with some Remarks on the Nature of the Spongige Marinse. 377 



And a portion of it is translated in an article " On the Metamorphoses of the 

 Reproductive Bodies of some Alga;, said to possess successively an animal 

 and a vegetable Existence," in the Mag. of Nat. Hist. vol. i. no. 4. for Novem- 

 ber 1828, p. 307. and is illustrated by a wood-cut. Here the locomotive glo- 

 bules, or more correctly the sporules or germs of the Ectosperma clavata, are 

 described as being " oval, dark at one extremity, and almost transparent at 

 the other ;" which characters exactly resemble those of the sporules of the 

 Spongilla. Also the account of their movements and mode of swimming is 

 very nearly the same, and is thus translated in p. 307 : " The minute globules 

 (were) unequal both in colour and size. Many of them swam freely here and 

 there, moving at their option, in one way or another, retiring and approaching 

 one another, gliding round globules that were motionless, stopping, and again 

 setting themselves in motion exactly like animated beings." I have therefore 

 no hesitation in asserting that the movements of both are in all probability 

 effected by the same means. 



But it unfortunately does not appear from Unger's figures in tab. 40, that 

 any powerful microscope had been used to magnify the locomotive sporules in 

 question, in order to prove whether or not they possessed cilia, or any other 

 like organs, by which their motions might be partly or altogether performed. 

 Nevertheless I have taken much trouble in endeavouring to ascertain by what 

 means the sporules of the River Sponge swim and move about. 



Under the highest power of Jones's improved compound microscope, with 

 which my observations on these sporules, whilst in their fresh and locomotive 

 state, were made, I could only perceive certain rapid streams or currents 

 taking place on their sides, which induced me to think they were currents or 

 vibrations in the water caused by little tufts of cilia, with which the membra- 

 nous coverings of the sporules seemed to be furnished, and by which their 

 movements, as 1 fancied, were effected. But having selected many of these 

 sporules when in full possession, and at the time they were actually making 

 use, of their moving power, I preserved them in a phial of spirits* : some of 

 these I have lately (November 26th) re-examined under a more modern and 

 perfect instrument, one of Powell's compound microscopes, and belonging to 



* This phial, containing many of these locomotive sporules immersed in spirits, I beg to present to 

 the Society. 



3 D 2 



