6o 



(b) Two roots kept in saw dust. 



The crown cuts were very slightly injured; the second and 

 third were more severely than the crown cuts, but less severely 

 than the second and third cuts of (a). 



(c) Two dried roots — allowed to dry on desk eighteen hours. 



Crown cuts and second cuts entirely uninjured. Very 



slight injury in cambium region of third cut. 



There is some indication that rapid wilting in case of some 

 plants reduces the injury from freezing. However, in the case of 

 most plants the difference is rather slight and with many plants 

 there is no apparent difference. In all cases the wilting was suf- 

 ficient to give the tissue a limp appearance. It seems rather certain 

 then that wilting so slight that it can not be easily detected by the 

 appearance or feel of the tissue could not influence the results in freez- 

 ing such tissue as our plants with roots or stem bases in solutions. 

 In case of plants with the surface wet, listed in the table as wet and 

 turgid, there seems strong evidence that the killing from freezing is 

 worse. 



Long continued partial withholding of water is different. The 

 rate of growth, sap density and possibly the resistance of the pro- 

 toplasm to the results of low temperature are increased. There 

 is no apparent reason to expect this of rapid wilting. It would tem- 

 porarily increase the sap density by reducing the amount of water 

 in the cell. It probably does not, however, increase the amount 

 of material in the cell to hold water. Plants growing with insuf- 

 ficient water supply are generally more resistant to cold (See tables 

 IV, V, and VI). We have also some results of this effect of con- 

 tinued partial withholding of water on dormant peach buds. On 

 November 20, 1910, typical branches of peach trees were girdled, a 

 ring being cut nearly through the sap wood, and another limb was cut 

 off and set up in the tree. This was done with several trees. The 

 following table gives the percentage of buds killed when the tempera- 

 ture went to -8° F., on January 3, 1911: 



