LUMBRICUS TERRESTRIS L. MULLER 95 



genital pores on the fifteenth segment between the b and c 

 bristles. The sperm matures in the vesicles. 



The female reproductive organs consist of one pair of ovaries, 

 one pair of oviducts and two pairs of sperm receptacles. The 

 ovaries are situated in the thirteenth segment. The oviducts 

 are extremely short tubes; they begin with a wide opening in 

 the thirteenth segment, perforate the dissepiment and end in 

 the two female genital openings on the fourteenth segment just 

 above the b bristles. The first pair of receptacula seminis are 

 round white bodies situated in the ninth segment and opening 

 to the outside in the lateral lines between the ninth and tenth 

 segments. The second pair of receptacles are similar to the 

 first, situated in the tenth segment and open to the outside in 

 the lateral lines between the tenth and eleventh segments. 

 Self-fertilization is impossible. The sperm is stored in the 

 receptacles during copulation. It passes later into the cocoon 

 which is secreted by the clitellum at the same time as the eggs 

 are deposited into it. Development is direct. 



Instructions 



1. Place the specimen in a dissecting tray with water and make 

 a full page drawing showing the side view. Count the segments 

 carefully. Label mouth, anus and clitellum. For the position 

 of the genital openings compare the specimen with what has 

 been stated in the paragraph on external anatomy. 



2. Open the specimen by a longitudinal slit parallel to the mid- 

 dorsal line and fasten the sides with pins. Make a full page 

 drawing showing dissepimenta, alimentary canal, dorsal blood- 

 vessel, aortic loops, nephridia and organs of reproduction. 

 Label pharynx with its dilators, oesophagus, calciferous glands, 

 crop, gizzard and intestine; dorsal blood-vessel, five pairs of aortic 

 loops surrounding oesophagus, parietal vessels beginning behind 

 the reproductive glands and connecting the dorsal with the sub- 

 neural vessel; nephridia and three pairs of large spermothecae. 



3. Remove the alimentary canal by cutting it across in the 



