THE DAHLIA 343 



The first thing was to find an individual that 

 revealed even the faintest pleasing aroma. In 

 general, dahlias have either no odor, or a slightly 

 disagreeable one. The tribe of composite flowers 

 to which the dahlia belongs depends as a rule 

 upon the conspicuous floral envelope to attract 

 the pollenizing insects, and has not developed 

 fragrance. 



But it is probably true with regard to fra- 

 grance as with regard to combinations of colors 

 that there are unrevealed hereditary factors in 

 the germ plasm of almost every flower. The pro- 

 duction of odoriferous oils and essences is so 

 characteristic a phenomenon with plants in gen- 

 eral, that we can hardly doubt that every tribe 

 has in its ancestral strains very complex elements 

 for the production of odoriferous compounds. 

 Odors appear to play a very important part in 

 plant life, not merely in the attraction of insects 

 to facilitate cross-fertilization, but also in giving 

 plants protection. 



Otherwise it would be hard to account for the 

 almost universal prevalence of odors of one kind 

 or another in connection with the various tissues 

 of the plant. 



Moreover there is a far closer relationship than 

 is commonly supposed between agreeable and 

 disagreeable odors. Attar of roses, properly 



