ASPECTS OF KINETIC EVOLUTION 27 1 



complete sterility, as in the familiar instance of the mule. 1 

 Many similar instances were observed in Guatemala. Coffee 

 plantations which, owing to unfavorable conditions, were dead 

 or dying, often showed occasional mutations which remained 

 healthy and luxuriant. Through some strange internal differ- 

 ence they were able to carry on their vital functions with con- 

 spicuous success while all their normal neighbors had completely 

 failed. If coffee were grown for the leaves like tea or for other 

 vegetative parts, these mutations would furnish new types of 

 great economic value, but of thousands of such variants which 

 have come under the observation of planters not one has proved 

 to be equal in fertility or normal seed production to the parent 

 type, under favorable conditions. 



PREPOTENCY OF NEW VARIATIONS. 



If only a small proportion of the progeny showed the new 

 character it might still gain a footing in the species, especially 

 if favored by selection. Those who have relied on the mathe- 

 matical doctrine of chance have felt it necessary to claim gen- 

 erous assistance from the principle of selection. Experiments 

 with new variations seem all to agree, however, that among 

 their own relatives, or under equal conditions of symbasis, they 

 have not merely an equal chance of reproducing themselves, 

 but that probabilities are distinctly in their favor. The variation 

 is not resisted but welcomed. The majority does not set the 

 fashion ; it is the few who are able to make pleasing modifica- 

 tions of style. The new pattern may not be better or more 

 beautiful than the old, but change is pleasing in itself and may 

 secure a wide vogue for an ugly or uncomfortable garment. 

 With organisms as with clothes the essence of beauty is fitness, 

 as Socrates long ago pointed out. The changes which make a 

 permanent contribution to evolutionary progress are those which 

 fit best into the existing structure and increase its fitness to its 

 surroundings. Our admiration for changes and likewise for 

 fitness in nature and in art, may be an intellectual reflection 

 of the evolutionary properties of organisms. 



1 Cook, O. F., 1904. The Vegetative Vigor of Hybrids and Mutations. Proc. 

 of Biological Society of Washington, 17: 83. 



