AN OUTLINE OF THE THEORY. 17 
preserved and will transmit its favorable peculiarity to 
some of its offspring, which peculiarity will thus become 
intensified till it reaches the maximum degree of utility. 
On the other hand, individuals presenting unfavorable 
peculiarities will be ruthlessly destroyed (Survival of the 
Fittest), 
The basis of the theory then is that animals and plants 
multiply very rapidly and, second, that the offspring al- 
ways vary slightly from the parents, though generally 
very closely resembling them. Mr. Alfred Russel Wal- 
lace says: “From the first fact or law there follows, nec- 
essarily, a constant struggle for existence; because while 
the offspring always exceeds the parents in number, gen- 
erally to an enormous extent, yet the total number of 
living organisms in the world does not, and can not, in- 
crease year by year. Consequently every year, on the 
average, as many die as are born, plants as well as ani- 
mals; and the majority die premature deaths. They kill 
each other in a thousand different ways; they starve each 
other by some consuming the food that others want; they 
are destroyed largely by the powers of Nature—by cold 
and heat, by rain and storm, by flood and fire. There is 
thus a perpetual struggle among them which shall live and 
which shall die; and this struggle is tremendously severe, 
because so few can possibly remain alive —one in five, 
one in ten, often only one in a hundred or even in a 
thousand. 
“Then comes the question, Why do some live rather 
than others? If all the individuals of each species were 
exactly alike in every respect, we could only say it is a 
matter of chance. But they are not alike. We find that 
they vary in many different ways. Some are stronger, 
some swifter, some hardier in constitution, some more 
cunning. An obscure color may render concealment 
more easy for some, keener sight may enable others to 
