THE LAW OF ANCESTRAL INHERITANCE 127 



of one-sixteenth, and so on. He concluded further, that what was 

 true of the characters investigated was true of all characters, that 

 what was true of the generations investigated was true of all 

 generations, and seemingly also that the resemblances were due 

 to ' contributions ' to the germ-plasm. The notion that ancestors 

 'contribute' to the heritage of the child (i.e. add definite and 

 apparently discrete ' units ' to the germ-plasm) is founded on, but 

 not tested by his facts. 



210. The principal difficulty in discussing the Law of Ancestral 

 Inheritance arises from the fact that since the nature of a 

 1 contribution ' is not defined, the hypothesis is not ' definite in 

 conditions.' Conceivably, the word implies a variation which 

 occurred in the germ-plasm at the time that an ancestor existed 

 a variation which may or may not blend with other variations 

 occurring in the same and in preceding and succeeding generations. 

 Or ' contributions ' may be regarded as discrete units which re- 

 present separate ancestors in the germ-plasm and have been added 

 to it by them. Since biometricians, as a rule, hold with Weismann 

 that the germ-plasm is continuous and that inheritance is usually 

 blended, it seems correct to conclude that what they mean by 

 their word ' contribution ' is a blend of the variations occurring in 

 a generation of ancestors. On the other hand the language used 

 appears to indicate clearly that what they mean is that the germ- 

 plasm is compounded of discrete units, each of which was somehow 

 contributed by a separate ancestor contributed by the soma to 

 the germ-plasm, by the dwelling to the inhabitant. Probably such 

 an interpretation would be repudiated. Nevertheless, it would 

 certainly seem to be implied that discrete units representing 

 ancestors do in some way come into existence in the germ-plasm 

 and influence the development of the individual from start to finish. 



211. "We seem to inherit bit by bit, this element from one 

 progenitor, that from another . . . while the separate bits are 

 themselves liable to some small change during the process of 

 transmission. Inheritance may therefore be described as largely 

 if not wholly ' particulate,' and as such it will be treated in these 

 pages. Though this word is good English and accurately ex- 

 presses its own meaning, the application now made of it will be 

 better understood through an illustration. Thus, many of the 

 modern buildings in Italy are historically known to have been 

 built out of the pillaged structures of older days. Here we may 

 observe a column or a lintel serving the same purpose for a second 

 time, and perhaps bearing an inscription that testifies to its origin, 



