ADRENALS 665 



It has been prepared synthetically, and in the body appears to be 

 formed, probably by the introduction of a methyl (CH 3 ) group, from 

 a compound arising from an aromatic amino-acid (tyrosin or phenyl- 

 alanin). While the natural adrenalin rotates the plane of polarization 

 to the left, the artificial substance is optically inactive. This is because 

 it consists of equal parts of laevo-rotatory and dextro-rotatory adrenalin. 

 The artificial adrenalin has approximately half the effect of the natural 

 on the blood-pressure, from which it may be inferred that the dextro- 

 rotatory isomer has only a very slight pressor effect. The left and right 

 rotatory moieties have been separated. The former has exactly the 

 same power of raising the blood-pressure as the natural adrenalin, the 

 latter only ^ to -^ s as much. Practically the same proportion holds 

 when the power of the two isomers in producing glycosuria is compared. 

 This constitutes important corroboration of the view already referred 

 to (p. 550), that adrenalin glycosuria is caused by an action on the 

 sympathetic system, for the effect on the blood-pressure is known 

 to be thus produced (Cushny). 



It is in the medulla of the adrenals that the epinephrin is formed. 

 The medullary cells contain a substance which gives a yellow or brown 

 stain with chromic acid or chromates, and for this reason the cells are 

 called chromaffin or chromaphil. Similar cells are found elsewhere in 

 the body e.g., within the sympathetic ganglia, and also strung out 

 in clumps along the course of the abdominal aorta below the level of 

 the adrenal glands (Vincent). These outlying masses of chromaffin 

 tissue appear to contain epinephrin, or a substance with similar physio- 

 logical actions, so that the formation of this compound seems to be a 

 property common to chromaphil tissue, no matter what its situation 

 may be. A remarkable fact, and one calculated to induce caution 

 in assigning a physiological function to epinephrin, is that the so-called 

 parotid gland of a Jamaican toad secretes it in a concentration not 

 much short of 5 per cent. (Abel). 



Function of the Adrenal Cortex. The function of the cortical cells is 

 obscure, but there is evidence that they, and not the chromaffin cells 

 of the medulla, are concerned in the production of the internal secretion, 

 whatever its nature may be, the loss of which leads so speedily to death 

 on removal of the adrenals. For example, the period of survival after 

 this operation is practically unaffected by the continuous intravenous 

 administration of adrenalin, although the loss of the medulla- might 

 be supposed to be compensated in this way. Still more convincing 

 is the fact already referred to that after removal of one adrenal and 

 denervation of the other in cats, epinephrin ceas>es to be discharged 

 in detectable amount, and yet the animal survives in good health. In 

 Addison's disease adrenalin is likewise powerless. 



The weakness (asthenia) of the skeletal, and to some extent of the 

 cardiac, musculature which is characteristic of Addison : s disease, is 

 produced experimentally within a few hours by ligation of both adrenals, 

 and all the evidence goes to show that it is the cortical and not the 

 mediillary region which is related to this disease. When the adrenals 

 are not completely extirpated, compensatory hypertrophy of the re- 

 maining portions may occur, and the animal survive indefinitely. In 

 such cases it has been found that the hypertrophy is confined to the 

 cortex. 



In animals like the rabbit in which accessory adrenals are not un- 

 common, when these are present complete removal of both adrenals 

 does not cause death. Now, the accessory adrenals consist of cortical 

 substance without medulla. Portions of the adrenal are readily 

 grafted under the skin, but only the cortex survives and grows. 



