VOL. 1h 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 together, 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 necessarily 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, dvanches from two nerves, 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 aéria} 
ocean, on or near the bottom of which they live, the necessary 
