110 LUTHER BURBANK 



that would otherwise grow into an ordinary 

 worker may be made to develop into a queen, 

 that is to say, a mature female, by special feed- 

 ing. In somewhat the same way a plant that has 

 an excess of nourishment may tend to take on 

 exceptional growth, and one manifestation of 

 this might be a disturbance of the equilibrium of 

 the floral envelope, with the production of an 

 unusual number of petals. 



It is known, on the other hand, that a shortage 

 of food supplies or disadvantageous conditions 

 of climate may hasten the maturing of a plant, 

 and cause it to fruit earlier than it otherwise 

 would do. And any disturbance of equilibrium 

 of this sort may lead to anomalies in the precise 

 character of the flower. 



Possibly the reason why the petals of the 

 flower are most likely to be altered as to number, 

 and also as to color, is the fact that these are 

 about the newest of all the plant structures. We 

 have seen that the petals are not themselves 

 essential to the fertilization of the plant — ^they 

 are only advertisements to attract insects. They 

 were developed late in the evolutionary history 

 of the plant, and their variability is an additional 

 evidence of their modernity. The fact that so 

 many of our cultivated plants have become 

 "double" is in itself sufficient proof of the tend- 



