388 POPULAR SCIENCE MONTHLY. 



ers originated in the same way as the white lilac. It will be enough 

 to point out a few facts that may contribute to the guidance of per- 

 sons who are seeking to learn the origin of these colored varieties. 

 The Papava alpinum has a very stable variety with yellow flowers, 

 which, according to Focke, has been observed in the polar regions, 

 while the white varieties have been seen in Switzerland. The cul- 

 tivation of the same species at Giessen, Germany, has made it pos- 

 sible to obtain specimens with white flowers by metamorphosis from 

 specimens with yellow flowers, but it is impossible to say whether 

 or not heat is the agent that produces the changes in these cases. 

 The experiments of MM. Schiibela and Bonnier have shown that 

 flowers become darker without changing their color in high re- 

 gions and in those near the pole; but this phenomenon is one of 

 light and not of color. Be their origin what it may, these white 

 and colored forms have remarkable fixedness. 



It will be observed that black does not figure in the table of 

 the classification of colors given above. Absolute black, in fact, 

 does not exist in any flower. If some parts appear black, it is only 

 because their tint is excessively dark. The black of the petals of 

 Pelargonium triste and of the bean is yellow, and that of the Orchis 

 nigra is a brown. Apparent blacks are, moreover, extremely rare. 



The gamut of the reds is much more varied than that of other 

 colors. The reds of the xanthic series are generally more lively- 

 hued, carnation or flame-colored; those of the cyanic series pre- 

 sent tints more nearly approaching violet. These two reds may 

 furthermore give rose-colors, but a little skill will divine their ori- 

 gin. The rose of the hydrangea inclines to blue, while that of the 

 rose tends rather toward yellow. Blue colors are the most vari- 

 able, and readily pass to violet and red, but most frequently to 

 white. The most tenacious hues are those of yellow, and we might 

 affirm that the bright and glistening yellow of the buttercup may be 

 said never to change. The paler yellows change more easily, but 

 rarely pass to anything but white. Green flowers, not being read- 

 ily distinguished from the foliage around them, need not be spe- 

 cially mentioned. They are believed to be much rarer than they 

 really are. 



Horticulturists are able, by cultivation, selection, and hybridi- 

 zation, to cause the colors of flowers to vary in considerable pro- 

 portions. Not much is known of the laws of these variations, 

 chiefly because gardeners who might tell botanists of them if they 

 would have not the scientific spirit. We cite here what MM. De- 

 caisne and Naudin * say respecting the variations of the color of 

 flowers: 



* Manuel de 1'amateur des jardins. 



