THE INVERTEBRATES 145 



V 



in the daytime after a heavy rain. They may be kept in 

 flower-pots filled with damp soil, and should be fed bits of 

 raw meat, preferably fat, bits of onion, celery, cabbage, etc. 

 Examine a live specimen put on a piece of moist paper. 

 Note that the body is made up of rings or segments. Are 

 there any legs? How does the earthworm move along? 

 Can you find some short fine bristles, called setae, on the 

 body? The broad thickened ring or girdle, including several 

 segments near the head, is called the clitellum. It secretes 

 the cases in which the eggs are laid. Make a drawing of 

 the worm, showing all the external features you can make 



out. 



Earthworms live in soft moist soil which is rich in organic 

 matter. Their food is taken into the mouth mixed with 

 dirt and sand. As this mixture passes through the long 

 alimentary canal the organic particles are taken up and 

 digested. The eggs are laid in a horny capsule which lies 

 in the earth until the young worms emerge. Only a part 

 of the eggs develop in each capsule, the rest being eaten by 

 the growing young. Earthworms of various kinds are 

 found in all parts of the world except in desert or arid re- 

 gions. In size these different kinds vary from i mm. (V, in.) 

 to 2 meters (2 -J- yards) in length. 



Leeches are familiar to boys who go in swimming. Some 

 live specimens should be brought into the schoolroom. The 

 body of a leech is flattened instead of being cylindrical as in 

 the earthworm, and tapers at both ends. In the live animal 

 it can be greatly elongated and narrowed, or much shortened 

 and broadened. It is composed of many segments (not as 

 many as there are cross lines, however, each segment being 

 transversely annulated), and bears at each end on the ven- 

 tral surface a sucker, the posterior one being the larger. 

 These suckers enable the leech to cling firmly to other 

 animals. The mouth is at the front end of the body on the 

 ventral surface and is provided with sharp jaws. Leeches 



