380 Missouri State Horticultural Society. 



rapid strides, and work toward a definite aim in the future, will de- 

 pend upon the extent to which the methods of science are applied 

 to the problem. When we can secure accurate, exact data, and 

 connect all oar observations with preceding facts, the time must 

 surely come when we shall be able to direct the forces of nature so 

 as to cause a production of fruits with definite qualities and for 

 definite purposes. The first eUort must be to determine Just where 

 we stand at present and what we- really know. No matter how 

 simple the question which is referred to us, as to the effect of hy- 

 bridization, the effect of selection, of cultivation, or of treatment, 

 we do not seem to have aught but impressions to offer in reply. 



For horticultural experiment it seems requisite to determine 

 numerically the effect of any procedure of ours by which we modify 

 or direct plant growth toward a certain direction. Thus, in 

 hybridization, what is the influence of variety ? What is the in- 

 fluence of species ? Does the female parent give form or quality, 

 or produce any other effect differing from that produced by the 

 influence of the male parentage ? What is the percentage of 

 variation in each experiment tried, and in what direction are the 

 variations ? What is the per cent, of variation as between the first, 

 second, or third generation after the original hybridization ? What 

 qualities are requisite in a fruit in order that it may become rot- 

 resisting, blight-resisting, or insect-resisting ? And so I might go 

 on almost indefinitely, for the field is a broad one. But I might 

 give my own view succinctly by stating that the future of horti- 

 cultural experiment depends largely upon the number of attempts 

 which are made Avith numerical data as their basis. The problem 

 of horticulture must be attacked from the mathematical side before 

 we can obtain that table of constants which shall be so essential 

 toward future advance. Very truly yours, 



E. Lewis Sturtevant. 



FREEZING OF SAP IN TREES. 



A correspondent inquires whether the sap freezes in winter in 

 trees or not. We have been so often over this topic before, that it 

 seems superfluous to go over again. But there are so many new 

 readers of the magazine, and so much interest evidenced in the 

 subject that it may do no harm to allude to it again. Experiments 

 have shown that instead of the branches of trees expanding in 

 winter time, as they would do if the sap froze, they actually con- 

 tract. If we break a twig in sharp freezing weather we find it 

 cracks " short off," just as it would when half dry in sum- 



