Embryology may be defined as that part of the science of Biology which deals with the formation of a new individual or embryo. The definition itself ought to be sufficient to explain the significance of the subject for every one, because one can hardly conceive of any more profoundly important knowledge than that which tells of the mode of origin, manner of growth, and ultimate birth of an entirely new being. In the absence of such accurate knowledge it is quite obvious that all one's ideas concerning the manner in which the new individual is to be treated must have a more or less haphazard, or at least empirical, basis. In fact only when the science of Embryology, or the development of the individual, becomes a part of the ordinary everyday mental equipment of those who are responsible for bringing into the world new individuals, and subsequently protecting and handling them, will it be reasonable to expect that these new individuals are dealt with in the best possible manner. In a word it is evident that education, using that term in the very widest possible sense, can never be anything more than a blind groping in the dark until those into whose hands it is entrusted realise and know at least the most important fundamental facts concerning development. It is lack of this kind of knowledge which has been responsible for so much of the mistaken systems of the past in dealing with the young, and it is the spread of this knowledge which alone is the hope of better things in the future. Wherever knowledge is absent superstition is rife, and in no sphere of life is this more painfully obvious than in connection with the subject which we are about to study. It would have been entirely impossible for many of the stupid and even cruel methods of mental and physical treatment which have been meted out to the young children in the past to have been tolerated for a moment had this knowledge been available and sufficiently widespread. Possessing it, a flood of light is thrown upon the fascinating and otherwise obscure problems of heredity; and thus it lays open the pages of the past for those who care to read them. Possessing it also it throws upon the mental screen pictures of possibilities in the future for all those who have eyes to see. So the study of Embryology links up the past with the present and joins the present with the future. Is it not, therefore, obvious that the study of such a subject means dealing with problems the importance of which it is impossible to exaggerate; problems which the parent, the teacher, the social reformer, the politician, and the philanthropist will grapple with in vain unless they call in science to their aid? Such is the meaning and significance of the subject of our study.