84 EAIITIIWOEMS, LEECHES, AND SEAWORMS 



parts. If one Im cut in two i-iieccs, each portion, under 

 favorable conditions, is callable of reproducing the lost 

 part witli its oi-gans, thus producing two coni[i]etc worms. 

 Morco^'er, the anterior half of one worm may be success- 

 fully grafti'd on to the posterior half of another. 



Its life history, — Each earthworm pioduces both sperms 

 and nva, but the ova are fertilized Ijy the sperms from a 

 different individual. Almut the time the eggs are ready 

 to be laid, a. band, or collar, is formed around the clitellum 

 from mucus secreted by the glands of this organ. The 

 collar, which is gradually slipped forward, receives the ova 

 and sperms as it passes along and is finally worked off 

 over the anterioi- end of the worm. The collar now Lie- 

 comes closed at b'oth ends and forms a horny capsule 

 containing the eggs. These capsules are deposited in 

 loose eaiih, or under logs and stones, where they re- 

 main until the >'oung worms emerge. Some of the eggs 

 in each capsule do not hatch l;,ut remain to furnish food 

 for the young worms produced from the other eggs. 



The distribution and habits of earthworms. — There are 

 many kinds of earthworms and they are found in all parts 

 of tlie world. They live in the earth in Ijurrows varj'ing in 

 dei")tli from a few inclies to several feet. The}^ are noctur- 

 nal animals and s])end the day liidden in their burrows 

 with tlie head l\ing near the surface if the groundds moist. 

 .\t ihglit tlicy come out in search of food, but usually remain 

 witli the posteiior enu attaclied at the mouth of the burrow, 

 ready to dis;ip|)c;ii- if danger threatens. They gather up 

 l)its of lea\'!'s foi' food and collect pebbles to line the upper 

 paits of llicir burrows and to stop up the entrances after 

 witlidra>\ ing tlic liody. As the ground liecomes dry in 

 Bummer tiay buiiow deeper and tleeper into the soil and 



