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THE AMEBIC AN NATURALIST [Vol. XL V 



The groups of species interchanged among the four 

 different localities include material upon which such 

 analysis may be most readily made. In addition, the 

 introductions are also arranged to simulate certain geo- 

 graphical movements and topographical effects. Spe- 

 cies from eastern America and from the lower plantations 

 are taken to the montane and xero-montane plantations 

 to meet conditions similar to those they might encounter 

 in a migration toward alpine or arctic regions. Species 

 from the montane locations and from the eastern states 

 are carried to the desert plantations to have the expe- 

 rience of a southward movement, or that of descending 

 mountain valleys, while all of these localities have fur- 

 nished forms for establishment in the maritime locality 

 characterized by equable conditions in which species may 

 range widely as to latitude and indefinitely as to longitude. 

 The preliminary exchanges included over a hundred spe- 

 cies, mostly biennials and perennials ; the survivals amount 

 to less than 80, while perhaps not more than a score of 

 these may be expected to yield results of value or interest. 



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 phaenotypic 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 multiplied vegetatively in the test, it might reveal a 

 possible complex character of the material in bud-sports, 

 but other divergences might be well ascribed to local 

 effects. On the other hand, if introduced in the form of 

 seeds, the possible complex character of the material 

 would soon become apparent, especially if the generations 

 were followed properly. In the actual management of 



