THE CARRIERS OF HERITAGE
Here is the actual bridge from this generation to the next.
Into these two little bodies—the larger not over one-twenty-fifth of an inch in diameter—is condensed the multitude of characteristics transmitted from one generation to another.
The vital part of the Ovum is the Nucleus, which contains the actual bodies that carry heritage—the little grains that are the mother's characteristics—Chromosomes. This nucleus is nourished by oils, salts and other inclusions, known as Cytoplasm. Floating in the cytoplasm may be found a tiny body known as the Centrosome, which acts as a magnet in certain phases of cell development. Around this whole mass is a Cell Wall, more or less resisting and protective.
The Spermatozoan is structurally much different from the ovum, but it also has its nucleus and chromosomes, which carry to the child the transmittable characteristics of the father.
The ovum is usually comparatively large and stationary, and whatever motion is therefore necessary to bring it into contact with the male cell devolves upon the latter, which possesses what is known as a locomotor tail. In addition there are usually many sperms to one ovum, so that the chances are that at least one male cell will reach the egg and effect fertilization, and the beginning of a new life.
The diagrams on the opposite page show the actual steps by which the spermatozoan unites with the ovum. It is the very first stage of the process of cell multiplication that results in the offspring.
THE FORMATION OF A NEW LIFE
