18 



HABITS OF WORMS. 



Chap. L 



latter organ is 



Mouth. 

 Pharynx. 



(Esophagus. 



Calciferous glands. 

 CEsopbagus. 



'A 



Gizzard. 



^'J Upper part of In- 

 testine. 



Fig . 1. 



Diagram of the alimen- 

 tary canal of an earth- 

 worm (Lumbricus), 

 copied from Ray Lan- 

 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 -^q to a little 

 more than the ^V ii^ch 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 tlie intestine, 



