370 Ewart— Variation: Germinal and Environmental. 
Hitherto, the tendency with many has been to regard conjugation as little 
more than a mere mechanical mixing of vital units, partly derived from the 
parents, and partly from the ancestors. 
Many breeders assume that one-quarter of the ‘‘blood” of the offspring is 
derived from the four grandparents, and one-eighth from the great-grand- 
parents. 
According to Galton’s law of heredity, a law which has formed the basis of 
so many elaborate calculations, the two parents contribute half, the four grand- 
parents one-fourth, the eight great-grand parents one-eighth, and so on of the 
total heritage of the average offspring. This law may or may not apply to some 
sections of the human family, but it does not profess to express the results 
obtained when one of the parents is decidedly prepotent, nor yet, I imagine, does 
it profess to indicate what happens when intercrossing is resorted to. 
Wilhelm Roux (following in the wake of Spencer), with a fine insight, has 
applied the principle of selection to the individual parts of the organism, and 
Weismann, in elaborating this brilliant conception, has especially insisted on the 
view, that ‘‘even the smallest living particles contend one with another, and 
those that succeed best in securing food and place, grow and multiply rapidly, 
and so displace those that are less suitably equipped” ;* and further, that the 
cause which gives the advantage to one particle over others, and the consequent 
possibility of struggle, ‘is to be sought in the relative power of reaction to a 
definite stimulus, and in the fact that a functional stimulus strengthens an organ.”* 
To the universal contention between equivalent parts, Weismann gives the name 
‘* intra-selection.”’ 
In the case of the ovisperm, the energy for the struggle between the equivalent 
parts is inherited or stored up during the growth and maturation of the germ- 
cells, the stimuli coming mainly in the form of nourishment under varying 
conditions through a long line of ancestors. In the ovisperm it is not, I imagine, 
so much a contention between the individual vital units as a struggle between 
groups of units; the most vigorous, most prepotent, though often in a minority, 
gaining the victory. 
As in a public meeting there may be several factions, and as in a re- 
presentative assembly several parties, so in the mass of protoplasm, formed by the 
union of a male and female germ-cell, there may be several contending groups of 
vital units struggling for supremacy. In medizval tournaments, various kinds 
of competitors entered the lists, from the simple bowman to the knight in complete 
armour. In the same way in the ovisperm, in addition to the groups of vital units 
representing the latest developments of the variety or species, there are groups 
* Romanes’ ‘‘ Lectures,” London, 1894, p. 12. 
