Mr. H. J. Carter on the Spermatology of a new species o/Nais. 29 



vesicle; possibly the opening into it, though freely admitting 

 water, might not be large enough to admit particles of carmine. 

 Then, again, the facts which I have brought forward to prove 

 that the " contracting vesicle w in the Infusoria is filled from the 

 vascular system connected with it*, are also opposed to the view 

 which I have assumed of the manner in which the tubular part 

 of the "segmental organ" in Nats is filled; while the latter 

 theory, after all, only rests on the inference that the direction of 

 the movement in the cilia indicates the opposite in the direction 

 of the contents. The question, therefore, is still open for in- 

 quiry. It is easy enough to see the large contracting vesicle in 

 the rotifer Brachionus become distended and contract, and there 

 can be little doubt that its contents pass outwardly; but the 

 slowness with which it becomes refilled affords us no informa- 

 tion as to where the fluid comes from ; so that, before this is 

 determined, it is impossible to say to which system this organ 

 belongs, viz. whether respiratory or renal. At one time I thought, 

 from the intimate connexion of the "segmental organ" in Nais 

 with the generative system, whose organs, as before stated, are but 

 mere modifications of it, and all equally contractile, that it was 

 the rudimentary form of the kidney in higher animals ; but sub- 

 sequently observing the direction of the ciliary movement in the 

 alimentary canal of Nats to be opposite to that of its contents, 

 I am now inclined rather to consider its functions respiratory; 

 at the same time, it is difficult, if this be the case, to conceive 

 why it should have an internal opening — while, again, it is not 

 always that the contents of the tube pass in the opposite direc- 

 tion to the movement of its cilia, as we shall see hereafter, viz. 

 in the floating-cells of the peritoneum, which get into the ovisac 

 through the so-called fallopian tube, which is but a modification 

 of the tubular portion of the segmental organ in front of the 

 elliptical body, and has the motion of the cilia in the same 

 direction. Are the functions of this organ both excretory and 

 respiratory ? or, in short, what are its functions ? and what is 

 the use of the tubular part, and what that of the fine granular 

 matter which surrounds it, respectively ? I must leave future 

 inquirers to determine, merely observing that the question is one 

 of much interest, as the organ appears to me to be traceable 

 through the " contracting vesicle in Infusoria, even into the 

 "vacuole" of the vegetable kingdom t. 



* Annals, vol. xviii. p. 126, 1856. 



t Since the above was written, I have distinctly observed the motion of 

 the body-cilia of a species of Spirostoma, when under a slip of glass, to be 

 whip-like, and the neighbouring particles to follow the forward movement 

 of the lash, which of course is the most powerful ; while the wave in the 

 cilia in totality was also forward, quite contrary to that which is observed 



