Chap. XIII. 



REVERSION. 



47 



low in the scale, are crossed, the progeny seems to be emi- 

 nently bad. Thus the noble-hearted Humboldt, who felt none 

 of that prejudice against the inferior races now so current in 

 England, speaks in strong terms of the bad and savage disposi- 

 tion of Zambos, or half-castes between Indians and Negroes; 

 and this conclusion has been arrived at by various observers. 47 

 From these facts we may perhaps infer that the degraded state 

 of so many half-castes is in part due to reversion to a primitive 

 and savage condition, induced by the act of crossing, as well as 

 to the unfavourable moral conditions under which they generally 

 exist. 



Summary on the proximate causes leading to Beversion. — When 

 purely-bred animals or plants reassume long-lost characters,— 

 when the common ass, for instance, is born with striped legs, 

 when a pure race of black or white pigeons throws a slaty- 

 blue bird, or when a cultivated heartsease with large and 

 rounded flowers produces a seedling with small and elongated 

 flowers,— we are quite unable to assign any proximate cause. 

 When animals run wild, the tendency to reversion, which, 

 though it has been greatly exaggerated, no doubt exists, is 

 sometimes to a certain extent intelligible. Thus, with feral pigs, 

 exposure to the weather will probably favour the growth of the 

 bristles, as is known to be the case with the hair of other domes- 

 ticated animals, and through correlation the tusks will tend to 

 be redeveloped. But the reappearance of coloured longitudinal 

 stripes on young feral pigs cannot be attributed to the direct 

 action of external conditions. In this case, and in many others, 

 we can only say that changed habits of life apparently have 

 favoured a tendency, inherent or latent in the species, to return 

 to the primitive state. 



It will be shown in a future chapter that the position of 

 flowers on the summit of the axis, and the position of seeds 

 within the capsule, sometimes determine a tendency towards 

 reversion ; and this apparently depends on the amount of sap or 

 nutriment which the flower-buds and seeds receive. The posi- 

 tion, also, of buds, either on branches or on roots, sometimes 

 determines, as was formerly shown, the transmission of the 



4 ' Dr. P. Broca, on 'Hybridity in the Genua Homo/ Eng. translat., 1864, p. 39. 



