THE president's ADDRESS. 31 



was the accumulation of data bearing upon the problems of in- 

 heritance and the origin of species, probably to be regarded as 

 the most important and most difficult of the biological problems. 

 From the formulation of Mendel's law, to its resurrection in con- 

 nection with DeVries' mutation theory, a decade ago, and on to 

 the present day, the work of scientific plant-breeding has in- 

 creased in intensity. It would be bewildering even to outline the 

 results, and to do so would not aid the purpose of this address 

 in any material way. 



The general result is what might have been expected. We have 

 been plunged into such a maze of facts bearing upon inheritance 

 and the origin of new forms, that the non-partisan is at a loss 

 what to believe. Many of the investigators are so competent that 

 we cannot doubt their data ; it is only when they begin to inter- 

 pret them that we grow cautious. In such a situation, the judi- 

 cial equipoise can be maintained by several considerations. Such 

 vast and difficult problems as inheritance and the origin of new 

 forms can be solved only by an amount of experimental work 

 that makes the work accomplished seem almost as nothing. It is 

 natural, therefore, that the few points of attack should reveal 

 confusing results. It is also natural for each investigator to 

 extend his own interpretation far beyond the facts upon which it 

 is based. All the facts cited may be true, and all the inferences, 

 when restricted to their facts, may be true also; but the time is 

 yet far distant when we can weave them all together, and many 

 more besides, into a common web, and get some adequate impres- 

 sion of the scheme as a whole. And still, the game is worth all 

 the effort, and those of us who are merely spectators must cheer 

 on the combatants, even to the point of seeming to be partisans. 



Out of the maze of data and interpretations, however, certain 

 conceptions are assuming a more definite form. The most sig- 

 nificant of these may be stated briefly. The advocates of Mende- 

 lism seem to have explained away the majority of cases, among 

 plants at least, that appeared to be contradictory, and in so doing 

 have brought out with much more definiteness that elusive con- 

 ception called the "unit-character." It is much more evident now 

 than it was a few years ago that the phrase "unit-character" 

 really stands for something that can be manipulated. It is a situ- 

 ation that needs much fuller analysis than it has received, espe- 

 cially from the standpoint of physiological chemistry; and in all 

 probability it must be defined presently in terms of chemistry 

 rather than in terms of external morpholog)'. 



