VOL. III.] Recent Literature. 183 



point to the conclusion that the auditory organ has arisen by the 

 bringing- together of two originally distinct sense organs which were 

 together sunk below the surface." He then gives the evidence for 

 this, which is mainly the distinct origin of the nerve roots which 

 supply the ear. He accordingly considers the membranous laby- 

 rinth as a vestigial structure, and prophecies that in the future ear 

 little will be left save the cochlea. Among the points in morphology 

 which he has discovered the following are of general interest: the 

 hair-bearing cells of the cochlea are probably never double, as was 

 formerly supposed; the sense organs on the floor of the cochlea 

 consist of a series of linear fibres closely united togetlier, and are 

 not a single band-like sensory apparatus, as described by previous 

 investigators; the basilar membrane does not possess sufficient elas- 

 ticity " to serve for the transmission of the delicate undulations 

 which it has been supposed to transmit, and from its composition a 

 great deal of the motion imparted to it would necessarilv be lost in 

 transmission;" "the evidence of comparative anatomy is entirely 

 against the existence of the spiral nerve bands;" " the ear is sup- 

 plied by two distinct nerves which have widely different origins in 

 the brain, and are, in reality, branches from tivo 7ierves, and so not 

 a discrete cranial nerve, as has formerly been supposed to be the 

 case;" "the so called membrana tectoria of previous authors is, in 

 reality, a hair-band or field of long, slender hairs which spring from 

 the tops of the hair cells and form a waving plume on the crest of 

 the ridge of the organ of Corti;" " the membrana tectoria, the mem- 

 brana reticularis, Loewenberg's net, and the three or four main 

 trunks of the system of spiral nerves of the cochlea have no exist- 

 ence as such in the living mammalian ear." 



The physiological results of Mr. Ayers' investigations are ot 

 equal importance with the morphological. He details experiments 

 conclusively proving that the semicircular canals are not indispen- 

 sable for the equilibration of an animal, which function he very 

 reasonably considers to be exercised by all the nerves of sense in 

 general. He may, however, be a trifle hasty in assuming that the 

 semicircular canals are without any function whatever. He consid- 

 ers " the outer and middle ear to be mere accessory structures ac- 

 quired by the higher vertebrates in ever-increasing complexity, for 

 the sole purpose of enabling the animal to preserve in the aerial 

 ocean, on or near the bottom of which they live, the necessary 



