The lowest forms of animal life, the one-celled animals, are without sex, and multiply by dividing into half, each half developing into a complete cell, which in turn is subjected to the same dividing process. Many species of these lowly organisms still exist, never having developed further than the unicellular stage. All higher forms, as of fishes, reptiles, birds, mammals, begin life at this point--as a single cell. The cell, germ, or ovum of an embryo (the young of a mammal before birth) when fertilized divides, forming two cells, the two divide into four, the four into eight, and so on, until there is a colony of similar cells enmassed, and with a little rod of tissue--the beginnings of the spinal column--running through. The embryo at this stage is passing beyond the lowest grand division, the invertebrates. Entering the vertebrate division the embryo passes into the fish group. Deep grooves, gill slits, appear on the side of the neck of the embryo and six pairs of arched branches of arteries arise, just as in fishes, as if to give blood to the gills. Later all but one of these pairs disappear. The arms and legs of the child, like the legs of all other embryos, begin to develop, and continue to do so for some time, on the same plan as the fins of fishes. Further along in its development the embryo assumes all the characteristics of the quadruped even to the tail which in the human embryo at this stage is longer than its legs. During the sixth month the entire body of the human foetus, except the palms and soles, is covered with fine, woolly hair. Thus far the human embryo has developed in the same way, has undergone the same changes, has passed through precisely the same stages as the embryo of other animals. In its further development it leaves them all behind except those nearest man. Its tail disappears, and it now has an opposable or thumb-like great toe which with the monkey and the ape is a permanent characteristic. It is only in the latest stages of development that the human embryo presents marked differences from the embryonic ape. Of the fact that the embryo in its development from a single fertilized cell passes through all the stages representative of the principal animal divisions, and in a progressive order from the simple to the complex and highly developed, there is no explanation but that of heredity and descent--of descent of the higher animals from the lower with heredity transmitting the records of the remote ancestral stages. Each stage, as of the fish, the quadruped, the ape, is a sign board along the route of man’s descent. The nine months’ embryonic period of each of us is an epitome of the history of the race down to the human period.