282 ON THE SENSES. 



"wreath of extremely fine and tender hairs, continually shaken by a kind of 

 lashing motioxi. Each little hair, in rapid motion, bends in a certain direction, 

 assuming the shape of a hook, then raises itself, again bends as before, and so 

 on. When we look, through the micros -jope, at a large row of such cellules, 

 with their numberless little lashing hairs, we have in miniature the same aspect 

 which a waving cornfield presents. The motion is so rapid that one at first 

 perceives only a kind of glimmering along the edge formed by the bases of the 

 vesicles, and only when the movements under the microscope gradually slacken 

 the single hairs become visible and recognizable. On account of. this phenom- 

 enon the said coating, consisting of vesicles, (cellules,) set with oscillating hairs, 

 is called cilliated epithelium. Physiology has yet no explanation for this 

 wonderful phenomenon ; Ave entirely ignore what force, inherent in the vesicles, 

 or working upon the hairs from without, causes the regular rhythmic oscillations 

 of the latter, we only know that it is a force which is rapidly extinguished on 

 the expiration of the organism. It is true, the epithelium separated from the 

 organism, nay, even the single entirely isolated cellule continues its motion for 

 a while, but the movement soon expires before we can discover a death change 

 in the little mechanism. Some of my readers may expect me to designate the 

 motive force of the hairs as "vital force," but I beg leave incidentally to remark 

 that this is a name and a conception long buried in the lumber-chamber of the 

 past, the resurrection of which would fill every conscientious physiologist with 

 horror. I defer the justification of this horror to some other time, observing here 

 that the forces which keep up the animal organism are no new or special ones, 

 but the same physical and chemical forces which rule inanimate nature, and 

 that they act in the organism according to the same inviolable laws which gov- 

 ern them in the outer world. But enough for digressions. Into this thus de- 

 scribed cuticle of the nasal cavity, and through it in all directions, spread the 

 tender and even microscopically hardly distinguishable fibres of the nerve of 

 smell. According to recent discovery, each of these fibres most probably, ap- 

 proaching one of the vesicles of the outer coating, fixes itself to its rear ex- 

 tremity. If this observation be correct, those vibrating cellules have the 

 significance of end-organs of the nerve of smell, that is, they are to be regarded 

 as the apparatus upon v/hich the odorous substance acts, producing a physical 

 or chemical process, which excites the nervous fibres springing from the cellule, 

 develops a nervous current and sends it to the brain. This vieAV is exceedingly 

 well supported. The fact that an odorous substance causes a sensation of smell 

 on the slightest contact with the cuticle of the nose becomes explicable when we 

 assume that the substance acts first on the cellules bordering on the nasal cavity ; it 

 remains an enigma if we have to assume that the odoriferous substance has to soak 

 through these cellules into the tissue of the membrane under it in order to reach 

 the nerve of smell which it is going to effect. But how an odorous substance, 

 whatever it be, acts upon the vesicles, and upon their contents ; what takes 

 place in the vesicles ; how by this process the nervous fibre becomes afiected ; 

 how the influences of the various odorous substances differ from each other ; 

 all these are problems toward the solution of which no path offers as yet to lead 

 us, or is likely soon to be discovered. We cannot hope to see the torchlight of 

 scientific inquiry illumining the mysterious processes which we have just hinted 

 at before accomplishing two essential tasks : First, the understanding of the 

 external affection of the nerve of smell, that is, of the qualities which ren- 

 der a substance odorous, and of the forces by which it indirectly acts upon 

 the nerves; and, secondly, a clear conception of the conducting process in the 

 nerve itself of the so-called nervous current. The unavoidable necessity of 

 making these preliminary scientific steps is as obvious as the sad truih that 

 physiology is yet helplessly ignorant of how to make them. Of our ignorance 

 of the nature of the afiections of the nerves, we have spoken in our first article ; 

 the complete obscurity of the exciting agent has been alluded to in this. If we 



