SPONTANEOUS GENERATION. 483 



ing in wound and abscess which so frequently converted our hospitals 

 into charnel-houses, and it is their destruction by the antiseptic sys- 

 tem that now renders justifiable operations which no surgeon would 

 have attempted a few years ago. The gain is immense to the prac- 

 tising surgeon as well as to the patient practised upon. Contrast the 

 anxiety of never feeling sure whether the most brilliant operation 

 might not be rendered nugatory by the access of a few particles of 

 unseen hospital-dust, with the comfort derived from the knowledge 

 that all power of mischief on the part of such dust has been surely 

 and certainly annihilated. But the action of living contagia extends 

 beyond the domain of the surgeon. The power of reproduction and 

 indefinite self-multiplication which is characteristic of living things, 

 coupled with the undeviating fact of contagia " breeding true," has 

 given strength and consistency to a belief long entertained by pene- 

 trating minds that epidemic diseases generally are the concomitants 

 of parasitic life. "There begins to be faintly visible to us a vast and 

 destructive laboratory of Nature wherein the diseases which are most 

 fatal to animal life, and the changes to which dead organic matter is 

 passively liable, appear bound together by what must at least be 

 called a very close analogy of causation." ' According to this view, 

 which, as I have said, is daily gaining converts, a contagious disease 

 may be defined as a conflict between the person smitten by it and a 

 specific organism which multiplies at his expense, appropriating his 

 air and moisture, disintegrating his tissues, or poisoning him by the 

 decompositions incident to its growth. 



During the ten years extending from 1859 to 1869, researches on 

 radiant heat in its relations to the gaseous form of matter occupied 

 my continual attention. When air was experimented on, I had to 

 cleanse it effectually of floating matter, and, while doing so, I was sur- 

 prised to notice that, at the ordinary rate of transfer, such matter 

 passed freely through alkalies, acids, alcohols, and ethers. The eye 

 being kept sensitive by darkness, a concentrated beam of light was 

 found to be a most searching test for suspended matter both in water 

 and in air a test indeed indefinitely more searching and severe than 

 that furnished by the most powerful microscope. With the aid of 

 such a beam I examined air filtered by cotton-wood, air long kept free 

 from agitation, so as to allow the floating matter to subside, calcined 

 air, and air filtered by the deeper cells of the human lungs. In all 

 cases the correspondence between my experiments and those of 

 Schroeder, Pasteur, and Lister, in regard to spontaneous generation, 

 was perfect. The air which they found inoperative was proved by 



sirten Ferment ableitet, oder gar aus ' Stickstoffsplittern ' die Balken zur Stiitze seiner 

 Faulnisstheorie zu zimmern versucht, hat zuerst den Satz ' keine Faulniss ohne Bacte- 

 rium Termo ' zu widerlegen." 



1 " Report of the Medical Officer of the Privy Council," 1874, p. 5. 



