8 38 THE POPULAR SCIENCE MONTHLY. 



fruits, and vegetables, become more aromatic in the northern latitudes, 

 through the long constancy of light in summer, but their color also 

 deepens, while the production of sugar decreases from the insufficient 

 quantity of heat. Thorough experiments will reveal the effects of 

 electric light upon vegetation, and we have no doubt that interesting 

 results will be obtained in time, with regard to the influence of this 

 light upon the pigment of flowers. 



Our knowledge of the chemistry of vegetable pigments is not yet 

 sufficiently advanced, for which reason the effect of artificial influence 

 upon the color-tone of flowers has not yet received its merited atten- 

 tion. According to my view, tannin is an important factor in the 

 generation of vegetable colors ; it is found in almost every plant, the 

 petals not excepted, and by the action of the most varying reagents 

 alkalies, earths, metallic salts, etc. it assumes the most manifold hues 

 from pale rose to deep black. A darker color, therefore, is produced in 

 flowers rich in tannin, when manured with iron-salts, since, as every- 

 body knows, tannin and iron-salts dye black, and produce ink. A prac- 

 tical use has been made of this fact in the raising of hortensias and 

 dahlias. The former, which in ordinary soil blossomed pale-red, be- 

 came sky-blue when transplanted into soil heavily manured with iron 

 ochre, or when occasionally watered with a dilute alum solution. Eng- 

 lish gardeners succeeded in growing black dahlias by similar manipula- 

 tions. It is well known to every florist that a change of location, that is, 

 a change of light, temperature, and soil (replanting), occasionally pro- 

 duces new colors, whence it may be deduced that an interrupted nutri- 

 tion of the flower may, under circumstances, effect a change of color. 

 We see no valid reason why the well-authenticated fact of the change 

 of color produced by manuring with iron oxide, thereby changing the 

 nutrition of the plant, should not be practically employed by the hot- 

 house gardener. Another very singular and successful experiment, 

 in producing a change of color in a bird, has recently been made. A 

 breeder of canary-birds conceived the idea of feeding a young bird 

 with a mixture of steeped bread and finely pulverized red Cayenne 

 pepper. Without injuring the bird, the pigment of the spice passed 

 into the blood, and dyed its plumage deep red. The celebrated orni- 

 thologist Russ believes that the color of the plumage of birds might 

 be altered according to desire, by using appropriate reagents. 



Apart from chemical operations, there are also physical ones which, 

 I believe, influence the color of flowers. It is a well-known fact that 

 a most intimate relation exists between color and form. We know 

 very well that the minute division of a pigment exerts a great influ- 

 ence upon its shade of color : a solid piece of vermilion does not pos- 

 sess the pale-red hue of the finely pulverized article ; it is dark brown, 

 and only shows a high red when scratched with a hard body, the color 

 increasing with a continued comminution. Mercury oxide, while deep- 

 red in a crystalline condition, becomes light orange-yellow upon con- 



