the Distinctive Characters in Amoeba. 149 



tents of two or more vesicles through a minute duct or aperture. 

 In short, the process is identical with that observable on the 

 coalescence of two adjacent soap-bubbles. 



But it has been shown, I think, satisfactorily, both on evidence 

 adduced in the preceding pages and from the opinion expressed 

 by Dr. Carpenter (p. 138, ante) — namely, that " the contractile 

 vesicle may be regarded as a vacuole with a defined wall," — that 

 the said wall is not identical in its degree of differentiation with 

 the wall of the ordinary vacuolar cavities. The fact, already al- 

 luded to, of the contractile organ never coalescing with the true 

 vacuoles would seem at once to establish this [differentiation. 

 Now it is not membranous in the usual acceptation of the term ; 

 but the appearance presented by its margin, its behaviour 

 when isolated from the body altogether, as spoken of by Mr. 

 Carter {' Annals,^ July 1863, p. 39), and, since the publication 

 of Mr. Carter's paper, verified by myself (with the exception of 

 the iodine test), clearly prove that the differentiation in question 

 is identical both in degree and character with that of the ecto- 

 sarc generally. It is true that Mr. Carter {loc. cit.) refers to 

 "the presence of condensed sarcode round the point of contrac- 

 tion manifested under the effect of iodine;" but this condensa- 

 tion is quite manifest without the iodine ; and were it not so, I 

 am inclined to think, as already urged, that the appearances pre- 

 sented after amorphous structure (such as that under notice) has 

 been subjected to the action of a powerful chemical reagent are 

 no guarantee that those appearances existed normally and prior to 

 its employment. The condensed layer, moreover, may be seen 

 whilst the contractile vesicle is still within the parent endosarc ; 

 and should it be isolated whilst in a state of contraction, the 

 true villous character of the condensed layer becomes so palpa- 

 ble, that, but for the previous knowledge of its origin, it might 

 readily be mistaken for a fragment of the villous appendage itself. 



Mr. Carter's remarks on this head have such a material bear- 

 ing on the view I put forward, that it is necessary for me to 

 quote them in detail : — " Towards death, the vcsicula, growing 

 weak, is not easily refilled, nor do the small sinuses which sur- 

 round it readily discharge their contents into it; so that by a little 

 pressure, when the group is at the margin, they may be made 

 to pass out into the water without bursting; and, at this time, 

 if iodine be applied, each may be seen to retain its cell-form, 

 puckered and tinted yellow by the iodine, although they may be 

 all quite isolated and separated from the rest of the sarcode and from 

 each other" (sec figures, loc. cit.). Mr. Carter then asks, " If 

 the vesicula be distinct, why not the sinuses ? " (p. 39 ut cupra). 



So far from admitting that Mr. Carter's view as to the per- 

 manent nature of the channel of communication between two or 



