76 ■ ALBERT KITNTZ 



I take pleasure in expressing my indebtedness to Professor F. A. 

 Stromsten for the use of a large number of embryos of this species 

 which were collected by him at the Dry Tortugas, Florida, during 

 the summer of 1910. It is a real pleasure also to express my deep 

 sense of obligation to Professor G. L. Houser for helpful sugges- 

 tions during the progress of this investigation and for reading the 

 manuscript. 



OBSERVATIONS 



Early development 



Cortical substance. The anlagen of the adrenals arise in 

 embryos of Thalassochelys caretta during the eighth day of incu- 

 bation as buds of cells which proliferate from the peritoneal 

 epithelium just laterad to the root of the mesentery and approx- 

 imately at the middle level of the mesonephros (fig. 1, ad). At 

 the close of the eighth day of incubation a short series of buds 

 may be observed on either side of the aorta rising into the mesen- 

 chyme between the aorta and the mesonephros. These buds 

 are at first more or less wedge-shaped with a broad base resting 

 on the peritoneal epithelium from which they arise (fig. l,ad). 

 There is no well marked differentiation apparent at this stage 

 between the cells composing the adrenal buds and the cells of the 

 adjacent mesenchyme. The nuclei of the former often appear 

 somewhat clearer than the nuclei of the latter and their cytoplasm 

 stains somewhat more intensely. These buds may be readily 

 recognized, however, by the relatively compact and more or less 

 regular arrangement of the cells composing them. The exact 

 number of buds taking part in the development of the cortical 

 substance of each adrenal organ is not easily determined. These 

 buds do not all arise simultaneously. During the ninth and the 

 tenth day of incubation, after the earliest buds have become nearly 

 or completely separated from the peritoneal epithelium, buds 

 may still be observed in the anterior region of the zone of prolifera- 

 tion which exhibit the earliest phases of their development from 

 the peritoneal epithelium. 



