the Distinctive Characters in Amoeba. 119 



from all aspects, and occupying only so much of the vesicular 

 chamber as to leave around it a clear hyaline space or ring, 

 varying from about ^tli to -rVtb of the total diameter of the 

 organ, and that this ring was broadest, in proportion to the 

 total diameter of the nuclear cell, in the smallest specimens. 



Without stopping to discuss the propriety of placing in an 

 entirely subsidiary light an organ of such importance as the 

 villous appendage (even granting, for the sake of argument, 

 that it had ever been previously included in any published 

 definition of A. princeps), I own myself at a loss to understand 

 how the character, specially alluded to as distinguishing that 

 form from all other freshwater Rhizopods examined by Mr. 

 Carter, could have been adduced under the circumstances ; for, 

 notwithstanding the " specific description " thus given of A. 

 princeps at the commencement of his paper, at the close of that 

 portion of it relating to Amoeba we are distinctly informed that 

 the villous appendage is " sometimes " altogether absent in A. 

 princeps, and even the grand distinctive feature of the nucleus 

 is inconstant ; whilst, as if to add to the perplexity inseparable 

 from the characters of A. princeps, as thus reconstructed, at the 

 same time that, in Plate III, figs. S d&cf, illustrating the paper 

 on this form (Annals, July 1863), the absence of the pellucid 

 ring around the nucleus is distinctly exhibited, in the same 

 plate (figs. 2 c &/) the missing pellucid zone reappears in quite 

 as marked a degree as in the figures of A. radiosa and A. Glei- 

 chenii appended to Mr. Carter's paper in the 'Annals^ for 1856 

 (vol. xviii. pi. 5. figs. 4, 10, 17 & 18). So that the only cha- 

 racters left intact of those named in the introductory specific 

 description are *' the size of A. princeps when it is large, and the 

 number of granules it contains " (Annals, July, p. 31). It need 

 only be added on this head, that we are not left in doubt as to 

 the size of the specimen depicted on the plate ; for, instead of 

 being under TTTjth of an inch in length (see the next page), 

 it is said in the explanatory references to be -yVth of an inch 

 long, the nucleus itself (fig. 2 c) being y^th of an inch in dia- 

 meter, whilst in fig. 2/ it is as much as 3-^th of an inch in 

 diameter. 



But I regret to say the difficulty of arriving at a clear view of 

 the subject does not end here ; for it seems doubtful whether 

 the pellucid ring referred to as characteristic surrounds the 

 nuclear cell-membrane, the nucleus within the membranous cell, 

 or the nucleolus within the nucleus. This will appear on refer- 

 ence to the three subjoined passages : — 



" It [the nucleus] is discoid in shape, of a faint yellow colour, and fixed 

 on one side of a transparent capsule, which, being generally more or less 

 large than the nucleus itself, causes the latter to appear as if surrounded 



