FACTORS OF ORGANIC EVOLUTION. 467 



finds its way into the market and is finally discarded. We will estimate 

 this element of waste as 20 per cent. Of the 80 per cent which is actually 

 sold, perhaps another 10 per cent is never planted, leaving about 70 

 per cent which finds its way into the ground. These two items of loss 

 are pure waste and have no elfect upon the resulting crop. JSTow, of 

 the seeds which are planted, not more than 75 per cent can be expected 

 to germinate; that is, there is certainly an average loss of 25 per cent 

 in nearly all seeds, and much more in some, due to inherent weakness, 

 and 75 per cent represents the survival in a conllict of strength. We 

 have now accounted for about half of the total seed product of any year. 

 The remaining half produces plants; but here the most important part 

 of the conflict begins. In the crops mentioned above much less than 

 half of the seeds which are grown ever appear in the form of a crop. 

 We must remember, moreover, that in making the estimate of the num- 

 ber of acres which these seeds would plant I have used the customary 

 estimates of the quantity of seeds required to plant an acre. Now, 

 these estimates of seedsmen and j)lanters are always very liberal. 

 Every farmer sows from five to twenty times more seeds than he needs. 

 Some years ago I sowed seeds according to the recommendation of one 

 of our best seedsmeu, and I found that pease would be obliged to stand 

 four-fifths of an inch apart, beets about twenty to the foot, and other 

 vegetables in like confusion. I suppose that of all the seeds which 

 actually come up not more than one in ten or a dozen, in garden vege- 

 tables, ever give mature plants. What becomes of the remainder? 

 They are thinned out for the good of those which are left. 



This simple process of thinning out vegetables has had a most power- 

 ful effect upon the evolution of our domestic flora. It is a process of 

 undesigned selection. This selection proceeds upon the differences in 

 the seedlings. The weak individuals are disposed of, and those which 

 are strongest and most unlike the general run are preserved. It is a 

 clear case of the survival of the unlike. The laborer who weeds and 

 thins your lettuce bed unconsciously blocks out his ideas in the plants 

 which he leaves. But all this is a struggle of Jew against Jew, not of 

 Jew against Philistine. It is a conflict within the species, not of species 

 against species. It therefore tends to destroy the solidarity of the 

 specific type and helps to introduce much of that promiscuous unlike- 

 ness which is the distinguishing characteristic of domestic plants. 



Let us now transfer this emphatic example to wild nature. There we 

 shall find the same prodigal production of seeds. In the place of the 

 gardener undesignedly molding the lines of divergence we find the 

 inexorable physical circumstances into which the plastic organisms 

 must grow, if they grow at all. These circumstances are very often the 

 direct causes of the unlikenesses of plants, for plants which start like 

 when they germinate may be very unlike when they die. Given time 

 and constantly but slowly changing conditions, and the vegetable 

 creation is fashioned into the unlikenesses which we now behold. With 



