ELEVENTH LECTURE. 



THE TRANSFORMATION OF SPOROPHYLLARY 

 TO VEGETATIVE ORGANS. 1 



PROF. GEORGE F. ATKINSON. 



(CORNELL UNIVERSITY, ITHACA, N.Y.) 



THE general effect of nutrition in plants is evident in their 

 growth and fruiting ; but the more subtle influences, under a 

 great variety of changing or special conditions, are but imper- 

 fectly understood. In general, an increase in food supply 

 within the plant, external conditions being favorable, increases 

 the entire plant product. In poor soil plants may be fed with 

 profit, the product increasing, though not in the same ratio, 

 with the increased supply of food. Not only is the vegetative 

 part of the plant increased, but the fruit also, within certain 

 limits. The ratio of increase, however, between the vegetative 

 portion of the plant and its fruit is not constant, but changes 

 with the varying food supply. After a given point the vegeta- 

 tive portion increases more rapidly than the fruit. Another 

 striking influence of increased food supply is that a point is 

 reached soon where the fruit portion decreases, or is even com- 

 pletely suppressed, while the vegetative portion still increases. 

 Our knowledge of these disproportionate and antagonistic 

 relationships between the vegetative and reproductive portions 

 of the plant is largely empirical, though some of it is based on 

 direct experimentation. It is not surprising, therefore, that 

 even among botanists there should be differences of opinion 

 concerning the fundamental laws governing these relationships. 



The genus Onoclea, as well as some others, presents an 

 interesting dimorphism of the leaves, some of the leaves being 



1 See Plates I-VIII at close of volume. 



