i8o EXPERIMENTAL EVOLUTION LECT. 



interest lies in the fact that they can help to show us 

 how and how far we can produce variation instead 

 of having to wait for its spontaneous appearance. It 

 must be said that up to the present date but little has 

 been done in this line. Such investigations are only 

 of speculative interest at least they seem so to most 

 people and they require much time and patience as 

 well as favourable conditions which are seldom 

 offered by our city laboratories. On the other hand, 

 we are allowed to use many facts of observation in 

 this demonstration of the influence of environment 

 upon parts or the whole of living organisms : they are 

 of as much value as direct experiments when we can 

 really ascertain what are the influences which have been 

 in action. Between observation and experimentation 

 there is not as much difference as is commonly said, and 

 when the conditions under which any phenomenon is 

 observed can be exactly recognised, the result of the 

 observation has all the value of that of an experiment. 1 

 The investigation of the direct influence of environ- 



Influence of the Environment upon the Organism. Proc. Roy. Phys. 

 Soc. Edin. 1887. 



1 An observation made under circumstances which allow all the 

 elements which co-operate to be well ascertained has as much worth as 

 an experiment ; the only difference being that in the latter case the 

 experimenter's will has determined the conditions while in the former he 

 has had no control upon them. But if he is exactly acquainted with 

 these, the result is quite as valuable, and the difference lies only in the 

 mental process which precedes the recording of the result. 



