200 LUTHER BURBANK 



rule. Each individual plant when grown from 

 seed has a slight difference in fragrance, and in 

 the amount of essential oil that it contains; this 

 oil being, of course, the source of the fragrance. 

 It is not difficult by selection alone to obtain 

 varieties that are of exceptionally fine fragrance 

 and that produce a relatively large percentage 

 of the essential oil for which the plants are 

 usually grown. 



When a new variety has been obtained, it is 

 not necessary to fix it so that it will breed exactly 

 true from the seed; for the most of these plants 

 can be increased by division. 



The mints hybridize naturally where various 

 species grow in the same vicinity, as we have 

 pointed out in another connection. 



In this way natural hybrids are sometimes 

 produced that are so vigorous as to replace the 

 original parent plants in the state of nature, 

 driving them out of existence on their own 

 ground. Among hybrid mints, whether natural 

 or produced by hand pollination, there will be 

 seedlings that grow with exceptional rapidity, 

 and that present peculiar shapes and much vari- 

 ation as to roughness and smoothness of leaves 

 and form of the spikes and blossoms. In work- 

 ing with all these plants, I found that quality 

 was the one thing lacking. In any lot of seed- 



