Some Subjects for Future liwestigatioii. 163 



tain magnitude of deviation from the average, with a 

 minimum expenditure of trouble. Is this its only sig- 

 nificance? Does the number of individuals with the 

 undesired qualities diminish exactly at such a rate as 

 we can calculate beforehand? That is to sav, is reo^res- 

 sion independent of the ancestry of a given parent; in 

 other words, does it make any difference whether the 

 seed parent is the result of repeated selection, or is 

 picked from a single sowing on a much larger scale? 



11. In such experiments attention should be paid to 

 one character and one only ; although interesting results 

 may often be obtained by measuring a second or even 

 a third character as a sort of collateral inquiry. The 

 selections carried out bv breeders involve as manv char- 

 acters as possible ; on account of correlations the improve- 

 ment of the chief features can be carried further in this 

 way, than would otherwise be possible. Such experi- 

 ments should be made with a purely scientific end in 

 view. 



12. In starting an experiment attention must always 

 be paid to the individual vigor of the seed-parents. If 

 this does not happen to coincide with the desired devia- 

 tion, it is advisable to take both the strongest individuals 

 and those exhibiting the greatest deviation, as seed- 

 bearers and to compare the posterity of the two. 



13. There is a particular kind of selection experiment 

 which should be carried out a great deal more than it is. 

 I mean one which would start by choosing as seed- 

 parents plants with the smallest petals, the smallest fruits, 

 those with the least degree of hoariness or the least num- 

 ber of spines, with the palest color in their petals, with 

 the smallest number of stamens and carpels and so forth. 

 According to the theory of natural selection such an ex- 



