58 The Plant World. 



while in others, distinctly new features are induced. The new 

 character may be fixed and permanent from the beginning" or 

 may be built up by the repeated action of the exciting agency. 



These generalizations are far in advance of any that might 

 have been made five years ago, and the entire subject is attract- 

 ing the attention and energy of experimentalists all over the 

 world. The plan for work upon the problems in connection 

 with the Department of Botanical Research of the Carnegie 

 Institution of Washington, implies the establishment of experi- 

 mental cultures in localities which furnish distinct types of 

 climate, or which have characteristic congeries of meteoric 

 factors, as indicated by the vegetation indigenous to them. 

 Secondly, these localities have been chosen with regard to their 

 geographical relations so far as possible, in order that the possible 

 and probable fate of migrating species might be studied. The 

 behavior of plants in these localities is recorded as to anatomical 

 alteration and physiological departure. Having detected some 

 such features of apparent importance, its reappearance in plants 

 from seeds carried to the original habitat and other locations 

 is followed as one line of evaluation. Contemporaneously, the 

 form is taken into the laboratory and here by analytical experi- 

 mental tests the effort is made to ascertain to what special 

 agencies the departures are due. 



Four main locations representing habitats from mountain 

 tops to seashore, have been established in connection with the 

 Desert Laboratory in accordance with this idea, and in addition 

 to the interchange of species from the various localities a number 

 of introductions have been made from eastern America. The 

 results already secured offer much of interest and suggest possi- 

 bilities of great importance. 



Our increased insight into the nature of natural groups of 

 organisms has shown the necessity and suggested the means of 

 observing certain distinctions and precautions in this work. 

 Thus, it is of the greatest importance that the living material 

 shall be shown to be either simple genotypes or that its phaeno- 

 typic nature be apprehended in order that the integration and 

 combination of these forms shall not be mistaken for environic 

 effects. When a lot of plants is taken from one plantation to 

 another, data of the original locality are preserved, as the stand 

 of the plant in that place serves as the control. If the plant is 



