ILL USTRA TIONS 1 2 1 



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 bora 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 



^<^=^ 



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 



