142 Dr. G. C. Wallich on the Value of 



has been rendered possible, owing to their having been con- 

 tinuously watched from the moment of their evolution, neither 

 they nor the primary contractile vesicle from which they were 

 evolved coalesce with the vacuoles or with the nuclear capsule, 

 even when powerfully appressed against each other. They 

 coalesce, however, with each other when they happen to come in 

 juxtaposition during their movements to and fro, even at a dis- 

 tance from the villous region. But they neither perform their 

 systole singly nor when so coalesced, until they once more reach 

 the posterior or villous margin. 



Now, assuming, for the sake of argument, that the primary 

 contractile vesicle is furnished with a fixed and determinate 

 orifice for the discharge of its contents, and that a corresponding 

 orifice occurs at some spot on the villous surface, it is quite ob- 

 vious that the coincidence of the two apertures can only be 

 maintained, in an organism of so polymorphous a nature, as long 

 as the contractile vesicle and the villous appendage maintain an 

 undeviating relation to each other. But it has been shown that 

 this is not the case in Amoeba villosa ; for the location of the 

 vesicle at the spot where it discharges is only temporary, and 

 its movements, when detached from that spot, conclusively prove 

 that all union whatever between the wall of the vesicle and the 

 villous region, apart from that provided by the general proto- 

 plasmic substance constituting the interior of the body, is de- 

 stroyed. Besides this, I am inclined to believe, from the ap- 

 pearances (although I cannot speak positively to it as a fact), 

 that the discharging orifice is not always in the same spot of the 

 villous surface, but that its position, although restricted to that 

 portion of the animaPs body, varies with the polymoi'phic cha- 

 racter of the villous organ itself and the situation it assumes 

 relatively to the nucleus or other contents when resting in the 

 vicinity. In the case of the supplementary vesicles formed 

 each in one of the minute villous caeca, the isolation from the 

 primary vesicle and from the villous appendage is quite as cer- 

 tain ; for, owing to their being generally of smaller diameter, 

 these supplementary vesicles move about with greater freedom, 

 passing in every direction round or along the diff"erent aspects of 

 the primary vesicle when at rest or when it also happens to be 

 roaming about the centre of the body, and, for the time being, 

 constituting as distinct organs as if they had been derived from 

 separate sources. This being the case, it seems, as already 

 urged, almost impossible to conceive that any permanent bonds 

 of union, such as sinuses, or any determinate apertures, should 

 exist either in the primary or supplementary vesicles. With re- 

 gard to the non-existence of a determinate and constant excretory 

 orifice at the villous surface, the evidence is quite as conclusive. 



