the Distinctive Characters in Amoeba. 135 



with the organization of the Ehizopods, at the same time that 

 it proves they cannot be regarded as unicellular. For although 

 my experience of Rhizopod structure compels me to deny the 

 normal presence of such an investiture as might legitimately be 

 termed either membranous, capsular, or vesicular — whatever 

 may be the true state of the case as regards A. bilimbosa, or the 

 encysted condition of any other form, I regard the exterior of 

 Amoeba as falling strictly within the definition of a ceW-" wall " 

 as propounded by Professor Karsten, the outer layer or ecto- 

 sarc for the time being, however indefinite, constituting the 

 homologue of the cell-membrane of the higher Protozoa and 

 Protophyta ; whilst the facts connected with the truly cellular 

 nature of the sometimes single, sometimes multiple nucleus 

 demonstrate the truth of the concluding sentence of that au- 

 thor's paper. His views are summarily embodied as follows : — 



"The primitive form which matter capable of organization 

 assumes is that of the vesicle — the cell, inseparably composed of 

 membrane (wall) and contents. Each of these two constituents 

 of the elementary organ, constantly exerting the most intimate 

 influences upon each other, is capable of advancing further in its 

 development by the aid of the phjsico-chemical forces to which it 

 is indebted for its existence." And again, " Owing to the com- 

 plicated structure of the tissue-cells which enter into the com- 

 position of developed organisms, it is erroneous to speak of 

 unicellular plants and animals. With as little reason can we 

 imagine cells without membranes ; such bodies, in my opinion, 

 should be designated drops or granules" * — thereby confirming 

 the opinion I guardedly expressed when speaking of the true 

 significance of a membranous nuclear cell in Amoeba villosa 

 (Annals, June, p. 438). 



The basal sarcode in Amoeba, and probably in all the lower 

 animals, is generally regarded as a homogeneous, colourless or 

 nearly colourless,, hyaline mucus, within which a number of 

 extremely minute granules are suspended. This granularity, 

 coupled with a high refractive power, serves at once to distin- 

 guish sarcode from water, and hence enables me to afiirm that 

 the clear space surrounding the nuclear mass of A. villosa is 

 composed of this substance. 



It will be observed that there is a discrepancy between Mr. 

 Carter's and my estimate of the size of the crystalloids, his 

 measurement of the largest met with being recorded as ^roVo^h 

 of an inch in length, whereas my largest is only 4 - ^'oo ^^^ of ^^ 

 inch in length. But inasmuch as Mr. Carter states that the 



* Translated by Dr. Arlidge from a separate impression from Poggen- 

 dorff's ' Annalen ' (vol. cxviii., Berlin, 186y), and published in the ' Annals ' 

 for July 1863. 



