20 W. P. Wilson. 



Vicia faba. 



Plants ith only the first leaf partially unfolded, four to six inches high, 

 grown in small pots. Nectaries secrete first on the lowest pair of slipules, 

 then on the stipules of younger leaves above. 

 Tuesday Feb. lO*'^. 



Plants placed in a cold room where the Ther. stood 2,5° C. 

 12 o'clock. 

 Feb. 11*^ Ther. 3,5° C. 12 o'clock. 

 Many nectaries secreting finely, 



Nectar removed from the nectaries with l)ibulous paper. 

 Feb. 12*^. Ther. 3,8° G. 9 o'clock A. M. 



The nectaries from which the nectar was taken away on the pre- 

 vious day covered with fluid. 

 Feb. 13*^. Ther. 3,5° C. 9 o'clock A. M. 



Nectaries still active. 

 Feb. U^^. Ther. 3,8° C. 10 o'clock A. M. 



Nectaries excreting. 

 Feb. 15*^ Ther. 4,6° G. 10 o'clock A. M. 

 Nectaries active. 



Nectar again removed with bibulous paper. 

 Feb. 16*'^. Ther. 4,8° G. 11 o'clock A. M. 



Nectaries which were dried with bibulous paper on the 15*'' cov- 

 ered with nectar again. 

 Feb. 17*^ Ther. 5,0° G. 10 o'clock A. M. 



Nectaries still active. 

 These plants remained in this room until the 18*'' of march. The nec- 

 taries were constantly active. The temperature gradually rose to 10° C. 



Comparison of the Action of Nectaries in High and in Low 



Temperatures. 



Prunus laurocerasus. 



Six branches of P. laurocerasus were selected as nearly equal in age 

 and appearance as possible. The nectaries were all inactive. Three of these 

 branches were placed in a warm room. The thermometer varied in this 

 room from 18° to 21?4 G. during the several days which the experiment 

 lasted. In the night the Ther. sank to 12° G. 



Three of these branches were at the same time placed in a cold room. 

 In this room the temperature varied very little between day and night. 



Feb. 9*'', on Monday the experiment began. On Wednesday 11*''. the 

 nectaries in the warm room were all actively excreting. 



