Some plants work under high light intensities, such as those which must adapt themselves on the desert areas of the southwestern United States. Others thrive best in the subdued light of a dense forest. One curious little moss grows in caves where there is almost no light at all. It is equipped with a plate of cells forming a battery of lenses capable of focusing the scattered light on the bodies especially concerned in carbohydrate formation. These are the chloroplasts which contain the mysterious substance, chlorophyll, which acts as a catalyst for action of sunlight on carbon dioxide and water. The shape and arrangement of cells containing the chloroplasts are such that the amount of chlorophyll exposed to the sunlight can be varied. A specially devised apparatus has been constructed in the Smithsonian laboratory for quantitative studies of the way plants absorb carbon dioxide under different lighting conditions. Not only is the process greatly effected by the intensity of the light, the experiments show, but the wave length also is of paramount importance. The experimental plants are grown with their roots in a nutrient solution and their tops extending into a double-walled glass tube. They are furnished light from surrounding lamps, so that the intensity and wave lengths of the light can be varied as desired. Through the tube, air containing different amounts of carbon dioxide can be passed. Thus every element of the process is under rigid control of the experimenters. The experiment already has shown that the correct combination of wave lengths is of the utmost importance in making up synthetic light. Thus, regardless of the intensity, the ordinary electric light when used alone has been demonstrated to be a poor light source. Its maximum energy occurs in the infrared region, below the limit of visibility, while that of sunlight falls in the green-blue region. If tomato plants are grown under high powered Mazda lamps in the Smithsonian’s special growth chambers, especially when the humidity is high, their leaves turn pale and almost white. Chlorophyll disappears under these conditions. _Venezuela’s Nocturnal Orchid_ A flower that opens only by moonlight is one of Venezuela’s plant curiosities. It is an ivory-white, velvety orchid which depends entirely on nocturnal butterflies to sip its nectar while pollenization takes place. The plant is one of 800 species of Venezuelan orchids. Among these is probably the prettiest and rarest of the orchid family, the mother-of-pearl flower, which can sometimes be found in the deep jungles of the Gran Sabana area at altitudes of more than 3,000 feet. Still another high mountain variety has square petals with fringed edges. Another, found in the jungles of the Upper Orinoco, has blossoms measuring up to 16 inches in diameter. A unique Venezuelan orchid grows only in water.