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 sufficient quantity is the final determining condition under the influence of which the cell acquires its final determinate character as male or female.

The genital glands are the organs in which the sex of the individual is most obvious, and in the component cells of which it is most conspicuously visible. At the same time it must be noted that the distinguishing characters of the species, race and family to which an organism belongs are also best marked in the genital cells. Just as Steenstrup, on the one hand, was right in teaching that sex extends all over the body and is not confined to the genital organs, so, on the other hand, Naegeli, de Vries, Oskar Hertwig and others have propounded the important theory, and supported it by weighty arguments, that every cell in a multi-cellular organism possesses a combination of the characters of its species and race, but that these characters are, as it were, specially condensed in the sexual cells. Probably this view of the case will come to be accepted by all investigators, since every living being owes its origin to the cleavage and multiplication of a single cell.

Many phenomena, amongst which may be noticed specially experiments on the regeneration of lost parts and investigations into the chemical differences between the corresponding tissues of nearly allied animals, have led the investigators to whom I have just referred to conceive the existence of an "Idioplasm," which is the bearer of the specific characters, and which exists in all the cells of a multi-cellular animal, quite apart from the purposes of reproduction. In a similar fashion I have been led to the conception of an "Arrhenoplasm" (male plasm) and a "Thelyplasm" (female plasm) as the two modes in which the idioplasm of every bisexual organism may appear, and which are to be considered, because of reasons which I shall explain, as ideal conditions between which the actual conditions always lie. Actually existing protoplasm is to be thought of as moving from an ideal arrhenoplasm through a real or imaginary indifferent condition (true hermaphroditism) towards a protoplasm that approaches, but never