760 Comparative Animal Physiology 



ovary, is followed by a period of rapid yolk deposition. During this latter pe- 

 riod the fatty stores are rapidly reduced and stabilized at a new lower level. 

 These changes occur in a closely similar manner in castrated animals, indi- 

 cating that the control of these changes resides outside of these organs. How- 

 ever, when allatectomy is performed in young adult females, the operated 

 animals continue to deposit fat for a long time, the fat bodies becoming tre- 

 mendously hypertrophied. It would thus appear that during normal develop- 

 ment of the corpora allata these organs undergo an endocrine alteration with 

 respect to factors controlling fat metabolism, in a manner directly adapted to 

 normal yolk deposition. Furthermore, in castrated but otherwise normal fe- 

 males there is observed an accumulation of non-fatty material which does 

 not occur in allatectomized-castrated specimens. This suggests that the cor- 

 pora allata are responsible for the accumulation of "precursory materials" 

 normally used up in the production of yolk but which, in the absence of 

 the ovaries, are forced to accumulate in other regions of the body, such as 

 the hemolymph. 



Water and Salt Regulation. The maintenance of the normal water con- 

 tent and the characteristic percentage compositions of various essential inor- 

 ganic constituents in the blood, tissue, and intracellular fluids is dependent 

 on a regulation of the relative rates at which these materials enter the body 

 and leave it, and also on a regulation of the distribution of the materials 

 among blood, tissue fluids, intracellular contents, and storage reservoirs. Im- 

 portant participants in such regulatory roles are a number of endocrine or- 

 gans of the body of the mammal, notably the pituitary, the adrenal cortex, 

 the parathyroids, and the kidneys. 



Extirpation of the cortical tissue of the adrenals of the mammal is rapidly 

 fatal. ^^ There are an increase in the rate of loss of sodium and chloride ions 

 in the urine and a decrease in the rate of their absorption from the gut. 

 Potassium ions accumulate in the blood. These eff^ects of adrenalectomy may 

 in some measure be compensated by administration of a diet low in potas- 

 sium and high in sodium. Sodium salts appear to leave the cells of the tis- 

 sues as well. In the absence of the cortex the water content of the blood de- 

 clines, the blood becoming concentrated as water passes to the tissue fluids 

 and also out of the body through the kidneys. Administration of extracts of 

 the cortex, and especially of one of the numerous steroids isolated from it, 

 namely desoxycorticosterone, prevents occurrence of these changes in com- 

 pletely adrenalectomized individuals. These hormones apparently diminish 

 the absorptive capacity of the gut, kidney tubules, and tissue cells for so- 

 dium and chloride ions. 



The parathyroids, through the action of their hormone, parathormone, 

 are essential to the maintenance of the normal calcium and phosphate ion 

 content and distribution within the body.^''^ In this role the hormone func- 

 tions chiefly through governing the movement of these ions between bone 

 and body fluids. The presence of the hormone favors the movement in the 

 direction of the blood; its absence favors movement from blood to bone. The 

 hormone also appears essential for the normal resorption of these ions by the 

 kidney tubules. In its absence the ions are largely lost from the body through 

 kidney filtration and a subsequent failure of resorption of these ions by the 



