18 



HABITS OF WOEMS. 



Chap. L 



Calciferous glands. 



Gizzard. 



Upper part of in- 

 testine. 



Fig . 1. 

 Diagram of the alimen- 

 tary canal of an earth- 

 worm (Lumbricus), 

 copied from Ray Laa- 

 kester in * Quart. 

 Journ. of Microscop. 

 Soc* vol. XV. N.S. 

 pi. vii. 



lined with a smooth thick 

 chitinous membrane, and 

 is surrounded by weak 

 longitudinal, but by power- 

 ful transverse muscles. 

 Perrier saw these muscles 

 in energetic action; and, as 

 he remarks, the trituration 

 of the food must be chiefly 

 effected by this organ, for 

 worms possess no jaws or 

 teeth of any kind. Grains 

 of sand and small stones, 



from the 2V ^^ ^ ^^^^^^ 

 more than the ^j^ inch in 

 diameter, may generally 

 be found in their gizzards 

 and intestines. As it is 

 certain that worms swal- 

 low many little stones, in- 

 dependently of those swal- 

 lowed while excavating 

 their burrows, it is prob- 

 able that they serve, like 

 mill-stones, to triturate 

 their food. The gizzard 

 opens into the intestine, 



