The Cause of the Excretion of Water on the surface of Ncctaries. 17 



luduciug the Excretion of Nectar ou Inactive Nectaries 



by a Sugar- Solution. 



Fritillaria imperialis. 



A flower stem of Fritillaria imperialis contained four flowers, The 

 secretion on the nectaries of three was entirely stopped by washing. No 

 excretion took place for some hours under a bell-jar in an atmosphere satu- 

 rated with moisture. On some of the inactive nectaries were placed moist 

 particles of sugar, on olhers a minute drop of sugar-solution, others were 

 left in their dry condition. The nectaries supplied with sugar er sirup 

 were, in from one to two hours filled with nectar and from this time on 

 continued to secrete as though they had not been stopped by washing. 

 Those nectaries left unprovided with sugar or sirup remained dry. The 

 nectaries of one flower of the Cluster were not washed and continued con- 

 stantly to secrete nectar. 



In the case of the flower with ripe pollen, which required but one 

 washing to stop the excretion of the nectar, an application of a sugar Solu- 

 tion brought all the nectaries inlo activity again. 



Prunus laurocerasus. 



On the under side, near the base of the leaves of Prunus laurocerasus 

 are generally to be fouud four nectaries, two on either side of the midrib, 

 Two branches, each with six or more leaves, the nectaries of which were 

 active, were selected. The nectaries were washed with wash-bottle and 

 dried with bibulous paper once each day until no further secretion ap- 

 peared. Some of the nectaries required but two washings, others three, 

 and still others as many as six repetitions. Some very young leaves re- 

 quired four washings. On some of these nectaries, after they had been 

 dry and inactive during three days, were placed minute particles of moist 

 sugar. On the following day large drops of nectar stood on these nectaries, 

 which from this time on continued to excrete as though they had not been 

 washed. With nectaries on which the excretion had been induced by 

 sugar one washing was generally sufficient to again stop its flow. When 

 bibulous paper was used for removing the nectar, a greater number of 

 repetitions was required before the nectaries remained dry. 



Eranthis hiemalis. 



The tubulär nectaries of seven flowers were washed and then dried 

 with bibulous paper. On the following day this was repeated. The flowers 

 remained under a bell-jar for several days until they withered, without 

 further excretion of nectar. 



Untersnchnngen ans dem botan. Institut in Tübingen. Bd. I. 2 



