246 GENEEAL HISTORY OF THE INFrSOEIA. 



quite unable to admit it as even probable. They have been supposed by- 

 several authors to have a benumbing effect upon the prey they may seize ; 

 but this view is merely hypothetical. '' It is nevertheless," says Claparede 

 {ojp. cit. p. 287), " quite certain that small animalcules and plants remain 

 adherent to them ; for these rays are true tentacles. Indeed, their contact 

 must have something very unpleasant about it ; for larger Infusoria, even 

 such as Paramecium Aurelia, on coming accidentally within their reach, start 

 back with the greatest rapidity, sometimes even dragging the Actinophrys a 

 considerable distance with them." So, again, Weston states — '' on the instant 

 of contact with these tentacles, the victim appears paralysed." Yet, withal, 

 it seems clear that, unless actual contact ensue, no harm attends proximity 

 to the formidable prehensile organs ; for animalcules may frequently be seen 

 swimming about unharmed among them. Kolliker rejected the supposition 

 of an intrinsic fatal influence existing in the filaments, wliich appeared to 

 him to serve only for retaining the prey by their adhesive surface, and pro- 

 bably to involve it with their extremely fine extremities, until they di-ew it 

 by their progressive contraction to the surface. Even after being seized upon, 

 an animalcule may escape, both by great exertions in tearing itself away, and 

 sometimes, as Mr. Weston remarks, by the act of the ActhiopTirys, when, as 

 it Avould seem, its appetite was " sated, or the prisoner was not approved ; 

 for after remaining stunned sometimes for a few seconds, four or five, some- 

 times much longer, ciliary motion (of a Vorticella, for instance) is feebly com- 

 menced, not ^^ith sufiicient energy to produce motion, but as if a return to 

 vitality were being effected by struggles ; shortly it is seen to glide off the 

 tentacle (as if this appendage possessed the power both of appropriation and 

 rejection), and, frequently with but little sign of recovered life, it slowly floats 

 out of the field." One function distinctly possessed by these tentacula is 

 that of sensibility. KoUiker has thus well conveyed this fact {op. cit. p. 33) : 

 — "Actinoj)h'i/s perceives mechanical influences, and reacts upon them by 

 movements. This is proved by what takes place when animalcules, &c. 

 remain aflixed to its tentacles, and moreover by the circumstance that, when 

 the water in which it is contained is carelessly agitated, every ActinopJirys 

 contracts its tentacles and even makes them disappear altogether (and, 

 indeed, with greater speed than is otherwise perceived in these creatures), 

 and when all is quiet they are again protruded. These filaments, conse- 

 quently, may just as well be called tactile as prehensile ; or it may more 

 generally be said, that the substance of the body is both contractile and 

 sensitive." 



Movements. — There is not much to be said respecting the movements of 

 the Actinophryina ; for these beings are even more sluggish than the Amcebcea, 

 and appear to change place rather as mere passive particles of matter than as 

 living animals. They may float hither and thither in the fluid surrounding 

 them, or rise to the sm-face ; but how this latter movement is effected we have 

 no data to show. On this subject KoUiker has the following paragraph : — 

 " Its power of moving from place to place is indubitable ; for it was found, for 

 instance, that when a vessel, with several individuals of Actinophrys, was 

 emptied into a flat glass capsule, they were all at flrst scattered about at the 

 bottom, but subsequently, after from 12 to 24 hoiu's, were all floating at the 

 surface, and, indeed, at the side of the capsule. Ehrenberg and Eichhom 

 assert that the ascension of Actinophrys in the water is effected by the taking 

 in, and the descent by the gi\ing out, of air. But this is certainly not the 

 case ; for whence could they obtain this air ? Can it be said they secrete it 

 within themselves like fishes ? In that case it must be visible. It appears 

 to the author more natural that the rising and sinking should be effected by 



