the evolution of modern medicine-第44章
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Then； in the last third of the century； came in rapid succession the demonstration of the relations of the pancreas to diabetes； of the vital importance of the thyroid gland and of the pituitary body。 Perhaps no more striking illustration of the value of experimental medicine has ever been given than that afforded by the studies upon those glands。
The thyroid body； situated in the neck and the enlargement of which is called goitre； secretes substances which pass into the blood； and which are necessary for the growth of the body in childhood； for the development of the mind and for the nutrition of the tissues of the skin。 If； following an infectious disease； a child has wasting of this gland； or if； living in a certain district； it has a large goitre； normal development does not take place； and the child does not grow in mind or body and becomes what is called a cretin。 More than thisif in adult life the gland is completely removed； or if it wastes； a somewhat similar condition is produced； and the patient in time loses his mental powers and becomes fat and flabbymyxedematous。 It has been shown experimentally in various ways that the necessary elements of the secretion can be furnished by feeding with the gland or its extracts； and that the cretinoid or myxedematous conditions could thus be cured or prevented。
Experimental work has also demonstrated the functions of the suprarenal glands and explained the symptoms of Addison's disease； and chemists have even succeeded in making synthetically the active principle adrenalin。
There is perhaps no more fascinating story in the history of science than that of the discovery of these so…called ductless glands。 Part of its special interest is due to the fact that clinicians； surgeons； experimental physiologists； pathologists and chemists have all combined in splendid teamwork to win the victory。 No such miracles have ever before been wrought by physicians as those which we see in connection with the internal secretion of the thyroid gland。 The myth of bringing the dead back to life has been associated with the names of many great healers since the incident of Empedocles and Pantheia； but nowadays the dead in mind and the deformed in body may be restored by the touch of the magic wand of science。 The study of the interaction of these internal secretions； their influence upon development； upon mental process and upon disorders of metabolism is likely to prove in the future of a benefit scarcely less remarkable than that which we have traced in the infectious diseases。
CHEMISTRY
IT is not making too strong a statement to say that the chemistry and chemical physics of the nineteenth century have revolutionized the world。 It is difficult to realize that Liebig's famous Giessen laboratory； the first to be opened to students for practical study； was founded in the year 1825。 Boyle； Cavendish； Priestley； Lavoisier； Black； Dalton and others had laid a broad foundation； and Young； Frauenhofer； Rumford； Davy； Joule； Faraday； Clerk…Maxwell； Helmholtz and others built upon that and gave us the new physics and made possible our age of electricity。 New technique and new methods have given a powerful stimulus to the study of the chemical changes that take place in the body； which； only a few years ago； were matters largely of speculation。 〃Now；〃 in the words of Professor Lee； 〃we recognize that； with its living and its non…living substances inextricably intermingled； the body constitutes an intensive chemical laboratory in which there is ever occurring a vast congeries of chemical reactions； both constructive and destructive processes go on； new protoplasm takes the place of old。 We can analyze the income of the body and we can analyze its output； and from these data we can learn much concerning the body's chemistry。 A great improvement in the method of such work has recently been secured by the device of inclosing the person who is the subject of the experiment in a respiration calorimeter。 This is an air…tight chamber； artificially supplied with a constant stream of pure air； and from which the expired air； laden with the products of respiration； is withdrawn for purposes of analysis。 The subject may remain in the chamber for days； the composition of all food and all excrete being determined； and all heat that is given off being measured。 Favorable conditions are thus established for an exact study of many problems of nutrition。 The difficulties increase when we attempt to trace the successive steps in the corporeal pathway of molecule and atom。 Yet these secrets of the vital process are also gradually being revealed。 When we remember that it is in this very field of nutrition that there exist great popular ignorance and a special proneness to fad and prejudice； we realize how practically helpful are such exact studies of metabolism。〃＇13＇
＇13＇ Frederick S。 Lee； Ph。D。： Scientific Features of Modern Medicine； New York； 1911。 I would like to call attention to this work of Professor Lee's as presenting all the scientific features of modern medicine in a way admirably adapted for anyone； lay or medical； who wishes to get a clear sketch of them。
CHAPTER VI
THE RISE OF PREVENTIVE MEDICINE
THE story so far has been of men and of movementsof men who have； consciously or unconsciously； initiated great movements； and of movements by which； nolens volens； the men of the time were moulded and controlled。 Hippocrates； in the tractate on 〃Ancient Medicine；〃 has a splendid paragraph on the attitude of mind towards the men of the past。 My attention was called to it one day in the Roman Forum by Commendatore Boni； who quoted it as one of the great sayings of antiquity。 Here it is： 〃But on that account； I say； we ought not to reject the ancient Art； as if it were not； and had not been properly founded； because it did not attain accuracy in all things； but rather； since it is capable of reaching to the greatest exactitude by reasoning； to receive it and admire its discoveries； made from a state of great ignorance； and as having been well and properly made； and not from chance。〃＇1＇
＇1＇ The Works of Hippocrates； Adams； Vol。 I； p。 168； London； 1849 （Sydenham Society）。
I have tried to tell you what the best of these men in successive ages knew； to show you their point of outlook on the things that interest us。 To understand the old writers one must see as they saw； feel as they felt； believe as they believedand this is hard； indeed impossible！ We may get near them by asking the Spirit of the Age in which they lived to enter in and dwell with us； but it does not always come。 Literary criticism is not literary historywe have no use here for the former； but to analyze his writings is to get as far as we can behind the doors of a man's mind； to know and appraise his knowledge； not from our standpoint； but from that of his contemporaries； his predecessors and his immediate successors。 Each generation has its own problems to face； looks at truth from a special focus and does not see quite the same outlines as any other。 For example； men of the present generation grow up under influences very different from those which surrounded my generation in the seventies of the last century； when Virchow and his great contemporaries laid the sure and deep foundations of modern pathology。 Which of you now knows the 〃Cellular Pathology〃 as we did？ To many of you it is a closed book；to many more Virchow may be thought a spent force。 But no； he has only taken his place in a great galaxy。 We do not forget the magnitude of his labors； but a new generation has new problemshis message was not for youbut that medicine today runs in larger moulds and turns out finer castings is due to his life and work。 It is one of the values of lectures on the history of medicine to keep alive the good influences of great men even after their positive teaching is antiquated。 Let no man be so foolish as to think that he has exhausted any subject for his generation。 Virchow was not happy when he saw the young men pour into the old bottle of cellular pathology the new wine of bacteriology。 Lister could never understand how aseptic surgery arose out of his work。 Ehrlich would not recognize his epoch…making views on immunit
