on the Animal or Vegetable Nature of Sponges. 423 



capsules have been detected. But, nevertheless, no one has yet 

 succeeded in proving either a tube-relation or a body -relation of 

 an individual animal towards these bodies as ova. 



Matters are very different in the case of the true animal-stocks 

 of the Ascidia composita and of Halcijonella stagnorum, which are 

 often very like a Spongia or Spongilla. Here we have numerous 

 separate individual animals, each in its separate tube, and united 

 into a mass, and the very numerous ova occurring at the bottom 

 of these may be recognized as belonging to individual animals, 

 just as those Rotatoria which bear tubes deposit their ova in the 

 bottom of the tubes. 



As, therefore, a polypoid individuality could never be detected 

 in sponges — as, also, the granules regarded as ova occur only in 

 the interior of the base — and as, furtlicr, the tubes of all sponges 

 (and I have examined them myself repeatedly in the fresh state 

 in various seas) are always open empty canals which allow the 

 currents of water produced by ciliary action to flow to and fro 

 freely, — the greater part of these bodies appears rather to be a 

 plant-like cellular structure, the basal fruit-production of which 

 (and this is not known in all) has its still indistinct analogue in 

 that of many different Algae only now beginning to be elucidated, 

 and perhaps even in the Rhizocarpece. 



Even in the true Rhisocarpece the conditions of structure have 

 only been very recently elucidated; and as to their developmental 

 conditions a somewhat satisfactoiy result has only been quite 

 recently arrived at, as in the case of many Algse, of which, how- 

 ever, many forms still require further investigation. The 

 swarming young of the Spongiacea do not differ from those of 

 the Vaucherice and Saprolegnia : these were observed by linger 

 in 1827 in green VauchericPy but long before him, in 1745, by 

 Gruithuisen and Needham in Algae; and upon their very different 

 character from Infusoria, leaving all ciliary movement out of the 

 question, I have given a very detailed historical and physiological 

 critique in my ^ Infusionsthiere ^ (1838, p. 37). In what way 

 the segmentation (cell-formation ?) of the supposed ova of the 

 SpongillcB is to be interpreted must be left to further investigation 

 to determine. 



^lorcover, according as we suppose the Sponge to be an animal 

 or a vegetable body, the question of its nutriment must be affected 

 in opposite ways. If the Sponges be animals, their nourishment 

 must be conveyed from in front and without, through apertures 

 capable of being closed ; if they be plants, the nourishment 

 must be supposed to pass from the root-like base outwards and 

 forwards by endosmose and exosmose (diffusion). Artificial 

 siliceous nourishment presented to the base alone in elongated 

 Spongilla may perhaps decide this point. 



