6io 



NATURE 



[January 27, 19 16 



society in regard to those emotions which, from primi- 

 tive times to the present day, have been the source 

 of enormous evils to mankind. The bodily changes 

 which in man accompany these powerful emotions have 

 only recently been in part made known ; but it has 

 already been made out with regard to a group of these 

 alterations in the bodily economy that they may be 

 regarded as responses adapted to preserve the indi- 

 vidual, and to promote his bodily welfare or his 

 efficiency. The emotions which man fighting experi- 

 ences call into sudden and potent action the muscular 

 and nervous forces which he needs for both offence 

 and defence. Hunger is a highly protective sensation. 

 Fear stimulates muscular and nervous exertion, so long 

 as the frightened animal can flee ; but, if the animal 

 is cornered, fear turns to fury, which develops the 

 extraordinary strength of desperation. The sucpessful 

 study to-day of these bodily changes and reactions" 

 prophesies a better understanding in the future of the 

 moral forces which make for rational conduct, and of 

 the public policies in regard to war and peace which, 

 long pursued, may gradually affect the sum of human 

 misery or of human happiness. 



The present terrible condition of Europe, and the 

 coincident sufferings of much of the rest of the world, 

 give fresh significance to the following remarks of 

 Louis Pasteur at the inauguration of the Pasteur Insti- 

 tute at Paris in 1888 : — " Two contrary laws seem to 

 be wrestling with each other nowadays — the one a law 

 of blood and of death, ever imagining new means of 

 destruction, and forcing nations to be constantly ready 

 for the battlefield ; the other a law of peace, work, and 

 health, ever evolving new means of delivering man 

 from the scourges which beset him. The one seeks 

 violent conquests ; the other the relief of humanity. 

 The latter places one human life above any victory, 

 while the former would sacrifice hundreds and 

 thousands of lives to the ambition of one. . . . 

 Which of these two laws will ultimately prevail, God 

 alone knows." 



The whole civilised world observes with delight that 

 the profession of medicine, including surgery and the 

 profession of public health and sanitation, stands out 

 distinctly among all the intellectual callings as being 

 steadily and universally devoted to curing the san- 

 guinary ills of war, alleviating human sufferings from 

 disease and folly, and extending for mankind the 

 domain of health and happy life. These professions 

 employ all the resources of physics, chemistry, and 

 biology for merciful ends, both in peace and in war. 

 The martial professions, on the other hand, employ 

 many scientific discoveries and inventions, originally 

 made for peaceful uses, as means of destruction and 

 death. Biological science has great advantage in this 

 respect over physical and chemical. It cannot so fre- 

 quently or easily be applied to evil ends. 



The development of public sanitation practice during 

 the past fifty years has taught democratic communities 

 important lessons on the just subordination of 

 individual interests or riglits to collective in- 

 terests or rights, whenever the fulfilment of 

 individual desires imperils the collective security. 

 Sanitary regulations often interfere with family 

 management, the schooling of children, the trans- 

 portation and selling of perishable goods, the estab- 

 lished practices of mining and manufacturine: corpora- 

 tions and of small tradesmen, and even the personal 

 habits of the private citizen. These interferences are 

 sometimes abrupt and arbitrary. On the whole, how- 

 ever, this teaching has been wholesome in the freedom- 

 loving nations, in which individualism is apt to be 

 exaggerated, and the sense of neighbourliness and 

 social unitv needs to be quickened. 



The rapid development of public sanitation "has also 

 given important lessons on promptly utilising so much 

 NO. 2413, VOL. 96] 



as we know of applied science, but also modifying 

 our practices rapidly whenever the subsidiary sciences 

 effect an advance. Forty years ago the filth and 

 fomites theory was the basis of sanitary practice. 

 Municipal and household cleanliness are still incul- 

 cated, but the emphasis on them is no longer exclu- 

 sive. Then, bacteria and other disease-producing 

 organisms became the chief objects of interest for 

 sanitarians, and sanitary practice was based on know- 

 ledge of these organisms, and study of the media 

 through which they reached man, such as the air, 

 water, the soil, dust, milk, and other uncooked foods. 

 Isolation of all cases of contagious disease was much 

 insisted on. Isolation is still useful in many cases; 

 but it is not regarded to-day as the one effectual 

 defence against epidemics and the diffusion of disease. 

 Next, insect and vermin carriers were made known, 

 and with them came in quite a new set of sanitary 

 practices — not a replacement but a large addition. 

 Lastly, the contact theory of contagion, with its demon- 

 strations that living bacteria may be carried from one 

 person to another in minute vesicles or droplets thrown 

 off in coughing, sneezing, or any convulsive effort, and 

 borne on the air, has gained general acceptance. At 

 the same time, abundant proof has been given that 

 pathogenic bacteria and protozoa develop'in the bodies 

 of many persons without causing any recognisable 

 symptoms. Yet the virulence of the germs these per- 

 sons carry may be extreme. 



These recent discoveries have introduced serious 

 difficulties into some departments of sanitary practice. 

 The apparently healthy carrier cannot be isolated, for 

 he remains unknown. If at any time such carriers 

 and missed cases are numerous in a given community, 

 isolation becomes useless, if not impossible. That is 

 the ordinary condition of most American communities 

 m regard to tuberculosis. Hence, bacteriologists have 

 before them a very useful piece of work in the study 

 of human carriers of disease who are not sick. Mean- 

 time sanitary practice is obtaining sound explanations 

 of the occasional failure of its former methods of 

 resisting epidemics, and preventing the spread of the 

 ordinary contagious diseases. 



The principal lesson to be drawn from the experi- 

 ences of sanitarians during the past fifty years is that 

 practitioners of any useful art must be prompt at every 

 stage of progress to make use of knowledge just 

 attained, even if it be empirical and incomplete, and 

 must not linger content or satisfied at any stage. This 

 lesson is applicable in every modern industry and 

 educational or governmental agency during either 

 peace or war. 



Biologists are now realising that biochemistry must 

 furnish the fundamental knowledge of the processes 

 which incessantly go on in the healthy body, and must 

 also provide the exact knowledge of those changes 

 in the normal processes which lead to disease and 

 death. The physician and the sanitarian have become 

 accustomed to the beneficial use of remedies and de- 

 fences which chemistry at present can neither analyse 

 nor synthesise, such, for example, as diphtheria anti- 

 toxin ; but they are aware that this condition of their 

 art is unsatisfactory and ought not to be permanent. 

 The animal body consists of well-known chemical sub- 

 stances, and its functions depend on chemical reactions. 

 Digestion is largely a chemical process. The animal 

 bodv consists of innumerable cells in great variety, 

 each of which acts under chemical and physical laws. 

 Hence the befief of the biologist of to-day that chem- 

 istry — analytical, structural, and physical — can and will 

 come to the aid of the science and art of medicine in 

 the large sense, and will ultimately enable biological 

 science to comprehend the vital processes in health 

 and disease, and to penetrate what are now the secrets 

 of life and death. 



