SECRETION OF THE DUCTLESS GLANDS. 777 



such as those of the brain or lungs, are provided with vasocon- 

 strictor nerve fibers. When adrenalin is injected into a normal 

 animal it may have an influence upon the nerve centers of the vaso- 

 motor nerves as well as upon the peripheral endings. Meltzer* has 

 shown that moderate doses under such conditions may cause a dila- 

 tation, while in parts whose connection with the nerve center is 

 destroyed only a constriction is obtained. Under normal condi- 

 tions at least these extracts when injected into the circulation soon 

 lose their effect. This fact may explain why injection of the ex- 

 tracts has failed to give permanent relief in animals from whom 

 the adrenals had been removed or in human beings suffering from 

 Addison's disease. Bearing in mind the results obtained in the 

 case of thyroidectomy, it has been suggested that grafts of the adre- 

 nals under the skin or into the peritoneal cavity may prove more 

 effective. Results by this method, however, have also been chiefly 

 negative, owing apparently to the fact that in such grafts the medul- 

 lary substance, which contains the material that causes constric- 

 tion of the blood-vessels, readily undergoes atrophy and absorp- 

 tion. It seems probable that, if the method of grafting is perfected 

 so as to preserve the medulla intact, this procedure may prove 

 effective as a therapeutical means in the treatment of Addison's 

 disease. 



The Physiological Rdle of the Adrenals. There seems to be 

 no question that the medullary substance forms epinephrin or adre- 

 nalin or some related compound which has a marked stimulating 

 effect upon the tone of the blood-vessels and upon the heart, and 

 that this material passes into the blood. The general view, there- 

 fore, has been that one at least of the functions of the adrenals is 

 the internal secretion of this material. It is assumed that its con- 

 tinued formation is necessary to the maintenance of the normal 

 metabolism of the muscular tissues either by a direct effect or 

 indirectly by influencing the activity of the nerve centers. Removal 

 of this secretion results in a marked loss of muscular tone and vigor, 

 exhibited by the blood-vessels, the heart, and the skeletal muscles, and 

 death follows rapidly. This general view is in accord with the 

 facts so far as they are known, but it must be confessed that it goes 

 somewhat beyond the facts. Another permissible, although less 

 probable view is that the adrenals produce an antitoxic substance 

 whose function is to neutralize or destroy certain (unknown) poi- 

 sonous products of body metabolism. Removal or disease of the 

 adrenals, on this theory, causes death because it allows these 

 toxic products to accumulate. 



Pituitary Body. This body is usually described as consisting 



*S. J. and Clara Meltzer, "American Journal of Physiology," 9, 252, 

 1903. 



