10 BURTON EDWARD LIVINGSTON 



the fact that we know our conditions much better when we make 

 them than we possibly can when we let nature furnish them to 



us. 



The study of plants in the field requires quantitative knowl- 

 edge of natural conditions, however, with all their great com- 

 plexity, and methods for measuring these are being developed 

 with considerable rapidity. This is the study that I have else- 

 where termed physiological ecology, — physiological, because it 

 regards the plant as a complex of processes controlled by physi- 

 cal and chemical conditions; ecology, because its aim is to inter- 

 pret the phenomena of plant life in nature and with reference 

 to natural conditions. 



These two aspects of plant physiology must go on developing 

 side by side. Ecology requires that natural plant phenomena 

 be interpreted in an etiological way, and physiology itself re- 

 quires that we should appreciate the fundamental principles of 

 plant dynamics. A parallel may be found in the relation between 

 mining and the chemistry of minerals, wherein very precise 

 laboratory studies (with extremely artificial conditions) are 

 just as important as the work of the prospector in the field. 



For the further advance of physiology, better methods for 

 producing controlled conditions are perhaps the greatest de- 

 sideratum at the present time, and if a student has not a liking 

 and a talent for creating physical and chemical conditions such 

 as never have occurred in nature, he should not cast his lot with 

 plant physiology, for the next generation. 



Need of facilities for artificial control of conditions. I cannot 

 forbear to dwell a moment longer on the need of controlled con- 

 ditions in physiological work. Having laid aside the older idea 

 that there is something everlastingly right in natural conditions 

 and something almost akin to blasphemy in the employment of 

 artificial ones, the physiologist comes to the same view-point 

 as that held by the modern chemist or physicist, and he employs 

 whatever conditions seem best for the enquiry in hand. Where 

 would the chemist be if he were constrained to study his salts 

 always as they occur in nature? If it is undesirable to study 

 plants growing in quartz sand, is it not just as undesirable to 



