482 ON THE CAUSATION OF 



by the stream of outflowing pus, but may be dislodged when the tube is taken 

 out, and left behind in the cavity. The germ theory tells us that these particles 

 of dust will be pretty sure to contain the germs of putrefactive organisms, 

 and if one such is left in the albuminous liquid, it will rapidly develop at the 

 high temperature of the body, and account for all the phenomena. 



But striking as is the parallel between putrefaction in this instance and 

 the vinous fermentation, as regards the greatness of the effect produced, 

 compared with the minuteness and the inertness, chemically speaking, of the 

 cause, you will naturally desire further evidence of the similarity of the two 

 processes. You can see with the microscope the torula of fermenting must 

 or beer. Is there, you may ask, any organism to be detected in the putrefying 

 pus ? Yes, gentlemen, there is. If any drop of the putrid matter is examined 

 with a good glass, it is found to be teeming with myriads of minute jointed 

 bodies, called vibrios, which indubitably proclaim their vitality b}^ the energy 

 of their movements. It is not an affair of probability, but a fact, that the 

 entire mass of that quart of pus has become peopled with living organisms 

 as the result of the introduction of the cannula and trocar ; for the matter first 

 let out was as free from vibrios as it was from putrefaction. If this be so, 

 the greatness of the chemical changes that have taken place in the pus ceases 

 to be surprising. We know that it is one of the chief peculiarities of living 

 structures that they possess extraordinary powers of effecting chemical changes 

 in materials in their vicinity, out of all proportion to their energy as mere 

 chemical compounds. And we can hardly doubt that the animalcules which 

 have been developed in the albuminous liquid, and have grown at its expense, 

 must have altered its constitution, just as we ourselves alter that of the 

 materials on which we feed. 



The only question, therefore, that remains to be answered is. Whence 

 have these vibrios originated ? Have they sprung, like higher animals and 

 plants, from pre-existing similar organisms, or have they arisen spontaneously 

 out of the pus from an alteration in its physical constitution, determined in 

 some inexplicable manner by the introduction of a cannula and trocar ? 



All analogy, gentlemen, is in favour of the former view. The doctrine 

 of spontaneous or equivocal generation has been chased successively to lower 

 and lower stations in the world of organized beings, as our means of investiga- 

 tion have improved. I remember a conversation I once had, when a student, 

 with an elderly gentleman, not indeed belonging to our profession, on the 

 subject of mites in cheese. He believed that they grew out of the cheese from 

 some change in its substance as the result of keeping ; and the view which 

 I advocated, that they had sprung from the eggs of pre-existing mites, seemed 



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