231 



zeiger, but I have no reason to doubt the accuracy of any of the 

 structural observations. The term Epidermistasche may well be sub- 

 stituted for the neuropore, as it really is a groove between preoral hood 

 and collar. I have never claimed for it that it passes into the interior 

 of the nerve-cord. 



The pre-oral pores appear to be subject to considerable variations. 

 Many specimens, although full-grown, do not have them, and some 

 have only one, hence I am quite prepared for the denial of their exi- 

 stence by some superficial worker. 



With these reservations I adhere to the account as published 

 in 1896. 



Professor Roule objects that I had, at the time of his writing, 

 only examined the fully-developed larva, which is perfectly true, and 

 also that this has led me "à des assertions erronées, à des exagérations, 

 qu'il aurait sûrement évitées, s'il s'était conformé à la bonne méthode 

 de l'embryologie" (p. 147), — which, with all due respect to Professor 

 Roule, is untrue, and is not a statement within the legitimate bounds 

 of scientific criticism from one who has not examined the same larva. 



I can only take a single instance of the kind of conclusions to 

 which Professor Roule's work leads him. I described in Actinotrocha 

 a vascular system of sinuses which were in a very primitive condition 

 but with perfectly definite relationships. In this I merely amplified the 

 statements of Wagener, Schneider, Metschnikoff, Leuckart, 

 and Pagenstecher, Krohn, Wilson and Caldwell. In parti- 

 cular, I described a dorsal vessel with contractile walls, and I have 

 since watched the contractions of the vessel in the living animal. 

 Caldwell especially describes this vessel as a marked structure in the 

 larva (a Mediterranean species, by the way ; apparently P. Kowalevskii), 

 and Schneider (1862) emphasizes the rhythmical contractions of this 

 vessel. In the face of all this evidence the learned Professor finds in 

 his larva no trace of a dorsal vessel, but in its place a "cordon 

 dorsal" of cells which becomes the intestine of the adult! Should not 

 this important discrepancy (one instance out of a dozen or more) teach 

 the Professor to hesitate before being quite so free with his accusations 

 of exaggerations and erroneous assertions? There is here a funda- 

 mental disagreement between the results of the Professor and those 

 of seven or eight workers, the great majority of whom, we may assume, 

 were not, as in my case according to Professor Roule) biassed by an 

 inordinate "désir de comparer I'actinotroche aux Bryozoaires Ptéro- 

 branches et aux Entéropneustes", and were in many cases working on 

 the Mediterranean species. The discrepancy must again be due to the 

 deficiency of his larva or to his own observations and methods, but I 



