Chap. XIV.] THE EARTHWORM. 283 



fold. Salivary glands have been described as opening into the 

 buccal cavity. 



Behind the pharynx is the long narrowed oesophagus, on the 

 side of which there are the three oesophageal or cakiferous glands. 

 These, or in any case the first pair, are diverticula of the oeso- 

 phagus, the anterior pair being the largest. Their walls are 

 lamellar in structure, containing deep follicles. If the hinder 

 pairs be punctured and squeezed a number of white bodies 

 exude, which contain in their centres a little fine granular 

 matter, which, on treatment with acetic acid, disappears with 

 effervescence, and which is carbonate of lime. The anterior 

 pair of diverticula contain one or two, or a few larger calcareous 

 concretions. In winter the glands seem to diminish in size. In 

 young worms there are often but two pairs. 



The oesophagus opens into an expanded crop, with muscular 

 contractile walls ; and this is followed by the very thick-walled 

 gizzard ; behind which the intestine passes, with but little change, 

 to the end of the body. The intestine is laterally sacculated, 

 and its lumen is much diminished by a thick longitudinal fold, 

 the typhlosole, which projects inwards from its dorsal wall. 

 Surrounding the intestine, especially at its anterior end, is a 

 yellowish-brown, easily ruptured tissue, which is in close con- 

 nection with the blood-vessels. Similar tissue may accompany 

 the dorsal vessel above the oesophagus. It has been described 

 as hepatic, and as producing a digestive secretion. It nowhere 

 communicates, however, with the interior of the canal, and its 

 close connection with the blood-vessels lends support to the 

 view that it is vasif active concerned in the production of some 

 constituent of the red fluid of the blood-vessels. 



Little is known of the process of digestion. Worms seem to 

 drag leaves, stalk forwards, into their burrows, and then moisten 

 them with an alkaline secretion. This rapidly acts on the 

 leaves, the cells with chlorophyll losing their green colour and 

 becoming brown. It also acts on the starch granules within the 

 cells, and on the protoplasmic contents of the cell-wall. The 

 leaves are thus partially digested before they are taken into 

 the canal. The function of the calciferous glands is not known 



