicula found within the substance of the sponge, there exists more de- 

 licate ones of the l-16th to 1-lOth of a Mm. long, having upon their sur- 

 face numerous little points, which elongate as their age increases." Mi- 

 croscopic Journal, i. p. 42. 



f He describes them as gelatinous globules, each containing " about a 

 hundred very small white opake particles, which lie close together on one 

 side of the globule, and occupy about a third of its capacity." The ge- 

 latinous portion is soluble, but the white particles suffered no change, 

 " though they seem to possess the power of slowly changing their posi- 

 tions." 



