and its Reproductive Cells. 39 



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 almost 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. 



Towards death the vesicula, growing weak, is not easily re- 

 filled, nor do the small sinuses which surround it readily dis- 

 charge 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 iso- 

 lated and separated from the rest of the sarcode and from each 

 other (figs. 10 & 11). Again, the fact of the dilatation of the 

 vesicula always taking place at the point where it contracted, 

 and the presence of condensed sarcode round the point of con- 

 traction, manifested under the efiect of iodine, induce me 

 directly and analogically to consider the vesicula as much a 

 distinct organ in Amoeba princeps as in other Infusoria. And if 

 the vesicula be distinct, why not the sinuses ? 



All these dilatations are considered by my friend Dr. Wallich 

 to be extemporized vacuoles. But I am glad to observe that he 

 supports me in the opinion that the vesicula, at all events here, 

 discharges its contents externally^. 



In jEthalium the vesicula, although present in the youngest 

 forms, does not appear in the more matured and larger masses, 

 so far as my observation extends. 



Nucleus (PI. III. fig. 3 6). — The nucleus in A. princeps, as 

 before stated, difl'ers in appearance from that of all the other 

 freshwater Rhizopoda that I have examined, in the absence of a 

 pellucid area round the nucleolus ; and this arises, as before 

 stated, from the border of the latter extending so much over the 

 inner surface of the nuclear cell as to pass beyond its equatorial 

 line, where it terminates in an undulating margin, which thus 

 leaves a transparent, irregular area. At least, this is distinctly 

 visible when the Amoeba is not more than the ^J-oth part of an 

 inch in diameter, viz. the minimum size above mentioned (figs. 3 

 &3c(,&c.). Whether the nucleolus, before this, is circular 

 and presents the usual pellucid area around it, or not, I do not 

 pretend to determine, but I think it very likely; and then this 

 state and the smallness of the Amoeba would preclude all possi- 

 bility of specific distinction : hence I do not think that there is 

 any necessity for us to concern ourselves about the appearance 

 * Loc. cit. p. 441. 



