350 BOTANICAL GAZETTE [NOVEMBER 
characteristics of the areas occupied by the respective associations, 
it will first be necessary to devise methods, and frequently instru- 
ments also, by which the climatic conditions of any given area may 
be so integrated as to bring out their relations to the processes of 
growth and reproduction in organisms. In the beginning, such 
methods will usually need to deal with single conditions or factors 
as they influence physiological phenomena, but biological science 
must eventually appreciate that single conditions, or any group of 
conditions comprising less than all the effective ones, cannot be 
considered as determining natural processes. Complexes of envi- 
ronmental factors must needs be analyzed into simpler ones, 
for purposes of study, but after knowledge of the effectiveness of 
each has been experimentally obtained (through maintaining all 
conditions other than the one in question not only constant but at 
a known and stated value or intensity), they must then be recom- 
bined and their effects integrated before real knowledge may be 
available. : 
If a plant thrives in a given locality, so as to form a part of the 
flora of that locality, it is obvious that there have not occurred here, 
since the arrival of its ancestors, any environmental conditions 
incompatible with its existence. In this we merely make the 
biological observation that the organism is and has been adapted’ 
to the environment in which we find it, and that the environment 
is and has been adapted to the organism. Thus, when the range 
or geographical extent of an organism or association has been 
determined, it is clear that the area or areas so circumscribed have 
been characterized for some time in the immediate past by con- 
ditions none of which have been adverse enough to annihilate the 
forms dealt with. Outside of these areas the conditions have not 
been such as to bring about the permanently successful entrance of 
these forms, up to the present time. It is of course clear that 
entrance may have been accomplished here, but if this has been the 
case each such entrance must have been followed by the occurrence 
of annihilating conditions. 
7 On a somewhat matter-of- fact view of biological adaptation, see the. olin 
per: Livincston, B. E., Adaptation in the living and non-living. Amer. 
47: 72-82. 1913. . See also Henprnson, L. J., The fitness of the environment. 
York 1913. 
New 

