Image from page 254 of "Popular science monthly" (1913)
Title: Popular science monthly
Publisher: New York : McClure, Phillips and Co.
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
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the callus t0 grow over itmon grapevine, and in various hook climbers. At first the tendrils of the grapevine are quite delicate and even edible,but later they become extremely hard and wiry. It would manifestly bea waste of energy from the economic point of view for tendrils todevelop excessive clasping strength by means of an increased cell turges-cence or osmotic pressure, since the clasping strength resulting fromthe normal turgidity or osmotic pressure of the cells is sufficient toanswer all requirements. On the other hand, the increased productionof mechanical tissue or a modification in the elasticity of the tendril isobviously of great advantage to it from the biological point of view.What is true for tendril plants appears to be true for climbing plants,such as the bean, as well as of plants with sensitive petioles, since thereis no loss of energy displayed in the development of a superfluousosmotic presure in the cells for the mere purpose of increasing its clasp-ing powers.
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24o THE POPULAR SCIENCE MONTHLY THE ABSOBPTION AND EMISSION CENTEKS OFLIGHT AND HEAT. By Dr. W. W. STRONG UNIVERSITY OF PITTSBURGH THE mechanical motions of nature are transmitted by solids andfluids from sources that consist of more or less well known me-chanical systems. Waves on a pond may be due to a boat moving overthe surface of the water. Sound waves in air may be due to the vibra-tions of a tuning fork. Wireless telegraph waves may be due to highfrequency electromotive force and current waves in electrical circuits.In general the source of the above type of wave motion is a kind ofmechanism that can be made in the laboratory or in the shop—a mechan-ism that is man-made and whose operation is quite obvious to us. The phenomena of light and radiant heat introduce to us a type ofwave motion that is altogether different. Not only may the mediumthat transmits this wave motion possess entirely different propertiesfrom that of matter, but the mechanisms that take part in the emissi
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