the Distinctive Characters in Amoeba. 139 



with the sarcode to which it belongs, it only discharges itself in 

 the neighbourhood of the villous or posterior end ; and such is 

 the case also with the egesta of the digestive spaces ; so that one 

 might also infer that there was a particular aperture through 

 the diaphane and pellicula at this part of the Amoeba for this 

 special purpose, as we see in most of the other Protozoa, where 

 the vesicula is stationary, and frequently fixed close to the anal 

 aperture,^' — in his observations on the contractile vesicle, pub- 

 lished in 1857 (Annals, ser. 2. vol. xvii. pp. 356 & 357), he writes 

 as follows : — " All the internal organs are imbedded in it [the 

 sarcode], part of which are fixed, and part moveable; it is also 

 the receptacle for food, which, in the Amoeba, passes into and 

 out of it, directly through the diaphane, as they have no special 

 apertures of external communication for this purpose ;" and, 

 as already stated, the latter view remained unaltered in any of 

 his published papers, up to the date of his recent notice on 

 A. princeps. 



Having thus far shown the grounds on which Mr. Carter now 

 infers the existence of a permanent excretory aperture through 

 the diaphane and pellicula, which, according to the above ad- 

 mission, invest the sarcode-substance at the villous region, I 

 would adduce the evidence upon which I have arrived at an op- 

 posite conclusion, and accordingly consider the excretory orifice 

 as being neither a permanent portion of the structure of the 

 contractile vesicle nor of the ectosarc of the villous organ. 



Premising that the following details have chiefly been gathered 

 from Amoeba villosa and its protean varieties, I have to observe 

 that, in its collapsed quiescent state, the contractile vesicle pre- 

 sents the appearance of a minute villous tuft suspended freely 

 within the endosarc. When the specimen is tolerably free from 

 foreign objects, the structure of the contractile vesicle can 

 readily be made out whilst it remains quiescent near the villous 

 organ, and then the identity in the intimate structure of the 

 two parts becomes at once manifest. This is a material point, 

 since it lends strong confirmation to the view, that whatever the 

 mode in which the excretory orifice is produced in the one organ, 

 it is in like manner produced in the other. But to this subject 

 I shall more fully revert hereafter. 



During the complete contraction of the contractile vesicle no 

 internal space is discernible. This is probably owing to the con- 

 solidation of the ectosarc of which the minute villi are composed 

 engendering a slight degree of opacity. The external surface of 

 the contractile vesicle, however, can readily be distinguished as 

 being composed of a number of minute papilliform villi, closely 

 appressed, and imparting so rough an outline to the organ that 

 it is somewhat difficult to believe that it can be identical with the 



