396 



MINNESOTA BOTANICAL STUDIES 



second leaves were about half unfolded, and no part of the plant 

 was removed. The transpiring area was based on the final leaf area. 

 Weighings were made soon after the pustules appeared. As far as 

 observation can permit one to judge, the growth of control and 

 rusted plants was proportional. 



Since higher transpiration rates in diseased plants were invari- 

 ably obtained, the results of only two experiments will be given in 

 table III. 



TABLE III 



Date of the be- 

 ginning of ex- 

 periment 



Duration 

 in hours 



Condition 

 of plant 



Transpiration in 

 grams per sq. 

 dm. of trans- 

 piring surface 



Percentage 

 of water 

 transpired 



The marked increased water loss as well as its constancy in all 

 determinations leaves no doubt that here again rusts do accelerate 

 transpiration. 



Further experiments of a similar nature merely confirm those 

 already given, so that only a single additional case with corn will be 

 recorded. 



On December 9 the first, second and third leaves of three corn 

 plants were inoculated as usual and placed with four control plants 

 in vessels of water under the bell jars. Two days later the glasses 

 were sealed and weighed and weighings were made each day there- 

 after at nine o'clock in the morning, for 13 days. The results are 

 shown in figure 8. 



