16 Winter Wheat Varieticfi rnid Winter- Kill Inn 



imhardened tissues. But iu coiiiparin;:: liardcncd tissues of different 

 varieties, assuniinj; them to be of similar structure, the moisture content 

 is perliaps larfjely a function of the relative imbibitional powers of the 

 cell colloids and the defrrec of ])reviows exposure to modifyiui; environ- 

 mental factors, for example, desiccating agents such as winds and low 

 temperatures. It seems, therefore that both the magnitude and order 

 of the values in any particular series of samples may be affected bv the 

 weather conditions preceding the date of collection. 



The fundamental importance of resistance to withdrawal of water 

 does not, of course, exclude the possibility of an important relationship 

 between the character or .state of the proteins and the secondary effects 

 following desiccation. In this instance, though the percentages do not 

 correspond uniformly to the known hardiness, yet Minhardi, the hardiest 

 variety used, liad somewhat the largest content of water-soluble nitrogen. 

 All varieties show an increase in amino nitrogen and water-soluble 

 nitrogen in tlic later collection. This is in harmony with the evidence of 

 Harvey (i!i) that s])litting of the proteins is associated with tjic hardening 

 process. 



The high content of sugars, especially sucrose, reported in Tabic \'l. 

 is cjuite remarkaljle. It has been noted already that sucrose was ap- 

 parently the only disaccharide {)resent. But liere again the varieties 

 could not be classified according to hardiness on the basis of the values 

 found. All suffered a loss between the collections of November 12 and 

 December 9, the percentage falling lowest in Kanrcd. The greater degree 

 of killing in this variety thus lends support to the observation of Pan- 

 taneUi (•■«) that luirdiness was proportional to the (piantitv of sugar 

 retained during exposure to low temperatures. 



A qualitative test for starch on the dried, ground residue Irom the 

 alcohol extraction gave entirely negative results in every case. This is 

 as expected from the observations of Miyake (32), Lidforss (26) and others. 



The above discussion indicates that we are still far from an exact 

 analysis of the factors influencing winter hardiness, but certain of the 

 observations, notably the failure of freezing the tissues to break down 

 the protoplasmic .structure in the hardened jilants, are very suggestive. 

 Furtlier investigation of tliis iilicnomcmm will be carried oul in the near 

 future. 



