Shading of Growing Crops: Growing Plants Under Colored Glass

ON THE PROGRESS OF SCIENCE. 213 waters of the earth is about one-hundredth of the volume of the water of the ocean. Furthermore, Prof. Fuller insists that this estimate is rot too low. Nearly all of this water is found within a thousand feet of the surface. It seems, then, that we must readjust our ideas of the amount of water held in the rocks beneath our feet. Still, a sheet of water one hundred feet thick, represents a tolerably large vol- ume of water. If modern investigation shall show the practica- bility of bringing annually one foot of this water to the surface, every acre of tillable desert soil on earth may be made to yield profitable -crops. —/. A. Widtsoe, Ph.D.

Shading of Growing Crops. Shade, as a factor in plant growth, is receiving considerable attention at present, both among practical gardeners and those who are engaged in scientific horticultural investigations. Large areas in the Connecticut River Valley are devoted to the culture of to- bacco grown in the shade of a cheese cloth covering. Only such varieties as are desirable for cigar wrappers are grown under such conditions, and the fiber of the leaf is such that the product is said to equal that grown in the tropics. It is well known the quality of salad crops is materially im- proved by shading. In pine-apple and coffee culture, shading is now extensively practiced. An eminent botanist has recently made the following statement: "It is believed that the matter of shading is of greater hor- ticultural importance in arid regions than the old question of plant nutrition or fertilization is in the east." Shading reduces transpiration, conserves the soil moisture, and where the cheese cloth covering is used, a slight increase in the temperature of the soil and atmosphere is noticeable. The covering also serves as a protection against frost, drought, dam- age by wind, hail and insects. —IF. H. Homer, Jr., M. S. Growing Plants Under Colored Glass. During recent years, many interesting experiments have been carried on, especially in France, the object of which has been to test the effect of the different colored rays of the solar spectrum