246 



Elementary Biology. 



of nerve fibres through the body, and which, in many re- 

 spects, takes the place of a series of specialised organs, 

 corresponding to the senses of touch, taste, sight, hearing, 

 and smell. Its sensitiveness to touch and its dislike to 

 sunlight are well known ; and, though not possessed of organs 

 of sight or of smell, it is able easily to find its way to stores 



of food and to retreat 



Fir,. 123. DIAGRAMMATIC REPRESENTATION OF {-___ _._ ___ r j 



THE ARRANGEMENT OF THK REPRODUCTIVE irOUl SOUTCCS OI Uan~ 



ORGANS OF Liimbricus terrestris. (Hurst.) ^^ j n O a burrOW 



The reproductive 

 system. The ovaria 



are two extremely 

 minute organs situ- 

 ated in the thirteenth 

 somite and attached 

 to the ventral portion 

 of the posterior side 

 of the septum sepa- 

 rating that somite 

 from its predecessor. 

 The ova are typi- 

 cal, nucleated cells, 

 which, when ripe, are 

 shed into the ccelom, 

 and find their way, 

 by some means not 

 yet known, into the 

 wide ciliated mouths 

 of one or other of 



A, n, c, the vesiculae seminales ; N, nerve-cord ; 

 o, ovary; OD, oviduct; s, spermathecae ; SF, 

 mouth of vas deferens, VD ; T, testis. 



two tubes which open internally on the anterior face of the 

 succeeding septum, and, after piercing it, open to the exte- 

 rior by a small aperture on the ventral surface of the four- 

 teenth somite, near the outer row of setae. Each of these 

 tubes is known as an oviduct. 



The earthworm is hermaphrodite, but, as in the case of 

 most, of the hermaphrodite higher plants, it does not fertilise 



