1912.1 



PUBLIC DOCUMENT — No. 31. 



157 



iiii*' iit first. Heavy galvanized iron nail electrodes were driven 

 into the branch 20 inches apart, and several half-hour readings 

 were taken. The branches were left ont of doors where the tem- 

 perature varied only a few degrees, and at the time the readings 

 were taken it was just above freezing. The results follow : — 



Ohms. 



8.30 A.M., 136,000 



9.00 A.M., 132,000 



9.30 A.M., 131,000 



10.00 A.M., 132,000 



10.30 A.M., 120,000 



This experiment was repeated several times with approxi- 

 mately the same results, and is not conclusive as regards influ- 

 ences of temperature. 



Experiment B. 



The same branch of maple was kept in the laboratory for five 

 days at a room temperature (about 70° F.), the only diiference 

 between this experiment and the one preceding being the fact 

 that the electrodes were placed 1 foot apart instead of 20 inches. 

 The readings obtained are as follows, taking half-hour pe- 

 riods : — 



Ohms. 



8.30 A.M., 72,000 



9.00 A.M., 72,000 



9.30 A.M., 74,000 



10.00 A.M., 75,000 



10.30 A.M., 77,000 



Very little variation was shown in the resistances. 



Expe7'iment C. 

 A branch of another maple of about the same diameter as the 

 preceding was cut under water and allowed to stand at room 

 temperature for five days, when a fresh cut was made under 

 water. During this time the leaves and flowers had started, and 

 there was evidently some transpiration. The electrodes were 1 

 foot apart. The following readings were obtained : — 



8..30 A.M., 



9.00 A.M., 



9.30 A.M., 



10.00 A.M., 



Ohms. 



64,400 

 6.5.000 

 68,000 

 67,000 



