206 



SCIENCE. 



[N. S. Vol. XVII. No. 423. 



been made. Without attempting to re- 

 view and estimate this, let us glance at 

 some of the landmarks. 



We owe to Warming, more than to any 

 other, the conception now familiar to us 

 under the name of plant society, which in 

 Warming 's conception included not merely 

 a collection of plants living together, but, 

 what the name expresses, an association of 

 plants with mutual relations among them- 

 selves and common adaptations to their 

 environment. The most conspicuous and 

 useful result of Warming's work was to 

 show so convincingly the predominant in- 

 fluence of water in determining plant so- 

 cieties that his classification, based on this 

 as the chief factor, has been universally 

 adopted, though, as he well knew, so simple 

 a grouping could not serve as a permanent 

 and complete system, however helpful it 

 may have been in the early development 

 of the subject. 



Later the great work of Schimper 

 brought us face to face with the tre- 

 mendous difficulties to be met and over- 

 come in attempting to account for some 

 of the most familiar facts of distribution, 

 but it has greatly broadened our concep- 

 tion of plant relations, presenting with 

 almost the force of a new idea the fact 

 that every plant on the surface of the 

 globe grows where it does because condi- 

 tions of air, light, temperature, water, soil 

 and the behavior of other plants and ani- 

 mals—not merely in present time, but 

 through an indefinite past, acting not alone 

 but together, not on a lifeless thing, like 

 clay in the hands of a potter, but on liv- 

 ing, changing, adaptive beings— have made 

 its presence possible. It is to such a com- 

 plicated study and to problems so appar- 

 ently hopeless of complete solution that 

 the student of ecology to-day addresses 

 himself, and it is well, perhaps, that here 

 as in other departments of human activity, 



there are some daring souls who, for the 

 very joy of treading new ground, do the 

 work of the pioneer, without too close cal- 

 culation of the probable reward. 



If a personal reference may be per- 

 mitted, I am glad to acknowledge my own 

 great indebtedness to such pioneer work 

 on the part of one of our own botanists. 

 The study of the distribution of plants 

 along shore at Lake of the Woods,* which 

 appeared in 1897, has more than realized 

 the hope of the writer that it 'might be 

 of service in stimulating eeologic study of 

 plants. ' It could never have been written 

 in the closet or the laboratory, however 

 much of such labor is still required to 

 verify or supplement the remarkable ac- 

 cumulation of observation and suggestion 

 there recorded. The author has shown the 

 practicability of tracing, here with reason- 

 able certainty, there less perfectly, among 

 most complicated relations, cause and ef- 

 fect. 



If it is said that these results are too 

 indefinite to be of scientific value, it may 

 be answered that it is upon precisely such 

 data that for many scores of years the 

 practical operations of forestry have been 

 conducted, and that on this distinctively 

 •ecological basis it has become one of the 

 most exact industries of the age, standing 

 perhaps next to life insurance in the cer- 

 tainty with which given results are at- 

 tained. It is true that individual judg- 

 ment is here an important factor, and 

 allowance must be made for the personal 

 equation, but this is also true in astron- 

 omy, one of the most exact sciences, and 

 in perhaps every other department of hu- 

 man activity that is worth considering. 



A still later large and increasing litera- 

 ture,' represented by the monographs of 

 Engler and Drude's 'Vegetation der Erde' 

 and many other recent contributions of 



* MaeMillan, Minnesota Botanical Studies, L. 



