January 24, 1919] 



SCIENCE 



83 



essary drain upon the family purse. Thus 

 the accumulations of years come, sooner or 

 later, into use. So it is with science. In 

 these last years of unusual and great stress, 

 tlie knowledge of woods has brought about the 

 utilization, with the minimum loss of time, of 

 spruce, black walnut and other materials in 

 the manufacture of airplane parts. 



No one should be so unimaginative as to 

 wish to check curiosit.v merely because one 

 may not see now what ixjssible use there 

 may be of the fruits of curiosity. Scientific 

 curiosity should have the heartiest support 

 and encouragement. There should be no 

 neglect of '" pure science " merely because 

 the world is hungry; but because the world 

 is hungry, can not we botanists take ac- 

 count of stock and make some estimate of 

 what parts of our field of study are likely to 

 help most to relieve the present need? As a 

 plant physiologist some parts of my subject 

 seem to me to have more immediate prospects 

 of usefulness than others, and to deserve for 

 this reason more study. I can conceive, for 

 example, no reason, scientific or other, for at- 

 tempting to carry the study of geotropic phe- 

 nomena any further until the chemist has 

 thro^TO more light \}pon the contents and the 

 changes within the cell. But that one should 

 conclude that all study of irritability should 

 stop is absurd. We may, perhaps, well con- 

 clude that further study of the directive 

 effects of light may cease for a time, for we 

 know pretty well about the movements, the 

 bendings, of motile and sessile organisms to- 

 ward or from sources of light: but how much 

 do we actuall.v know about the effects of light 

 upon that chain of processes which ends in 

 the production of fruit and seed? The ob- 

 servations of Delpino, the experiments of 

 Vochting and Tvlebs, the experience of agri- 

 culturalists and horticulturists in the sunlit 

 arid regions of our western country and in 

 the greenhouse, all point to light as the most 

 effective stimulus to reproduction in plants 

 that we know. Would there be any unworth- 

 iness in the student of plant physiology who 

 is interested in the phenomena of irritability 

 choosing to work on the influence of light 



rather than on the directive influence of 

 gravity? 



The most important chemical reaction in 

 all nature, from the standpoint of man and 

 other living things at least, is that which re- 

 sults in the combination of carbon dioxide and 

 water into sugar. The botanist has been fond 

 of saying that plants stand between the ani- 

 mal kingdom and starvation ; but what has 

 he done about it? I do not ignore the in- 

 valuable studies of plant nutrition which have 

 been carried on and are now in progress; but 

 too many. of us have given little tliought to 

 the problems involved in that reaction of 

 which the botanist is peculiarly the custodian. 

 Need the world have been as hungry to-day as 

 millions of its inhabitants are, if we botanists 

 had reflected as much upon the processes of 

 nutrition in plants as we have, for example, 

 upon the possible or probable course of evolu- 

 tion? Do we realize that, while water can 

 only be moved, it can not be made, food can 

 be made, and made so near to the points of 

 maximum consmnption, that the problems of 

 transport can be very greatly reduced, if the 

 kinds of food and the methods of culture are 

 more accurately adjusted to the demand? 

 This is not merely a problem for the econ- 

 omist; it is a pi'oblem of first rate importance 

 for the botanist. 



My allusion to the doctrine and the studies 

 of evolution must not be misunderstood; for 

 no one acknowledges more frankly the enor- 

 mous benefits, material as well as intellectual, 

 which have flowed from the emancipation of 

 the race from the bonds which held it for 

 generations, however deplorable the results of 

 a misguided application of one of Darwin's 

 doctrines may have been in the last four years. 

 But whatever the course of evolution may 

 have been, we know that it is possible, be- 

 cause plants are plastic under cultivation, to 

 breed strains which will withstand, for a 

 time at least, conditions and enemies which 

 others can not endure. Acquired characters 

 may or may not be heritable; but conditions 

 may be so modified that, in the new complex, 

 a new and endurable balance is established. 



