V MilATlMN AND HKKKMTY 



11 



compared with an organism. They "ha iinal 



,u common, ihat if .-ith.-r is diMurU-,1 without trans- 

 gressing the range of its stahil 

 it will tend to re-estahli- 



that U. if tipped to the ri-ht or left 

 it \\ill fa!! Lack upon the original 



. it if t is passe.: 



will to; i- into a new position 



tal'ilitx. This illn-tiat- a mil 



Then- is now a new p- 

 tion of itabilit] 01 ;i\--rtige COlidi- 

 i about which there will be 



In thf present state of our knowl- 

 edge of variation w- an- unahlc to 

 say dogmatically whether SJM 

 have arisen by the slow accumu- 

 lated adjustments of ilu.-tu.-r 



on, or by the more rapid 

 process of mutation. In >upport of 

 the first theory then* are numerous 

 cases where species are connect, i 

 by intermediate grades. There is 

 much experiim-ntal .-vidence to sup- 

 port the second theory. 



In 1900, when De Vries in Hol- 

 land, < Wrens in Germany, and 

 Tschermak in Austria ind>-p<-nd 

 ently, and almost simultaneous 1\ . 



hed results from the experimental study of heredity 

 which have modified our views of the origin of species, 

 the whole subject of heredity took on added interest 



Galton, op. rif., p. tt. 





K 3. D.-pr.m illu* 

 ting a Mutation. 



