208 



SCIENCE. 



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



leaeh a student to critically report in de- 

 cent English a direct observation in the 

 field, than to secure from him a tabulated 

 statement of artificially produced reac- 

 tions. 



And yet no true worker in science can 

 go on with his daily task of accumulating 

 data without at least attempting to answer 

 to himself the insistent question 'What 

 does it all mean?' We need and shall 

 always need the thoughtful and original 

 workers who give us not only 'facts well 

 proved,' but also 'conclusions * * * de- 

 duced from facts well proved,' and we 

 owe a debt even to those who have the in- 

 sight sufficient to offer fruitful suggestion. 



As a single example, may I refer to a 

 recent paper by Paul Jaccard * in which, 

 from a comparative statistical study of 

 plant distribution in alpine regions, in- 

 volving an enormous accumulation of data, 

 some most interesting conclusions are 

 drawn. It is shown that, while in the 

 region studied there is an almost mathe- 

 matical relation between number of spe- 

 cies and variety of ecological conditions, 

 the generic coefficient, or ratio of genera 

 to species, is inversely proportional to 

 such variety of conditions; that is to say, 

 in the struggle for existence between the 

 numerous species of a habitat, the species 

 of one and the same genus are in great 

 measure crowded out by species of differ- 

 ent genera. Thus it is shown, 'in the 

 course of a purely statistical study, that 

 the struggle for existence works toward 

 the elimination of like elements and selec- 

 tion of unlike, and that, furthermore, the 

 resultant of a number of external factors 

 operates as a selecting cause, not merely 

 on the single species, but on the grouping 

 of species, on the society.' In these 

 istudies then, the genus becomes 'a real 



* ' Gesetze der Pflanzenvertheilung in der 

 :alpmen Region,' 'Flora,' 90: 349-377, 1902. 



ecological unity with a definite intrinsic 

 value. ' 



Whether or not we accept the author's- 

 conclusions throughout, we are at aU 

 events indebted to him for an ecological 

 study- carried out with mathematical pre- 

 cision, from which some at least of the 

 conclusions have been drawn with mathe- 

 matical certainty. It is, to be sure, a 

 question how far, at present, quantitative 

 results can be looked for in this line of 

 work, but he is not the highest type of 

 scientific worker who demands to know at 

 every step what he shall have for his pains. 

 It is certain, I think, that by just such 

 studies as those of Jaccard we shall be able 

 through careful field work to designate 

 and make increasingly accurate estimates 

 of dominant factors. But many problems 

 must necessarily be taken to the labora- 

 tory, and it is to such a union of field and 

 laboratory work that we are to look for 

 the rational development of ecological in- 

 vestigation. Ecology standing alone would 

 present much the same anomaly as physi- 

 ology getting on without physics and 

 chemistry. But all things in their time. 

 When one of our foremost ecologists de- 

 clares that ecology must be brought more 

 and more to a physiological basis, he states 

 an obvious truth; it is also true, perhaps, 

 that physiology should take rank as speed- 

 ily as possible with the exact sciences and 

 record its conclusions more and more in 

 mathematical formulse. These great con- 

 summations, however, are likely to require 

 some little time, and meanwhile those of 

 us who have not yet learned always to 

 think in equations may, nevertheless, find 

 much to do. 



It is hardly necessary to call your at- 

 tention to the need of a settled nomen- 

 clature, nor to the fact that we are likely 

 to have a great deal more than we want 

 when we get it. To speak plainly, it 

 seems to the writer little short of scientific 



