6 EARTHWORMS AND LEECHES [CH. I 



also animal substances, fat being especially attractive to 

 them. By the sucking action of the muscular pharynx 

 and the lips leaves are drawn to the burrow, and over 

 the surface is discharged an alkaline fluid which softens 

 and discolours the leaf-tissue, and appears to effect the 

 partial digestion of both protoplasmic contents and starch 

 granules. The fluid is derived from glandular cells in the 

 skin of the anterior part of the body. Fragments of the 

 softened leaf are sucked off by the worm, there being no 

 teeth, and swallowed. 



In passing along the oesophagus the food encounters the 

 secretion from the calciferous glands. In Lumbricus terres- 

 tris there are two pairs of these glands in addition to a pair 

 of oesophageal pouches; in Helodrilus(Allolobophora)longus 

 the latter alone are present. It is probable that the primary 

 function of these glands is to excrete calcareous matter 

 derived from leaves. It is well known that such matter 

 accumulates in the leaf-tissue and is not withdrawn with 

 other substances when the leaf is detached from the 

 parent tree, but is, as it were, excreted by the plant in the 

 falling leaf. The majority of the leaves devoured by 

 worms are such as have fallen in the natural order of 

 things, and moreover all vegetable mould is very largely 

 the product of decayed leaves. Hence worms are likely to 

 take in a large amount of calcareous matter, and since 

 they form neither shell nor bone there is no outlet for 

 this substance and some special excretory apparatus seems 

 necessary. At the same time it is probable that the 

 calcareous fluid discharged into the ossophagus does play a 

 part in digestion in serving to neutralise more or less the 



