100 D. P. Penhalloio — Tendril Movements in 



Second, When W, is a constant. 



Then E is a minimum when E / is half E. 



The electrical efficiency increases with E y . 



The current diminishes as E ; increases. 



W diminishes from infinity to W, when the efficiency is unity. 

 These are the limits. 

 T/iird, When W is a constant. 



Then W, is a maximum only when the efficiency is uuity, 

 in which case E and E ; are infinite. 



E has a minimum value of VRW when E, is zero. 



(The case of the motor driven mechanically is not included.) 



The electrical efficiency increases with E y . 



The current decreases as E y increases. 



Jacobi's law applies only to the first case. When a battery 

 is to be employed to run an electric motor, then E is the proper 

 term to consider constant; but if it is required that the motor 

 furnish a definite amount of power, then the graphical illustra- 

 tion of hyperbola I shows that E has a minimum value and 

 points out some of the conditions of high efficiency. 



Art. IX. — Tendril Movements in Cucurbila maxima and C. Pepo ; 

 by D. P. Penhallow. 



(Continued from page 57.) 



Observations upon the movement of both tendril and ter- 

 minal bud were made both day and night for an entire week, 

 and thus the motion of each arm, for almost its entire period of 

 activity, was secured. Temperature and other meteorological 

 conditions were noted at each observation, taken during the 

 night at intervals of an hour — sometimes less — and during the 

 day as often as seemed necessary from the activity displayed, 

 thus frequently at intervals of two minutes. 



Tendril No. 1. 



At 9.30 in the morning of August 12th, one of the longest 

 arms was selected after it had been sometime uncoiled, and its 

 movements were noted until there was no further motion. The 

 entire time over which the observations extended was ten 

 hours and thirty minutes. During this time, the tendril tip 

 traversed a distance of 343 'lo 0111 , giving an average movement 

 of 0*54: cm per minute. 



The greatest rate of movement at any one time was 2 , 06 cm 

 per minute, and occurred two and one-half hours after the 

 wave of maximum temperature had passed. The waves of 

 most rapid motion extended from 2.30 to 4.30 P. M., closely 



