208 THE OLFACTORY ORGAN, BY PROFESSOR BABUCHItf. 



be regarded as the optical expression of the surrounding 

 olfactory cells. Moreover, it does not affect the whole thick- 

 ness of the cell, but is limited to the surface. At the external 

 extremities of the cells, which are free from cilia, a row of 

 minute points can be distinguished, which encircle the entire 

 extremity, and do not call to mind the appearances presented 

 by the ordinary columnar epithelial cells at the surface. The 

 inner half of the cells in question are not so uniform as the 

 external, yet I very much doubt the statements made by 

 several authors, that they consist of branching processes. They 

 exhibit a great variety of forms, and we may represent- these 

 halves as more or less thick cylinders, composed of a soft and 

 transparent mass, in which the round bodies and granules 

 of the olfactory cells are everywhere imbedded. Folds thus 

 originate, the borders of which, sharper than the remaining 

 substance, project, giving rise to the appearance of figures that 

 simulate the processes of authors. But by staining with anilin 

 it may be shown that a very delicate transparent and longitu- 

 dinally striated substance is stretched between these processes. 

 The independency of this striation comes still more clearly into 

 view at the base, where it altogether fails to give the impres- 

 sion of the presence of fibrous elements. The internal process 

 gradually enlarges in a cone-like manner towards the subjacent 

 connective tissue, and breaks up into numerous very short 

 fibrils. It is very remarkable that the internal process pre- 

 sents a different appearance under the influence of many 

 reagents. If for example the epithelial cells of the Proteus be 

 treated with Muller's fluid or with iodized serum, and be then 

 placed for a short time in diluted glycerine, all traces of the 

 transparent substance vanish, and the above-mentioned folds 

 make their appearance in the form of branched processes. If 

 the mucous membrane of the olfactory region of an animal 

 which does not exhibit any decided coloration of this part be 

 treated with nitrate of potash, we obtain a very delicate pic- 

 ture, which shows distinctly how the olfactory cells are topo- 

 graphically related to those just described. Annular figures, 

 which appear to be the ends of large cells, come into view, 

 surrounded by a number of black dots, which are more or less 

 closely arranged in different animals, and which are simply 



