I.— PHYSIOLOGY. 185 



of the brain cells ; it facilitates sensory impressions and the association 

 of ideas. In large dose the caffeine beverages induce restlessness and 

 nervous excitability, and they may produce disturbed sleep, headache 

 and confusion. Few people, no doubt, take caffeine to this extent, but 

 most of us take from 2 to 5 grains of caffeine daily, and the effect of this 

 continued as a daily ration throughout life is a factor the significance 

 of which is unknown. We do know, however, that caffeine increases 

 sensitiveness to ordinary physical as well as mental sensations. 



England was once a drunken nation, and the larger towns contained 

 such notices as, ' Here you may get drunk for a penny ; dead drunk 

 with clean straw for twopence.' Before the revolution the consumption 

 of beer alone in England and Wales was 90 gallons a head per annum ; 

 now it is about a quarter of this. With this diminution of beer drinking 

 is associated a truly enormous increase in tea and coffee drinking. To me 

 it seems not unlikely that this substitution of tea for beer is not wholly 

 unconnected with the tendency of highly civilised nations to become 

 supersensitive and neurotic, for this is the groundwork upon which drug 

 addiction is built. 



I have endeavoured to show that all precise knowledge in therapeutics 

 is based upon controlled experiments on animals or man, and that the 

 elucidation of the action of medicaments by the methods and data of 

 experimental physiology is one of the most important steps taken to 

 place medicine on a scientific basis. How important this is may be 

 gauged from the fact that all fundamental advances in treatment in the 

 last thirty years have originated directly or indirectly from experiments 

 on animals. 



There can be no doubt then that the future of therapeutics, and 

 therefore of medicine as a whole, is intimately connected with physio- 

 logy ; there can be no doubt that advance in the practice of medicine 

 is dependent on those trained in the methods and fundamental truths 

 of physiology, who devote themselves in the ward and biological 

 laboratory to investigating how best to prevent or cure disease and so 

 relieve suffering. 



Britain for fifty years has every reason to be proud of her progress 

 and achievements in physiology ; it is acknowledged that she can show 

 records second to none and that her savants have included some of 

 the world's greatest investigators. It remains for us to hope that in the 

 future she may attain equal success in the associated sciences directly 

 concerned with the relief of suffering and cure of disease. 



