Chap. XIV.] THE EARTHWORM. 279 



slightly projecting conical lobe, the prostomium. The vent is in 

 the middle of the last body-ring. Other apertures to the body 

 are numerous. Every segment of the body except the first has 

 a dorsal pore opening into the anterior part of the ring in the 

 mid-dorsal line, and two very minute pores, one on each side of 

 the ventral line, which are the external orifices of the nephridia 

 or segmental organs, whose function is excretory. In addition 

 to these openings there are in each worm the orifices connected 

 with the generative system ; for the worm is hermaphrodite, 

 each individual having both male and female genital organs. 

 The male pores of the vasa deferentia open by tumid lips on 

 the ventral aspect of the fifteenth ring. The female pores of 

 the oviducts have a similar position in the fourteenth segment, 

 and between the ninth and tenth and tenth and eleventh seg- 

 ments respectively, are the usually paired openings of the sper- 

 mathecse or receptacula seminis. 



There are eight setae or hair-like projecting spines to each 

 segment, except a few of the most anterior and most posterior. 

 They can be felt as a living worm is pulled backwards through 

 the fingers, and can be readily seen with a lens, especially in 

 a worm rigidly contracted by drowning in spirits. They are 

 arranged in two double rows on each side. The outer double 

 row is where the darker-coloured dorsal region shades off into 

 the lighter-coloured ventral region. The inner double row is 

 nearer the ventral line, Each seta is curved and pointed, and 

 is lodged in a muscular sac, so that it can be protruded or re- 

 tracted. On the tenth to the fifteenth rings, on the clitellum, 

 and on a glandular prominence of the sixth ring in front of the 

 clitellum, the spines are modified and often somewhat longer 

 and thinner than elsewhere. 



General Internal Anatomy. The worm is readily killed by 

 the vapour of chloroform ; but it should not be too long exposed 

 to this vapour, since it thus becomes contracted, and satisfactory 

 dissection in this condition is impossible. It should, therefore, 

 be soon removed and immersed in water for half-an-hour. The 

 student will find it convenient to dissect the worm in a saucer 



