382 Charles R. Stockard. 
that any factor which might come in during early development 
to lower the developmental energy could possibly induce similar 
defects. In mammals such monsters probably arise as the result 
of some weakening or debilitating influence of the environment 
during early developmental stages, which need only have acted 
for a short space of time. 
b. Defects of the auditory organs 
A very pronounced suppression in the development of the audi- 
tory apparatus is often noticed in the embryos which have been 
treated with weak solutions of alcohol. In many individuals only 
one ear exists. When this condition is found in an embryo with 
only one eye, two unequally developed eyes or a cyclopean eye 
with asymmetrical components, it is of interest to find that in all 
cases observed, the ear is on the same side of the head as the better 
formed eye. In rare cases both ears are absent, and again it 
often happens that the ears are apparently normal while the 
eyes are deformed. Fig. 16, a horizontal section through the 
head, shows two small abnormal eyes with a lens between them 
and two perfect ears with cartilaginous capsules, near the hind 
brain. Fig. 18, which is a section through the ear region of the 
embryo shown in fig. 4, illustrates two poorly formed ears; on the 
right side the ear issmall and two semicircular canals are represented 
only by their ampulla, the epithelial lining of which forms papillz 
of cells with long hair-like processes growing from them as is 
indicated in the drawing. The left ear is almost entirely absent, 
its median section showing only the small cavity and ampullary 
papilla seen in the figure. . Both ears, however, are surrounded by 
well formed cartilaginous capsules. 
A remarkably abnormal ear is seen in fig. 17. The auditory 
vesicles have united so as to occupy a dorsal position above the 
posterior end of the brain. Only two semicircular canals are devel- 
oped on each side. The cartilaginous capsules in this case seem 
unable to meet the situation and extend for only a portion of the 
way around the huge auditory cavity. This union of the lateral 
auditory vesicles, although formed by an entirely different princi- 
ple, suggests the large double cyclopean eye. 
