80 



ESSENTIALS OF ZOOLOGY 



thus further increasing the surface, and all the endoderm is 

 ciliated. 



The earth is taken up by the buccal cavity being protruded 

 in succession through the mouth and the muscular action of 

 the pharynx, which is also rotated forwards and backwards. 

 It is passed along the oesophagus by a series of contractions 

 following one another, an action which is termed peristalsis. It 

 is charged with lime by the oesophageal glands. Harrington * 



Ectoderm 



"* &. 



Peritoneum 

 Parietal ves. 



Dorsal ves. 

 Septum 



Eff. neph. ves. 

 Lot. neur. ves. 



FIG. 38. Lumbricus. Posterior view of half a segment of 

 [the intestinal region. 



says that small pebbles of lime are secreted by the first pair 

 and a milky limy fluid by the last two pairs. It is understood 

 that the pebbles are passed along the alimentary canal un- 

 changed and may therefore be excretory, while the fluid lime 

 serves to neutralise the acids of the humus and thus allows of 

 digestion taking place in a neutral or alkaline condition. The 

 food is received by the crop and then passed to be mixed up and 

 pulverised in the gizzard, when it is passed into the intestine 

 for further digestion and absorption. The folds of the typhlo- 

 sole bring a greater area of endoderm into contact with the 

 food, which is spread into the flattened crescentic space it 

 makes. The anterior end of the alimentary canal is formed 



1899. Jour, of Morph. vol. 15. 



