420 TOWER, DARWINISM. 
the collective answers to the question depends the fate of Dar- 
wın’s Hypothesis of Natural Selection. If the collective results from 
the work of many investigators with divers organisms in different 
places and not in collusion show the preponderance of either one 
of the two alternatives presented, we shall then know far more 
certainly than is known today whether the principle of Natural 
Selection is a reality in nature or not. 
In this paper are presented a digest and a general statement of 
some results obtained with reference to the fundamental question 
asked concerning the operation of the principle that underlies the 
Hypothesis of Natural Selection. These results are derived frem 
two types of effort; first, by statistical observations devised to 
give an answer to the question; and, second, by experimental 
tests, employing large enough groups so that whatever resulted 
would be “expressed statistically in sufficient frequencies to be 
significant. 
BY STATISTICAL OBSERVATION IN NATURE. 
Biometric biology arose in response to the demand for evidence 
concerning the validity of DARWIN’s Hypothesis, and along with 
this requirement went the hope that by statistical methods know- 
ledge could be obtained concerning the rate of evolutionary chan- 
ges and their direction. The results thus far are disappointing, and 
this is often attributed to the statistical method itself, when, in 
fact, it is mostly due to improper use of statistical methods. In 
these observations I have employed statistics solely as the means 
of determining and expressing the answers obtained to definite 
questions. 
My method has been first to formulate a precise proposition 
for investigation and then to find in nature or to arrange the proper 
settings to test the proposition. Whatever happened would be the 
result of actual operations expressed statistically and would leave 
me no opportunity for interpretation or explanation. Whatever 
resulted would be impersonally determined and the errors possible 
would be in judgment with respect to the organization of the test 



