1892.] NATURAL SCIENCES OF PHILADELPHIA. 367 



fulness of every flower in Gaura parvifiora. On one spike exam- 

 ined, 148 flowers had bloomed, and each had produced a perfect 

 capsule. Many more flowerbuds had yet to open. The result of 

 the observations showed that the plant is absolutely a self-fertilizer. 

 On every night of my observations the first blossoms commenced 

 to open at 7.15 o'clock, and by 7.30 all had opened that would open on 

 that evening. The expansion is so extremely sudden that it is only 

 with great difficulty that the process can be observed. The eye can 

 be taken for an instant from one flower to another alongside, and 

 instantly back again, only to find that expansion has occurred. A 

 good magnifier is necessary to see the process distinctly. On ex- 

 pansion the petals stop wdien at a right angle with the axis, but the 

 sepals fly completely back on a line with the ovarium. Opening 

 some flowers at 7 o'clock, no pollen is visible, but the anther cells are 

 ruptured and abundantly pollen-covered at expansion. We may 

 conclude that this act is simultaneous with the opening. The anthers 

 . are held to the stigma by the gelatinous pollen, except an occasional 

 one that is held fast by the expanding petal or sepal, and drawn 

 over, which also shows that the anther cells rupture at the time of 

 expansion or a little before. As evening progresses the stamens 

 draw their anthers more or less away from the stigmas, but they 

 alone can fertilize the pistils. By a lamp, later in the evening, 

 small night moths are found about the flowers, and some moth hairs 

 on many of the glutinous stigmas show that the flowers have been 

 visited by them. The flowers commence to fade at daylight, the 

 stamens dropping first, then the pistil, and by 8 A. M. the petals 

 wither, unless the day be cloudy, when they continue a little longer. 

 The upper portion of the leaves of this species are vertical, the 

 result apparently of a continuation of the coiling tendency longer 

 than in some other plants, and w'ithout any j^hysiological signifi- 

 cance. 



Gaura biennis. — In this species some open at 8 P. M. ; all are 

 open at 8.30 P. M., that are to expand that evening. They open 

 by jerks. First there is a sudden flying apart of the sepals, just 

 enough to show the pinkish-white petals, the openings being not 

 more than two lines in width. After about three minutes another 

 efibrt occurs, when both the sepals and petals are at right angles 

 with the axis. After another rest of about three minutes the sepals 

 fall back on the ovarium. An effort was made to encourage a 

 flower to open earlier in the evening by separating the sepals 



