1912.1 



PUBLIC DOCUMENT — No. 31. 



157 



ing at 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 out 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: — 



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 laboratorj^ for five 

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

 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., 



9.30 A.M., 



10.00 A.M., 



10.30 A.M., 



Very little variation was shown in the resistances 



72,000 

 74,000 

 75,000 

 77,000 



Experiment 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 

 65,000 

 68,000 

 67,000 



