6 BIOLOGY AND TECHNIQUE 



observe and correctly interpret bacterial spores and to demonstrate 

 their high powers of resistance against heat and other deleterious 

 influences. 



Meanwhile, Pasteur, parallel with his researches upon sponta- 

 neous generation, had been carrying on experiments upon the subject 

 of fermentation along the lines suggested by Cagniard-Latour. As a 

 consequence of these experiments, he not only confirmed the opinions 

 both of this author and of Schwann concerning the fermentation of 

 beer and wine by yeasts, but was able to show that a number of 

 other fermentations, such as those of lactic and butyric acid, as well 

 as the decomposition of organic matter by putrefaction, were directly 

 due to the action of microorganisms. It was the discovery of the 

 living agents underlying putrefaction, especially, which exerted the 

 most active influence upon the medical research of the day. This is 

 illustrated by Lister's work. The suppurative processes occurring 

 in infected wounds had long been regarded as a species of putrefac- 

 tion, and Lord Lister, working directly upon the premises supplied 

 by Pasteur, introduced into both the active and prophylactic treat- 

 ment of surgical wounds the antiseptic principles which alone have 

 made modern surgery possible. 



There now followed a period in which bacteriological investiga- 

 tion was concentrated upon problems of etiology. Stimulated by 

 Pasteur's successes, the long-cherished hope of finding some specific 

 microorganism as the causal agent in each infectious disease was 

 revived. 



Pollender, in 1855, had reported the presence of rod-shaped bodies 

 in the blood and spleen of animals dead of anthrax. Brauell, several 

 years later, had made similar observations and had expressed definite 

 opinions as to the causative relationship of these rods to the disease. 

 Convincing proof, however, had not been brought by either of these 

 observers. Finally, in 1863, Davaine, in a series of brilliant investi- 

 gations, not only confirmed the observations of the two authors 

 mentioned above, but succeeded in demonstrating that the disease 

 could be transmitted by means of blood containing these rods and 

 could never be transmitted by blood from which these rods were 

 absent. Anthrax, thus, is the first disease in which definite proof of 

 bacterial causation was brought. 



Speaking before the French Academy of Medicine at this time, 

 Davaine suggested that the manifestations of the disease might in 

 reality represent the results of a specific fermentation produced by 



