OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. J 35 



In all these cases of change of shape of the epithelial cells 

 we have probably to do with a definite function which is of im- 

 portance to the epithelium. If these epithelial cells were not 

 provided with this high amount of contractility and elasticity it 

 is very likely that serious mechanical injury might be inflicted 

 on the epithelium as a whole^ if this should be called upon sud- 

 denly to cover a surface greatly larger than at a preceding moment. 



One of the best illustrations of this kind is the epithelium 

 of the urinary bladder. In a vertical section made through the 

 mucous membrane of a bladder hardened in the expanded con- 

 dition we notice that the epithelium is considerably thinner than 

 if the bladder had been allowed first to shrink. In the latter 

 instance the epithelium consists of many more laminse than in 

 the former. [Of course I am not referring to the distortion that 

 takes place if the bladder is extended artificially beyond a certain 

 degree.] To the change in shape of the epithelial cells of the 

 laminated epithelium of the skin and mucous membranes I shall 

 have to return later on. 



The goblet cells which are found amongst the epithelial cells 

 of the surface, and amongst those of the crypts of Lieberkilhnj 

 show, just like those in the stomach of newt, the mtracelMar 

 network ; its meshes are wider than in the ordinary epithelial cells 

 on account of the presence of mucin,i which, as I mentioned in 

 my first paper, is contained in the meshes of the network. In 

 hsematoxylin specimens the contents of the goblet cell is stained 

 in a deep purple-blue colour, and on account of this it is by no 

 means an easy matter to distinguish the network ; but if the 

 specimen be only slightly stained with hsematoxylin, or still 

 better, if the sections are stained with picrocarmine, the network 

 comes out with sufficient distinctness. Thin sections of intestine 

 of pig, dog, or cat (hardened in mixture of chromic acid and 

 spirit), are those in which the netivorJc of Jibrils in the 

 goblet cells can be made out distinctly. Pig. 3 represents 

 such a goblet cell, in a as viewed from the surface, in b from 

 the side. Although the nucleus of the cell had been pressed 

 downwards as far as possible, while the interfibrillar or inter- 

 stitial substance had swollen up to the extent as to change the 

 shape of the ordinary columnar cell into that of the goblet,^ 

 it is still possible to discern that there is a connection between 



^ That the goblet-cells contain mucin, wliioh is poured out by them, hi;s 

 been knoMm to Briicke, and has been carefully worked our, besides other 

 things, by F. E. Schulze, in ' Archiv f. mikrosk. Anatomic,' Band 3. 



* The knowledge that the goblet cells are derived from ordinary columnar 

 epithelial cells we owe to the researches of Briicke, Strieker, and especially 

 to F. E. Schulze. 



