+ 
28 ORIGIN OF SEX. 
future products of the seeds produced under these circumstances. ~ 
General Pleasonton* of this city has lately determined that both q 
animals and plants thrive better under a violet colored light, — 
which is in harmony with the experiments of Dr. Daubeny.f ~ 
Mr. Thomas Andrew Knight { observed that the relative quantity — 
of light and heat determined the sex of the flowers produced by 4 
certain plants. Lindley says, “It will be found that no pollen is 
scattered in damp, cold weather, but in a sunny, warm, dry morn- 
ing the atmosphere surrounding such plants, is, in the impregna- 
ting season, filled with grains of pollen discharged by the anthers. 
In wet springs the crops of fruit fail, because the anthers are not 
sufficiently dried to shrivel and discharge their contents, which 
remain locked up in the anther cell till the power of impregnation 
" is lost.” 
Gaertner § has pointed out in his “ Notice sur des Expériences 
concernant la Fécondation de quelques Végétaux,” the decided i 
fluence of the state of the atmosphere on the process of fecun 
tion. He insists on the maturity of the pollen as essential to the 
process. During a warm time the stamens of the rue accomplish 
their movements in two or three days, whilst they are, by a cold 
air and an advanced season, scarcely terminated in eight days. 
Fecundation requires also a greater quantity of pollen in the la 
case than in the other. || F 
This being the case, we can readily understand that a few Y 
days may prevent the pollen from being disseminated, while the 
ovules continue developing, and fecundation is retarded from this 
cause, and it is for this reason that the production of a larger 
proportion of exclusively male-producing-grains i is due. 
Darwin§ says that “walnut trees, which are properly mo 
cious, sometimes entirely fail to produce male flowers ;” and “th 
female silver maple will not unfrequently put forth branches 
— male flowers.” — 
: Some cultivator has recorded ** a series of experiments 
“ftir, Lines 1 sche aia na bii. Phil. Trans., 1836, p 
Mr. Knight’s Physiological Papers, pp: wan out of the 
PE E E tliche Abhandlungen, Tubingen, 1826, t 
Koelrenter. Vorlanoties Nachricht von Einingen das cae pon banun 
treffenden Versuchen, pp. 10, 19, from Dondi sima Chronicle, 1847, pp. 541-558. _ 
3 paar oann e pani cation 
** American A; t » Orange Judd, M. A. Editor. 
