CH. X] 



LUMBRICUS 



139 



are consequently known as the male genital 

 openings. The other openings into the body 

 are minute and require the aid of a lens to 

 make them out. There are paired openings on 

 each segment, except the first three and the 

 last, situated latero-ventrally; these are the 6"' 

 openings of the nephridia; in addition to 

 these a median dorsal -pore opening into the 

 body-cavity is situated in each groove behind 

 the tenth segment (11, Fig. 63). The earth- 

 worm is hermaphrodite, that is, it contains 

 both male and female organs in its body. 

 Through two slit-like openings in the ventral 

 surface of the fourteenth segment the eggs are 

 discharged: these are called the female gene- 

 rative openings. Two pairs of pouches called 

 spermathecae, which are reservoirs for sper- 

 matozoa received from another worm (y. p. 97), 

 open, one pair between the ninth and tenth, 

 the other between the tenth and eleventh 

 segments, all on the ventral surface. 



If a worm killed in alcohol be drawn through 

 the fingers a certain roughness may be felt 

 along the sides and lower surface. This rough- 

 ness is due to the presence of a number of small 

 bristles, called chaetae (Gr. x at/T *?> hair), which 

 project from the body (7, Fig. 59, and Fig. 62). 

 Each segment bears eight of these chaetae ar- 

 ranged in four pairs, one pair on each side being 

 lateral and the other nearer the ventral middle 

 line. It is by means of the chaetae that the worm 

 crawls about; since by protruding the chaetae 

 and implanting them in the soil a fixed point 

 is obtained from which the anterior end of the 



Fm. 59. Latero-ventral view of Lumbricus terrestris, 

 slightly smaller than life-size. From Hatschek 

 and Cori. 



1. Prostomium. 2. Mouth. 3. Anus. 4. Opening 

 of oviduct. 5. Opening of,vas deferens. 6. Geni- 

 tal chaetae. 7. Lateral and ventral pairs of chaetae. 



xv, xxxn, and xxxvn are the 15th, 32nd, and 37th seg- 

 ments. The 32nd to the 37th form the clitellum. FIG. 59. 



xv 



XXXVII 



