124 REVERSION AND ALLIED PHENOMENA 



In the mosaic which composes an inheritance there may be 

 included items of ancient origin which can lie latent generation 

 after generation, remaining unexpressed in development for 

 lack of the appropriate liberating stimulus, or for other reasons. 

 Certain potentialities or initiatives, which really form part of 

 the inheritance and are really transmitted from generation to 

 generation, may be kept under by other components of the 

 inheritance, or in some way prevented from asserting them- 

 selves. At length, in the reconstitution which is associated with 

 the maturation and fertilisation of the germ-cells, or in the inti- 

 mate germinal struggle which is possibly always going on amongst 

 the diverse hereditary items, the long-latent items find their 

 opportunity and the result is a reversion due to the reassertion of 

 long-latent characters. 



The garden of a shepherd's cottage swallowed up in a deer- 

 forest lost all trace of its previous cultivation and became a 

 weed-ground. After many years it was delved, and soon there 

 appeared many different kinds of old-fashioned flowers whose 

 seeds had lain dormant for several generations. So may ancient 

 flowers and weeds now and again reappear out of latency in 

 that garden which we call our inheritance. 



So far the old view — a hypothetical interpretation which may 

 hold good in certain cases, such, perhaps, as the appearance of a 

 fourth toe on a guinea-pig's hind foot, or of horns in a hornless 

 race of cattle. What is the new view, which rests on a definite 

 experimental basis ? It is briefly as follows. In establishing 

 domesticated or cultivated varieties, man seems to have been for 

 the most part assisting in the " unpacking " of the extremely 

 complex inheritance of the wild type. Thus the colour-varieties 

 of the domestic rabbit are the results of analysing out in varying 

 measure and mixture that beautiful synthesis of hues which we 

 see in the wild rabbit. When certain colour-varieties are crossed 

 and the offspring are of the wild type, this is due to " repacking." 

 Colour-factors which have been separated out by anatysis come 



