6 



SCIENCE 



[N. S. Vol. XXXVII. No. 940 



giving first place to physiology, probably 

 because of its ready appeal to our senses. 

 It is easy to interest a boy in the thing that 

 responds, whether it be a kicking frog 

 stimulated by an electrical discharge, or a 

 green plant whose stimulation is a properly 

 directed beam of sunlight. And yet it is 

 well for us to remember that the plant is 

 first of all a structure, whose complexity 

 may well challenge the most acute minds. 

 We find it far easier to record the responses 

 of plants to our planned stimuli than to 

 unravel a structural complex, and so no 

 doubt we shall continue to entertain our- 

 selves and our students with what are too 

 often futile experiments. 



In this part of the botanical field are 

 pathology, which grew up from our ob- 

 servation that organs may not respond nor- 

 mally; ecology, which developed from the 

 observation that plants tend to live in com- 

 munities; and phytogeography, having to 

 do with the means for and the results of 

 distribution. Thex'e are signs that for 

 economic reasons pathology may become 

 rather sharply set off from physiology, of 

 which it is properly a part, much as 

 through the zeal and enthusiasm of the 

 ecologists there was once the suggestion of 

 a physiological schism. The latter is hap- 

 pily no longer imminent, and it may be 

 hoped that it will not again threaten the 

 unity of plant physiology. And so it may 

 be hoped that the pathologists will not 

 wholly secede from association with the 

 phj^siologists. 



Taxonomy, or as we used to call it, classi- 

 fication, occupying the third division of the 

 field of botany, long received the almost 

 exclusive attention of botanists. And even 

 to-day it is the pretty general opinion of 

 our non-botanical friends that we are con- 

 stantly employed in collecting specimens, 

 and in some intricate and mysterious way 

 determining their classification and affix- 



ing to them their proper Latin names. 

 And it must be admitted that every bot- 

 anist does a good deal of just such work, 

 quite as every chemist makes many an- 

 alyses, and tries to arrange in orderly 

 sequence the chemical substances which he 

 has in his cabinet, and the astronomer 

 classifies and names the heavenly bodies 

 with which his science deals. . At first even 

 the botanists knew but few plants, just as 

 now most men know scarcely more than a 

 score. But as the botanists came to know 

 a larger number of plants, it was impera- 

 tive that they should be named, and then 

 grouped conveniently for easier reference. 

 Thus arose such crude, primitive classes as 

 herbs, shrubs and trees, which served their 

 purpose until the numbers became too 

 great again, when additional structural 

 differences were brought in to help sepa- 

 rate the large numbers into smaller groups. 

 This was the earlier classification, based 

 upon structure alone. It was taxonomy 

 without doubt, and it was helpful, since it 

 enabled us to arrange plants in an orderly 

 fashion, but it ignored the fact that plants 

 have ancestors, and that the plants of to- • 

 day are what they are through their in- 

 heritance of ancestral characters, accom- 

 panied by modifications peculiar to them 

 alone. AVhen, however, the doctrine of 

 evolution came into botany it brought with 

 it the idea of descent, and thereafter tax- 

 onomy included phylogeny. To-day the 

 taxonomist is no longer content to stop 

 with a knowledge of the structural differ- 

 ences between plants; he must know how 

 this structure arose from that; he must 

 know which is the primitive structure and 

 which the derived. Phylogeny has so far 

 entered into taxonomy that it has given 

 new meaning to the work of the systematic 

 botanist, and it is bringing into this de- 

 partment of the science something of the 

 philosophical aspect which was nearly 



