The Problem of Adaptation 21 
The phenomenon of old age (apart from its possible con- 
nection with the cessation of the power of reproduction), 
which leads to the death of the individual, has been looked 
upon by a few writers as an adaptation of the individual for 
the good of the species. It has been pointed out by these 
writers that the longer an individual lives, the more likely it 
is to become damaged, and if along with this its powers of 
reproduction diminish, as compared with younger individuals, 
then it stands in the way and takes food that might be used 
by other, younger individuals, that are better able to carry on 
the propagation of the race. It is assumed, therefore, that 
the life of the individual has been shortened for the benefit 
of the race. Whether such a thing is probable is a question 
that will also be discussed later. We are chiefly concerned 
here only in recording the different groups of phenomena 
that have been regarded by biologists as adaptations. 
The so-called secondary sexual characters such as the 
brighter colors of the males, ornaments of different kinds, 
crests, color-pattern, tail feathers, etc., organs of offence and 
of defence used in fighting members of the same species, 
present a rather unique group of adaptations. These char- 
acters are supposed to be of use to the individual in conquering 
its rivals, or in attracting the females. They may be consid- 
ered as useful to the individual in allowing it to propagate at 
the expense of its rivals, but whether the race is thereby 
benefited is a question that will be carefully considered later. 
The colors of flowers, that is supposed to attract insects, 
have been already mentioned. The sweet fluid, or nectar, 
secreted by many flowers is sought by insects, which on enter- 
ing the flowers bring about cross-fertilization. Thus while 
the nectar seems to be of no immediate service to the plant it- 
self, it is useful to the species in bringing about the fertiliza- 
tion of the flowers. The odors of flowers also serve to attract 
insects, and their presence is one of the means by which in- 
sects find the flowers. This also is of advantage to the, race. 
