18 



HABITS OF WORMS. 



Chap. I. 



Mouth. 



Pharynx. 



(Esophagus. 



Calciferous glands. 



(Esophagus. 



latter organ is lined with a smooth thick 

 chitinous membrane, and 

 is surrounded by weak 

 longitudinal, but 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 ^ to a little 

 more than the ^ 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 thev serve, like 

 mill-stones, to triturate 

 their food. The gizzard 

 opens into the intestine, 



Crop. 



Gizzard. 



Upper part of in- 

 testine. 



Fig. 1. 

 Diagram of the alimen- 

 tary canal of an earth- 

 worm (Lumhricus), 

 copied from Ray Lan- 

 kester in ' Quart. 

 Journ. of Microscop. 

 Sc/ vol. xv. N.S. 

 pi. vii. 



