308 ADRENALS IN CARBOHYDRATE METABOLISM 



would show a powerful vasoconstricting effect unless in 

 injection it were spread out over a long space of time. Each 

 one of us will necessarily value the above objection accord- 

 ing to his own idea whether the adrenal medullary substance, 

 from a stimulus passing along the nerve paths to it, dis- 

 charges its store of suprarenin suddenly, or whether it 

 allows it to ooze out slowly. But this is the same old story: 

 as long as an accumulation of adrenin in the blood after 

 the glycosuric puncture is not actually proved, we will lack 

 authority for assuming that the puncture glycosuria is 

 caused by such means. Here is a place in physiology where 

 we are forced, if we are not willing to lose the ground under 

 our feet, to hold on to things we can see, even if we are very 

 well aware that there is plenty which we do not see. It has 

 been well said i ' that the negative finding in reference to the 

 sugar puncture proves nothing more than the impossibility 

 of demonstrating an adrenaemia from this disturbance but 

 in no way contradicts the possibility of its existence. ' ' 29 We 

 are here not after something that is possible (many things 

 are possible), but something that is probable. The fact that 

 a hypothesis starts up in an investigator's brain and that 

 at the time we are not in position to fully prove its incorrect- 

 ness does not force us by a great deal to accord reality to 

 it. It does not lie at our door to bring proof that a hypo- 

 thesis is incorrect; but whoever proposes a hypothesis has 

 to bring the positive proof that it is correct. In this way 

 and not in the reverse we hold in other exact sciences, and so, 

 too, it should be held in physiology. 



Here is a rare little verse which perhaps has occurred 

 to some in this connection : 



* l Oh, learned man, 'tis thus I know you, face to face ! 

 What you don 't touch stands miles from you apace ; 

 What you don't grasp, for you is gone for woe and weal; 



R. H. Kahn, Pfliiger's Arch., 144, 271, 1912. 



