Since it has been established that the endocrine glands are essential for growth, an understanding of the morphological and physiological activities of these glands during the process of development of the embryo becomes important. The endocrine glands compose a system which functions as a regulator in maintaining a balance of the physiological processes of living protoplasm. At present there is little information regarding the exact time in embryological development when the hormones of the various endocrine glands become available for use by the organism. Therefore, it is the purpose of this paper to correlate the morphological and known physiological activities of some of the developing endocrine glands of the chick embryo.