10 E. A. Schäfer, 



The protoplasm of the cells is Mglily vacuolated; the vacuoles 

 being so numerous and closely set as to confer upoii the rest of the 

 protoplasm a flnely reticular aspect in optical section. The only other 

 appearance which seems especially noteworthy is that of fine lines or 

 streaks ninning longitudinally in the protoplasm and brought out by 

 certain methods of hardening the tissue; they are most evident in 

 that part of the cell which is nearest the striated border. 



The oval niicleus, with its nucleolus, Single or multiple, and its 

 somewhat close intranuclear network, calls for no particular remark. 

 Cells the nuclei of which are in process of division by karyokinesis 

 (karyomitosis) are not rare, a fact I shall have occasion to refer to later on. 



The free thickened border of the cell consists of two parts. 

 One of these, that nearer the interior of the gut, is much the thicker 

 and may be termed the striated border proper. In chromic acid spe- 

 cimens it looks as if composed of short rods set compactly side by 

 side; these rods if this appearance is really to be taken as representing 

 actual structure, are of equal length. I have never in hardened 

 specimens seen them projecting unequally at the free border in the 

 manner described and figured by Thanhoffer, ') but in view of the 

 observations of Wiedersheim^) who describes what appear to be amoeboid 

 protrusions from the columnar cells it is possible they may during 

 life be subject to alterations of length. 



In specimens that have been teased out after 24 hours Immersion 

 in dilute chromic acid (1 part of chromic acid to 2,000 of salt Solu- 

 tion), it often happens that this striated border of the epithelium 

 eomes away from the cells in slireds, portions belonging to a number 

 of adjacent cells adhering together to form a sort of membrane which 

 is marked out into polyhedral areas corresponding to the several cells 

 from which the shred is detached. Such a shred when seen on the 

 flat has a finely punctated appearance. 



Although, after it has been exposed to the influence of hardening 



But any forking of the end of a cell which may thus be produced never passes the 

 hasement membrane. 



') Loc. cit. 



*) Wiedersheim, Über d. mechan. Aufnahme d. Nahi'ungsmittel in d. Darmschleim- 

 haut. Festschrift d. 56. Versamml. deutsch. Naturforsch, u. Aerzte. Freiburg i.Br., 1883. 



