34§ 
The Ohio Naturalist. 
[Vol. VIII, No. 7, 
considerable interest as showing that by the use of the quanti¬ 
tative method we are passing to an equally definite and exact 
determination of the importance of environmental conditions. 
The points brought out in this communication may be sum¬ 
marized thus: 
(1) The data above presented show clearly that a biomet¬ 
ric record of secondary growth in trees furnishes a very valuable 
criterion for the comparison of the conditions of different plant 
habitats. They are data involving climatic and edaphic factors 
which are of the greatest importance to plant life, and hence 
may be best correlated with functional and structural changes. 
(2) The response to environment in the case of Acer rubrum 
is rapid and pronounced. The annual growth of wood auto¬ 
matically records in duration, intensity and quality the effect 
of the “various ecological factors working in concert” (3). 
The differences in amount and size of wood cells, in thickness 
of walls, extent of infiltration, etc., clearly indicates differences 
in type. 
(3) In a study such as this the biometric data seem more 
valuable than long records of temperature, light, humidity, 
wind velocity, and others. The effect of these is included as 
far as they influence the plant. Greatly varying as meteorolo¬ 
gical and soil data are, it is indeed almost impossible to combine 
them so as to exhibit their united action to climatic and edaphic 
centers of development. Hence the biometric point of view is 
an additional criterion to furnish a suitable basis for comparing 
ecological data, and for determining the relation of a locality 
to the whole range of the species, and to the direction of its mi¬ 
gration (1). It seems certain, therefore, that if such statis¬ 
tical data were exhibited for various regions, climatic and edaphic 
centers of distribution could be clearly indicated (9). It is 
hoped that investigators in other places will make studies sim¬ 
ilar to the one here presented for the purpose of testing the value 
of this criterion. 
(4) It is well known that the ability of plants to transmit 
acquired characteristics is readily demonstrated in forest trees, 
where climatic influences continue to show themselves with 
plants grown from seed derived from different localities. It 
becomes a problem of practical as well as theoretical import¬ 
ance to determine to what extent such distributions in functional 
variations persist. The advantage of the biometric method 
to know definitely the behavior of plants and the effect of en¬ 
vironment is apparent. Whether or not individuals which 
have proven to be more variable would be favorable to any 
selection process remains to be seen from experimental deter¬ 
minations. 
Botanical Laboratory, O. S. U. March, 1908. 
