FACTORS AFFECTING SEASONAL ACTIVITIES. 19 



about with comparative rapidity in five years. On the other 

 hand, Lysimachia tcrrestris has been transferred from a terres- 

 trial habitat to an aquatic, with similar sweeping changes by way 

 of accommodation in even a briefer period. 



So important are the possible results in this phase of experi- 

 mentation held to be that the Department of Botanical Research 

 of the Carnegie Institution of Washington has established plan- 

 tations, under permits from the management of the National 

 Forest, at 8,000 feet, in a moist alpine climate, and at 6,000 feet 

 in an arid situation in the Santa Catalina Mountains, in connec- 

 tion with a small experimental farm, at 2,200 feet in the alluvial 

 irrigated soil of the Santa Cruz Valley near Tucson. Without 

 going into detail at this time it may be stated in general that the 

 experimental work carried on at these plantations involves an in- 

 terchange of plants among the three stations, and also introduc- 

 tions from various locations in different parts of the world. In 

 the two seasons that have elapsed since organized, ample reward 

 has been obtained for the effort expended. 



The methods and the results discussed above refer wholly 

 to adaptive or responsive changes made by the bodies of plants 

 subjected to any given environment, and forming accommoda- 

 tions to it. These alterations are of the greatest importance in 

 the extension of the range of any plant, and by a study of them 

 the accommodation response may excite the plant to increase the 

 very feature of its structure of economic importance, and sup- 

 press those useless or harmful in its application to our needs. 



Still a last possibility is to be taken into account in the 

 great changes to which plants are subjected in acclimatization 

 work. I have recently demonstrated that external agencies may 

 be made to act upon the germ cells of plants in such manner that 

 changes take place which are expressed in the progeny, and are 

 heritable from generation to generation, constituting in fact the 

 origin of new forms having the standing of species. The experi- 

 mental methods used are fairly simulated by natural forces 

 Likewise Dr. Tower has been able to induce similar changes in 

 the germ cells of beetles by the application of such stimuli 

 as variations in temperature and moisture. It is to be said, 

 therefore, that in taking plants from their native habitats to the 



