268 APPENDIX D 



(1) 'The different degrees of fluctuating variability can 

 undoubtedly be seized upon by any one who wishes to make 

 them the starting-point for the breeding of certain distinct 

 variations. Thus, for instance, by constantly selecting for 

 the reproductive process those plants in which a given 

 deviation is strongly marked, after a certain time and after 

 a series of generations, a plant can be obtained for which the 

 Galton curve would indicate a displacement of its culminating 

 point in the direction of the selected variation. In this way an 

 increase in the yield of sugar obtained from the beet roots 

 has been arrived at from about 7 per cent, to 13 or 14 per 

 cent. Thus also ears of maize have been produced that 

 bore 20 rows of grain, whereas the kind from which the 

 experiment had started always bore 12 to 14 rows. 



' As soon, however, as such conscious and voluntary selec- 

 tion ceases, the next generations successively return to the 

 original curve.' (p. 209.) 



(2) ' . . . breeding variations to the right or to the left 

 of the norm, can never exceed certain limits. Agencies are 

 at work there which prevent the fluctuating variability 

 from going any further. The existence of such limits 

 compels us to acknowledge that there is no possibility that 

 species might arise in nature according to the same plan 

 by which certain breeds originate under artificial selection.' 

 (pp. 209-10). 



(3) 'We have seen that fluctuating variability leads to 

 slow changes and furnishes farmers with the material to 

 improve the races of animals and plants.' (p. 210.) 



(4) * ... by means of fluctuating variability certain local 

 and improved races may indeed be bred, but that in nature 

 new species never arise through its agency.' (p. 210.) 



(5) ' As long as the mutation has not appeared, there can 

 be no question of the origin of a new species ; the species is 

 then constant, and only submitted to fluctuating variability, 

 which can produce local races (not elementary species) under 

 the constant cooperation (either artificial or natural) of 

 selection, but which never leads to the formation of species.' 

 (p. 216.) 



(6) ' The elementary species are stable. Selection calls 



