105 



anything under appropriate conditions, and is not destined to be some 

 particular structure. 



One of tlic most interesting recent results of experimental morphology 

 lias been thai obtained in experimental work on heterospory. It has been 

 shown that it is possible to develop megaspores from cells that ordinarily 

 develop microspores. It is such results that are playing fast and loose 

 with our old conceptions of rigidity of structure and function. 



I can merely mention the field of plant physiology. If I speak of the 

 changes that have taken place within the last twenty-five years, I must 

 show the atmosphere in which we are living by assuring you that I am 

 not the one to make such a presentation. In the old days one man taught 

 all there was of botany, and probably he taught all there was of science. 

 Today I have been compelled to ask a competent plant physiologist con- 

 cerning the notable changes. He tells me that tbere are two conspicuous 

 changes in the point of view. One is the gradual passing of the old vital- 

 istic idea, which implied that there was some such thing as vital force that 

 explained most things. Now the facts are explained, not in terms of vital 

 force, but in terms of chemistry and physics. Another shifting point of 

 view is a change from the old idea that form and structure are the result 

 of some mysterious law of development, to the idea that form and struc- 

 ture are entirely expressions of the conditions under which growth has 

 been conducted. 



The very new field of ecology at present is in the condition of these 

 other fields more than a decade ago. Young fields are largely jokes to the 

 older ones ; but there has been a change in ecology during the last few 

 years. It has passed from the stage of inchoate observation, in which in- 

 struction in ecology could not be differentiated with distinctness from a 

 holiday excursion, to methods of precision. 



In conclusion, as one looks out over this great progress, he finds that 

 it is all really an inevitable evolution from the stimulus that was given 

 first by Hofmeister in 1898 to morphology, and ten years later by Charles 

 Darwin to biology in general. 



University of Chicago, 

 Chicago. 111. 



