October 11, 1895.] 



SCIENCE. 



465 



is known of the diffusion of volatile con- 

 tagion." 



Whilst it had long been known that 

 filthy conditions in air, earth and water 

 fostered fever, cholera and many other 

 forms of disease, and that the disease ceased 

 to spread on the removal of these condi- 

 tions, j'et the reason for their propagation 

 or diminution remained under a veil. 



Leeuwenhoek in 1680 described the yeast- 

 cells, but Schwann in 1837 first showed 

 clearly that fermentation was due to the 

 activity of the yeast-cells; and, although 

 vague ideas of fermentation had been cur- 

 rent during the past century, he laid the 

 foundation of our exact knowledge of the 

 nature of the action of ferments, both or- 

 ganized and unorganized. It was not until 

 1860, after the prize of the Academj^ of 

 Sciences had been awarded to Pasteur for 

 his essay against the theory of spontaneous 

 generation, that his investigations into the 

 action of ferments enabled him to show that 

 the effects of the yeast-cell are indissolubly 

 bound up with the activities of the cell as a 

 living organism, and that certain diseases, 

 at least, are due to the action of ferments 

 in the living being. In 1865 he showed 

 that the disease of silkworms, which was 

 then undermining the silk industry in 

 France, could be successfully combated. 

 His further researches into anthrax, fowl 

 cholera, swine fever, rabies and other dis- 

 eases proved the theory that those diseases 

 are connected in some way with the intro- 

 duction of a microbe into the body of an 

 animal ; that the virulence of the poison 

 can be diminished by cultivating the mi- 

 crobes in an appropriate manner ; and that 

 when the virulence has been thus diminished 

 their inoculation will afford a protection 

 against the disease. 



Meanwhile it had often been observed in 

 hospital practice that a patient with a 

 simple-fractured limb was easily cured, 

 whilst a patient with a compound fracture 



often died from the wound. Lister was 

 thence led, in 1865, to adopt his antiseptic 

 treatment, by which the wound is protected 

 from hostile microbes. These investiga- 

 tions, followed by the discovery of the ex- 

 istence of a multitude of micro-organisma 

 and the recognition of some of them — such 

 as the bacillus of tubercle and the comma 

 bacilus of cholera — as essential factors of 

 disease, and by the elaboration by Koch 

 and others of methods by which the several 

 organisms might be isolated, cultivated, 

 and their histories studied, have gradually 

 built up the science of bacteriology. 

 Amongst later developments are the dis- 

 covery of various so-called antitoxins, such 

 as those of diphtheria and tetanus, and the 

 utilization of these for the cure of disease. 

 Lister's treatment formed a landmark in 

 the science of surgerj^, and enabled our 

 surgeons to perform operations never before 

 dreamed of; whilst later discoveries are 

 tending to place the practice of medicine on 

 a firm scientific basis. 



The study of bacteriology has shown us 

 that, although some of these organisms 

 may be the accompaniments of disease, yet 

 we owe it to the operation of others that 

 the refuse caused by the cessation of animal 

 and vegetable life is reconverted into food 

 for fresh generations of plants and animals. 

 Tliese considerations have formed a point 

 of meeting where the biologist, the chemist, 

 the physicist and the statistician unite with 

 the sanitary engineer in the application of 

 the science of preventive medicine. 



The early reports to the Association show 

 that the laws of hydrostatics, hydro- 

 dynamics and hydraulics necessary to the 

 supply and removal of water through pipes 

 and conduits had long been investigated by 

 the mathematician. But the modern sani- 

 tary engineer has been driven by the needs 

 of an increasing population to call in the 

 chemist and the biologist to help him to 

 provide pure water and pure air. The 



