Seasonal changes in the composition of winter wheat plants, in relation to frost resistance

1. The adaptation of plants to resist frost appears to depend on seasonal changes which give the protoplasm stability. A study has been made of the changes occurring in winter wheat plants, of varieties differing widely in winter hardiness, during the fall and winter months. 2. By analysing the press-juice as well as the entire tissues at progressive dates, it has been possible to study the distribution of the more important constituents between the physiologically active cell fluids and the relatively inert supporting framework. 3. One of the most important changes in the quantitative relations of the various plant constituents is the reduction in moisture content. This takes place to a greater degree in hardy varieties. The resulting concentration of colloids and sugars in the cell fluids increases the resistance to freezing.