COLOR IN FLOWERING PLANTS. 8? 



of Dutchman's pipe, Bryophyllum, and Cirrhopetaluin, and the 

 spathes of the skunk-cabbage ; the glittering, dew-like drops of 

 butterwort and the unicorn plant occur again in the false flower- 

 glands of Parnassia and the deceptive, sparkling ovary of Paris ; 

 and that disagreeable odor is a common characteristic in both 

 classes strengthens the belief that in both carrion-loving flies (or 

 beetles) are the objective points of the attraction, with this unes- 

 sential difference that in the one class the plant feeds the flies, in 

 the other the flies feed the plant. 



VI. Attractive Color. — Leaving aside the negative evidence 

 derivable from cleistogamy and the existence of only inconspicu- 

 ous flowers in places where insects and flower-frequenting birds 

 are absent, it remains to prove that attractive qualities actually 

 have reference to the visits of animals, thereby establishing their 

 usefulness — i. e., their eligibility as characters upon which natu- 

 ral selection may work. 



Where there are bright flowers there are color-minded animals. 

 All orders of insects are represented to an altitude of 2,300 metres, 

 butterflies, flies, and certain bees even to 4,600 metres. The num- 

 ber and kind of insects are in close relation to the number and 

 kind of flowers and their hours of wdking and sleeping. Climate 

 affects the color of all parts of a plant. Cereal grains are said 

 to be brighter in the North. Fruits are invariably so. Many 

 travelers have observed the intensity in the color of Alpine flowers 

 up to certain limits of temperature. But if the brighter color is 

 useless it will not be retained after a few generations, as the in- 

 conspicuous character of the flora of insect -poor Greenland 

 shows ; if serviceable, it will be not only preserved, but deepened 

 as time goes on. The absolute number of flowering plants de- 

 creases with increase of latitude or altitude. As men flock to 

 cities until the average compensation becomes equal to less than 

 what they can obtain in the country, so all insects would stay on 

 the plains or in the tropics until their number, becoming dispro- 

 portioned to that of the flowers, better rewards can be obtained in 

 less crowded regions. To this interdependence of insects and 

 plants, and to the constancy of the numerical relations between 

 the two, inherited intensity of color must be largely due. If the 

 insects are greatly in excess of the attractive flowers, inconspicu- 

 ous and conspicuous blossoms would be searched and fertilized 

 alike in the resulting scarcity of food. If the number of flowers 

 is much larger than that of the insects supported by them; the 

 latter, becoming fastidious, frequent only the brightest or more 

 fragrant, neglecting the others, which accordingly remain incon- 

 spicuous and self-fertile. When both insects and flowers are 

 scarce, the former will remain only so long as the greater attract- 

 iveness of the latter makes it as easy to obtain the same amount 



