332 Biology in America 



being debarred from entrance, are so numerous and won- 

 derful as to need for their description a volume in itself. 

 We must content ourselves with a single instance. 



In one of the Salvias (S. officinalis) the stamens ripen 

 before the pistil, so that the flower cannot fertilize itself 

 with its own pollen. 1 The corolla of the flower consists of 

 two lobes or lips, an upper and a lower, the former enclos- 

 ing the style and stamens and the lower serving as a landing 

 stage for insect visitors. Before the ovary ripens the style 

 is withdrawn within the upper lobe of the corolla, as shown 

 at 1 in the preceding figure; after ripening it hangs down 

 over the lower lip, 5. In the former position it is not ordi- 

 narily touched by an insect entering the flower, while in the 

 latter it obviously must be. The functional stamens are two 

 in number, placed close together at the base of the hood. 

 Each stamen bears two anthers, separated by a long connec- 

 tive, which stands upright beneath the hood. The lower 

 pair of anthers contain little or no pollen, while the upper 

 pair are full of it. If a bee alights on the lower lip and 

 attempts to make his way into the flower tube, where the nec- 

 tar is hidden, his head must first of all encounter the lower 

 pair of partly developed anthers. As these are pushed before 

 him in his effort to enter, the upper pair are swung down 

 upon their hinge, striking the bee's back and depositing 

 thereon their load of pollen. Thus the bee, visiting this 

 Salvia, is either besprinkled with pollen to be carried to an- 

 other flower, or deposits some of its pollen upon the hanging 

 styles ready to receive it, according to the stage of develop- 

 ment of ovaries and stamens. 



The question of the part played by flower color in these 

 transactions is very perplexing, and calls for much more in- 

 vestigation. Some authors maintain, while others deny, the 

 power of insects to distinguish color, and more especially 

 to discriminate between color patterns in flowers. An in- 

 sect's power of sight is probably very limited, so that its 

 distinction of the form, and possibly also of the color of 

 flowers at any considerable distance is doubtful. There are 

 however some very clear experiments showing ability on the 

 part of insects to distinguish color, but the whole question is 

 still very doubtful. 



Animal colors fall into two classes the chemical and the 

 physical, or a combination of the two. The chemical colors 

 are due to pigments diffused mainly through either the sur- 



1 In some species of plants the flowers are on the contrary so con- 

 structed as to insure self-fertilization. The whole question of the in- 

 fluence of inbreeding upon virility in both plants and animals is very 

 uncertain at the present time. See page 85. 



