AQUATIC MICROSCOPY FOR BEGINNERS. 



Many narrow, colorless tubes, with a ciliated lining, 

 are to be noticed on both sides of the intestine. 

 They are much looped and twisted, and are supposed to 



Fig. 153. — Ndis. 



play some part in respiration, or to represent the kid- 

 neys of animals higher in the scale. They are bathed 

 in^the colorless fluid filling the cavity of the body, and 

 float out of position rapidly as this fluid flows to and 

 fro, following the movements of the worm. 



Ndis is one of the commonest of our aquatic worms 



being very frequently found 

 among Algse in shallow 

 water, or on the leaflets of 

 various plants, especially, 

 according to the writer's experience, in Sphagnum, in 

 company with Pristina and Chsetogaster. 



To those that desire to make a profound study of 

 the aquatic worms, F. E. Beddard's "Monograph on 

 the Order of Oligochseta" may be commended. It is 

 published in London. There is no American book on 

 the subject. 



Fig. 154. — Fodal Spine of Ndis. 



