NATURE OF THE DEMANIAN FLUIDS 433 



Direction of Flow in the Demanian System. Evidently a considerable 

 amount of matter is contributed by the intestine to the demanian system. 

 Zur Strassen had no difficulty in assuming the entire amount to be so con- 

 tributed in pristiurus (for he appears to have been unaware of the connection 

 in pristiurus of the uterus with the uvette, and hence with the demanian 

 system). 



However, quite frequently in the contents of the enteric efferent of living 

 Metoncholaimus pristiurus near and in front of the uvette pore, refractive, 

 curved, wave-like effects are seen such as would be produced by the gradual 

 mixing of two viscid fluids of unequal refractiveness, an appearance that 

 might readily be produced by the flowing of a liquid through the uvette 

 pore from the uterine efferent into the enteric efferent in such quantity that 

 some of it passed slightly forward, perhaps through cover glass pressure. 



On various occasions, I have seen a considerable quantity of matter in 

 the main enteric vessel close to its junction with the intestine. While this 

 is no proof that this matter was actually derived from the intestine, it is 

 favorable to that conception. Such matter never contains intestinal debris, 

 nor sperms (see F. H. Stewart, 1906), nor pseudo eggs, "balls of finely gran- 

 ular substance," (see zur Strassen.) 



If the demanian system emptied into the intestine, it is to be expected that 

 it would do so through an aperture, pore, similar to those of other affluent 

 enteric glands, those emptying into the oesophagus for instance. In nemas 

 such pores are extremely small, have a definite refractive lining, and are 

 adapted to check any "backwash" due to movement of the contents of the 

 enteron, e.g. just such a structure as occurs in the uvette of pristiurus. 

 But no such pore has been seen in connection with any enteric demanian vessel. 



Moreover, against the flow of any of the demanian fluids being toward the 

 enteron, it may be urged that in pristiurus a special secretion is at times 

 actually seen issuing rather copiously from the pores near the tail, the 

 external outlets of the demanian system, and there is not the slightest 

 reason to suppose that in this region the flow is ever anything but backward 

 and outward. There is no evidence that the demanian system is, for in- 

 stance, a water- vascular system; or that sea water is taken in through the 

 antecaudal lateral pores. 



Again, there is little if any reason to believe the demanian system accessory 

 to digestion, because whatever digestive function would be advantageous to 

 adult females would seem also to be advantageous to the young nemas; yet 

 there are no such organs in young oncholaims, for they come into existence 

 at the last moult. The same may be said of any supposable ordinary excre- 

 tory function. 



But if it be supposed that, for some unexplained reason, adult egg-producing 

 females require to excrete (not secrete) matter peculiar to them, in other words 

 that the demanian system, or some part of it, be a sort of temporary mal- 



