1888.] NATURAL SCIENCES OF PHILADELPHIA. 281 



admitted as almost certain that some structures, such as .... a long 

 tubular corolla have been developed in order that certain kinds of 

 insects alone should obtain the nectar." ( Cross-and Self-fertiliza- 

 tion, Chap. X, p. 382.) The honey-bee visits all these forms freely. 

 The honey nearly fills the tube, and bees have no difficulty in col- 

 lecting freely. It can scarcely be believed that the plant made an 

 effort to exclude short tongued visitors, and that the long tube Avas 

 the result of that effort, and then secreted so much nectar as to 

 nearly fill the tube by which the short tongued insects could get as 

 much as before the effort was made. 



Nor must we lose sight of the supposed objects for which insect 

 visitors are to be encouraged, namely, cross-fertilization. 



In order to make no mistake in our conclusions, it is proper to 

 note hei'e, that modern literature has misconceived the whole idea of 

 cross-fertilization. There cannot possibly be any physiological bene- 

 fit from one flower crossing another on the same plant; but this is 

 about all that is involved in much that is written in connection 

 with the visits of insects. Yet Darwin takes especial pains to ex- 

 plain that this is not cross-fertilization. He says : " cross fertiliza- 

 tion always means a cross between distinct plants raised from seeds" 

 (p. 10). Even distinct plants, unless under distinct conditions 

 scarcely constitute crossings in his mind. "The mere act of crossing 

 two distinct plants, which are in some degree inter- related, and 

 which have long been subject to the same conditions does little good" 

 (p. 61). Referring to Composite (p. 173) he notes that the florets 

 were " self-fertilized " though with different florets from the same 

 head. On p. 345 he declares " pollen from the same plant is equally 

 injurious or nearly so, as from the same flowers." And, after all, it is 

 difficult to tell what i\tr. Darwin really means by " injurious," for 

 tlie most of his experiments, when in his mind resulting beneficially, 

 referred to vegetative luxuriance, in many little related to those 

 greater vital questions on which the good of the race depends. He 

 distinctly states (p. 327) " tliere is therefore, no evidence at present, 

 that the fertility of plants goes on diminishing in successive self- 

 fertilized generations, althougli, there is some rather weak evidence- 

 that this does occur with respect to height and growth." Still 

 it is clearly his idea, and evidently the proper one, that the cross- 

 fertilization can only be fairly entertained wlien the physi- 

 olocfical conditions varv in the individuals crossed. Thousrh the- 

 honevsuckles referred to are all from cuttings from the one in- 



