444 Recent progkess in physiology. 



mauy things and no little purification effected, the time for the final 

 judgment on the question will not come until Ave shall more clearly 

 understand than we do at i)resent what we mean by physical and 

 chemical, and may perhaps be put off until somewhere near the end of 

 all things, when we shall know as fully as we ever shall what the forces 

 to which we give these names can do and what they can not. Mean- 

 while the great thing is to push forward, so far as may be, the chemical 

 analysis of the j)henomena presented by living beings. Hitherto the 

 physiological chemists, or the chemical physiologists, as perhaps they 

 ought rather to be called, have perhaps gone too much their own gait 

 and have seemed to be constructing too much a kind of chemistry of 

 their own. But that, may I say, has in part been so because they did 

 not receive from their distinctly chemical brethren the help of which 

 they were in need. May I go so far as to say that to us physiologists 

 these our brethren seemed to be lagging somewhat behind, at least along 

 those lines of their science which directly told on our inquiries? That 

 is, however, no longer the case. They are x^roducing work and giving 

 us ideas which we can carry straight into i^hysiological problems. The 

 remarkable work of Emil Fischer on sugars, one of the bright results 

 of my period of thirteen years, may fully be regarded as opening up a 

 new era in the physiology of the carbohydrates, opening up a new era 

 because it has shown us the way how to investigate physiological 

 problems on purely and distinctively chemical lines. Not in the carbo- 

 hydrates only, but in all directions, our younger investigators are 

 treating the old problems by the new chemical methods; the old 

 physiological chemistry is passing away; nowhere, ])erhaps, is the out- 

 look more promising than in this direction; and we may at any time 

 receive the news that the stubborn old fortress of the proteids has 

 succumbed to the new attack. 



Another marked feature of the period has been the increasing atten- 

 tion given to the study of the lower forms of life, using their simpler 

 structures and more diffuse phenomena to elucidate the more general 

 properties of living matter. During the greater part of the present 

 century physiologists have, as a rule, chosen as subjects of their 

 observations almost exclusively the vertebrata; by far the larger part 

 of the results obtained during this time have been gained by inquiries 

 restricted to some half a dozen kinds of backboned animals; the frog 

 and the myograph, the dog and the kymogr-iph have almost seemed 

 the alpha and the omega of the science. This has been made a reproach 

 by some, but, I can not help thinking, unjustly. Physiology is, in its 

 broad meaning, the unraveling of the jwtentialities of things in the 

 condition which we call living. In the higher animals the evolution -by 

 differentiation has brought these potentialities, so to speak, near the 

 surface, or even laid them bare as actual properties capable of being 

 grasi^ed. In the lower animals they still lie deep buried in primeval 

 sameness; and we may grope among them in vain unless we have a 



