RESEARCHES ON THE PHYSICO-CHEMICAL PROP- 

 ERTIES OF VEGETABLE SAPS 



2. Note on a comparison of the physico-chemical constants 

 of the Juice of apples and pears of varying size and fertility^ 



J. ARTHUR HARRIS and ROSS AIKEN GORTNER 

 (Station for Experimental Evolution, The Carnegie Institution of Washington) 



(WITH PLATE 2) 



Introduction. The problem of the relationship betweeii pollina- 

 tion and the development of the ovary has been treated by various 

 botanists, Ewart, Fitting, Müller-Thurgau, Moll, Solacolu, Treub, 

 and by one of us. 



That there is a distinct correlation between the number. of seeds 

 and the size of the fruit in which they are produced, and that this 

 interdependence is independent of the correlation between the num- 

 ber of ovules formed and the size of the fruit, and that it is prob- 

 ably not due to both the ovules and the fruit having been exposed to 

 like nutritional conditions was, we believe, first demonstrated by 

 one of us.^ 



The nature of this relationship, which is probably a more or less 

 direct causal one with fertility as the independent and size attained 

 by the fruit as the dependent variable, is quite unknown. Naturally 

 the Suggestion arises that it is of the nature of a hormone. Cer- 

 tainly the most promising lines of research in the attempt to ex- 

 plain such correlations as those demonstrated between fertility (seed 

 production) and the size of the fruit in C er eis and Staphylea would 

 seem to lie in the direction of determining whether fruits which 

 differ in fertility also differ in chemical composition. A priori it 

 might seem possible that the mechanism by which variations in size 



1 For the first paper in this series see Bull. Torrey Bot. Club, 40, 27-34; I9I3- 



2 Harris, J. Arthur: Bot. Gas., 50, 1 17-127; 1910. Ibid., 53, 204-218, 396-414; 

 1912. 



196 ■ 



