184 THE AUDITORY NERVE AND COCHLEA, BY W. WALDEYER. 



completely free position as a gelatinous screen or veil (Gallert- 

 schleier) over those terminal portions of the terminal auditory 

 apparatus which bear the hair cells, are also, it appears to me, 

 much more in accordance with the view of its being a damper, 

 than of its acting in the manner maintained by Hasse. 



COMPARISON BETWEEN THE ORGAN OF CORTI AND THE RETINA. 



We are easily led to institute a comparison from a morphological point 

 of view, between the two sensorial apparatuses that are specifically 

 adapted to transfer regularly recurring vibrations to the extremities of 

 the nerves. 



The comparison appears so much the more appropriate since the 

 works of Strieker, Schenk, Torok and others, quoted below, show 

 that genetically there is no essential difference between the vesicles of 

 the labyrinth and the primary eye vesicle, whilst both proceed, in the 

 Batrachia at least, from the same germinal lamina the Epiblast or 

 sensorial lamina. Our knowledge of the process of development is 

 doubtless insufficient to permit of a complete and detailed comparison 

 between the two ; what is already known on this subject, however, 

 taken into consideration with our knowledge of the mature organ, 

 supplies the means for drawing a parallel, which I shall here briefly 

 endeavour to give. 



No one will question that the sclera and osseous cochlear capsule cor- 

 respond to each other, and I would just notice the formations of bone that 

 occur in the sclera of the Bird, and of cartilage in the sclera of the 

 Batrachia, etc. The connective-tissue wall of the ductus cochlearis is 

 comparable with the choroid coat, and consequently the scala3 represent 

 greatly developed perichoroideal spaces (see p. 141). The lamina fusca 

 of the sclera is also represented, since both the periosteum of the coch- 

 lear wall and the central delicate portion of the external connective- 

 tissue cushion (e, figs. 321 and 322) contain similar large branched 

 pigment cells. The corpus ciliare is evidently represented by the stria 

 vascularis, which indeed, in Birds, presents in the tegmentum vasculo- 

 sum exactly the same structures as we meet with in the processus ciliares. 



In order to carry the comparison further, it must be borne in mind 

 that in the eye an involution of the primary eye vesicle takes place, 

 so that this acquires the form of a cup, the foot of which is repre- 

 sented by the optic nerve, and the walls of which, owing to the fact 

 of their being constituted by an involution, are necessarily double.* 



* Kolliker (62), p. 276. 



