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In endeavouring to answer this question there are only two alternatives: either the characters are blastogenic that is, they arise from some change in the gametocytes occurring somewhere in the succession of cell-divisions of these cells or they arise in the soma and are impressed on the gametocytes by the influence of the soma within which these gametocytes are contained that is to say, they are somatogenic.
Modern researches have shown that the nucleus, when the cell divides, assumes the form of a spindle of fibres, associated with which are distinct bodies called chromosomes, that the number of these chromosomes where it can be counted is constant for all individuals of the same species, and that before the gametes are ready for fertilisation two cell-divisions take place, which result in the reduction of the number of chromosomes to half the original number.
Instead of saying that the zygote composed of ovum and spermatozoon is incapable of giving rise in the male to ova, or in the female to sperms, we should hold that the gametocytes ultimately give rise to ova or to sperms according to the metabolic processes set up and maintained in them through their successive cell-divisions under the influence of the double or single X chromosome.
The Mendelian theory therefore is that when an ovum has two X sex-chromosomes it can only after a number of cell-divisions, at the following reduction division, give rise to ova, while an ovum containing one X sex-chromosome, or two different, XY, chromosomes, at the next reduction division gives rise to spermatozoa.
A recessive character is the absence of some positive character, and if in the cell-divisions of gametogenesis the factor for the positive character passes wholly into one cell, the other will be without it, will not 'carry' that factor.
How comes it then that the female quality entirely disappears? Whether the gametocytes are distinguishable at an early stage in the segmentation of the ovum, or only at a later stage of development, we know that the gametes ultimately formed have descended by a series of cell-divisions from the fertilised ovum or zygote cell from which development commenced.
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