22 REPORT— 1895. 



and water fostei'ed fever, cholera, and many other forms of disease, 

 and that the disease ceased to spread on the removal of these con- 

 ditions, yet 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 current during 

 the past century, he laid the foundation of our exact knowledge of the 

 nature of tlie action of ferments, both organised and unorganised. It 

 was not until 1860, after the prize of the Academy of Sciences had 

 been awarded to Pasteur for his essay against the theory of spon- 

 taneous generation, that his investigations into the action of ferments ' 

 enabled him to show that tlie 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 diseases proved the theory that those diseases are con- 

 nected in some way with the introduction of a microbe into the body of 

 an animal ; that the virulence of the poison can be diminished by culti- 

 vating the microbes 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 investigations, followed by the discovery of the existence of a 

 multitude of micro-organisms and the recognition of some of them — 

 such as the bacillus of tubercle and the comma bacillus 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 bac- 

 teriology. Amongst later developments ai'e the discovery of various 

 so-called antitoxins, such as those of diphtheria and tetanus, and the 

 utilisation of these for the cure of disease. Lister's treatment formed a 

 landmark in the science of surgery, 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. And the 

 science of bacteriology is leading us to recur to stringent rules for the 



' In speaking of ferments one must bear in mind that there are two classes of 

 ferments : one, living beings, such as yeast — ' organised ' ferments, as tbey are 

 sooietimes called — the other the products of livicg beings themselves, such as 

 pejjsin, &c. — ' unorganised ' ferments. Pasteur vvorked with the former, very little 

 with the latter 



