NOTES ON ECHINODEEM MORPHOLOGY. 606 



from the oral blood -vascular ring through the " glandular 

 canal," and the fluid being forced on by the contractions 

 of the ventral intestinal vessel which joins the oral ring. One 

 would wish, however, for something more than the mere asser- 

 tion of Koehler that a liquid is secreted by the gland. He 

 describes a coagulum found in its excretory duct as the 

 "coagulated secretion^' of the organ. ^ But he finds the 

 same coagulum in the vessels ramifying on the surface of its 

 lower portion and in the internal vessel of the intestine.^ If 

 the one is a glandular secretion, why not the other too ? They 

 are both described in exactly the same terms, and are evi- 

 dently of the same nature as the coagulum so often found in 

 the blood-vessels of other Echinoderms. I have met with it 

 over and over again in the radial, and also in the intervisceral 

 vessels of Crinoids. Is this a coagulated secretion too ? Not 

 even Professor Perrier himself, who has recently published a brief 

 note^ " On the Organisation of Crinoids," has ventured to assert 

 that the so-called ovoid gland of these creatures communicates 

 with the exterior, though he will not admit the existence of 

 any intervisceral vessels connected with it. But as regards 

 the Echinozoa, 1 would still ask for proofs, based not merely 

 on the results of injection, but also on the section method, that 

 the " excretory duct " of the ovoid gland communicates with 

 the exterior, and not with an aboral ring in which the genital 

 vessels originate, as described by Ludwig in the Stellerids. 

 The direct communication with the exterior of the blood- 

 vascular as well as of the water-vascular system would, if 

 established beyond dispute, be a somewhat important mor- 

 phological fact ; and before accepting the apparently well- 

 grounded conclusions of Koehler and Perrier respecting the 

 regular Urchins, one would like to know what Ludwig has to 

 say on the subject. This will appear, I hope, ere many 

 months are past. 



' Op. cit., pp. 98, 99. 

 2 Op. cit. pp. 77, 90. 

 ^ ' Comptes reudus,' t. xcvii, No. 3, pp. 187 — 189. 



