HS 
Lacn individual is vossessed of a given inheritance which 
will cause it to develoo in e certain way. It does not develop to 
maturity in a vacuum, however, but in response tc a given environment. 
Individuals with identical heritage may accordingly be modified within 
certain limits by differences in environment, which thus mask in greater 
or less degree genetic similarity or identity. 
At the same time a given population may be quite diverse ge- 
netically, that is, the individuals may have a diverse heritage and 
may differ morphologically. Plant species are often composites of 
several small races variously differentiated. For example, one may 
sometimes find, in a field of blue lupines, a single white flowered plant. 
Or he may find in certain Gilias, a patch here which is quite white, a 
patch there wiich is uniformly pink. The difference is striking, and 
the beginner may be misled by it. Or, when single individuals of var- 
jant races are compared, tne differences may seem of sufficient weight 
to justify specific segregation. 
The effect of racial intermixture is more difficult to judge. 
When single individuals of variant races are compared, the differences 
may seem of sufficient value to justify specific recognition. However, 
when whole vovulations are studied or several races are compared, such 
differences often disappear and the species is found to consist of sev- 
eral forms which in nature merge to form a unit. It is accordingly de- 
sirable to study not a single individual but several individuals at the 
same time and, when convenient, rom several places, bearing in mind, 
always, that living forms are plastic changing things. 
