454 Evolution and Adaptation 
author. While the only test of utility is the success of the 
organism, even this does not indicate the utility of one part 
of the economy, but rather the net fitness of the whole.” 
Keeping in mind the admonitions contained in the two pre- 
ceding quotations, let us pass in review and attempt to ana- 
lyze more fully the different points that have been considered 
in the preceding chapters. 
It has been pointed out that the evidence in favor of the 
theory of evolution appears to establish this theory with great 
probability, although a closer examination shows that we are 
almost completely in the dark as to how.the process has 
come about. For example, we have not yet been able to 
determine whether the great groups of animals and plants 
owe their resemblance to descent from a single original spe- 
cies or from a large number of species. The former view is 
more plausible, because on it we appear to be furnished with 
a better explanation of resemblances as due to divergence 
of character. Yet even here a closer scrutiny of the homol- 
ogies of comparative anatomy shows that this explanation 
may be more apparent than real. If discontinuous variation 
represents the steps by which evolution has taken place, the 
artificiality of the explanation is apparent, at least to a certain 
degree. 
Admitting that the theory of evolution is the most prob- 
able view that we have to account for the facts, we next 
meet with two further questions, — the origin of species and 
the meaning of adaptation. These are two separate and dis- 
tinct questions, and not one and the same as the Darwinian 
theory claims. The fact that all organisms are more or 
less adapted to live in some environment appears from our 
examination to have no direct connection with the origin of 
the adaptation, for, in the first place, it seems probable that, 
in general, organisms do not respond adaptively to the envi- 
ronment and produce new species in this way; and, in the 
second place, there is no evidence to show that variation 
