520 EVOLUSION 
the parent and not of another kind, although there may be much 
difference in size of plants, length of ears, size and shape of ker- 
nels, etc. In spite of variations there is inheritance which is 
an imparting of something by the parents to the offspring, 
which as a result develop some of the parental features. Dar- 
win also thought that not only the resemblances to parents, but 
also whatever variations the offspring may have are inheritable. 
Assuming that variations are transmitted to succeeding gen- 
erations in which they may become more pronounced, he could 
explain the origin of new characters and new species. If a 
variation is such as to better adapt individuals to their en- 
vironment, those individuals in which the variation is most 
pronounced have a better opportunity to survive and propagate 
in greater numbers than individuals in which the variation is 
less pronounced. Thus through many successive generations in 
which the individuals with the variation most pronounced are 
more favored than other individuals, the variation is intensified 
by natural selection and eventually becomes a character of a new 
species. Darwin drew this conclusion from some of his experi- 
ments as well as from general observations of plants and animals 
under domestication. He observed that through selection both 
plants and animals changed much under domestication. Starting 
with wild forms of plants, he was able by selecting the variants 
from the progeny for a number of generations to obtain indi- 
viduals differing strikingly from the original wild forms. He 
found that continuous selection gradually built up the selected 
character until the desired result was obtained. He concluded 
that in nature such a selective process was brought about by 
the competition among individuals for existence; but, while 
any character might be built up by artificial selection, only those 
which enable the individual to withstand competition are built 
up in nature. : 
Fitness for Environment. —It is common observation that 
different kinds of plants and animals require different condi- 
tions under which to live. As pointed out in the discussion of 
Ecology, some plants and animals live submerged in the water, 
but most plants and animals can live only on land. The Cacti 
are so constructed that they can endure the drought of the 
desert, but Corn, Wheat, and most plants require a medium 
amount of moisture. Again some plants which are well pro- 
