An Experimental Approach to the Development of Ear Capsule in the Turtle, Chelydra Serpentina.

THE effects of the elimination of the otic placode or otocyst on the development of the cartilaginous ear capsule and columella auris have been observed in several fishes, amphibians and birds and are summarized by de Beer (1937), Yntema (1955) and Benoit (1957). More recent work includes that of Benoit (1960) and Toerien (1963). Except in the fish Acipenser (Filatow, 1930) the development of a cartilaginous ear capsule is completely suppressed following the removal of the otocyst. The effect of the operation on the development of the columella is not so clear and the resultant deficiency in the medial aspect has been interpreted in various ways. Yntema's (1965) method for using turtle eggs has made the early stages of reptilian embryos available for experimental studies. The purpose of the present investigation, therefore, is to study the effect of the removal of the placode on the development of the auditory region in yet another vertebrate class.