32 Mr. H.J. Carter on the Ultimate Structure of Spoiigilla. 



May we not infer from this that these indicate the presence of 

 similar cells in the interior of Amoeba, &c. ? If this should be 

 the case, and that they are homologous with the liver-cells of the 

 Planarice, then I shall have been right in my original conjecture 

 that the "granules" are the homologues of the "spherical 

 cells*." 



It is proper to notice here, also, the affinities which Spongilla 

 has to the vegetable kingdom. I have already alluded to the 

 resemblance between it and the cell of the Characese at an early 

 period, when both are filled with vacuoles ; nor is the plurality 

 of the contracting vesicle in the Rhizopoda generally, when ma- 

 tured, a less striking instance of the transition of the vesicula or 

 contracting vesicle in the more animal Infusoria, into the passive 

 vacuoles of the vegetable protoplasm. The nucleus of the Rhi- 

 zopoda is typical of that which exists in the vegetable cell. 

 Similar "granules" are also seen in motion at the extremity of 

 the root-cell of Chara, in the "fixed protoplasmf;" and at pre- 

 sent no difierence can be shown between the molecular proto- 

 plasm in each ; while as regards the production of starch, that 

 is so common in every specimen of Spongilla that is met with, 

 more particularly at the end of the season, that its presence is 

 no novelty whatever. The mode of taking nourishment is dif- 

 ferent, but I have already stated that when the protoplasm 

 leaves the cell of Spirogyra%, and even before its exit, it encloses 

 nutrient matter after the manner of Amoeba. For the last 

 year, some plants of Chara, which I reared from the nucules, 

 and have grown in a glass jar, have only been kept vigorous by 

 dead grasshoppers, which every now and then, when the Chara 

 begins to grow lighter in colour and meagre in appearance, have, 

 by being thrown into the water, restored it to its former condi- 

 tion §. So that the same elements, under dififerent circum- 

 stances, are thus made subservient to the same purposes. Hence 

 the sponge-cell appears to be but a naked condition of the 

 vegetable cell, and thus to become the first, or among the first, 

 of animal organisms. 



I would here also recur to the forms which the substance of 

 Spongilla assumes when, under the dread of starvation, it leaves 



* Annals, vol. xviii. p. 125. t Idem, vol. xix. pi. 3. fig. 2/. 



X Idem, vol. xix. p. 259. 



§ In this instance I have noticed, that the moment the plants become 

 robust, they cease to bear fruit ; while, when they become impoverished, 

 they throw forth nucules, — the physiology of which appears to be evident : 

 viz. so long as there is plenty of nourishment to build up more structure 

 for ultimately making more propagative germs, this alone occupies the 

 instinct of the plant ; but the moment the nourishment ceases, the instinct- 

 ive fear of faiUng in the propagative department causes the plant to turn 

 its attention to preserve itself by forming seeds. 



