Mr. H. J. Carter on the Subs2)herous Sponges. 19 



Now, surely, it cannot be said that these globular crystal- 

 loids, firmly packed in between the cells of an Ascidian and 

 bound down by its general tough integument, can be the 

 " ovaria " of this animal. 



In short, I can see nothing to account for the opinion that 

 the globular crystalloids of the crust of Geodta and Pachyma- 

 tisma (for they are both alike) are " ovaria," excepting the 

 undiscovered presence of any other propagative form in the 

 species, in which case, if the crystalloids were ovaria, they 

 would demonstrate the fact directly. These animals do not 

 propagate by a gemmule here and there, but by tens of thou- 

 sands ; and among all the crystalloids of these two sponges 

 that I have examined in all stages of development, by fire, 

 Avater, fracture, and acid, I have not been able to find one 

 with anything approaching to a central cavity. 



With reference to the Ascidian mentioned, I might also here 

 cursorily state that it is almost as full of starch -granules, dis- 

 persed among the crystalloids, as would be an equal amount of 

 potato-substance. The conical projections of the crystalloids, 

 too, have very much the appearance of" dog's tooth " calcspar, 

 as if structurally developed under a combination of animal 

 and mineral influence. 



Reproductive Elements. 



In an illustrated paper on the identity of the seed-like body 

 of Spongilla and the winter-egg of the freshwater Bryozoa 

 (Annals, ser. 3. voL iii. p. 331, 1859), I have endeavoured 

 to show that the seed-like bodies of 8pongilla are so nearly 

 allied in their structure and nature to the winter-eggs of the 

 so-called freshwater polypes that, for the present at least, we 

 must regard them as gemmules. This resemblance was pointed 

 out long ago by Meyen {pp. Johnston, op. cit. p. 154, footnote). 

 They are chiefly formed in the oldest part of the structure 

 (that is, at the base of Spongilla)^ and are eliminated on the 

 disintegration of the mass, which is more or less effected by 

 the winds and the diy weather to which it is exposed after the 

 water has left it adhering to the sides of the tanks and quarry- 

 pits in the island of Bombay, where it so abundantly grows. 

 Subsequently, when the tanks become refilled by " the rains," 

 towards the end of July, the eliminated seed-like bodies may 

 be seen in great numbers, together with the winter-eggs of the 

 freshwater Bryozoa, floating about on the surface of the water, 

 where, after having become thoroughly soaked, they begin to 

 throw out their sponge-like substance, and, adhering to float- 

 ing objects on, or to rocks beneath, the water, finally grow 

 there into new sponges ; while the seed-like bodies still re- 



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