SEVENTEENTH ANNUAL MEETING. 263 



These observations, however, received but little attention from scientific 

 men, and many theories of fermentation were advanced, in which these living 

 organisms were entirely ignored. In 1848 Liebig presented a theory of fer- 

 mentation, which, from the authority of his position, was generally adopted by 

 chemists. He assumed that the vibrating molecules of decaying matter were 

 the cause of fermentation. This was in fact but a revival of an old theory ad- 

 vanced by Willis in 1659, and again by Stahl in 1697. 



The researches of Pasteur from 1857 to 1861 finally established the true 

 theory of fermentation. The familiar processes included in the general term 

 of fermentation, he proved to be the function of living microscopic organisms. 



He claimed that each species of the living ferments produced a specific fer- 

 mentation as a result of their processes of nutrition and that the residuum of 

 these vital activities was the fermented product. 



This marked the first stage in the development of this new department of 

 biological science. 



About this time the theory of spontaneous generation was revived and quite 

 widely discussed as a sequence or corollary of Darwin's Origin of Species which 

 was first published in 1859. It is not surprising that his theory of natural 

 selection should give rise to a revival of the old assumption that inert matter 

 could under certain conditions take on the characteristics of living matter, as 

 it furnished a convenient starting point for the theory of the evolution of life 

 on the globe, and it was an easy matter to overlook and ignore the experiments 

 of Redi, Spallanzani, Schultze and Schwann, (1668 to 1837) which gave evi- 

 dence to the contrary. 



The arguments in favor of spontaneous generation appeared to be plausible*, 

 and the advocates of the hypothesis even made experiments which they claimed 

 to be conclusive proof of the truth of their hypothesis. 



In the controversy which arose Prof. Huxley remarks that "the great tragedy 

 of science — the slaying of a beautiful hypothesis by an ugly fact," was often 

 enacted, but it remained for Pasteur and Tyndall to prove that "spontaneous- 

 generation is a chimera." In their experiments the fallacies and defective 

 methods of their opponents were fully exposed and they left no escape from the 

 conclusion that the manifestations of life involved the pre-existence of living 

 matter from which it originated. 



This marked the second step in the development of the new science. 



In 1850 Davaine discovered rod-shaped microbes in the blood of cattle affect- 

 ed with anthrax, but the real significance of these organisms as the cause of 

 the disease was not demonstrated until 1863 and 1864, when he published the 

 results of his experiments in which he succeeded in producing the disease in 

 healthy animals by inoculation. 



Pasteur published his researches on the diseases of wines, which were caused 

 by false ferments, in 1866, and the same year he made public the results of his 

 masterly investigation of the silk worm disease which had paralyzed the silk 

 industry of France. He not only succeeded in tracing the life history of the 

 microbe which caused the disease, but pointed out a remedy that has led to the 

 complete revival of this important industry. 



From this time up to 1875 there were many papers published on fermenta- 

 tion and the germ theory of contagious diseases, among which those giving the 

 results of the experiments of Pasteur, Tyndall, Koch, Lister, Klein and Klebs, 

 are of particular interest. 



In 1876 Koch discovered the spores of the anthrax bacillus and the condi- 

 tions under which they are developed. Their remarkable powers of vitality 



