BOTAXICAL RESEARCH — MACDOUGAI,. 121 



Godfrey Sykes in the spring- and summer, and Prof, and Mrs. A'. M. 

 Spalding- also beg-an some observations near the shore at Mecca, California, 

 early in October, at the maximum height of the water. 



INFLUENCE OF ALTITUDE AND CLIMATIC FACTORS UPON 

 VEGETATION: ACCLIMATIZATION. 



As a result of the activities of horticulturists and botanical gardens a large 

 number of species have been transferred from one country to another, and 

 some observations as to alterations in habit and form are recorded, resulting 

 from such removals. A few experimental tests have been made in the culti- 

 vation of species through a range of altitudes, and some of the morphological 

 changes induced have been described. It is known that the color, time of 

 bloom, habit, structure of the root and shoot, general aspect of plants, and 

 economic value may be greatly altered by cultures at various altitudes, but 

 no systematic tests have been made to determine to what factors in the 

 climates concerned these differences are due. The solution of the problems 

 involved would settle some of the most important problems in general 

 physiology, and would also go far in enabling us to account for the structure 

 and form of the species of which the vegetation of the earth is composed. 



It is by means of experimental observations of this kind that it also may be 

 hoped to obtain evidence as to the inheritance of acquired characters, a ques- 

 tion which has been a much vexed one for many years. No adequate tests 

 have yet been made to ascertain whether or not the marked changes induced 

 in plants by cultivations at higher or low^er altitudes than the normal are 

 fully transmissible to succeeding generations grown under other conditions. 



The practical problems of acclimatization offer some highly peculiar condi- 

 tions. Thus two separated localities may offer meteorological conditions 

 apparently similar, so far as ordinary methods of weather records show, yet 

 the exchange of plants between the two places will be attended with but 

 indifferent success, even when differences in composition of the soil are 

 accounted for. It seems unnecessary to point out that when the factors in 

 climate have been accurately analyzed as to their effect upon vegetation a 

 much more rational basis will be afforded for efforts at acclimatization. 



The entire plan for investigations in connection with the above entails the 

 establishment of small plantations, each embracing a fraction of an acre at 

 an elevation of 2,300 feet in the alluvial valley of the Santa Cruz River, at 

 the well-site of the Desert Laboratory, near Tucson; at the Laboratory, in 

 an arid situation, with a rainfall averaging 12 inches ; at Castle Rock, a spur 

 of the Santa Catalina Mountains, with a limited rainfall, upon which observa- 

 tions are being taken, and at an elevation of 8,000 feet, near the summit of 

 the Santa Catalina Mountains, in a locality where the rainfall is probably 

 greater than the possible evaporation. Steps are being taken to secure 

 thermometric data in all of the localities, and to otherwise ascertain the cli- 



