GASTRODES PARASTTTCUM KOROTNEFF. 73 



GASTRODES PARASITICUM KOROTNEFF. 



Historical Remarks. 



Gastrodes parasiticum Korotneff is a peculiar coelenterate living 

 parasitic in the body of Salpa. It was described first by Korotneff 

 in 1888; the generic name was given with reference to the structure 

 of the body which resembles that of a gastrula. As to the systema- 

 tic position of the animal, the author stated that, " Wenn wir aber die 

 Verwandschat der Cunoctantha mit dem Gastrodes konstatiren, sind wir 

 eo ispso gezwungen, den Gastrodes als die Larvenform einer Cnnina 

 zubetrachten " ('88, p. 657). This opinion was discarded afterwards 

 ('91) by the same author when he had undertaken a renewed study 

 of the animal. He arrived at the conclusion that, " Im Grossen und 

 Ganzen habe ich konstatiren konnen, dass es sich um eine entoparasitische 

 Aktinie handelt, die sich wegen ihrer Lebensweise sehr vereinfacht und 

 zugleich modificirt hat, indem sie sich einem Scyphostoma bedeutend 

 nahert" (p.614). Against this, however, Heider ('93), another worker 

 on the same animal, expressed his opinion that, "Der zweistrahlig 

 radiare Typus, welcher dem Baue von Gastrodes zu Grunde liegt, legt 

 die Vermuthung nahe, dass es sich hier um eine parasitare Ctenophore 

 oder um den parasitaren Jugendzustand einer Ctenophore handelt " (p. 

 117). 



Recently, the present author has ascertained that the animal is a 

 ctenophore unmistakably, and moreover that it is a form most probably 

 referable to the peculiar group Platyctenida ('20, b). 



Material and Methods. 



The material were all secured from Salpa fusiformis Cuvier, which 

 is the commonest Salpa in the neighbourhood of Misaki. More than 

 twenty individuals of the parasite were collected during the first five 

 days of April 19 19 and observed alive. Many of them were fixed and 

 examined in sections as well. In addition, more than one hundred 

 examples were obtained from specimens of Salpa which had been 

 collected in the same locality by Mr. Aoki a few years before and 

 preserved in formalin. In fresh examples much of the internal structures 

 may be observed from outside. In fixing the material, acetic sublimate 

 solution (saturated aqueous solution of corrosive sublimate 100 parts 



