OF THE PROTOZOA. ACINETINA. 261 



aystalUna, and in the so-called Acimta with the tongue-like process 

 (XXIII. 17, 20). 



If this account be admitted, that certain Acinetce display no power of self- 

 nutrition, and seem destined only to subserve, as mere media, the purposes of 

 reproduction, an independent nature could scarcely be attributed to such 

 beings, and their history would be entirely comprehended in that of the 

 beings in whose cycle of development they might enter as one link. Lach- 

 mann (A. N. H. 1857, xix. p. 222) has the follomng account of the mode in 

 which Acinetina nourish themselves : — "Each ray" (tentacle) "is a sucking 

 proboscis, and we soon see that a cuiTent of chjTue-particles runs from the 

 alimentarj' cavit}' of the captured Infusorium into the body of the Acinetaj 

 through the axis of the rays, which, after seizing the prey, have become 

 shortened and thickened. In the body of the Acineta the chyme-particles 

 still run at first in a slender row, but afterwards they coUect in a di'op, which 

 although drops are also formed in the chjTne of the Acineta by other suckers, 

 soon becomes amalgamated with these. AMien a considerable quantity of the 

 chyme of the captured animal has passed over into the body of the Acineta^ 

 a remarkable change gradually takes place in its appearance: if it was pre\dously 

 pale, nearly transparent, and only very finely granulated, larger dark globules, 

 resembKng fat-di'ops, now make their appearance here and there ; and these 

 soon increase so that the body (which at the same time, of coui^se, increases 

 in thickness) acquires a coarsely-granular aspect, and becomes opaque. The 

 globules or drops which make their appearance can only be formed in the 

 body of the Acineta, as they are far larger than the chyme-particles which 

 are seen flowing through the sucker. The animal whose contents are thus 

 sucked out, gradually coUapses and dies ; many become liquefied when only 

 a little of the chyme is extracted from them, others still live for a long time ; 

 in large animals, such as Stylonychia Mytilus, Paramecium Aurelia, &c., the 

 sucking often continues for several hours." 



Origin' and Development of Ace^etina. — In our history of the development 

 of Vorticellina, Stein's hypothesis of the transformation of those highly-de- 

 veloped Ciliata into Acinetiform beings as a stage of existence necessary to 

 their development by embryos, and of the reconversion of the embryos into 

 Ciliata of the primitive type, is sufficiently enlarged upon. In the same 

 chapter, moreover, Cienkowsky's contradictory statement and observation are 

 detailed, viz. that, though Acinetce develope ciliated embiyos, yet these 

 embryos give origin to beings like those they issue from, and are not trans- 

 formed into Vorticellhia. According to this opinion, the Acinetina take a 

 position as independent beings in the animal series. Stein determined, to 

 his own satisfaction, an Acinetiform phase in the following Vorticellina and 

 Ophrydina : — 



Cothurnia maritima. SpirocJiona gemmipara. 



Epistylis branchiophila. Vaginicola crystallina. 



Opercularia articulata. VorticeUa microstoma, 



Opercularia berberina. VorticeUa nebulifera. 



Opercularia Lichtensteinii . ZootJiamnium affine, 



Ophrydium versatile. CarcTiesium pygmceum ? 



The description of the Acinetiform beings assigned to the species enume- 

 rated is given in the Systematic History of the Acinetina, which wiU likewise 

 afford a more complete idea of the structure and forms of this peculiar class 

 of beings than the above general history itself. 



