ACTIVE PRINCIPLES OF INTERNAL SECRETIONS 190 



Persulphate Reaction. This is the most delicate of all the tests for 

 adrenaline, detecting one part of adrenaline in five million of solution. 

 Potassium persulphate is added to the solution to the extent of one- 

 tenth of a per cent., and the test-tube is then heated by immersion in 

 boiling water. 



Phosphotungstic Acid Reaction. With Folin and Macallum's "uric 

 acid reagent," which consists of a mixture in specified proportions of 

 sodium tungstate and phosphoric acid, adrenaline yields the blue color 

 which Uric Acid, Alloxantin, certain Dihydrophenols, Aminotyrosine and 

 other substances including the vitamines also yield. The test will 

 detect one part in 3 million of adrenaline. 



Adrenaline constitutes about one-tenth of a per cent, of the fresh 

 tissue of the suprarenal gland. One bullock's gland, weighing about 

 ten grams, should therefore yield about ten milligrams. 



The origin of adrenaline is unknown. The close relationship to 

 Tyrosine would suggest this as the parent substance, but the trans- 



Normal 



A 



20 mg.Tethelin 20 mg.Tethelin 1 cc. Split Product 



-* Minutes > 

 FIG. 6. Tracing showing effect on the uterus (guinea-pig) of split products of tethelin. 



formation of tyrosine into adrenaline would involve a series of changes 

 not merely decarboxylization, but also the introduction of two hydroxyl- 

 groups, one of them in the benzol-ring, followed by methylation 

 of the resultant compound. We are not familiar with any mechanism 

 which could bring about this rather complicated series of transforma- 

 tions. There are some indications, however, that the suprarenal 

 glands may contain precursors of adrenaline which are devoid of 

 pressor-action, and yet yield a coloration with oxidizing-agents. 



The important physiological actions of adrenaline will be separately 

 discussed (cf. Chapter XVI). 



The posterior lobe or Infundibulum of the Pituitary Body contains a 

 nitrogenous substance which exerts an action upon the uterus as 

 distinctive as that of ergot and has also the peculiar property of exciting 

 the secretion of the Mammary Glands. The structure and even the 

 composition of the active substance are unknown, but since it yields a 

 red color with Diazobenzene Sulphonic Acid (see Histidine), it probably 



