THE ALIMENTARY CANAL 371 



only a very indistinct cuticular border ;md such border is entirely 

 lacking in the fundus cells of the glands. The epithelium of the glands 

 appears to take no part in the process of absorption and therefore con- 

 tains no fat globules. It secretes a mucous fluid. 



At the neck of the gland the epithelium frequently contains mitotic 

 figures which have been demonstrated in man (Scliall'er, 1S!)^ ) as well 

 as in the lower mammals (Bizzozero, 1887). Little or no mitosis has 

 been demonstrated in the fundus of the gland or upon the free surface 

 of the villi. On these facts the so-called wander theory of Bizzozero 

 is founded. According te this theory there exist in the neck of the 

 glands certain indifferent cells which are capable of reproduction by 

 mitosis and whose daughter-cells move toward the free surface, being 

 at the same time differentiated into either the goblet or the columnar 

 cells of the villi. 



Bizzozero originally considered that the granule cells of Paneth at 

 the fundus of the glands were intermediate phases in the formation 

 of goblet cells, but as there is little or no mitosis in the region where 

 these peculiar cells occur and as the granule cells are never displaced 

 toward the surface, it seems more probable that, as also in the gastric 

 glands, the indifferent genetic cells of the neck of the tubule develop 

 on the one hand the superficial goblet and columnar cells which clothe 

 the villi, and on the other hand, the true secreting cells in the fundus 

 of the intestinal glands. 



The granule cells of Paneth (Arch. f. mikr. Anat, 1888) are con- 

 fined to the extreme tip or blind extremity of the fundus of the glands. 

 They are pyramidal or low columnar cells whose spheroidal nuclei are 

 situated close to the basement membrane. Their cytoplasm presents 

 a delicate reticulum which is filled with coarse granules which in some 

 cells are of a basophil nature (Klein, Amer. Jour. Anat., 1902). In 

 others they contain still coarser granules which are strongly eosinophil. 

 The exact function of these peculiar cells is unknown, but that they are 

 true secreting cells seems highly probable. 



Still other types of granular cells of unknown significance have 

 recently been described by Kull (Arch. mikr. Anat.. 81, 3, l'.i:5) in the 

 fundus of the intestinal glands, and among the epithelial cells clothing 

 the villi: (1) 'acidophil cells/ with the basal oxyphilic granules liner 

 than those of the Paneth cells; and (') Yliromaffin cells' with yellowish 

 basal granules, coarser than those of the acidophil cells and tiner than 

 those of the cells of Panel li. These three types of cells are present in 

 man and certain vertebrates; they are said to have no genetic relation- 

 24 



