ON INTER-CELLULAR BRIDGES IN COLUMNAR EPITHELIUM 2Ô5 



subscquently treated as recommended by that author. The sections varied 

 in thickness from 1 n to 5 n and were stained on the slide either by M. 

 Heidenhain's substractive method with Bordeaux red and iron haemato- 

 xylin, orby Mann's methylblue eosin (I used his long method), and finally 

 mounted in balsam (1). 



The sections were examined with Leitz's 1/12 oil immersion objective 

 and compensating eyepieces, and subsequently photographed. 



It is commonly believed that the columnar epithelial cells lining the 

 alimentary canal are held together by a clear interstitial cernent substance 

 which is blackened on treatment with silver nitrate when exposed to light. 

 So recently however as last year Th. Cohn (2), working under the direction 

 of M. Heidenhain, has shown that this view requires important modifica- 

 tion. He states that the cells are throughout the greater part of their extent 

 separated from each other by a narrow lymph space, bridged across by 

 cellular prolongations. He further states that this lymph space is eut off 

 from the cavity of the stomach by a thin layer of true cernent substance, 

 which is présent only near the free extremity of the cells, where it forms a 

 délicate intercellular network -■- « cernent net » — that surrounds the cells 

 in that région. His observations were made on the salamander. Bonnet (3) 

 has described a similar arrangement in the human stomach (1895). 



In the stomachs of the various animais examined by me (cat, dog, rab- 

 bit, hedgehog, rat, mouse), this cernent network is very visible and entirely 

 cuts off the lymph space between the cells from the cavity of the organ. 

 This network is very thin and in vertical sections of the epithelium appears 

 as little dots between the cells just at the points where their free extremities 

 begin to separate from one another, and sometimes it happens in the sect- 

 ions that a ring of this cernent substance is seen encircling the cell body 

 near the free end where the cross diameter of the cell is greatest, and when 

 viewed from the epithelial surface it présents the appearance of a fine net- 

 work through the meshes of which the free ends of the cells project; it is 

 remarkably well demonstrated by treatment with Bordeaux red and iron 

 haematoxylin (M. Heidenhain's method) by which it is stained deep black. 



My observations on this point are therefore quite in agreement with 

 those of Cohn. 



(1) For détails of methods see : M. Heidenhain : Arch. fur mikr. Anat., Bd. 43, pp. 436-443. 

 — G. Mann : Fixing solution; Proc. Scott, microsc. Soc, Vol. I, p. 154, and Journ. Anat. and 

 Physiol. , Vol. XXIX, p. 483. — Staining solution ; Proc. Scott. Microsc. Soc, Vol. I, p. i63, and 

 Journ. Anat. and Physiol., Vol. XXIX, p. 4S3. 



(2) Loccit. 



(3) Bonnet : Schlussleisten von Epithelien ; Deutsche med. Wochenschrift, 1S95. 



