772 THE ADRENAL GLANDS 



where it can usually be recognized by staining the tissue with chromic acid. 

 Sometimes accessory chromaffin tissue is located in distant parts, 

 as in the epididymis of the rat, for example. It is said that life can 

 be maintained if one-eighth of the total amount of the adrenal substance 

 be present in the body. Attempts to prolong life after adrenalectomy 

 by adrenal transplantation have almost invariably met with negative 

 results, because the graft undergoes a rapid process of necrosis and dis- 

 appears; although it is said that transplantation may sometimes be suc- 

 cessfully accomplished if the grafting is done into the kidney. Adminis- 

 tration of suprarenal extract is also without definite benefit after 

 adrenalectomy. 



Adrenal Disease in Man. Besides the hypertrophy of the cortex, which 

 has already been alluded to, destructive disease (usually tuberculous) 

 of the adrenal gland occurs, which has been recognized to be the cause 

 of a characteristic clinical condition known as Addison's disease. This 

 condition, which runs a more or less protracted course and is almost in- 

 variably fatal, is characterized by muscular weakness, low blood pres- 

 sure, pigmentation of the skin and gastrointestinal disturbances. Injec- 

 tions of epinephrine have little or no influence over the symptoms or over 

 the course of the disease; administration of extracts of the whole gland 

 are, perhaps, of more benefit. Though it is almost universally accepted 

 that inadequacy of the adrenals is responsible for the disease, the imme- 

 diate cause of the symptoms is obscure, nor is it known whether cortex or 

 medulla is at fault. It might appear that the muscular weakness and ar- 

 terial hypotonus were due to incompetency of the medulla; yet the results 

 of epinephrine administration do not support such a conclusion. Further- 

 more, as we shall see, it has been demonstrated conclusively that epine- 

 phrine is not a factor in the maintenance of normal arterial tone (page 

 785). 



The bronzing of the skin, a prominent symptom of Addison's disease, is 

 due to an increase of the normal pigment melanin in the Malpighian 

 layer. To account for the excessive deposition of pigment (chromatosis) 

 Halle 7 has suggested that there is an increase of tyrosine, the precursor 

 of melanin, in the tissues. Part of the tyrosine of the body is believed 

 to be converted, under normal conditions, into epinephrine. This belief 

 is supported by a comparison of the formulae of the two substances 

 (epinephrine C 9 H 13 N0 3 , tyrosine CgH^NOs) and by the following experi- 

 ment: An emulsion of the gland was divided into two halves, to one of 

 which tyrosine was added; the two portions were incubated for six days, 

 after which period analysis showed that the portion to which the amino 

 acid had been added contained from 15 to 33 per cent more epinephrine 

 than the control. That melanin may be produced by the action of the 

 enzymes upon tyrosine is well known, for example, an extract of the 



