The Origin of Chrysanthciuiun Segetum Plenum. 187 



We thus see that the hmit has been reached. Any 

 fnrtlier impro\'enient of the race will only increase the 

 number of doubles and consequently of sterile individ- 

 uals. Seed-parents therefore must always be chosen 

 amongst the plants with the same degree of ''doubling" 

 as in this year (1900). In this respect my new race be- 

 haved, immediately after its origin, exactly like the old- 

 established Chrysantheniwn inodonun plenissimuni} 



It still remains to give some account of the general 

 conditions of fertilization of the seed-parents in the vari- 

 ous years. No doubt the experiment would have been 

 purer and more demonstrative if the corn marigold were 

 capable of self-fertilization. But this either does not 

 occur at all, or only to a totally inadequate extent. Each 

 year I have therefore left a group of a few selected plants 

 to flower together after the eradication of the rest; and 

 have been obliged to content myself with collecting the 

 seed of each in a separate package. Future experiments 

 will have to determine what the effect of this crossing 

 m.ay have been on the progress of the race. Meanwhile 

 it may be of interest to place on record the number of 

 ])lants which have flowered together each year, showing 

 the stringency of selection to which they were subjected. 



In the summer of 1895 the original parent of the 

 whole race, which was raised from seeds obtained by ex- 

 change (1895, No. 1), could not be isolated until late 

 and then incompletely, but as the plants flowering at the 

 same time also belonged to the 21 -rayed race the curve 

 of the offspring was very "pure" in this respect (p. 176). 

 In the next year the number of seed-bearers was reduced, 

 about the middle of August, to three very vigorous indi- 



^ The Matricaria Uore tofo alho plcnissimo , described by ^fuN- 

 TiNG in 187 1, the best specimens of which also set no seed, was prob- 

 ably the same variety {Waarc Ocffcningc dcr Plantcn, p. 527). 



