ILLUSTRATIONS 



121 



taken as serious pieces of evidence in favour of the reversion theory, 

 but they may serve to hint at the readiness with which the hypo- 

 thesis of characters lying latent has been adopted. As we shall 

 see, reversions in the strict sense are apparently few and far be- 

 tween. 



A foal is sometimes born with a few stripes on its fore-legs, 

 as if reminding us of striped wild horses. A dovecot with 

 carefully bred pigeons was left to itself for some years, after 

 which it was found to contain numerous blue pigeons, resem- 

 bling in many ways the wild rock-dove (Columba livia). A 



***U 



Fig. 25. — Devonshire pony, showing the occurrence of stripes. (From 

 Darwin.) 



dark-coloured child may be born in a family where there has 

 been some Eurasian mixture. Cultivated flowers and vegetables, 

 such as pansies and cabbages, sometimes produce forms hardly 

 distinguishable from their wild progenitors. The nectarine derived 

 from a peach may produce what is practically a peach again. The 

 white-flowering currant — derived from the common red form — may 

 have branches with red flowers. These are preliminary illustrations 

 of what are usually called reversions — the hypothesis implied being 

 that they are returns, or " throw-backs," to an ancestral type. 



§ 2. Suggested Definitions 



Darwin's introductory exposition (1868, vol. ii. p. 28) was as 

 follows : " When the child resembles either grandparent more 



