RECENT ADVANCES IN SCIENCE. 357 



chemical fight which the blood is carrying on in all the tissues of the 

 body. It may be perhaps to-morrow that we shall learn of some work 

 of a kind wholly unexpected which is carried out by that great Mal- 

 pighian layer of the skin which wraps round our whole frame. In any 

 case, the line of inquiry is one of the most fruitful of those of the 

 present day. I may add, too, I think, that it is one which has been of 

 the greatest direct use to mankind, and promises still more. It is true 

 that Bernard's discovery of glycogen, and perhaps especially the 

 diabetic puncture, raised hopes which have not been fulfilled. Not 

 to-day, any more than forty years ago, is it in our power wholly to 

 remove the disease which we call diabetes. But short of complete 

 mastery, how great is our power now compared with then. And when 

 we remember that the pancreatic relations of sugar are far from being 

 worked out, and that such knowledge as physiologists already possess 

 has not yet made much way in clinical study, we may look forward to 

 marked progress possibly in no very distant time. 



Further, if there be any truth in what I have insisted upon — that the 

 value of a discovery is to be measured not only by its immediate appli- 

 cation, theoretical and practical, but also by the worth of the idea 

 which it embodies and to which it gives life; and if it be true, as I 

 have suggested, that by the genesis of ideas the discovery of glycogen 

 is mother of all our knowledge of internal secretion, in its widest 

 sense, of the work of the thyroid and other like bodies, then the good 

 to suffering mankind which maybe laid to the door of Bernard's initial 

 experiment is great indeed. 



The next result to which I will call your attention is again an experi- 

 ment, and once more an experiment on a living animal. In 1850 

 Augustus Waller described iu the Philosophical Transactions the his- 

 tological changes which division of the hypoglossal and glosso- 

 pharyngeal nerves in the frog produced in the fibers of the distal 

 portions of the nerves, and shortly afterwards developed this initial 

 result into the more general view of the dependence of the nutrition of 

 a nerve fiber on its continuity with a cell in the central nervous system, 

 or in the case of afferent fibers, in the ganglion of the posterior root. 



This discovery was at the time and has since continued to be of 

 value as a contribution to physiological ideas. It had its share in pro- 

 moting the progress — which, though slight, is still a progress — of our 

 understanding the obscure influences which the part of a cell inclosing 

 the mysterious nucleus exercises over all the rest of the cell, and per- 

 haps even to-day the theoretical value of that degeneration of nerve 

 fibers the knowledge of which we owe to Waller is not adequately 

 appreciated and the lead which it gives not followed out as it might 

 be. In spite of all we know, we a,re much too apt to fall back on 

 the conception that when no nervous impulse is traveling along a 

 nerve fiber the nerve fiber is in a state of motionless quiescence, and 

 that a nervous impulse, when it does come, sweeps over the fiber as a 



