114 EVOLUTION 



organism is, or has, to start with, in virtue of 

 its hereditary relation. We cannot compare 

 organic inheritance to a patrimony; for the 

 organism and its inheritance are, to begin 

 with, one and the same. Nor do we any 

 longer think of heredity as a power or a prin- 

 ciple, as a fate or a force; we study it as a 

 genetic relation, which is sustained by a visible 

 material basis, namely the germ-cells; as a 

 relation of resemblances and differences which 

 can be measured and weighed, or in some way 

 computed. 



The hereditary relation is such that like tends 

 to beget like, while at the same time oppor- 

 tunity is afforded for the individual new 

 departures which we call variations. Both 

 the tendency to persist and the tendency to 

 diverge are included in the hereditary relation, 

 so that it is confusing to make an absolute 

 antithesis between heredity and variation. 

 Heredity, seen in its fullest sense, is the larger 

 concept, and includes both inertia and diver- 

 gence, both continuance and change. What- 

 ever be the terms used, there are two comple- 

 mental facts: that like tends to beget like, 

 yet that every new creature has in some way 

 an individuality of its own. 



WHY LIKE TENDS TO BEGET LIKE. The 

 fundamental hereditary relation is such that 



