Some Subjects for Future Investigation. 159 



KER among mathematicians. Botanical work in this 

 field, has also been done by Verschaffelt, Burkill, 

 Haake, Davenport, Blankinship, Mac Leod and 

 many others.^ 



Let us summarize the foregoing discussion. The 

 mental and moral characters of men exhibit fluctuating 

 variabihty. The laws therefore which describe this phe- 

 nomenon can be profitably applied to such characters. 

 And we shall have to be contented with this manner of 

 treating the subject so long as a direct investigation by 

 biometric methods, and by experiments in selection are 

 out of the question. The foundations of sociolog}^ must 

 be furnished by biology. And we may hope that the 

 time is not far distant Avhen a fruitful cooperation be- 

 tween these two sciences, apparently so much akin but 

 actually so far apart, may be brought about. 



But no theory of the origin of species can have any 

 bearing at all on this subject. 



§ 20. SOME SUBJECTS FOR FUTURE INVESTIGATION. 



In the preceding discussion I have had occasion to 

 draw attention not merely to the splendid achievements 

 of my predecessors but also to the numerous gaps in our 

 knowledge. 



The study of variability as opposed to mutability is 

 a branch of human knowledge which has developed witli 

 great rapidity in the last few years. The statistical 

 method of dealing with this phenomenon is, as we have 



^ A survey of the literature on this subject has been given by 

 G. DuNCKER, Die Methode der Variationsstatistik ; Roux's Archh' 

 filr Entzvickclnngsmechamk, Vol. VIII, 1899, p. 167; and by Oster- 

 HOUT, Problems of Heredity in Contributions Bot. Semin. Univ. 

 California 1898. 



