174 XATTJKAL HISTORY SOCIETY OF DUBLIN. 



kingdom, or as tending towards a mutation of its vegetable nature. And 

 from this it of course follows that an organism whose structural affinities 

 and reproduction are unknown, but which may possibly present an ac- 

 tively contractile, even locomotive, power, need not on this latter account 

 be assumed as therefore necessarily an animal. In the former category 

 fall the Volvocinacege and Ehizidium ; in the latter category Euglena 

 and its allies, the so-called Astasisean Infusoria, suggest themselves; 

 and these must of course wait until their reproduction and history are 

 better known before we can feel satisfied as to their true position, yet 

 it seems highly probable that these will presently, if they do not even 

 now, take their place amongst admitted plants. 



Several writers have indeed, from time to time, as is well known, 

 put forward the (now, I think, generally accepted) view that the proto- 

 plasm of the vegetable and the sarcode of the animal cell are identical 

 in nature ; and, in seeking for analogies as regards contractility in the 

 vegetable protoplasm as compared with the animal, and as demonstrative 

 thereof, special attention has been directed to several of the now familiar 

 phenomena displayed by certain vegetable cells. Such are the vibratory 

 movement of cilia, the drawing in of these, the circulatory movements 

 of the cell- contents, as in the hairs of the stamens of Tradescantia, &c, 

 the contractile vacuole in G-onium, Vol vox, &c, and so forth. But while 

 these are, I think, unquestionably to a considerable, but more limited, 

 extent, manifestations of the same phenomenon, it seems to me that none 

 of these cases present so exact an analogy, strongly as they may indicate 

 it, with the rhizopodous contractility, as do the amoeboid bodies of Ste- 

 phanosphsera, of Yolvox, of the Moss-radicles, and of Ehizidium. The 

 amoeboid bodies of Stephanosphaera seem to display this rhizopodous 

 contractility in greatly the most marked or exaggerated degree, as their 

 vigorous and energetic powers of locomotion indicate; in them, and in- 

 deed in those of Volvox, of the Moss and of Ehizidium, the pseudopodal 

 processes and their mode of protrusion and withdrawal, the flow of the 

 granules, and the locomotion of the whole body, were in all respects 

 analogous to the similar phenomena evinced by a true Amoeba. 



But I need hardly add, after what has been advanced, that I do not 

 suppose for a moment that there was in these cases actually an absolute 

 conversion of the vegetable cell into an animal. In the case of the 

 Stephanosphasra and of Ehizidium, this condition is certainly but very 

 temporary — a few hours at most, and the quasi-animal condition becomes 

 relinquished for the strictly vegetable. In not one of the cases cited 

 were there to be seen any foreign bodies of any kind within the sub- 

 stance of the amoeboid structures. It may be said, indeed, so far as this 

 bears upon the question, that it is only negative evidence ; and in the case 

 now brought forward there were very few, if any, foreign bodies at all 

 existent in the material under examination. In his memoir, describing 

 his recent and masterly researches on certain minute parasitic Eungi,* 



* " Ann. des Sciences Naturelles," IV. Serie, tome xx (Botanique), p. 5 ; also " Flora" 

 (1863), p. 163. 



