22 MICROSCOPICAL OBJECTS FOUND 



Whether the sponge is an animal or a vegetable 

 is as yet an undecided question. Dr. JohnstoR 

 holds the latter opinion ; whilst Dr. Grant and 

 others, judging from the anomalous movements 

 they communicate to surrounding fluids, so often 

 spoken of as a circulation,* and from the develope- 

 raent and motion of their ciliated germs, contend 

 for their animal nature. The latter, however, 

 have been already shown to be phenomena 

 often observed in the lower departments of the 

 vegetable kingdom. Mr. Bowerbank, after point- 

 ing out the existence of spicula in some of the 

 Corallid8e( Anthopora) so closely resembling those 

 of many of the Halichondrise (fig. 46) as not to be 

 distinguished from them, argues from this and 

 some other analogous facts in favour of their 



* This peculiar movement is admitted by all to be a diffi- 

 culty in the way of their being regarded as vegetables. It is 

 much to be desired that the term " circulation" should cease 

 to be applied to it, as the expression gives an erroneous idea 

 of the nature of the movement, and most probably of its object 

 also ; for to consider sponges as possessing a true circulation 

 and capillary vessels, as is done by some microscopic observers, 

 is to set at defiance all the fundamental truths of physiology 

 — truths not to be assailed except after long observation, and 

 on the clearest possible evidence. 



