iv'ith some Remai-hs on the Nature of the Spongice Marinee. 371 



were extraneous and parasitical bodies, entirely independent and unconnected 

 with the material of the Sponge itself, because they did so extremely resemble 

 some of the Infusorian Animalcules. 



These bodies are very minute, though some are less than others, and are 

 plainly visible to the naked eye ; they are white, of a somewhat globular, or 

 rather, more oval shape, the lower or smaller portion being opake, and the 

 upper transparent and membranous. Their movements in swimming were no 

 less astonishing than elegant ; ascending from tlie Sponge at the bottom of the 

 water to the surface ; floating gently on the surface ; or traversing the middle 

 of the fluid, like a balloon in the air; or suspending themselves nearly in one 

 spot ; or whirling round and round, describing larger or smaller circles in the 

 water ; approaching or avoiding each otlier ; but, when performing their 

 quicker progressions, they move along on their sides with their rounder ends 

 precedent. Indeed Baker's account of the motions of the P'olvox glohator*, 

 which he calls the Globe animal, is so strikingly descriptive of the movements 

 of these germlike bodies, and so similar, that I trust you will pardon me with 

 quoting it here : " It moves in all directions, forwards or backwards, up or 

 down, either rolling over and over like a bowl, spinning horizontally like a 

 top, or gliding along smoothly without turning itself at all. Sometimes its 

 motions are slow, at other times very swift ; and when it pleases, it can turn 

 round (as it were upon an axis) very nimbly without removing out of its 

 placef." Rœsel has depicted that minute Infusorian in his work on ' Insecten,' 

 vol. iii. plate 101, at figures 1 to 3 inclusive. Yet the germlike bodies more 

 nearly in form resemble the description of T^olvox globulus'^ ; so much so, that 



* But the spontaneous movements of the Volvox globator are performed by the agency of cilia : 

 for, according to Dr. Ehrenberg, its body is furnished with those minute organs. So indeed Baker 

 suspected ; and he thought that it appeared as if it were set round with short moveable hairs. 



t See " Employment for the Microscope," by H. Baker, 2nd edit., Lond. 1764, p. 323. 



% This species I have never met with. But I have just seen many living specimens of V. globator 

 under the microscope. I could easily perceive some differences between them and the locomotive germ- 

 like bodies of the River Sponge, as well with respect to their colour and structure as their motions. 

 These Infusoria axe yellower, much more transparent, and more completely globose ; within many of 

 the larger are distinctly seen several young or round transparent balls, which altogether resemble their 

 gravid parents ; they swam and moved about with greater power and \'igour ; and their more active 

 and busy movements struck me as if they were under a more decidedly spontaneous control or infln- 

 ence. Rœsel's figures above referred to are accurate — J. H., May 16, 1839. 



