HEREDITY 485 



the conception of the creature as a historic being. Let us 

 think over this idea. 



(a) There is, in the first place, the remarkable persistence 

 of the main body of the inheritance, with but rare divergence. 

 There is racial inertia; the entailment of what is called 

 specificity. As was said of old time, " All flesh is not the 

 same flesh : but there is one kind of flesh of men, another 

 flesh of beasts, another of fishes, and another of birds." This 

 is confirmed by modern research, which has demonstrated, 

 for instance, that the ciliated epithelium lining the windpipe 

 of a dog is different from that from a rabbit. A fish can 

 often be identified from a few scales, a bird by a single 

 feather. This specificity goes through and through: thus 

 Reichert and Brown (1909) have shown that the various 

 species of mammals, so far as they have been tried, differ 

 in the minutiae of their haemoglobin crystals. In this way it 

 is possible to distinguish the blood of a domestic dog from 

 that of a wolf, or even from that of the Australian dingo; 

 red fox, grey fox, and Arctic fox are crystallographically 

 specific! Every creature has its own particular kind of 

 colloidal substratum and its own particular chemical routine 

 taking place therein. The largest fact of inheritance is the 

 persistence of specificity, and we have here the reason why 

 new departures of great moment are not likely to occur 

 from specialised types. The relatively generalised types are 

 most likely to be strikingly inventive. 



The antiquity of the various parts of the hereditary frame- 

 work is one of the most impressive facts of biology. Galton 

 has used the illustration of modern buildings in Italy which 

 have sometimes been built out of the pillaged edifices of 

 ancient times; here is an antique column and there a lintel 

 unified afresh. 



