ROTIFERA. 



fc< that the branchiae possess a vascular system ; for, when the local 

 contractions occur in the body of the animal, we see distinctly a 

 certain number of filaments (vessels ?) loose and delicate." The 

 opinions of the Professor himself concerning the nature of the 

 organs which he describes being so indefinite, we must pause before 

 adopting the physiological views to which their admission would 

 lead ; more especially as, from the very fact of the whole visceral 

 cavity being perpetually filled with aerated water, the existence of any 

 localized organs of respiration could hardly be esteemed necessary. 



(166.) The last subject which we have to consider relative to the 

 internal economy of the rotifera is, the conformation of their gene- 

 rative apparatus, which now assumes a considerable perfection of 

 developement. The reproductive system is composed apparently 

 of two distinct parts : the one subservient to the formation of the 

 ova ; the other destined either to furnish some secretion essential to 

 the completion of the egg, or, as is more probably the case, secret- 

 ing a fertilizing fluid by which the impregnation of the ova is 

 effected prior to their escape from the body. 



The ovary, as we might term it, or female portion of the system, 

 (jigs. 48 c, 49 7n, n 9 50 &, A*, 5iy,) is a transparent sacciform organ, 

 in which, at some seasons, the eggs are distinctly perceptible through 

 the pellucid coverings of the animal, as represented in the figures. 



The male organs, or testes,as we may call them, are two in number 

 (Jigs. 50 /, and 50 h) ; they resemble long wavy cseca, extending 

 nearly the whole length of the animal, and terminating near the oral 

 extremity by closed extremities. It is to these organs that the small 

 appendages mentioned above as organs of respiration are appended ; 

 and, should the latter not perform the office of respiratory branchiae, 

 they are most probably organs of secretion, such as in many other 

 animals we shall see appended to the spermatic tubes. 



Both the ovigerous organ and the two seminiferous vessels 

 terminate in a common receptacle (Jig. 51, g,) that may be named 

 the cloaca ; this consists of a transparent vesicle endowed with 

 great irritability, in which the fertilization of the ova is apparently 

 effected, the eggs being here brought in contact with the secretion 

 of the testes before they escape through the excretory passage 

 (Jig. 51, d). 



The ova of the rotifera, before they are hatched, form very in- 

 teresting objects for the microscope ; as the movements of the in- 

 cluded young, and even the action of the cilia forming their 

 wheel-like organs, may be distinctly seen through the exquisitely 

 transparent investment of the egg. 



