333 Mr. H. J. Carter on the Seed-like Body of Spongilla 



within the last three months I have considered them more par- 

 ticularly like sporangia, and hence have suggested this as more 

 suitable for them*. They have also been compared by some to 

 the " winter-eggs " of Polypes ; and this indeed was the most 

 fortunate conjecture of all, for, as will presently be seen, they 

 are almost identical with them in every respect. Before, how- 

 ever, entering upon the comparative descriptions of these bodies in 

 S'ponx/illa and the freshwater Bryozoa, it is desirable that I should 

 briefly describe the structure of Sponffilla itself, that the reader 

 may know exactly what is now presented for his information. 



To obtain an idea of the structure of Spungilla, we have only 

 to conceive a branch of canals to which are attached a number 

 of spherical bodies like a bunch of grapes, and this branch, &c., 

 imbedded in a gelatinous mass charged with spicules and per- 

 meated in all directions with another class of canals opening on 

 the surface of the gelatinous mass by numerous holes, into the 

 internal parts of which dip the spherical bodies. We have now 

 to enclose all this, except the end of the branch, within a delicate 

 soft membrane, like a bag or veil, perforated with apertures, and 

 kept at a distance from the gelatinous mass, &c., by bundles of 

 spicules projecting from the latter. Add to this a rush of the 

 water (in which the Spongilla may be growing), with any nutri- 

 tive particles that may be suspended in it, in through the aper- 

 tures of the enclosing membrane; then into the canals of the 

 gelatinous mass; then the particles being caught up by the 

 spherical bodies, which are respectively covered with a cortical 

 layer of monociliated and unciliatcd polymorphic cells for this 

 purpose; then the nutritive particles undergoing digestion in 

 these polymorphic cells, as in Amopbce ; and, finally, the ingesta 

 in like manner discharged into the branch of canals to which 

 the spherical bodies are attached ; — and we have the type of 

 Spongilla, that is, the first portion of Spongilla which grows 

 from the " seed-like body.^^ Afterwards, when the Spongilla 

 has attained a larger size, it consists of a number of such typical 

 portions agglomerated undistinguishably and inseparably into 

 an amorphous mass ; hence it is only when the Spongilla is first 

 grown from the seed-like body, or probably from the ciliated 

 gemmule, that it can well be studied elementarily f. 



It may now be asked. What are these spherical bodies ? Are 

 they each animals of the Spongilla, and analogous to the polypes 

 of a polypidom ; or is this typical portion to be considered a 

 single animal, and the spherical bodies as the digesting organs 

 situated in the cavities of the gelatinous mass, as a stomach, 



* Annals, vol. iii. p. 13, 1859. 



t For a more detailed description of Spongilla, see ' Annals,' vol. xx. 

 p. 21, 1857. 



