and Reproduction of the Polythalarula. 317 



inner sense corresponding with the object to be indicated, as I 

 assert to be the case with the word " protoplasm/' in which the 

 mystery of an entire organism is intimated, we must prefer this 

 to one which is less significant. 



Although, from what has been stated, tiie contractile cortical 

 substance of the large Rhizopoda, as well as of the small ones, 

 consists of a protoplasm not capable of resolution into cells (not- 

 withstanding that, in regard to its development, it may be refer- 

 able to one or several cells), this by no means implies that the 

 whole inner part of the Rhizopod-body enclosed within the shell 

 must necessarily consist of the same substance. In my work on 

 the organization of the Polythalamia, I have already called atten- 

 tion to the fact that in all the larger Rhizopoda we have to distin- 

 guish an inner, usually coloured and more quiescent part, from 

 the external, colourless, motile part which exclusively emits pro- 

 cesses. The two parts pass gradually into each other; and 

 definite data as to essential differences in the internal organiza- 

 tion were not obtained by my observations. Vesicles of colour- 

 ing matter, large granules, and nucleoli, which render the mass 

 opake, distinguish the inner from the outer substance ; but I was 

 unable to detect any cellular composition, or any differentiation 

 of definite systems of organs, even in this part of the body of 

 the Rhizopoda. Ehrenberg assumes such a differentiation, and 

 speaks, for example, of an intestinal canal permeating the body 

 of the Rhizopod, which, of course, must have had a special wall, 

 different from the surrounding substance. Evidence of the ex- 

 istence of anything of the kind is not adduced ; and I must most 

 positively dispute its existence from numerous observations, 

 repeated down to the most recent time, upon living and, especially, 

 transparent Polythalamia. 



Of the fact that, as I previously asserted, young, transparent 

 forms of Cornuspira, Miliola, and Rotalia are destitute of a 

 contractile vesicle, I have also repeatedly (and, as I believe, posi- 

 tively) convinced myself. 



Nevertheless, as 1 have stated, there exist in the freshwater 

 Rhizopods, and even in Amoeba, indications of a difference be- 

 tween the cortical and medullary substance. If the organisms 

 have been produced from one cell, this might be referred to the 

 difference between the cortical layer of the protoplasm and the 

 internal parts, observable in many young, membraneless cells 

 (I mean the diff'erence which exists in the embryonal cells figured 

 by Remak in pi. 11. fig. 17 of his work upon the development 

 of the Vertebrata, consisting in the hyaline basal substance of 

 the protoplasm here rising, at least in sj)ots, above the portion 

 enclosing the granules). Indeed the same thing is observed in 



