UNDER THE APPLE-TREES 
hold upon life, —an abounding, or plus, vitality, — 
while the opposite is true of others. In a brood of 
chickens or a litter of pigs or of puppies this in- 
equality of the gift of vitality is often very pro- 
nounced; it of course has its prenatal causes, 
but they are involved in the hidden activities of 
the cells. The term “a good constitution” has a 
scientific value, though quite beyond the tests of 
scientific analysis. The term “constitution” is only 
a name for a certain totality of physical endowment, 
as the word “vitality” is only a name for certain 
activities in matter; but if the latter has no stand- 
ing in the court of science or of philosophy, neither 
could the former have standing. Yet how very 
real both are to us. The diathesis of a person — his 
predisposition to certain diseases — is a very real 
factor in his physical life. No doubt by artificial 
or arbitrary selection a race of very long-lived men 
might be developed. By allowing only the off- 
spring of long-lived parents to marry, the term of 
human life could doubtless be greatly lengthened. 
But Nature does not work on this plan. She con- 
stantly crosses these opposite tendencies, because 
her solicitude is not about the few, the exceptional, 
but about the many, or the average. Tall men are 
prone to marry short women, one temperament 
to unite with its complementary, the robust with 
the delicate. Robert Browning marries the invalid 
Elizabeth Barrett. In the human species Nature 
284 
