584 INTERNAL SECRETION 



turn from a rose colour to red and eventually brown. It forms 

 salts, and an aqueous solution of the chloride having a strength 

 of 1 in 10,000 will blanch the normal conjunctiva within a minute, 

 while an injection of 0-000,001 grm. per kilogram of body-weight 

 will raise the blood pressure of an animal by 14 mm. of mercury. 

 The chemical structure of adrenalin has been worked out by von 

 Fiirth, Jowett, and Pauly ; it appears to be a secondary alcohol 

 of the formula C 6 H 3 (OH) 2 . CH(OH)CH 2 . NH . CHg. 1 The ketone 

 called adrenalone C 6 H 3 (OH) 2 CO . CH 2 NH . CH 3 is about one-tenth 

 as effective as adrenalin in the production of glycosuria. 



Since the preparation of adrenalin and its salts in the pure 

 state numerous experiments have been made upon its physio- 

 logical action. The most important results are those of Langley, 

 who has been able to give a wider significance to the action of 

 adrenalin ; the effects produced by adrenalin upon any tissue are 

 such as follow excitation of the sympathetic nerve which supplies the 

 tissue. This generalisation has been confirmed by Brodie and 

 Dixon and by Elliott ; the former observers found that adrenalin 

 cannot constrict the pulmonary vessels, a striking difference in 

 behaviour as compared with the marked constriction of the 

 systemic arterioles, and one which receives a simple explanation 

 if the adrenalin acts only upon sympathetic nerve-endings. The 

 muscles of the pulmonary blood-vessels are not supplied with 

 constrictor fibres, and in default of sympathetic nerve-supply 

 plain muscle does not react to adrenalin. Adrenalin may, there- 

 fore, be used as a test for the existence of sympathetic nerves in 

 any organ ; it stimulates the substance at the junction of the 

 muscle and nerve, not the sympathetic nerve-cell, nerve-fibre, or 

 muscle-fibre. Its effects may in one organ be shown by contrac- 

 tion, in another by inhibition ; thus it causes contraction of the 

 spleen and inhibition of the movements of the stomach, but in 

 each case it resembles in its effect the excitation of the sympa- 

 thetic supply of those organs. It has already been pointed out 

 that adrenalin is only formed in the medulla of the gland which 

 is developed from the sympathetic system. 



HO 



1 The structural formula according to Dakin is H0<^ \ CH (OH) . CH 2 

 NHCH 3 . Catechol, the aromatic nucleus, and not the side chain oxyethylinethyl- 

 amine, is the active part. Dakin has prepared a substance with the same 

 action, and very closely related if not the same as adrenalin, by heating catechol 

 with chloracetyl chloride, and then acting on the chloracetyl catechol with 

 methylamine. (Editor's Note.} 



