BASES OF UNKNOWN CONSTITUTION 109 



constitution. Its physiological action has, however, been studied in 

 some detail and such correspondence as exists between the action of 

 the pituitary body and of adrenaline has been found to be " superficial 

 and illusory". 



The chemical investigation of the pituitary active principle is greatly 

 hampered by its instability and by the difficulty of procuring enough 

 material. The infundibular portions, dissected clean from fresh glands, 

 are ground up with sand and boiled with water acidulated with acetic 

 acid. After filtration a clear colourless extract is obtained, which 

 contains a little protein and some phosphates. By the addition of 

 uranyl acetate the phosphates may be precipitated and most of the 

 protein is carried down with the precipitate, but the solution remains 

 physiologically active. Almost the only precipitant for the active 

 principle itself is phosphotungstic acid, as has for instance been found 

 by Engeland and Kutscher [1911] and by Meister, Lucius and 

 Briining (see Fiihner [1913]). The chemists of the Hoechst firm, 

 on decomposing the phosphotungstate with baryta, and removing the 

 excess of baryta with sulphuric acid, obtained on concentration in vacua 

 a pale yellow crystalline sulphate, which was physiologically active 

 and apparently homogeneous, but was afterwards separated by fractional 

 crystallisation into four different substances, all crystalline, and all 

 having some physiological activity. Two of these were more active 

 than the others ; the more abundant of the two is a colourless sulphate, 

 readily soluble in water, but only slightly so in alcohol, acetone, or 

 ethyl acetate. It gives Pauly's histidine reaction with p-diazobenzene- 

 sulphonic acid and also the biuret reaction. Its picrate is readily soluble 

 in water. In contact with alkali a volatile amine is at once given off. 



According to Fiihner, who has examined physiologically the various 

 substances from the phosphotungstate, they all contribute to the 

 activity of the gland ; thus there would be four active principles. 



The facts at present available do not, however, absolutely exclude 

 the possibility that these four substances all owe their activity to con- 

 tamination, in various degrees, with one and the same highly active 

 substance which has so far escaped isolation. The further chemical 

 examination of the most active of the four substances should prove of 

 great interest. That this substance gives the biuret reaction may be 

 considered in conjunction with an observation by Dale [1909] that 

 the activity of pituitary extracts is rapidly destroyed by trypsin and 

 much less rapidly by pepsin. This would point to a polypeptide struc- 

 ture. The activity is also fairly rapidly lost when an aqueous solution 

 is evaporated to dryness ; perhaps this is owing to hydrolysis. 



