FUNDAMENTAL PRINCIPLES 19 1 
the result if all the seeds produced by one of our large 
forest trees were able to mature. And yet the total 
number of any given kind of fern, of hedge mustard, or 
of forest tree does not appreciably change from year to 
year. The reason, of course, is that not all of the spores 
and seeds produced are allowed to come to maturity. 
The direct result of the enormous number of spores and 
seeds produced is a struggle for existence for sufficient soil, 
water, light, and food to insure a healthy, mature plant. 
174. Elimination of the Unfit. As a result of variation 
certain individuals will succeed better than others in the 
struggle for existence. Those most poorly adapted to 
their surroundings will perish, and only the more vigorous 
ones those best adjusted to their surroundings will 
persist. The result of this struggle for existence was 
called by Herbert Spencer the "survival of the fittest." 
What really takes place in nature is the elimination, by 
death, of the unfit. Darwin called this natural selection, 
implying that the result is similar to that when plant 
breeders select out of a progeny the best individual for 
further breeding. What really takes place in nature, 
however, is not so much the selection of the fittest, but a 
rejection of the unfit. Thus, among the 50,000,000 
progeny of a single fern-plant, some are sure to have a 
weaker constitution than others; to develop a weaker root- 
system, less chlorophyll in their leaves, a less number 
of sporophylls or spores, or to be inferior in other ways. 
The result will be that, in the course of only a few years, 
the descendants of the most vigorous or otherwise superior 
plants will alone be left to perpetuate the race. 
175. Problems to Solve. In the preceding paragraphs 
we have called attention to a number of the problems 
