THE SENSE OF SMELL. 281 



substance ; in the brain we must suppose apparatus at tlic extremities of tlie 

 same fibres in wliich the current causes a specific process, still entirely unknown 

 to us, out of which the soul forms a sensation of smell. This is the general 

 answer which we ha\ e already previously attempted to establish ; a special 

 answer in regard to the nerve of smell we can as yet give only in the most 

 imjjerfect way. In vain do we look with the microscope for apparatus at 

 both ends of the tender fibres of this nerve, the mechanism of which would be 

 so visible to us that we could explain by it the action of the nerve of smell, and 

 its difference fi'om the action of other nerves. With astonishment we discover 

 at the extremities of the brain the same small, grainy, dark vesicles (nervous 

 cellules) which we also find on all other nerves of sense. None of the power- 

 ful means of discernment of physiology gives us yet the slightest clue 

 to the process which the nervous current produces in these vesicles ; by 

 what that process is distinguished from one taking place in the vesicles of the 

 nerve of sight; and, still less, an answer to the question how this process can 

 work upon the soul and force upon it that sensation which we call a sensation 

 of smell. We do not fare much better when attempting to analyze the external 

 extremities of the same nerve. Quite a short time ago nothing more could be 

 stated than that its fibres probably ended in free points on the fundamental 

 tissue of the cuticle of the .nose, which tissue is precisely like that of every 

 other cuticle. No mention was made of separate apparatus, the necessity of 

 the existence of which the physiology of the time did not apprehend. Quite 

 recently, however, a philosopher of great merit took an important step in 

 advance, by showing the formerly presumed, but not seen, extremities of 

 the nerve fibres, and by proving the existence of peculiar elements of tissue 

 at those extremities. We would fain give up the attempt to produce a sketch 

 of this, as we fear we shall not be able to accomplish a clear picture; but, beiu"- 

 afraid, on the other hand, lest our elaboration be censured for incompleteness, 

 we risk to be reproached with a want of lucidity. Imagine a nose cut open 

 tlirough all its length from right to left, or the whole external nose cut off, from 

 the nostrils to the forehead, so that you can look without hindrance into the 

 inner cavity, the aspect will be represented by the figure here attached. The 

 whole nasal cavity is divided into two halves by a perpendicular partition 

 (marked S) extending from the rear to the front. 



You feel the beginning of this partition at the entrance of the nose, which is 

 divided by it into two entrances, the two nostrils N N. Our figure shows you the 

 very irregular shape of the nasal cavity, the external walls of each half forming a 

 multitude of conspicuous projections jutting into the cavity. Three principal 

 projections are noticed on each side which are designated nasal shells in con- 

 sequence of their resemblance to a muscle-shell. In general, they form a kind 

 of bent ledges extending from the front to the rear, projecting into the cavity 

 with a kind of free list, and partly supplied with secondary ledges. Our figure 

 represents these shells a h c in the cut, showmg how they divide each half of 

 tlie nasal cavity into layers overlying or freely communicating with each other, 

 and, above all, how through them tind their secondary projections a considerable 

 increase of the surface of the nostril partition is brought about. The whole 

 surface, with its prominences and corresponding hollows, is lined with a soft 

 skin, the so-called cuticle, as shown by the double contours. This cuticle con- 

 sists of two layers of a soft membrane directly overlying the bony wall, the 

 base of which is formed by a net of thin fibres and a softish substance filling up 

 the meshes of the net, and secondly, of an external coating in the direction of 

 the nasal cavity. A microscope shows us this coating to consist of innumerable 

 small, oblong, cylindrical vesicles, standing thick and perpendicular, in regular 

 order, on the described base. Each of these vesicles has a pointed rear ex- 

 tremity by which it is attached to the base, and a broad front extremity directed 

 towards the nasal cavity. On this broad basis of each single vesicle stands a 



