1883.] 



MICROSCOPICAL JOURNAL. 



i'5 



exists in the vagina, but the human 

 female is not thus restricted, and here 

 we find the delicate ciliated epitheli- 

 um replaced by a thick stratified per- 

 manent variety, better adapted to 

 frequent insults. The ciliated epithe- 

 lium of this region being limited to 

 the tubular glands of the fornix, and 

 introitus vagina. In the male sexual 

 organs we find the ciliated epithelium 

 of the vas efferens, coni-vasculosi, 

 canal of epididymis, and beginning 

 of vas deferens assisting its motile 

 kinsmen the spermatozoa, through 

 the tortuous and most difficult portions 

 of their journey, and landing them at 

 a part of the canal from which they 

 can readily find their way to portions 

 where they will be accessible to the 

 emittent power of muscles concerned 

 in placing them within the female. 



We have yet to consider vibratiie 

 cilia in connection with two of the 

 most important functions of the body, 

 viz., the senses of hearing and smell- 

 ing. In the membranous labyrinth of 

 the semicircular and cochleal canals 

 we find a variety of ciliated cells which 

 has been called the neuro-epithelium, 

 and their cilia the auditory hairs. 

 These cells as they occur in the vesti- 

 bule are spindle shaped, and are un- 

 doubtedly the bearers of the terminal 

 organs of the vestibular nerves, which 

 seem to be continued into their grad- 

 ually tapering prolongations or cilia. 

 In the organ of Corti we have two 

 series of ciliate cells, — the inner and 

 outer hair-cells, — the free extremities 

 of which carry a thick tuft of staff- 

 shaped cilia; in man very long and 

 stifl". 



These hair-cells number in man 

 about 21,000,* constituting the most 

 important or essential portion of the 

 cochleal apparatus, carrying as they 

 flo the terminations of the auditory 

 nerve. Several beautiful theories have 

 been advanced to explain the part 

 played by these auditory hairs in the 

 appreciation of tones. 



Hensen having observed that among 



* 3,300 inner hair cells, 18,000 outer hair 

 cells. —7 Waldeyer. 



those of the Crustacea some will vi- 

 brate to particular notes, just as when 

 a person standing before an open 

 piano sings any note, it is noticed that 

 certain strings, corresponding in pitch, 

 are thrown into vibration ; considered 

 that for each tone there existed a hair 

 of the requisite length to answer its 

 peculiar vibrations. It was, however, 

 urged that the auditory hairs of mam- 

 mals are of equal length, and therefore 

 cannot act as organs for analyzing 

 sound. It seems to me that this does 

 not follow. We may readily see how 

 difficult would be the task of distin- 

 guishing between different ciliated 

 cells, were specimens of each variety 

 to be placed at once under a cover 

 glass and examined microscopically. 

 Yet we know that each of these cells, 

 in its proper position, performs func- 

 tions peculiar to itself. It would 

 seem to follow, from the independence 

 of ciliate cells to the general conditions 

 of the body, that there must be in 

 each variety some difference in molec- 

 ular arrangement. Thus bathed in 

 the endolymph an auditory cilium se- 

 lects from the complex vibrations of 

 that fluid, such as are in harmony with 

 its particular molecular arrangement. 

 Allowing this to be the case, we can 

 easily imagine the auditory cilia to be 

 so constituted, that they respond only 

 to certain tone vibrations communi- 

 cated to them by the endolymph, and 

 in their turn, communicating these vi- 

 brations to the nerve filaments which 

 have become blended with or end in 

 their substance. In the case of the 

 cilia which in birds and amphibians 

 are found in the olfactory regions, it 

 is uncertain as to their position in re- 

 gard to the nerve terminations ; but 

 it is settled that they represent no 

 necessary condition to the perception 

 of smell, since in mammalia and man 

 they are wanting. When they do exist, 

 their function may possibly be the 

 mechanical one of drawing odorous 

 particles into proximation with the 

 terminations of the olfactory nerves. 

 This seems probable, as they are 

 known to have a motion of their own 



