92 Caroline McGill, 



The wall of the intestine of Necturus consists of four typical 

 layers; serous, muscular, submucous and mucous. It is only the mucous 

 and submucous coats that require description here. The mucous coat 

 is made up of an inner lining of simple columnar epithelium. This 

 rests upon a loose connective stroma, the tunica propria. The epi- 

 thelium is thrown up into large folds, by some described as villi. There 

 is no distinct muscularis mucosa, muscular fibers scattered throughout 

 the tunica propria and submucosa apparently taking its place. The 

 tunica propria blends with a heavier connective tissue layer beneath, 

 the submucosa. Just beneath the epithelium occurs a thick felt-work 

 of fibroglia fibrils. There are also scattered fibroglia fibrils throughout 

 the subepithelial connective tissue, down as far as the muscular coat. 

 Immediately beneath the epithelium these fibrils are so numerous that 

 they form a distinct basement membrane (Figs, lb and 3b). 



Morphologically, these fibrils found in the intestinal wall of Nec- 

 turus so closely resemble the fibroglia fibrils of Mallory that a separate 

 description of the individual structures is hardly necessary. They are, 

 in the main, heavy fibrils, round or oval in cross-section, of approxi- 

 mately uniform caliber throughout the entire length. With ordinary 

 stains, they usually appear homogeneous. The fibrils in Necturus vary 

 more in thickness than do those described by Mallory. They range in 

 size from strands as fine as the fine fibrils of smooth muscle, to those 

 as coarse as the coarse myofibrils. In places the coarse fibrils break 

 up into bundles of finer fibrils (Figs. 3bf and 4bf). 



It is in their relation to the cell body and in their general course 

 that these fibrils differ from those of Mallory. Some of these fibrils 

 very closely resemble in their arrangement those of Mallory (Figs. 4 

 and 5). That is, they bear the same relation to the cell protoplasm 

 as do neuroglia fibrils, merely touching the border or, perhaps, running 

 through it for a short distance. One fibril may pass through the pro- 

 toplasm of several connective tissue cells. In such tissue as this the 

 connective tissue cells are flattened with oval nuclei. The fibrils tend 

 to run parallel with the long axis of the cell, but many of them spread 

 out in other directions, forming more or less of a network. Besides 

 these fibrils, the cell protoplasm around the periphery may contain col- 



