BIRTHMARKS RARE.--And yet the very fact that cases of birthmarks are comparatively rare, proves the greatly preponderating influence of heredity over the constitution of the offspring, modified by the disposition of the parents at the time of procreation. Professor Cope has some explanatory remarks on that subject which deserve quotation. He says--after referring to the hypothesis that growth-force may be, through the motive force of the animal, directed to any locality, whether the commencement of an executive organ has begun or not--that "A difficulty in the way of this hypothesis is the frequently unyielding character of the structure of adult animals, and the difficulty of bringing sufficient pressure to bear on them without destroying life. But, in fact, the modifications must, in most instances, take place during the period of growth. It is well known that the mental characteristics of the father are transmitted through the spermatozoid, and that, therefore, the molecular movements which produce the mechanism of such mental characters must exist in the spermatozoid. But the material of the spermatozoid is combined with that of the ovum, and the embryo is compounded of the animal contents of both bodies. In a wonderful way the embryo develops into a being which resembles one or both parents in minute details. This result is evidently determined by the molecular and dynamic character of the original reproductive cells which necessarily communicate their properties to the embryo which is produced by their subdivisions." Professor Cope goes on to say, "Richard Hering has identified this property of the original cells with the faculty of memory. This is a brilliant thought, and, under restriction, probably correct. The sensations of persons who have suffered amputation show that their sensorium maintained a picture or map of the body so far as regards the location of all its sensitive regions. This simulcrum is invested with consciousness whenever the proper stimulus is applied, and the character of the stimulus is fixed by it. This picture probably resides in many of the cells, both sensory and motor, and it probably does so in the few cells of simple and low forms of life. The spermatozoid is such a cell, and, how or why we know not, also contains such an arrangement of its contents, and contains and communicates such a type of force. It is probable that in the brain-cell this is the condition of memory of locality. If, now, an intense and long-continued pressure of stimulus produces an unconscious picture of some organ of the body in the mind, there is reason to suppose that the energies communicated to the embryo by the spermatozoid and ovum will partake of the memory thus created. The only reason why the oft-repeated stories of birthmarks are so often untrue, is because the effect of temporary impressions on the mother is not strong enough to counterbalance the molecular structure established by impressions often repeated