336 BOTANICAL GAZETTE [May 
inspection of even a few experiments with these distinctions in mind 
is likely to convince anyone at all familiar with such observations, that 
the best functioning plants, rather than the general average, represent 
the proper test of the possibilities of the species under the given con- 
ditions. Adjustment to local conditions is in these cases a more 
striking phenomenon than acclimatization, and it is to be looked upon 
as quite apart from structural divergence. While conclusive experi- 
ments may not as yet be admissible, the data at hand make it highly 
probable that the resistant forms among the hydrophytes and meso- 
phytes in the mixed bog formations arise through gradual rather than 
sudden development, and that functional variation is the essential 
criterion. One of the results of introducing agricultural varieties into 
bog conditions is the comparative lack of uniformity in type, variants 
departing in both directions from the normal, and different varieties 
responding in different ways to the same conditions. Planting a 
species in a new place is in the nature of a test of the stability of its 
characters under the new conditions. Some changes result in a new 
place-function, but many of the changes of character that occur do 
not serve as responses, but result in wide individual differences and 
deterioration from loss or from disturbance of functional adjustments 
to previous established conditions. To inquire, therefore, into the 
nature of the adjustments of disturbed characters is to gain an indica- 
tion, not so much of the many forms that the plant is able to assume, 
as especially the possibilities of the restoration of a balanced expression 
of functions which thus allow the most advantageous changes again 
to be established. An adapted and resistant form, if segregated 
through continued selection, may thus prove the basis of valuable 
data in the study of plasticity-and fixity of organs or of type. It may 
prove doubtful whether the substratum solution is of a nature - 
bring out the greatest variation in form and in resistance. Expeti- 
ments will have to be performed on a larger number of plants of 
widely different relationship before definite conclusions can be 
reached. Much economic value would attach to an extension of these 
experiments by using a salt or a mixture of more than one salt to 
ascertain a physiologically balanced solution for other kinds of plants. 
As has been stated above, there is an indication that the toxicity of 
the habitat is not the same for all agricultural plants and forest trees, 
