EFFECTS OF AMPHIMIXIS ON ONTOGENY 277 



for certain that the ids of another species are present, even 

 although they may not produce a perceptible effect. We may 

 conclude from the phenomena of ' pseudo-monogonic ' heredit}' 

 exhibited by these hybrids, that the ids of one parent may, as 

 has already been explained, prevent those of the other from 

 taking part in the control of the cell, group of cells, or part of 

 the body. 



We may therefore assume that if by means of the reducing 

 division, all the idants luJiicJi controlled or dominated the 

 ontogeny of the motlier^ for instance, reach one of the germ-cells 

 produced by this parent, this germ-cell will be capable under 

 certain circumstances of reproducing the maternal 'type'* in 

 the child. But in order that this may happen, it is necessary for 

 this cell to unite with a sperm-cell, the germ-plasm of which 

 possesses on the whole a weaker controlling power than its own, 

 so that the germ-plasm of the father is dominated by that of 

 the mother. 



As in the case of crosses between species, the controlling 

 power of the idioplasm will not always be dependent on the 

 same cause. 



We cannot enter more deeply into those cases in which a more 

 marked force of heredity of individual characters occurs. Darwin 

 mentions, for instance, that the ' white ' colour, in flowers as well 

 as in animals, is very commonly transmitted to the offspring 

 when white individuals are crossed with dark-coloured ones, the 

 majority of the descendants inheriting the white colour. We 

 can in this case only assume that those biophors which domi- 

 nate the cell, and give rise to the white colour, must be 

 'stronger' than those which cause the formation of pigment, 

 and this ' strength ' must, in fact, be attributed to the possession 

 of a greater power of assimilation. 



The case is diff'erent in many other instances in which the 

 greater hereditary power is attributable to quantitative differ- 

 ences in the constitution of the paternal and maternal groups of 

 idants. 



The number of ids contained in each idant is certainly 

 constant, or nearly so, in all individuals of the human spe- 



* I shall make use of the term ' type ' (' Bild '), to express the whole aggre- 

 gate of essentia] characteristics which together constitute the individuality 

 of a human being. 



