Chap. XIV. SUMMARY. 83 



apparently come under the same law of reversion. It is assuredly 

 an astonishing fact that the male and female sexual elements, 

 that buds, and even full-grown animals, should retain characters, 

 during several generations in the case of crossed breeds, and 

 during thousands of generations in the case of pure breeds, 

 written as it were in invisible ink, yet ready at any time to 

 be evolved under the requisite conditions. 



What these conditions are, we do not in many cases at all 

 know. But the act of crossing in itself, apparently from causing 

 some disturbance in the organisation, certainly gives a strong 

 tendency to the reappearance of long-lost characters, both co£ 

 poreal and mental, independently of those derived from the 

 cross. A return of any species to its natural conditions of life, 

 as with feral animals and plants, favours reversion ; though it is 

 certain that this tendency exists, we do not know how far it pre- 

 vails, and it has been much exaggerated. On the other hand, 

 the crossed offspring of plants which have had their organisation 

 disturbed by cultivation, are more liable to reversion than the 

 crossed offspring of species which have always lived under their 

 natural conditions. 



When distinguishable individuals of the same family, or races 

 or species are crossed, we see that the one is often prepotent 

 over the other in transmitting its own character. A race may 

 possess a strong power of inheritance, and yet when crossed 

 as we have seen with trumpeter-pigeons, yield to the prepo- 

 tency of every other race. Prepotency of transmission may be 

 equal in the two sexes of the same species, but often runs more 

 strongly m one sex. It plays an important part in determining 

 the rate at which one race can be modified or wholly absorbed 

 by repeated crosses with another. We can seldom tell what 

 makes one race or species prepotent over another; but it some- 

 times depends on the same character being present and visible 

 m one parent, and latent or potentially present in the other. 



Characters may first appear in either sex, but oftener in the 

 male than m the female, and afterwards be transmitted to 

 the offspring ; of the same sex. In this case we may feel con- 

 fiden that the peculiarity in question is really present though 

 atent m the opposite sex; hence the father may transmit 

 through his daughter any character to his grandson ; and the 



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