^ AND 



^^£RICAN HERD-BOOTi 



DEVOTED TO 

 AGRICULTURE, HORTICULTURE, AND RURAL AND DOMESTIC AFFAIRS. 



Perfect Agriculture is the true foundation of all trade and industry. — Liebiq. 



Vol. XII.— No. 7.] 



2iid mtH (February) 15th, 1848. 



[Whole No. 157. 



PUBLISHED MONTHLY, 



BY JOSIAH TATUM, 



EDITOR AND PROPRIETOR, 



No. 50 North Fourth Street, 

 PHILADELPHIA. 



Price one dollar per year. — For conditions see last page. 



For the Farmers' Cabinet. 



Effect of Different Coloured Lights upon 

 Plants. 



Mr. Editor, — I take the following article 

 from the Scientific American — an excellent 

 paper published in the city of New York. 



"The warmth of the sun has compara- 

 tively little to do with the specific action of 

 his rays on the chemical functions of the 

 plant, which is illustrated by the experi- 

 ments of Mr. Hunt of the Royal Agricultu- 

 ral Society of England, on the effect of the 

 rays of light of different colours on the grow- 

 ing plant. He sowed cress seed, and ex- 

 posed different portions of the soil in which 

 the seeds were germinating, to the action of 

 the red, yellow, green, and blue rays, which 

 were transmitted by equal thicknesses of so- 

 lutions of these different colours. 'After 

 ten days, there was, under the blue fluid, a 

 crop of cress of as bright a green, as any 

 which grew in full light, and tar more abun- 

 dant. The crop was scanty under the green 

 fluid, and of a pale green unhealthy colour. 



Cau.— Vol. XIL— No. 7. 



Under the yellow solution only two or three 

 plants appeared, but less pale than those un- 

 der the green ; while beneath the red a few 

 more plants came up than under the yellow, 

 though they were also of an unhealthy co- 

 lour. The red and blue colours being now 

 mutually transferred, the crop formerly be- 

 neath the blue in a few days appeared blight- 

 ed, while on the patch previously exposed 

 to the red, some additional plants sprang up.' 

 " Besides the rays of heat and of light, 

 the sun-beam contains what have been called 

 chemical rays, not distinguishable to our 

 senses, but capable of being recognized by 

 the chemical effects they produce. These 

 rays appear to differ in kind, as the rays of 

 different coloured lights do. It is to the ac- 

 tion of these chemical rays on the leaf, as- 

 sociated with the blue light on the solar 

 beam, that the chemical influence of the 

 sun on the growth of the plant is to be as- 

 cribed, by the decomposition of the carbonic 

 acid absorbed from the air by the leaf of the 

 plant on the interior of the leaf, the reten- 

 tion of the carbon, and the rejection or omis- 

 sion of the oxygen contained in the carbonic 

 acid of the plant, which is returned to the 

 atmosphere, which carbon retained, uniting 

 with the elements of water — hydrogen or 

 oxygen, — absorbed at the same time by the 

 roots, give rise to and furnish the elements 

 for the formation of woody, cellular fibre, 

 &c., and for which cause it is that 'z/ light 

 be excluded, vegetation never produces a 

 leaf or a stock.'' 



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