One thing we find is that the word is frequently used, even by accredited authorities on biology, in a variable sense; in the course of an argument the word has two or more distinct meanings, and the arguer does not seem to be aware of the variation. This of course indicates a nebulosity in the reasoning and leads to confusion and wrong conclusions. For instance, in a particular case, where a lecturer is reported, we find that he uses the word (1) in the sense of "the fact that organic cells reproduce their kind," and (2) in the sense of "some power or faculty in virtue of which they reproduce their kind." These two senses are quite distinct, and would have been given separate heads in a dictionary; to ignore the distinction in an argument both arises from and creates confusion. But let us at present consider the second meaning--that of some power or property in virtue of which an organic cell can reproduce its kind. Biology, within its present scope, must confine itself to admitting the existence of this power and to tracing its workings. The source of the power lies outside the field of ordinary biological research. For, granted that physical matter is actuated by an agency, that agency must be immaterial; or at least, if material, then material in another sense than that in which physical matter is material. Now biologists may claim that this phase of the subject does not concern them; and that point we should be willing to concede in all cases where the investigations were confined to their appropriate limits--that is, to the limits appropriate to a confessedly limited science. But what we often actually find is that theorists overstep these limits and assume an attitude of positiveness and authority to which (by the logic of their own admission) they are not entitled. We even find proposals to base legislation upon biological theories; and there is the danger that in small self-governed communities such experiments may actually be carried into effect. When it comes to this therefore we are justified in inquiring more jealously into the credentials of biology; for we do not readily concede the right to be governed by people who have confessed that certain vital phases of their subject do not concern them. Hence, however the case may stand as regards merely theoretical science, when there is an attempt to apply theories to matters of government and public policy, the restrictions become a matter of vital importance. If we are to achieve successful results in applied biology, then we must positively know something about these mysterious potencies which lie behind matter and which many biologists say do not concern them; for these forces actually exist and count, whether biologists understand them or not; and though they may be ignored on paper, their effects cannot be ignored.