172 SCIENCE PROGRESS 



chemical constitution. It is a nitrogenous substance and there- 

 fore arises in some way from proteid. It is an aromatic substance, 

 and therefore probably arises from one or more of the aromatic 

 nuclei of the proteid molecule. Whatever the chemical potentiali- 

 ties of such cells as those of the suprarenal gland, we are well 

 justified in believing that they need some special chemical sub- 

 stance from which to elaborate the final specific product. It is 

 extremely probable that adrenaline is formed from one of the 

 aromatic amino-acids derived from proteid. Now a constant 

 supply of adrenaline is absolutely necessary for the body. This 

 being so, be it noted that the 7 grammes, or thereabout, of 

 suprarenal tissue which are present in the human body will, 

 on a liberal estimate, contain no more than some 200 mg. of total 

 aromatic substances derivable from the whole of the gland 

 proteids. But in starvation the medulla of the gland undergoes 

 comparatively little wastage, and 1 per cent, of the total gland 

 tissue is the very most that would waste in a day. To these 

 considerations we might add others, for it is much more likely, 

 in my own belief, that some one, and not all of the aromatics 

 derivable from proteid can serve as a basis for the elaboration ol 

 adrenaline, and, lastly, it is unlikely that the elaboration from 

 the available precursor would be complete. If, then, the assumed 

 limitations in the chemical potentialities of the glands hold good, 1 

 it will be seen that the available supply of material within the 

 gland itself, for the daily production of adrenaline, is almost 

 infinitesimal, and though the active substance is produced in 

 very small amount, its continued supply would undoubtedly 

 call for assistance from other tissues ; while to supply enough 

 of the particular amino-acid required, and to secure its duly 

 reaching the gland, a not inconsiderable amount of proteid must 

 be broken down. Similar considerations may apply to the 



1 Some, impressed by the wide range of chemical capacities displayed by 

 the body, may prefer to believe that such a substance as adrenaline may be 

 prepared by the gland de novo, starting from indifferent nitrogenous precursors ; 

 if this were the case, the quantitative considerations offered above would lose their 

 weight. But I believe that to attribute such indefinite powers to an animal 

 cell when simpler chemical possibilities are available is of the nature of resort 

 to vitalism, and is against what is so far known of metabolism. French workers 

 have offered evidence, which is by no means conclusive, that tryptophane is a 

 precursor of adrenaline. However this may be, some experiments indicating 

 that an individual amino-acid may be essential for special purposes in the body, 

 other than tissue repair, will shortly be published from the Cambridge laboratories 

 by Miss E. G. Willcock. 



