3i6 BOTANICAL GAZETTE [November 



reduces both vegetation and reproduction. Kraus and Kraybill 

 cite literature showing that various conditions that greatly retard 

 growth produce high carbohydrate plants. It seems that such con- 

 ditions retard the use of carbohydrates for building new tissue to a 

 greater degree than they do photosynthesis, and thereby lead to an 

 accumulation of carbohydrates. 



Hedlund (9) finds that under like cultural conditions those 

 varieties of winter wheat that have a higher percentage dry weight 

 in the autumn are generally more winter hardy than the ones having 

 a low percentage dry weight, and that cultural conditions that make 

 for high percentage dry weight in any variety also make for winter 

 hardiness. He finds, as do Kraus and Kraybill, that high per- 

 centage dry weight is due to high percentage carbohydrate, and 



. . ... carbohydrate 

 therefore high rv— 



Ribera (16) finds that all cultural conditions that increase the 



percentage dry weight in wheat decrease lodging. From this and 



the two investigations previously mentioned it is evident that 



, . . carbohvdrate . , , , , . 



high - „ - increases straw strength and decreases lodging. 



High percentage of carbohydrate is said to increase hardiness, at 

 least in part, by the greater amount of glucose present, and it 

 may increase straw strength by inducing greater development of 

 mechanical tissue along with greater thickness of walls, as Kraus 

 and Kraybill found for certain tissues of the tomato. 



Methods and results 



GREEN PLANT AT VARIOUS STAGES OF DEVELOPMENT 



Preparation of samples. — Samples were secured on June 3, 

 June 20, and July 8 consecutively from a vacant lot on 59th Street 

 and Ingleside Avenue, Chicago. On June 20 samples were taken 

 from two places, namely, the manure pile (rich soil) and the knoll 

 (poor soil) for comparative work. The soil particles adhering to 

 the roots and rootlets were removed by running water from a 

 filter pump. As the velocity of water was very great, the soil 

 particles were removed without difficulty. The roots were par- 

 tially dried by the air current from the laboratory air line, and 



