PRELIMINARY NOTES ON GASTRODE S FARASITICUM KO^OTNEFF, ETC. 589 



e id towards the free surface of the epidermis. They grow to a fairly 

 1 irgë size (length up to 0.06 mm., breadth up to 0.04 mm., diamètre 

 of nucleus and nucleolus 0.03 mm. and 0.01mm. respectively), possibly 

 by absorbing nutriment directly from the host. A few of the cells 

 were also observed freely lying outside of the epidermis. Even in the 

 smallest individuals examined, the same cells, nearly as large as in the 

 older specimens, were sometimes found. In spite of this fact and of 

 their origin apparently from the ectoderm, I am inclined to agree with 

 KOROTNEFF in regarding them to be the egg. As points standing in 

 favour of this view may be mentioned the very large size attained by 

 the cells as well as by their nucleus, and also the fact that they are 

 sometimes seen lying freely outside the body of the animal, 



With regard to the systematic position of Gastrodes, there can be 

 no doubt whatever that it belongs to the Ctenophora. Which, then, of 

 the orders of that class should it be assigned to ? 



From the presence of well-developed comb-plates in the larger 

 individuals, it may reasonably be assumed that the animal, after a period 

 of parasitism in the early part of its life, leaves the host and becomes 

 free. Possibly, on entering the latter period, it may undergo a more 

 or less marked change in structure. Necessary as it appears that we 

 should have a more complete knowledge than we at present possess 

 about the animal in order to be able to definitely settle its position 

 among the Ctenophora, yet from observations on its parasitic stages, so 

 much may, I think, be now said that it shows several features which 

 seem to point towards its affinity with the group Platyctenea. In the 

 first place, the fact that the ventral surface of body is lined all over 

 with the ciliated epithelium, as also the fact that profuse foldings are 

 developed in the central region of that surface, makes it highly probable 

 that the ventral surface of Gastrodes is morphologically of the same 

 nature as that of platyctenids. If that be so, the surface may be 

 regarded to have arisen, as I have shown in the article on the develop- 

 ment of Coeloplana in the present journal, as t'ie result of the turning 



