SECRETION OF THE DUCTLESS GLANDS. 877 



The Cortical Tissue. — Most observers agree that the cortex 

 does not contain epinephrin. This and the additional fact that 

 the cortical cells have a separate 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 cor- 

 tical substance exists as a separate 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 cortical tissues have some specific and 

 essential internal secretion, and it would seem possible, more- 

 over, that the fatal result always following extirpation of the 

 adrenal bodies is due to loss of the cortical rather than the med- 

 ullary substance. Some experimenters, who have studied care- 

 fully the effects of partial or complete 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, par- 

 ticularly 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 clevelops 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, "Inncre Sekretion," Berlin, 

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



