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.  This head consists almost entirely of the nuclear material which is supposed to determine the characters of the future individual.

The ovum or egg contributed by the mother is much larger—­nearly round in shape and about 1/120 of an inch in diameter.  Besides its nucleus, it contains a considerable amount of what used to be considered as “stored nutritive material” for the early development of the individual.

In ancient times the female was quite commonly supposed to be a mere medium of development for the male seed.  Thus the Laws of Manu stated that woman was the soil in which the male seed was planted.  In the Greek Eumenides, Orestes’ mother did not generate him, but only received and nursed the germ.  These quaint ideas of course originated merely from observation of the fact that the woman carries the young until birth, and must not lead us to imagine that the ancients actually separated the germ and somatic cells in their thinking.

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.  At the time, the “preformation theory” was probably the most widely accepted—­i.e., that the adult form exists in miniature in the egg or germ, development being merely an unfolding of these preformed parts.  With the discovery of the spermatozoon the preformationists were divided into two schools, one (the ovists) holding that the ovum was the container of the miniature individual, the other (animalculists) according this function to the spermatozoon.  According to the ovists, the ovum needed merely the stimulation of the spermatozoon to cause its contained individual to undergo development, while the animalculists looked upon the spermatozoon as the essential embryo container, the ovum serving merely as a suitable food supply or growing place.

This nine-lived notion of male supremacy in inheritance was rather reinforced than removed by the breeding of domestic animals in the still more recent past.  Attention has been focused on a few great males.  For example, the breed of American trotting horses all goes back to one sire—­Hambletonian 10.  The great Orloff Stud Book, registering over a million individuals, is in the beginning founded on a single horse—­a male.  It is not strange that we still find among some breeders vestiges of the ancient belief that the male predominates in