TWO AQUATIC OLIGOCHiETES. 5 



used. The Indian material which was fixed with either sublimate 

 or formalin gave tolerably good results. The Japanese materials 

 were killed, after narcotising with dilute alcohol, with acetic 

 sublimate and Perenyi's fluid. For histological studies sections 

 were cut 4-7 p- thick. 



The stains used were 1) Delafield's hsematoxylin and eosin, 

 2) Malloky's connective tissue stain, at the suggestion of Prof. 

 Ijima. For general observations 1) was more suitable, but 2) 

 gave excellent results for minute details, though less favourable 

 for study under a low power. 



1. Body wall. 



The body wall consists of 5 layers. 



1). The cuticle is very thin and structureless. I have not 

 been able to find any striations or other markings, nor the large 

 pore canal figured by Vejdovsky in Limnodrilus udekemianus Clap. 

 at the most anterior part of the prostomium. According to L. 

 Atheston, the cuticle of Tubifex rivulorum, when isolated, shows 

 openings or markings of two sorts. " These are probably the 

 pore canals from the gland cells and the openings occupied in 

 the living condition by the hairs from the sense cells." He used 

 dilute Kuskow's fluid for the purpose of maceration. 



In fresh materials left in a o% aqueous solution of caustic 

 potash for about two days, I found, though with great difficulty, 

 many pore canals in the cuticle of the cliteilar part and other 

 regions, but the openings of the other sort could not be observed. 



At the two ends of the body the cuticle is reflected inwards 

 and is continued into the mouth and anal cavity. 



The cuticle is thickest at the cliteilar part and becomes 

 thinner at both ends of the body. At the cliteilar part it is 

 1.3-1.5 ja thick, in the neighbouring segments 1.0-1.2/*; at the 

 most posterior part and in the mouth cavity 0.5-0.8 /*. 



2). The hypoclermis consists of two well marked types of 

 cells, viz. gland cells and columnar hypodermal cells. The sense 

 cells which are undoubtedly present could not be well observed 



