No. 511] PRESENT PROBLEMS IN PLANT ECOLOGY 431 



In trying to unravel the problems of mountain vegeta- 

 tion, it must never be forgotten that the plants of the 

 present are descended from preexisting ones; facts of 

 heredity are everywhere; phenomena that are found to- 

 day not seldom hark back to conditions of the past. 



In concluding, allow me to offer a plea for a service, 

 which I have been thinking for several years would he 

 one of the most helpful which could be rendered to this 

 adolescent science of ecology, namely, that some one 

 whose knowledge of physics and physiology fits him for 

 such a task should overhaul and scrutinize our ideas and 

 methods. Not counting minor and ephemeral papers, 

 there can be no question that ecology, at the present time, 

 contains not a little of discernible error. Rumors have 

 been heard that zoologists are beginning to study ecol- 

 ogy and looking to botanical methods for hints for de- 

 veloping their own. Within the family, it may be said 

 that if wide-awake guests are coming, it is time to set 

 the house in order. Moreover, ecology is finding a large 

 place in elementary text-books, and in this way errors 

 are being propagated. The interest alike of science and 

 education in this field could in no way be better served 

 than by a relentless pruning. 



DISCUSSION OF PROFESSOE SHAW'S PAPER. 

 DR. LIVINGSTON: A remark was made by Professor Shaw in the be- 

 ginning of his paper, which suggests that we sometimes lose sight of physi- 

 cal facts. A certain plant is not killed or shut out by the fact that other 

 plants are near it, but by the fact that light conditions or moisture con- 



from those h/which they might live. It seems to me that to speak of 

 biotic and physical conditions leads to confusion; the thing the plant feels 

 must be a physical thing. 



PROFESSOR SHAW : In my remark I meant to clear up certain cases 

 where one might lose sight of the fact that plants had largely modified 

 physical conditions. I presume the very case which gave rise to that 



