Page:The Harveian oration (electronic resource) - Royal College of Physicians, 1881 (IA b20411911).pdf/35

 power to develop animal and vegetable life, when it was found that, if other circumstances remained the same, the life was developed without the presence of electricity. But it was not so with regard to chemical change. Putrescence or fermentation was found to be almost invariably present; and there was evidently some correlation between the two facts thus established. So far, the law of their being was, with a few exceptions, absolute.

The law was absolute, but indefinite; and the existence of exceptions made it necessary to seek for a clearer insight into its meaning. The hypotheses which have been suggested divide themselves into three main classes. First, there was the old popular belief that putrefaction breeds worms, refined and transformed by scientific research into the statement that during the devitalisation of previously living organic matter, new life in another form sprang into existence—in principle, perhaps, not unlike the present view of the conservation of force. Secondly, there was the view, diametrically opposed to it, that the germ comes from without, and by its presence and power of development excites the chemical change which accompanies the presence of the fully-formed being. Thirdly, that the putrefying or fermenting material offers a suitable nidus for its growth and development. The first, I think one may say, has for the present passed into the region of oblivion. The second has