846 STUDIES FOR STUDENTS 
nomenal influence which the Darwinian hypothesis has exerted 
upon the investigations of the past two decades is a monumental 
illustration. But while a single working hypothesis may lead 
investigation very effectively along a given line, it may in that 
very fact invite the neglect of other lines equally important. 
Very many biologists would doubtless be disposed today to cite 
the hypothesis of natural selection, extraordinary as its influence 
for good has been, as an illustration of this. While inquiry is 
thus promoted in certain quarters, the lack of balance and com- 
pleteness gives unsymmetrical and imperfect results. But if on 
the contrary all rational hypotheses bearing on a subject are 
worked coérdinately, thoroughness, equipoise, and symmetry 
are the presumptive results in the very nature of the case. 
In the use of the multiple method, the reaction of one 
hypothesis upon another tends to amplify the recognized scope 
of each. Every hypothesis is quite sure to call forth into clear 
recognition new or neglected aspects of the phenomena in its 
own interests, but ofttimes these are found to be important 
contributions to the full deployment of other hypotheses. The 
characters at the hands of 
b) 
eloquent expositions of ‘‘prophetic’ 
Agassiz were profoundly suggestive and helpful in the explica- 
tion of ‘undifferentiated”’ types in the hand of the evolu- 
tionary theory. 
So also the mutual conflicts of hypotheses whet the discrim- 
inative edge of each. The keenness of the analytic process 
advocates the closeness of differentiating criteria, and the sharp- 
ness of discrimination is promoted by the codrdinate working of 
several competitive hypotheses. 
Fertility in processes is also a ‘natural sequence. Each 
hypothesis suggests its own criteria, its own means of proof, 
its own method of developing the truth; and if a group of 
hypotheses encompass the subject on all sides, the total outcome 
of means and of methods is full and rich. 
The loyal pursuit of the method for a period of years leads 
to certain distinctive habits of mind which deserve more than 
the passing notice which alone can be given them here. As a 
