The Earthworm. 27 



again into the pharynx. The pharynx has very muscular walls, 

 and from it arises the (esophagus, a narrower tube. Attached 

 to the walls of the oesophagus are one to three pairs of 

 glands, situated in the tenth to the twelfth segments. The 

 first of these, when there are three, as in Fig. 12, opens 

 into the oesophagus, and is sometimes distinguished from the 

 others as oesophageal pouches. The two other glands open 

 into each other and then into the pouch in front, so that on 

 each side of the body there is a chain of glands opening by 

 means of the most anterior one into the oesophagus. These 

 (esophageal glands are sometimes termed the calciferous glands, 

 or " glands of Morren ; " their function is to secrete carbonate 

 of lime. The oesophagus dilates in segment 13 into a thin- 

 walled wide crop. Immediately upon this follows a thick- 

 walled gizzard with a particularly thick chitinous lining. After 

 this comes the i?ifesfine, which passes to the anus at the oppo- 

 site extremity of the body. The dorsal wall of the intestine is 

 folded, and the fold projects into the lumen of the gut, thus 

 increasing its secretory surface. This fold is known as the 

 typhlosole. The intestine is covered externally with a yellowish 

 mass (the chloragogen), which consists of large cells containing 

 excretory products. ' These cells, sometimes, but erroneously, 

 spoken of as the hepatic cells, are simply that portion of the 

 lining of the coelom which lies upon the gut. 



The earthworm's nervous system chiefly lies upon the ventral 

 surface of the body within the body cavity. It is a continuous 

 chain, with a swelling to each segment ; the swellings are the 

 ganglia, which contain the bulk of the nerve-cells ; the inter- 

 mediate thinner parts are the connectives which unite ganglion 

 with gangUon. At the anterior end of the body, lying on the 

 dorsal surface of the gut just in the furrow which divides the 

 buccal cavity from the pharynx, is the double supra-cesophageal 

 ganglion. This, is connected with the ventral chain by a com- 

 missure running round the gut. The reproductive organs of the 

 animal are complicated. The essential organs are the ovaries 

 and the testes, collectively spoken of as the gonads. These are 

 simply local proliferations of the lining cellular membrane of 

 the body cavity. The testes are two pairs of litde pear-shaped 



