POLLENIZATION, CROSS-FERTILIZATION, ETC. 145ft 



45 9e. The service thus performed by insects in behalf of veg- 

 etation is very important. Numerous species are wholly depend- 

 ent on bees, moths, flies, for the dissemination of their pollen, 

 and consequently for their very existence. Many other species, 

 although capable of self-fertilization, are still greatly benefited 

 by the intercrossings of pollen which the visits of insects occa- 

 sion. Of course the bees have no idea of these benefactions. 

 They visit the flowers solely for their own good. The nectar 

 which they seek is always so situated as to oblige them to dis- 

 turb the pollen or pollinia as they pass and repass, get besprink- 

 led with it, and so encounter the stigmas from flower to flower. 



459/1 It would seem important that the bee or moth should 

 confine its visits during any one excursion to plants of the same 

 species. And this it actually does, as shown by observation, 

 avoiding the mingling of its nectars as well as the confusion of 

 its pollens. In accomplishing this, the insect may be led by 

 habit, becoming accustomed, for the hour, to one form of nec- 

 tary ; on it may be drawn by uniform odor of the flowers, or by 

 their gay and special colors. For we observe that the flowers of 

 grasses and of forest trees whose pollen is wafted by the wind, 

 requiring no aid from insects, are destitute both of bright colors 

 and of fragrance, and of honey. 



459g. From these observations and a thousand others of simi- 

 lar import, it is inferred that Nature insists on the fertilization 

 of the stigma in every plant by all means, at least when growing 

 in its native home ; also, that of the two general modes, self or 

 cross, she greatly prefers the latter. 



45 9h. What are the reasons for this preference ? The solu- 

 tion of this inquiry has engaged the attention of many skillful 

 investigators,* until it seems to be proved that the offspring of 

 cross-fertilization are as a rule decidedly superior in size, vigor, 

 and variety. 



fieritw. First requisite concerning the pollen. The 3d. The 3d. Define self-fertili- 

 zarion. Cross-fertilization. Hybridization. Define CleMogene flowers. Flowers favoring 

 both kinds of fertilization. Crossing only. How in Iris ? Dichogamous Plants. Di- 

 morphous Plants. The services of insects essential , beneficial. Motive of the bee. His 

 visits how limited. Why no bright colors or honey in Grasses? Nature's preference. 

 Wherefore f 



* Sprengel, Hildebrand, Muller, Darwin, etc. 



