764 Fluctuations 



way the color and the number of the flowers on 

 each raceme were seen to vary. Thousands of 

 hybrids were produced, and only those which 

 exhibited real advantages were selected for 

 trade. These were multiplied by grafting, and 

 each variety at present consists only of the buds 

 of one original individual and their products. 

 No constancy from seed is assumed, many 

 varieties are even quite sterile. 



Of course, no description was given of the re- 

 jected forms. It is only stated that many of 

 them bore either single or poorly filled flow- 

 ers, or were objectionable in some other way. 

 The range of variability, from which the choices 

 were made, is obscure and only the fact of the 

 selection is prominent. What part is due to 

 the combination of the parental features and 

 what to the individual fluctuation of the hybrid 

 itself cannot be ascertained. 



So it is in numerous other instances. The 

 dahlias have been derived from three or more 

 original species, and been subjected to cultiva- 

 tion and hybridization on an ever-increasing 

 scale for a century. The best varieties are only 

 propagated in the vegetative way, by the roots 

 and buds, or by grafting and cutting. Each of 

 them is, with regard to its hereditary qualities, 

 only one individual, and the individual charac- 

 ters were selected at the same time with the 



