266 CONTRIBUTIONS TO THE NATURAL HISTORY 



lation with the very form of the animal. But if there is no organic communication be- 

 tween the tubes and the bulb, we should not overlook the circumstance, that, before reach- 

 ing the base of the sensitive bulb, each vertical tube, as figured in Plate II. Fig. 8, is dilated, 

 and divides into two tubes, b, b, which are the connecting branches of the circular tube ; 

 or, in other words, on the inside of the inner surface of each sensitive bulb, there are three 

 tubes meeting in a common triangular dilatation, (Fig. 8, a,) and this sac-like dilatation 

 rests upon the inner surface of the sensitive bulb, and constitutes the connecting ampulla 

 between the vertical and circular tubes. (Plate II. Fig. 11, e, b, b, and 13, b, a, a.) It 

 does not seem to me that this sac-like dilatation is to be considered as any thing more than 

 a mere swelling of the tubes at their point of junction ; but I can easily conceive how such 

 swellings may be found of larger dimensions, assuming the functions of pulsating sacs, or 

 becoming a kind of heart, which would be here chymiferous hearts, in contradistinction from 

 chyliferous or blood hearts of the higher animals. But the vascular swelling of Hippocrene 

 is so small, that it can hardly be considered as such. It is rather a varicose dilatation of 

 the tubes themselves ; and, though I have noticed that this cavity is at times wider than 

 at others, I have been unable to see it beat. 



The whole chymiferous system, therefore, consists here of the four vertical tubes 

 and the circular tube, without any ramifications into the tentacles, containing a fluid which 

 is circulated to and fro in all directions. How nutrition is efi'ected by this apparatus can- 

 not easily be appreciated, unless we assume that there is an active process of endosmosis 

 going on between this cavity and its contents and the surrounding tissues. The intimate 

 connection of the sensitive bulbs with the nourishing system is so striking, that I can- 

 not but insist again and again upon this feature in the structure of these animals. No 

 doubt there is an organic connection between them more intimate than the mere relation 

 of apposition ; for the branching of the tubes corresponds with the swelling of the ner- 

 vous cord into the large ganglia, and the dilatations of the chymiferous system, which 

 might in some respects be considered as chymiferous hearts connected with the inner 

 surface of the sensitive bulb, show further a more mutual dependence of these parts. 

 Whether the circular tube should be considered as one tube, or as four distinct tubes ex- 

 tending each from one bulb to another, and meeting there with the vertical tubes, is a 

 question of no importance whatever, as soon as it is understood that there is a free 

 passage from each vertical tube, in two opposite directions, into the circular tube below, 

 and also a free passage behind each bulb from one arc of the circular tube to the other, 

 as may be inferred from Plate I. Fig. 2, 3, 4, and seen in Plate II. Fig. 8, 13. 



The nervous cord, following closely the course of the circular chymiferous tube, is 

 placed along the inner margin of that tube. It can easily be seen, either from above or 



