and Laboratory Methods. 1415 



The author has carried on investiga- 

 Reuter. K. Zur Frage der Darmsresorption. ^-^^^^ ^^ ^j ^^^ obstetrcans, in regard 

 Anat. Anz. 19: 190-203, 1901. -^ _ > o 



to the morphological changes in the 



intestinal epithelium during its periods of secretion and absorption. 



A previous paper on the intestinal spiral of AlytesX^d to a number of experi- 

 ments on vertebrates — mouse, rat, guinea pig — accompanied by histological stud- 

 ies. Mingazzini worked on the absorption processes in the intestine of the fowl, and 

 finds that there are distinct changes in the epithelium corresponding to the dif- 

 ferent stages of absorption. The absorption of albumen is especially worthy of 

 mention, while fat absorption proved to be of much less value in the investiga- 

 tion. Mingazzini finds the first indication of absorption in the cells to be a 

 granular clouding at the base ; as the process continues the cell contents become 

 watery. The whole process appears in some sort as an internal secretion. 



The evidence of these researches goes to show that the so-called Gruen- 

 hagen's spaces are no artifact, but that they are truly the morphological 

 expression of an internal secretion formed from absorbed nutritive material. 

 By careless fixation and hardening on these absorption studies artifacts can easily 

 be made. Careful work has made the following points fairly certain. The 

 whole absorptive process, the passage from alimentary tract to blood and lymph, 

 takes place in two chief stages : First, from the lumen of intestine through the 

 epithelium into adenoid tissue ; second, the passage from the adenoid tissue 

 into the blood and lymph capillaries. In the first part of the course, albumens 

 and fats pass readily. In this process two stages are visible : the taking up of 

 material from the free ends of the epithelial cells, and, second, the passage into 

 the basal part of the cell below the nucleus. This is doubtless due to the 

 activity of the living cell. In all previous investigations absorption has been 

 considered a purely physical process, due to osmosis, no account has been 

 made of the individuality of different cells. Quite notable variations in absorp- 

 tion are due to this factor. Thanhoffer thought that the cells absorbed through 

 pseudopodic processes, but the author, repeating his experiments most carefully, 

 could distinguish no changes ; the cell margins were uniform and at rest, the fat 

 drops showing brownian movement, but no evidence existed of a mechanical 

 taking up of these. Hardened material also showed no change in these margins 

 that could be counted as any morphological change during absorption. In the 

 author's opinion the border of the cylindrical epithelium acts as an osmotic 

 membrane through which the soluble substances diffuse into the epithelial cells. 

 The fat absorbed in small granules can be followed by the use of osmic acid, 

 while the absorbed albuminous substances lying above the nucleus can only be 

 traced by the protoplasmic conditions. The process of separation from the 

 cylinder cells is in both substances entirely unlike. That of albuminous sub- 

 stances is intracellular ; the whole process closely resembles mucous secretion 

 with this difference, that the excretion product cannot be fixed and stained, this 

 can be done only for the protoplasmic network that contains it. The fat on the 

 contrary, is passed into the intercellular spaces between the separate cylinder 

 cells. The contents of these spaces passes into the spaces of the adenoid tissue, 

 where they probably undergo further changes by the agency of leucocytes, 



