FACTORS OF ORGANIC EVOLUTION. 



465 



illustrate how important external stimuli are in originating variation 

 and how it is that some of these variations persist. 



Let me begin by saying that a good gardener loves his plants, Now, 

 a good gardener is one who grows good plants, and good plants are 

 very unlike poor plants. They are unlike because the gardener's love 

 for them has made them so. The plants were all alike in IsTovember; 

 in January the good gardener's plants are strong and clean, with large 

 dense leaves, a thick stem, and an abundance of perfect flowers; the 

 poor gardener's plants are small and mean, with curled leaves, a thin 

 hard stem, and a few imperfect flowers. You will not believe now that 

 tbe two lots were all from the same seed pod three months ago. The 

 good gardener likes to save his own seeds or make his own cuttings; 

 and next year his plants will be still more unlike his neighbor's. The 

 neighbor tries this seed and that, reads this bulletin and that, but all 

 avails nothing simply because he does not grow good plants. He does 

 not care for them tenderly, as a fond mother cares for a child. The 

 good gardener knows that the temperature of the water and the air, 

 the currents in the atmosphere, the texture of the soil, and all the little 

 amenities and comforts which plants so much enjoy, are just the factors 

 which make his plants successful ; and a good crop of anything, whether 

 wheat or beans or apples, is simply a variation. 



And do these unlikenesses survive? Yes, verily! The greater part 

 of the amelioration of cultivated plants has come about in just this 

 way — by gradual modifications in the conditions in which they are 

 grown, by means of which unlikenesses arise; and then by the selec- 

 tion of seeds from the most coveted plants. Even at the present day 

 there is comparativaly little plant breeding. The cultivated flora has 

 come up with man, and if it has departed immensely from its wild pro- 

 totypes, so has man. The greater part of all this has been unconscious 

 and unintended on man's part, but it is none the less real. 



As an illustration of how large the factors of undesigned choice and 

 selection are in the amelioration of the domestic flora, let me ask your 

 attention to the battle of the seed bags. In the year 1890 the census 

 records show for the first time the number of acres in the United States 

 devoted to the growing of seed. I give the acreage of three repre- 

 sentative crops, and these figures I have multiplied by the average 

 seed yields per acre in order to arrive at an approximate estimate of 

 the eiitire crop produced and the number of acres which the crop 

 would plant. I have used low averages of yields in order to be on the 

 safe side, and I have likewise used liberal averages of the quantity of 

 seed required to plant an acre when making up the last column : 



