388 Dr. R. Greef on the Structure and 



firm, limited cortical layer and an inner space has not yet 

 been evolved, nay in many cases even an outer skin cannot be 

 demonstrated ; in these, however, the organs of the body have 

 not yet found any definite position, but they are driven about 

 in the interior with the mass of contents. Nevertheless I am 

 far from supposing the whole Amoeban body, especially in 

 the large, independent, infusorium-like Amoebce, to consist of 

 a simple homogeneous protoplasm ; but no doubt, as I hope to 

 demonstrate more completely on another occasion, we have 

 here to distinguish various substances and structures differing 

 from each other in form and vital manifestation. Far less can 

 we declare that an animal body comparatively so highly 

 organized as that we have before us in the Vorticell^e, consists 

 of mere protoplasm. Might we not, with almost equal justice, 

 refer a great part of the Ccelenterata, Vermes, &c. to the rank 

 of protoplasmic creatures ? 



It is sufficient that the observations cited determine me to 

 accept for the Vorticellan body a cortical layer situated under 

 the cuticula and not rotating with the rest of the contents, 

 embracing within, with a firm boundary, a space, the body- 

 cavity , which therefore, as, according to what has been stated, 

 the wedge-shaped hinder part of the Vorticellan body is filled 

 with the firm cortical parenchyma, has a shape like that of a 

 cup or finger-stall. 



The contents of the body-cavity consist of a thinly fluid 

 paste of incepted or more or less dissolved nutriment, l. e. of 

 chyme, which, by the constant accession of fresh nourishment 

 and water from without through the mouth, and by giving off" 

 exhausted material through the anus, is engaged in continual 

 change. In the interior of the body-cavity this nutritive paste 

 circulates constantly, as has been already fully described ; and 

 by this means the fine division and chymification (in other 

 words, the digestion of the nutritive substances on the one 

 hand, and on the other their diff'usion through the whole body) 

 are assisted. In the body-cavity of the Vorticellfe we conse- 

 quently see a gastrovascular space, in the full sense of the 

 words — a body-cavity in which digestion and circulation, i. e. 

 nutrition, is effected in precisely the same way as in the 

 Ccelenterata. 



By no means can this paste be regarded as " consisting 

 throughout of mere sarcode," as Stein mantains very decidedly 

 in favour of the protoplasm-theory. Leaving out of considera- 

 tion that such a universalization of protoplasm would lead us 

 to remote and obscure paths, as was the case formerly by 

 Dujardin's means, unprejudiced and careful observation is in 

 this point also strongly opposed to any such conception. And 



