244 GENERAL HISTORY OF THE INFUSORIA. 



although slower than even those of Amoeba. Stein represents the usual orbi- 

 cular figiu'e to be frequently exchanged for a pear-shaped, an oblong, or a 

 partially angular and lobed one, — varieties dependent, according to his state- 

 ments, upon inherent changes taking place in connexion with progressive de- 

 velopmental phenomena. The aspect of the entire organism is, moreover, 

 modified from time to time, by the altered length, direction, and disappear- 

 ance of a portion of the filaments, chiefly consequent on the act of prehension 

 in which they are engaged. Stein, indeed, represents still more considerable 

 modifications, involving the complete disappearance of tentacles from various 

 portions of the surface, and the aggregation of the rest upon angular emi- 

 nences in a penicillate manner, — an occurrence which would assimilate still 

 more closely the Actiiiojyhryina and the Ac'inetina. Lastly, the figure is varied 

 durmg the acts of self-division and of conjugation, as will be presently noticed 

 at large. 



In coloiu' the Actinopliryina are commonly of a milky-yellow or greyish 

 hue, the intensity of which is determined by the number of contained granules, 

 or, in other vvords, by the supply of nutriment. Acetic acid and cold solution 

 of potash remove colour ; the latter fluid, when heated rapidly, dissolves the 

 entire mass, and indicates its nitrogenous natiu^e. Observers are not agreed 

 on the point of the existence of an integment. Dujardin, Xolliker, and Cla- 

 parede deny it, whilst Stein, Perty, and Mr. Weston {J. M. S. 1856) affirm its 

 presence. Among the latter, one speaks of it as a hyaloid membrane ; another 

 declares it to be double, consisting of a delicate elastic membrane immediately 

 investing the contractile substance of the animalcules, covered by an outer 

 fii^mer timic. This statement is especially made by Stein of Podophrya, which 

 is, in his opinion, a merely stalked variety oi Actino_phrys, and indistinguishable 

 from it even as a species (XXIII. 1, 3, 4, 5). On the contrary, Cienkowsky 

 (J. M. S. 1857, p. 98) remarks that he could discover no membrane surroimd- 

 ing the body of that animalcule. To account for this diversity in descriptive 

 details, we must suppose that the different authors have not had the same 

 animalcule under observation ; indeed Stein asserts that Kolliker did not 

 examine Actinophrys Sol, as he supposed, but Act. Eichornii. Lieberkuhn 

 likewise suggests that Claparede and Kolliker have written upon difi'erent 

 species under the same name ; and Stein must, we beheve, have committed 

 a similar mistake ; for the Actinophrys and Podophrya described by him difter 

 in so many important particulars from beings bearing the same name in the 

 writings of others, that it seems impossible they can be identical with them. 

 The fact seems to be that certain Acinetoi have in external characters so close 

 resemblance to Act inophryma, thai they may be mistaken for them. Be this how 

 it may, if we take into consideration the pecuhar relation of the tentacles with 

 the body, their movements, and especially the mode of introducing food into 

 the interior, it seems quite improbable that there should be a firm investing 

 membrane. These remarks, indeed, apply only to the usual forms or phases 

 of these beings ; for when an encysting process proceeds, then, certainly, 

 an external envelope mil manifest itself, yet not without the sacrifice of the 

 tentacula and of the ordinary phenomena of vital activity, the ingestion of 

 food and the like. " It is impossible," to quote Claparede {A. N. H. 1855, xv. 

 p. 286), " to admit the existence of a general integument, as Actinophrys can 

 push out the mucous or gelatinous matter of which its body is composed, take 

 in nourishment, or evacuate the residue of digestion, from any point of its 

 surface at pleasure." In this same observer's opinion, Perty's notice and 

 figures of a capsule are evidently erroneous, the consequence of optical illu- 

 sion. Mr. Carter adopts an intermediate opinion, by admitting the existence 

 of an enveloping pellicula, like that in Amoeba, which, although not a separable 



