First, biology would lead to certain modifications of practice--particularly in our treatment of children, and of persons deemed criminal or insane. The biologist, when anything was amiss--before she pronounced any one to be mentally or morally unsound, defective, or bad--would presume, to start with, that there was some definite physical trouble to be set right, not necessarily anything dangerous in itself or mysterious. In New York they now make it a rule to examine for adenoids every young offender against the law, before punishing him; and it is amazing how often adenoids are found, and when removed carry the child's wickedness away with them. Adenoids and divers glands are responsible for a great proportion of youthful wrongdoing; and yet other physical troubles will account for a great proportion of the rest. The writer herself once came across a young girl who was, in intention and attempt, a murderess--yet was so only through the effect of a common physical condition, easy enough to treat when once ascertained. Until our general conception of a child--or indeed of a human being--is a more truly biological one, framed more closely upon the facts of its bodily life, we shall have but little effective intuition into its state. And such a sound biological conception is not to be had apart from some good measure of sound biological knowledge. When, however, the most careful observation reveals no local or definite mischief to be dealt with in the person under consideration, the biologist will still not hastily set him down as bad--or even as unsound or defective. He will next suspect that he is one whose physical organisation is not fitted for its environment: if he can be placed in a better environment perhaps he will grow better. If this change is, from whatever circumstances, impossible, the biologist in treating him, however troublesome he may be, will still never regard him as wholly responsible for what he is, will still try to ascertain the exact ways in which the environment presses injuriously upon him, and to help him in those definite particulars. If we desire the work of our reformatories and prisons and the disciplinary work of our schools really to be and not merely to appear effective, it is only by such nicely-calculated methods that we shall attain our object.