140 Development of Har and VII-VIII Cranial Nerves 
This investigation was originally concerned only with the acoustic 
complex, later it was extended to the ear vesicle, and it was found 
possible to add several new features concerning the development of this 
structure and the formation of the membranous labyrinth to that which 
was already known from the work of His, Jr., 89, who, as far as could 
be learned, is the only investigator that has made a direct attack on 
this region in the human embryo since the introduction of wax plate 
reconstruction methods. It is, of course, to be remembered that in his 
work attention was mainly directed toward the nerve and ganglion 
masses, while the finer structure of the ear vesicle was not considered in 
detail. 
The contributions here reported include both additional early stages in 
the development of the ear vesicle and further details in the formation 
of the individual parts of the labyrinth. Also some apparently funda- 
mental errors in the work of the above investigator have been here 
corrected. One of these regards the saccule, which as represented by His, 
Jr., develops as a compartment pocketing out from the upper end of 
the cochlea, but which in our specimens develops as a com- 
partment or subdivision of the utricle. Instead of the saccule developing 
from the cochlea, the cochlea develops from the saccule, though this 
occurs at a considerable time before the separation between utricle and 
saccule is complete. 
The facial nerve, and especially its sensory division or pars intermedius, 
bears such a close relation to the auditory apparatus that it was found 
convenient to include it in some of the reconstructions. It was possible 
to identify conditions in the embryo confirmatory of what is now the 
generally accepted opinion as regards the adult, 1. ¢., that the nervus 
intermedius is the dorsal and sensory root of the seventh, its fibers 
arising in the geniculate ganglion and continued peripherally in the 
chorda tympani and great superficial petrosal. 
MATERIAL AND METHODS. 
This work was made possible through the kindness of Professor Mall, 
who gave the writer, for the purpose of this investigation, free access 
to his large collection of human embryos. In the following list are 
tabulated the embryos which were selected for reconstruction : 
