LIGHT AND LIFE. itt 
Flowers, fruits, and leaves, then, are elaborated by the 
help of luminous vibrations. Their tissue holds the sun’s 
rays. Those charming colors, those fragrant perfumes, and 
delicious flavors, all the innocent pleasures the vegetable 
kingdom yields us, owe their creation to light. The subtile 
working of these wonderful operations eludes us, as does 
that which guides the fleeting diffusion and thousand-fold 
refractions displayed by the imposing spectacle of the 
dawn; but is it nothing to gain a glimpse of those primal 
laws, and to possess even a twilight ray upon these mag- 
nificent phenomena ? 
MMe 
Light exerts a mechanical influence on vegetables. The 
sleep of flowers, the bending of their stems, the nutation 
of heliotropic plants, the inter-cellular movements of chlo- 
rophyll, offer proofs of an extremely delicate sensitiveness 
of certain plants inthis respect. Pliny mentions the plant 
called the sunflower, which always looks toward the sun, 
and steadily follows its motion. He notices, too, that the 
lupin always follows the sun in its daily movement, and 
points out the hour for laborers. Tessier, at the end of 
the last century, took up the study of these phenomena, 
and inferred ina general way that the stems of plants al- 
ways turn toward the light, and bend over, if necessary, to 
receive it. He noted, too, that leaves tend to turn toward 
the side whence daylight comes. Payer made more exact 
experiments. He tried them with young stems of common 
garden cresses grown on damp cotton in the dark. These 
stems have the property of curving and turning quickly 
when placed in a room lighted only from one side or in a 
box receiving light on one wall only. The upper part of 
the stem curves first, the lower part remaining straight. 
By a second movement the top erects and the bottom bends 
over, so that the plant, though leaning, becomes almost 
