370 EwAHT — Variation : Germinal and Environmental. 



Hitherto, the tendency with man 3^ 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-fourt]}, the eight great-grand parents one-eighth, and so on of the 

 total heritage of the average offspi-ing. 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 tlie principle of selection to tJie 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 afunctional 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 mediaeval 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. 



