888 PHYSIOLOGY OF DIGESTION AND SECRETION. 



servers agree that the cortex does not contain epinephrin. This 

 and the additional fact that the cortical cells have a different 

 origin embryologically make it probable that its functions are 

 different from those of the medulla. Biedl has shown that in 

 those fishes in which the cortical substance exists as a sep- 

 arate structure, the interrenal body, extirpation of this organ 

 is followed by 'a condition of progressive muscular weakness 

 ending in death. This result would indicate that the corti- 

 cal tissues have some specific and essential internal secretion, 

 and it would seem possible, moreover, that the fatal result al- 

 ways following extirpation of the adrenal bodies is due to loss of 

 the cortical rather than the medullary substance. Some experi- 

 menters, who have studied carefully the effects of partial or com- 

 plete removal of the adrenals in mammals, record their opinion that 

 it is the cortex rather than the medulla that is essential to life.* 

 The nature of the secretion furnished by the cortex and its normal 

 functional value are matters of speculation only at present. 

 Chemical examination of the cortex shows the presence of much 

 lipoid material, particularly of the cholesterin esters, and it may be 

 that through this material the tissue influences the metabolism in 

 other parts of the body. 



Observers have also called attention repeatedly to the fact that 

 the cortex has some relation to the activity of the sexual glands. 

 During pregnancy the cortex undergoes hypertrophy, and in some 

 cases pathological changes affecting the cortex alone have been fol- 

 lowed by precocious development of the sexual organs. On the 

 other side, castration causes changes in the adrenal bodies and, 

 indeed, the various phases of sexual life are accompanied by histo- 

 logical changes in the adrenals. But others of the glands of inter- 

 nal secretion have some similar functional relation with the repro- 

 ductive glands or their contained interstitial tissue, and no specific 

 suggestion can be offered at present in regard to the particular part 

 taken by the adrenal cortex.f 



Pituitary Body (Hypophysis). This body is usually described 

 as consisting of two parts a large anterior lobe of distinct glandu- 

 lar structure and a much smaller posterior lobe of nervous origin 

 and composed chiefly of neuroglia cells and fibers. Embryologic- 

 ally the two lobes are entirely distinct. The anterior lobe arises 

 from an invagination (Rathke's pouch) of the buccal ectoderm. A 

 portion of this epithelium soon develops into a glandular structure, 

 belonging to the type of glands which have no excretory duct and 



* Crowe and Wislocki, "Johns Hopkins Hospital Bulletin," October, 1914, 

 and Swale Vincent, "Endocrinology," 1, 140, 1917. 



t For details and references to literature on this and other points in inter- 

 nal secretion consult the excellent work by Biedl, "Innere Sekretion," Berlin, 

 1913, and "The Endocrine Organs," Schafer, London, 1916. 



