This report is one in a projected group dealing chiefly with the development of the cartilaginous otic capsule and the contained membranous labyrinth in human embryos. It will ultimately include a complete study of these parts in embryos of 17.5, 22.8, 29 and 40 mm.1 length.
The importance of information concerning the cartilaginous capsule in certain other investigations of the human ear now being conducted by the department of otolaryngology and anatomy occasioned the selection of the current problem as a fundamental one. The 29 mm. (crownrump) embryo was chosen as the first subject since, from the work of Schönemann2 (1904), Streeter3 (1906) and Macklin4 (1921), it was evident that this stage represents a crucial one in the development of the capsule and the labyrinth, one in which the ground plan of the adult structures is already established.
MATERIAL AND METHODS
The reconstructions described and figured in this paper were