542 H. p. KJERSCHOW AGERSBORG 



as in other animals, by the connective tissue which intervenes 

 between an outer muscular layer (although in this case the 

 muscular layer is very thin) and an inner mucous layer. The 

 latter consists of ciliated columnar epithelium, and, as in the 

 stomach, is glandular in nature (PI. 33, fig. 44), but the secretion 

 of the intestine does not harden after it reaches the lumen of 

 the tract. The epithelium contains large and small vacuoles 

 which are formed in the neighbourhood of the nucleus but 

 in the distal region of the cell. As in the stomach, these 

 vacuoles or secretion droplets coalesce into larger ones 

 which either break up into smaller droplets before leaving the 

 cell, or pass directly into the lumen. But in no case does the 

 epithelium form into regular goblet-cells, nor does the secretion 

 form into protection-plates of the lining as in the stomach. 



(4) The Intestine. 



That the intestine is the principal digestive region of the 

 alimentary canal is well shown by the different conditions of the 

 food in the stomach and in the intestine. In the former, the 

 food seems to have undergone little or no disintegration, 

 while in the latter, only the skeletal parts of the food remain. 

 As the food passes through the pyloric diverticulum, it is 

 perhaps acted upon in such a way that the intestinal juices 

 more easily complete the digestion that takes place in the 

 posterior part of the alimentary canal. The slightly enlarged 

 part of the anterior portion of the intestine has parallel corruga- 

 tions externally, which may go to show that it is capable 

 of considerable enlargement. In specimens 7 cm. long the 

 corrugated enlargement was circ. 7mm. in diameter. 



The absorptive surface of the intestine is increased very 

 greatly by the presence of a typhlosole which extends from the 

 pyloric diverticulum to the anus. The typhlosole is very large 

 in the anterior portion of the intestine, where it protrudes into 

 the intestinal cavity from the ventral side until there is little 

 free space left between it and the rest of the intestinal walls. 

 Posteriorly, the typhlosole gradually decreases in size, and just 

 before reaching the anus it is obliterated in the ventral part of 



