PREFACE XXV 



by augmenting the capabilities of the soil, and by extra care of the plant. We 

 shall now attempt similar effort by making better plants. Of course there has 

 been remarkable progress in varieties of plants; but for the most part it has 

 been fortuitous and unpredicted. The new plant- breeding is more important 

 than the old insistence on fertilizing of the land. But we are even yet mostly 

 concerned with the production of concrete varieties, following the age-long 

 conception that species and varieties are entities. Very likely we shall find 

 that the best plant- breeding is that which produces gradual improvements 

 inside the variety, until a variety shall develop into something better than 

 itself. We seem now to care more for something that we can name, than for 

 something that we can measure. We shall work out such constants that 

 each grower will know how to increase the efficiency of a crop, as well by 

 breeding the plant as by manipulating the soil. The grower will not need to 

 rely solely on a professional maker of new kinds. Plant- breeding will be 

 valuable in proportion as it gives every man the power to breed plants for 

 himself. 



We need a new plant physiology, — a broader, keener, more vital body of 

 knowledge than the laboratory alone can give us; for physiology is the science 

 of life, and this life relates itself to every condition in which the plant lives. 

 It includes ecology and ethology and other special fields. Part of this new 

 knowledge will come from the botanists, part from the horticulturists, and there 

 will be no clear line of demarcation. Suppose the botanists give us the funda- 

 mental histological and physiological data: we horticulturists will work them 

 out in plant forms that will help the race in its progress. 



In working out these practical breeding problems we will also be recon- 

 structing the route by which the vegetable kingdom has arrived at its pi'esent 

 stage. The plant- breeder and the animal -breeder are exponents of the 

 organic evolution idea. They participate in the progress. They see the 

 pageant. Working forward for definite ends, they also work backward to the 

 beginning. I know of no persons who so much need to be philosophers. 

 Inevitably they will contribute much to the discussion of evolution, for these 

 discussions must tend to emerge from speculation into definite experiment. 



Up to this time, the evolution of plant forms has been essentially undi- 

 rected by man. If such marvelous transformations have taken place in 

 cultivated plants under such conditions, what may be expected under the 

 explicit efforts of the future? We have every reason for saying that the 

 progress will be remarkable. We shall work on the species that we now cul- 

 tivate, and we shall extend our effort to species not yet domesticated. All 



