just as propounded by De Vries. The great point is that 

 an advance has been made, the most important advance 

 since the time of Darwin, by way of helping to elucidate 

 one of the great questions in which man is interested. It 

 is not to be supposed that we have as yet any final answer 

 to this question, final answers are not indeed the goal of 

 any one scientific research. It was Sir Isaac Newton, I 

 think, who said that the seeker after ultimate causes did 

 not show the true scientific spirit, and he was right. What 

 we have is one of the proximate causes demonstrated to a 

 degree which had not been previously attained. A scien- 

 tific theory is like an organism, it grows and it may also 

 propagate itself, and all the theories of evolution from 

 Lamarck to De Vries, and those that will follow, will 

 themselves be an example, as it were, of the principle that 

 they teach. A theory starts life an intellectual pigmy, 

 may develop, if it have the vitality, into a veritable intel- 

 lectual colossus, and, after it has run its course, may leave 

 behind its offspring. It is not a cause of reproach but 

 rather of congratulation that the scientific theory of today 

 may be discarded tomorrow, for no theory w r ill be aban- 

 doned until a better one has been brought forward to take 

 its place, one which can explain the facts in a way more 

 satisfying to the human mind. Change in such a case is 

 progress, and since science must of necessity be always 

 progressing so also must it be always changing. 



To those who are conversant with the problems con- 

 nected with the origin of species it must be obvious that 

 this consideration of the subject does not cover the whole 

 ground; so obvious indeed that perhaps it is unnecessary 

 for me to remark that it is not intended to. There are 

 other theories to be considered and other equally import- 

 ant matters that are more or less interwoven with any one 

 theory of the evolution of new forms. Thus no reference 

 has been made to Mendel's researches on heredity, or 



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