flasks and their contents have been thoroughly raised to the temperature of boiling water for ten minutes or more. These experiments we may mentally label as series A. Other experiments, which we may similarly label series B, had also shown that a brief exposure in the moist state to a temperature considerably below the boiling-point of water, is destructive to all kinds of living matter submitted to its influence. The experiments of series A, therefore, taken in conjunction with those of series B, must (if the latter results are as reliable as the former) be held to prove that living matter can originate independently, or de novo, through the mere productive properties of certain infusions or solutions.
If the facts are true, is it possible to stave off the conclusion? While the candid reader is asking himself this question, I may further point out to him that, as the previously discredited results belonging to series A are no longer denied, doubt is now only possible upon a subject hitherto supposed to be settled—namely, as to whether living matter is really killed by exposure in the moist state to a temperature of 212° Fahr. Obviously, at such a juncture, it rested more especially with the panspermatists, who chose still to be opponents of "spontaneous generation," to show that this belief concerning the destructive efficacy of boiling water, upon the truth of which they had previously relied, was erroneous—seeing that the advocates of spontaneous generation had demonstrated the truth of their position with reference to experiments A. Should the panspermatists fail to produce this evidence as to the untruthfulness of their old view, they must not expect to hear that they have the best of the argument; and still less will they be able to hold their ground if, while abstaining themselves from all experiments belonging to series B, their scientific opponents do make careful investigations in this direction, and arrive at the conclusion that not only was the old opinion right as to the destructive action of boiling water, but that living matter unaccustomed to the influence of heat is killed by a brief exposure even to the much lower temperature of 140° Fahr.
This is the present aspect of the problem, and those most interested in it may remember that knowledge would not advance in the rapid way which it does, were it not for the fact that the difficulties of one generation of men often disappear before the clearer, because more unprejudiced, vision of the next. Growing gradually more familiarized with the facts, those who come after us will be more and more influenced by them, and at the same time less warped by theoretical considerations already out of harmony with our present state of knowledge. We are now in a stage of transition. We are gradually learning to accept the doctrines of Evolution, as applicable to different departments of knowledge, though, as is so frequently the case when new doctrines are being adopted, this transition is being effected by many in a partial manner—they, unconsciously perhaps, endeavor to make
