81 
Influence of Moisture upon Dehiscent Fruits, 
By B. D. HALsTep and D. G. FAIRCHILD. 
(Plate CXVI1). 
The changes wrought by moisture and dryness upon the 
dehiscent fruits doubtless assist in the dispersion of seeds in 
more cases than at first one is willing to grant. A number of 
the ordinary fruits have been experimented upon by artificially 
alternating a moist and dry condition, and the results are abbre- 
viated in the following paper. 
In experimenting with the fruits it was found necessary to 
immerse them in a vessel of water in order to get the most 
marked results, although evident signs of movement were ob- 
served when only a moist chamber was used. The dry conditions 
were generally supplied by the bright sunlight or in case this 
was absent, by the use of an oil stove. 
In the majority of cases examined it will be noted that the 
hygroscopic movement is much more rapid upon the absorption 
of water than upon its evaporation from the fruit; but whether 
there is any advantage in this to the plant, may be a question. 
The capsules of Campanula Americana, as noticed by Gray 
in contradistinction to C. rapunculotdes, have their valves situated 
near the top, and in dry weather the flaps curl outward and up- 
ward, thus allowing free access to the winds which whistle 
through the openings and whirl out the light, flat seeds. These 
flaps uncurl and close in from ten to thirteen minutes when 
placed in water, but require a much longer time to open when 
placed in warm dry air—the exact time was not noted, but at 
least fifty minutes are required (Figs. 1-2). 
The hard horn-like capsules of Veronica Virginica ( Figs 3, 
4, 5), are examples of a large class of dehiscent fruits, which open 
and close quite rapidly ; that is, fifteen to twenty minutes in clos- 
ing, and an hour or more in opening. A few examined belong- 
ing to this class, are Syringa vulgaris, (Figs. 6, 7, 8), Stetronema 
longifolium, ( Figs. 9-10), and Viola palmata var. cucullata. 
The various species of Viola* as is well known, eject their 
; i f these opening valves 
of ae de tee “Die. Schlpadesi-ochte und ihe im pAb 
chen Bau begrundeter Mechanismus. Pringsheim’s Jahrbiicher fur Wissenschaft- 
lichen Botanik, 1873-4, VOL. ix, pp. 235-276, taf. 1-3. 
