ABCHEE ON STEPHANOSI'H^ERA PLUVIALIS (COHN). 173 



granular, are powerfully and rapidly acted upon by momentary and ever 

 fitful changes of the lobose expansions and the contractile efforts of the 

 protoplasmic mass, and the granules flow. In the other, the contents, 

 still maintaining a coherence and much of their original disposition, are 

 slowly (hut surely) acted upon by the gradual, and except at intervals 

 imperceptible, but not less actual, contractile power of the protoplasmic 

 mass, and they are thereby carried with it. Even in the latter instance 

 there does exist a certain amount of the same kind of movement of the 

 solid contents as in the former ; but as the whole process is so greatly 

 slower, and the contractile force comparatively so much less energetic, 

 it is not so perceptible. In my mind the analogy is exact — the difference 

 is in degree. 



Now, let us for a moment imagine an Amoeba princeps or diffluens 

 imprisoned within such a rigid cyst as that of the parent-membrane of 

 my MesoUenium miriflcum, or within the cavity of a joint of a Spirogyra, 

 and with only one narrow aperture, considerably smaller than itself by 

 which it could possibly get free. Now, further, let us suppose our Amoeba 

 acted upon by the impulse to go out, — there can be no doubt but that it 

 could perform the feat — and its modus operandi, so far as I see, would 

 not essentially differ from that of the true vegetable cell, in actually 

 effecting the same object in the course of its own natural developmental 

 vital processes. 



Starting, then, from such cases, and passing on through the more 

 decidedly reptant amoeboid bodies of Rhizidium, of the Moss, of Volvox, 

 we arrive at the vigorously, and actively and freely crawling, energe- 

 tically and comparatively rapidly locomotive, amoeboid bodies of Stepha- 

 nosphsera. We must regard, I think, the whole as manifestations of one 

 and the same phenomenon — in the first, lasting for a shorter period, and 

 more feebly and slowly evinced ; in the latter, persisting for a longer 

 period, and in the cases cited gradually more and more energetically 

 and decidedly displayed, until (leaving the Myxogastres aside for the 

 present), in the case of Stephanosphaera this extraordinary condition 

 seems to culminate. 



If this reasoning be correct, then, contractility, amoeboid contractility — 

 for I can find no more comprehensive and expressive single adjective 

 term — must be accepted as an inherent quality or characteristic, occa- 

 sionally more or less vividly evinced, of the vegetable cell-contents, and 

 this in common with the animal ; in other words, that the nature of 

 the protoplasm in each is similar, as has indeed, as is well known, before 

 been urged on grounds not so strong; thus reversing Siebold's doctrine 

 that this very contractility formed the strongest distinction between ani- 

 mals and plants, as he assumed it to be present in the former, and absent in 

 the latter of the two kingdoms of the organic world. Therefore an or- 

 ganism whose known structural affinities, and whose mode of growth and 

 of ultimate fructification, point it out as truly a plant, but of which, 

 however, certain cells may for a time assume a contractile, even a loco- 

 motive quasi-rhizopodous state, must not by any means on this latter 

 account alone be assumed as even temporarily belonging to the animal 



