150 ANATOMY AND PHYSIOLOGY 



from our European species S.fluviatilis, which I have had 

 frequent opportunities of observing^ and of confirming the 

 history given by him of their locomotive powers and con- 

 tinual inherent motions. The author designates these 

 bodies " sponge-cells," and treats of them as if they had a 

 well-defined cell-wall, while their eccentric changes of form 

 are perfectly inconsistent with such a structure. Lieberkuhn, 

 in treating of these bodies under the name of motile spores, 

 states that he has never succeeded in discerning a " cell- 

 membrane " around these particles, and my own observa- 

 tions are in perfect accordance with his experiences. The 

 truth appears simply to be that any minute mass of sarcode, 

 whether separated voluntarily or involuntarily, has inherent 

 life and locomotive power, and is capable of ultimately de- 

 veloping into a perfect sponge ; and in the course of this 

 process the dermal membrane is produced at a very early 

 period, and this, surrounding an agglomeration of minute 

 masses of sarcode, may have been mistaken by Carter for a 

 cell membrane. The same author, in his observations 

 ' On the Species, Structure, and Animality of the Fresh- 

 water Sponges in the Tanks of Bombay,' states " that when 

 the transparent spherical capsules which contain the granules 

 within the seed-like bodies are liberated by breaking open 

 the latter under water in a watch-glass, their first act is to 

 burst ; this takes place after the first thirty-six hours, and 

 their granules, which wiU presently be seen to be the true 

 ova of a proteaniform infusorium, varying in diameter from 

 about the ^^th part of an inch to a mere point, gradually 

 and uniformly become spread over the surface of the watch- 

 glass. On the second or third day (for this varies) each 

 granule will be observed to be provided with an extensible 

 pseudo-pediform base ; and the day after most of the largest 

 may be seen slowly progressing by its aid, or gliding over 

 the surface of the watch-glass in a globular form by means 

 of some other locomotive organs." 



This description is strikingly similar to the same author's 

 account of the masses of sarcode separated from the sarco- 

 dous lining of the interstitial canals of Spongilla ; but it 

 must be observed that, in the development of the egg, the 



