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Only one spermatozoon can bore its way into the yelk at one pole of the ovum-axis; its head or nucleus coalesces with the female nucleus, which remains after the extrusion of the directive bodies from the germinal vesicle. This now undergoes total segmentation, dividing into two, four, eight, sixteen, thirty-two cells, and so on.
But in this case it would be the whole of the chromosomes coming from the original female gamete which would disappear, and the spermatozoon would be incapable of transmitting characters derived from the female parent of the individual in which the spermatozoa were formed. An individual could never inherit character from its paternal grandmother.
Let us consider this fertilized egg the contributions of the father and the mother. The total length of the spermatozoon is only about 1/300 of an inch, and 4/5 of this is the tail. This tail does not enter the egg, and has no other known function than that of a propeller. Its movement has been studied and found to be about 1/8 of an inch per minute. Only the head and neck enter the egg.
The fertilized egg-cell, formed by the union of egg and spermatozoon, is a single cell, like the individual resulting from the conjugation or fusion of two protozoa. But in the many-celled individual, which develops out of the fertilized egg, there are two kinds of cells. 1.
A modern version of this old belief was the idea advanced by Harvey that the ovum consisted of fluid in which the embryo appeared by spontaneous generation. Loeuwenhoek's development of the microscope in the 17th century led immediately to the discovery of the spermatozoon by one of his students.
It is impossible to explain in a mechanical way the power which directs the innumerable different chemical and physical processes within the organism, whether they be the bewilderingly purposeful reactions in the individual life of the cell, which seem to point to psychic processes within the plasm, or the riddles of development and of inheritance in particular; for how can a spermatozoon, so small that 500 millions can lie on a cubic line, be the bearer of all the peculiarities of the father to the son?
In the case of the human subject, the cell from which each child begins its development is formed by the fusion of two cells or globules of protoplasm, one furnished by the mother, and called the ovum, or egg; the other furnished by the father, and called the spermatozoon.
If they be examined under the microscope as a part of a normal nocturnal emission, they will be found to be almost motionless or very greatly lacking in typical spermatozoon activity. Now let us suppose that the young man, instead of curbing his sexual appetite, resorts, after a season of erotic imaginations, to the act of masturbation.
Longer but much narrower than the ovum, the tiny arrow-shaped spermatozoon is particularly distinguished by its active motility, for it has a tail that propels it.
If so, the toxin passed from the guinea-pig to its spermatozoon or ovum, and caused in the development of the embryo a general disturbance, which, however, had no visible effects except at one point or another of the organism when developed.
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