ASPECTS OF KINETIC EVOLUTION 265 



progress toward fertility and seed-production than in the much 

 longer growing season of Texas. These experiments afford a 

 definite intimation, to say the least, that by the proper choice of 

 conditions for the first planting the neotopic stimulation of trop- 

 ical varieties can be held sufficiently in check to permit the ma- 

 turing of at least small amounts of seed. This opens the way 

 to the practical acclimatization in the United States of useful 

 varieties of cotton, corn and other important food-plants of 

 tropical origin. 



Further experiments have shown that the second generation 

 of cotton in the United States is notably earlier and more 

 productive than the first generation, when grown from seed 

 of the same origin and planted in adjacent rows. It has also 

 become evident that there are at least three stages or kinds of 

 new place effects to be considered in the acclimatization of 

 different varieties and types of cotton. The changes of hered- 

 itary behavior which can be induced by the transfer to new 

 conditions are not limited merely to increased size or vigor, but 

 have obvious bearing upon the phenomena of mutation, since 

 the plants may change in a very definite manner in characters 

 which would usually be considered of varietal or even of specific 

 importance. The lack of fertility which accompanies the aber- 

 ration from normal characters affords a further analogy with 

 mutations. Nor does the interest of the experiment end here, 

 for it has been proved that this neotopic form of mutation 

 may supervene in a perfectly definite manner even after the 

 plants have grown for a time according to the specifications of 

 normal form and habits of the variety. 



When the change takes place early the whole plant may show 

 the abnormal characters and may be more or less completely 

 sterile. In another locality plants of the same origin may grow 

 for a time in a normal manner and remain normally productive, 

 but may then change suddenly and completely to the abnormal, 

 infertile, neotopic condition. In this form of neotopism the 

 behavior of the individual plants grown from the same lot of 

 imported seed is often remarkably uniform and the result is 

 closely parallel to that described a few years ago by Dr. C. A. 

 White in tomatoes. Two lots of seed produced, with much 



