REVIEWS. 357 



longing to the suhldngdom Protozoa, having a more or less distinctly 

 differentiated skin., sometimes furnished with cilia, and a nucleus, but 

 with no other distinction of parts ; generally associated in masses, the 

 common body being strengthened by hard parts which are usually spicula ; 

 nutrition always by absorption of dissolved animal and vegetable matter 

 through the skin, there being neither mouth nor power of enclosing 

 prey. It is the view here presented of sponge structure, supposing a 

 sponge to be not an animal but a colony of closely united animals, 

 partaking in a common life and common plans for figui'e, aeration and 

 nutrition, each so-called amsebiform cell being a unicellular animal, 

 one individual of the colony, which seems to us to justify the connec- 

 tion of the ThalassicoUidse, and even the Gregarinidse, with Spongiadse, 

 as members of the same class, and taking the nutrition by absorption 

 as the most peculiar characteristic we would propose for the class the 

 name Rhopetica.* 



Dr. Bowerbank appears to us to treat the whole sponge as an ani- 

 mal, and the sarcode lining, composed of cells, which we consider as 

 the animalcules, as being its digestive system. There are no doubt facta 

 connected with the differences in different parts of sponges, and with 

 their reproductive system which seem to favour this view, though we 

 think them reconcilable with what we have proposed. But, leaving 

 questions of this kind for the present, and limiting our attention to the 

 true Sponges, which alone form the subject of Dr. Bowerbank's work, 

 we will ■ endeavour to collect some interesting particulars respecting 

 their organization. 



If a reader to whom the subject is altogether novel will inspect a 

 piece of the sponge of commerce, he will observe that it consists of a 

 flexible horny substance, seen with a magnifier to consist of a fine 

 net-work of inosculated fibres, presenting everywhere minute pores on 

 its surface, and having much larger openings scattered at intervals or 

 raised on elevations above the general surface. He understands that 

 this sponge has been cleaned from its animal matter, which consisted 

 of sarcode (the animal substance of Protozoa — an homogenous ani- 

 mated jelly,) covering all the fibres so as to form a lining to the chan- 



*From the Greek 'l?o<l>iw, absorbeo, " animals living by absorption." Should 

 the writer's view of tlie nature of Sponges be admitted, the new name is wanted 

 and he hopes will be found unobjectionable. If each Sponge is an individual 

 animal, Dr. Grant's name Porifera should not be superseded. In that case I have 

 HolLiug to suggest, respecting the affiuities of Thalassicollidse or Gregarinidffi. 



