I.— PHYSIOLOGY. 151 



prognosis he relies chiefly on past experience, and must also bring great 

 skill and judgment to bear on each particular case. The symptoms of 

 disease which enable him to make a diagnosis are very often of an 

 adaptative or compensatory nature, and the application of physiology to 

 the problems of medicine is often of considerable value from this point of 

 view, since it teaches that the mere alleviation of symptoms may be quite 

 the wrong way to attack the problem. In cardiac or renal dyspnoea, for 

 example, the exaggerated breathing is of an adaptative nature — the 

 patient is not ill because of the overbreathing but overbreathes in con- 

 sequence of the disease and would possibly succumb if he did not. More 

 usually the meaning of symptoms is less clear, and it is the difficidty in 

 recognising the underlying causes of disease which makes the practice of 

 medicine at once so exquisitely difficult and so fascinating. 



In treatment, too, two important principles arising from actual 

 observation receive support from physiological knowledge. One is that 

 the consequential alterations which take place in the course of the disease 

 are of the nature of adaptations which tend to restore the function to 

 normal ; these adaptations take the form of increase or diminution of 

 some particular factor, of hypertrophy or atrophy often of some definite 

 organ, always of some function — it is, in fact, the Vis medicatrix of the older 

 physicians, the underlying principle of expectant treatment. The other 

 principle is that nearly all positive measures of treatment, including 

 drugs, produce their effects by augmenting or restricting some function or 

 other. 



The applied aspects of physiological knowledge concern the related 

 subjects of hygiene and preventive medicine, medicine, surgery, and 

 veterinary and agricultural sciences in their widest senses. 



Investigations on diet, ventilation, industrial fatigue, and on the 

 contraction of and resistance to infections, soundly based on the fundamental 

 principles of physiology, have done much to make conditions of life more 

 tolerable for the present generations than for their predecessors. Few 

 medical students at the present time become acquainted with those severe 

 or fatal cases of rickets, scurvy, diabetes or pernicious anaemia which we 

 all knew could be seen in the wards of any large hospital twenty years ago, 

 and this gift of life and health to the afSicted is the grateful offering of 

 physiological research to its respected parent, medicine. 



No aspect of scientific activity is so generally misunderstood as that 

 which concerns the making of discoveries, and in matters of medical 

 research ignorance is particularly widespread. 



The popular idea seems to be that an investigator sets out with the 

 intention of making a particular discovery, such as a new element, or a 

 cure for a certain disease, but every scientific worker knows that real 

 discovery, as distinct from invention, is never achieved in this way. A 

 discovery is the process by which an idea of new relationships is revealed, 

 and involves two factors, observation and reflection. The origin may be 

 a chance observation which suggests a hitherto unappreciated relation, 

 and leads to the formulation of an hypothesis which, if possible, is then 

 deliberately tested by experiment. The history of the discovery of 

 insulin may be given as an illustration. The fundamental discovery here 

 was made by a chance observation that removal of the pancreas produced 



