820 Fluctuations 



perience of breeders of domestic animals, and of 

 Louis de Vilmorin, and with the result of the 

 theoretical considerations concerning the fac- 

 tors of fluctuation has led me to suggest the 

 method of selecting, which I have made use of in 

 my experiments with tricotyls and syncotyls. 



Seedling variations afford a means of count- 

 ing many hundreds of individuals in a single 

 germinating pan. If seed from one parent- 

 plant is sown only in each pan, a percentage- 

 figure for the amount of deviating seedlings 

 may be obtained. These figures we have called 

 the hereditary percentages. I have been able to 

 select the parent-plants after their death on 

 the sole ground of these values. And the re- 

 sult has been that from varieties which, on an 

 average, exhibited 50 - 55^ deviating seedlings, 

 after one or two years of selection this propor- 

 tion in the offs]3ring was brought up to about 

 90^ in most of the cases. Phacelia and mercury 

 with tricotylous seedlings, and the Eussian 

 sunflower with connate seed-leaves, may be 

 cited as instances. 



Besides these tests, others were performed, 

 based only on the visible characters of the seed- 

 lings. The result was that this characteristic 

 was almost useless as a criterion. The atavists 

 gave, in the main, nearly the same hereditary 

 percentages as the tricotyls and syncotyls, and 



