128 RETROGRESSION 



while as to the other stones, though the mason may have chipped 

 them here and there, and altered their shapes a little, few, if any, 

 came direct from the quarry. This simile gives a rude but true 

 idea of the exact meaning of Particulate Inheritance, namely, that 

 each piece of the new structure is derived from a corresponding 

 piece of some older one, as a lintel was derived from a lintel, a 

 column from a column, a piece of wall from a piece of wall. 



212. "I will pursue this rough simile just one step further, 

 which is as much as it will bear. Suppose we were building a 

 house with second-hand materials carted from a dealer's yard, we 

 should often find considerable portions of the same old houses to 

 be still grouped together. Materials derived from various structures 

 might have been moved and much shuffled together in the yard, 

 yet pieces from the same source would frequently remain in 

 juxtaposition and it may be entangled. They would lie side by 

 side ready to be carted away at the same time and to be re-erected 

 together anew. So in the process of transmission by inheritance, 

 elements derived from the same ancestor are apt to appear in 

 large groups, just as they had clung together in the pre-embryonic 

 stage, as perhaps they did. They form what is expressed by the 

 words * traits ' traits of feature and character that is to say 

 continuous features and not isolated points. 



213. u We appear, then, to be severally built up out of a host 

 of minute particles of whose nature we know nothing, any one 

 of which may be derived from any one progenitor, but which are 

 usually transmitted in aggregates, considerable groups being 

 derived from the same progenitor. It would seem that while the 

 embryo is developing itself, the particles more or less qualified for 

 each new post wait as it were in competition, to obtain it. Also 

 that the particle that succeeds, must owe its success partly to 

 accident of position and partly to being better qualified than any 

 equally well placed competitor to gain a lodgment. Thus the 

 step by step development of the embryo cannot fail to be influ- 

 enced by an incalculable number of small and mostly unknown 

 circumstances." l 



214. Many biologists evidently do mean by 'contribution' 

 a unit added to the germ-plasm. For example, we are told, " The 

 Law of Ancestral Inheritance proves that all ancestors, however 

 remote, are able to leave the impress of their individuality upon 

 the sex-cells in diminishing proportion according to their remote- 

 ness. Such a fact can only be accounted for by assuming the 



1 Galton, Natural Inheritance, pp. 7-9. 



