18 W. P. Wilson. 



HeUeborus purpurascens. 



The cup-shapped nectaries of two flowers washed and dried. After 

 the second washing no more nectar appeared. Minute drops of a sugar- 

 solution were plaeed in a few of the nectaries. Secretion again appeared 

 in two or three hours and continued two days until the nectaries feil from 

 the flowers. The nectaries not provided with sirup reraained dry. 



In the case of some of the HeUeborus species I have found flowers in 

 which the washing of the nectaries seemed not to have the slightest effect 

 on the secretion of the nectar. Some of the nectaries were as active after 

 eight and nine washings, applied during a period of six days, as at first. 



Acacia lophanta. 



Plant two feet high with 25 to 30 leaves. Plaeed under a bell-jar. 

 Four nectaries on the petioles of the leaves washed and then dried. Three 

 secreted no more nectar, the fourth required a second washing. 



After two days of the most favorable surroundings, during which time 

 these nectaries remained dry, sugar-sirup was applied to them. In a few 

 hours the secretion accumulated and seemed to be going on normally. On 

 the following day these nectaries were again washed. The youngest leaf 

 again required the second manipulation before the flow of nectar ceased. 

 After waiting one day in order to be sure that these nectaries did not 

 again secrete, the sanie melhod of applying sirup, inducing the excretion, 

 and again stopping it by washing, was for the third time repeated, and with 

 similar results. 



This treatment was applied to many other leaves on the same plant. 

 Not a Single nectary was observed to begin its secretion for a second time 

 after it had once been left dry by washing. With very young plants the 

 nectaries on the unfolding and rapidly growing leaves often required from 

 three to five washings to effect a total stoppage of the nectar. 



Acer pseudoplatanus, 



Several branches plaeed under a bell-jar, Nectar secreted very freely, 

 flowing in large drops over the discs and Standing on the surface of the 

 perianth. 



Flowers in which the pollen was ripe required but one washing to stop 

 the flow of nectar. Younger flowers required from two to four, ac- 

 cording to Iheir age. The application of a minute drop of sirup readily 

 recalled the excretion. 



