15
define the meaning of the term "Laws of Nature." No greater hindrance to progress can arise than when, in the employment of scientific language, a restrictive sense is present to the mind of the person using it, which others are not aware of, and are consequently not prepared to adopt. It will be in the recollection of most of my hearers that not long ago, when the laws of the development of life during putrefaction were very much under discussion, Professor Tyndall announced an observation of some importance, as bearing on the subject. Dr. Bastian had cited experiments in which he found that in a certain putrescible fluid, the most rigid exclusion of the atmosphere failed to prevent the development of living organisms, and concluded that some other cause must be sought than the introduction of germs by that medium. Professor Tyndall, on the other hand, alleged that such fluids might be fully exposed to the atmosphere, provided It was so free from suspended matter that it seemed quite pure to a beam of electric light, and argued that the development of such organisms as are commonly found was due to the presence of impure air. Dr. Bastian's reply was short, sharp, and decisive. Professor Tyndall had not used the same fluid as Dr. Bastian, and the assertions made regarding a-bio-genesis applied to that fluid, and that fluid only, and to none other. Between the two philosophers, there could be
