Problem 

 Progress 



SCIENTIFIC SIDE-LIGHTS 



556 



2737. PROBLEM OF SCIENCE, A 



Flowers and Trees Absorb Different Colors 

 1 8 the Plant Affected by the Difference? 

 Both in foliage and in flowers we have stri- 

 king differences of absorption. The copper 

 beech and the green beech, for example, take 

 in different rays. But the very growth of 

 the tree is due to some of the rays thus 

 taken in. Are the chemical rays, then, the 

 same in the copper and the green beech? 

 In two such flowers as the primrose and the 

 violet, where the absorptions, to judge by 

 the colors, are almost complementary, are 

 the chemically active rays the same? The 

 general relation of color to chemical action 

 is worthy of the application of the method 

 by which Dr. Draper proved so conclusively 

 the chemical potency of the yellow rays. 

 TYNDALL Lectures on Light, lect. 1, p. 39. 

 (A., 1898.) 



2738. PROBLEM OR HYPOTHESIS 

 NOT TO BE MADE DOCTRINE" We must 

 draw [it is said] a strict distinction 

 between what we wish to teach and what we 

 wish to search for. The objects of our re- 

 search are expressed as problems (or hy- 

 potheses). We need not keep them to our- 

 selves; we are ready to communicate them 

 to all the world, and say, ' There is the 

 problem ; that is what we strive for.' . . . 

 The investigation of such problems, in which 

 the whole nation may be interested, cannot 

 be restricted to any one. This is freedom 

 of inquiry. But the problem (or hypothe- 

 sis) is not, without further debate, to be 

 made a doctrine." TYNDALL Fragments of 

 Science, vol. ii, ch. 15, p. 397. (A., 1900.) 



2739. PROBLEMS OF THE DEEP 



When it was found that animals can and 

 do live even at the greatest depths of the 

 ocean, the interest of naturalists was con- 

 centrated on the solution of the following 

 problems. Firstly, do the animals consti- 

 tuting the fauna of the abyss exhibit any 

 striking and constant modification in corre- 

 lation with the physical conditions of their 

 strange habitat? And, secondly, from what 

 source was the fauna of the abyss derived? 

 Was it derived from the shallow shore 

 waters, or from the surface of the sea? Is 

 it of very ancient origin, or the result of, 

 comparatively speaking, recent immigra- 

 tions? HICKSON Fauna of the Deep Sea, 

 pref., p. 10. (A., 1898.) 



2 7 4O. PROBLEMS YET UNSOLVED 



Decision of Science Waits for Facts Ten- 

 tative Hypotheses. It must be admitted, 

 then, that the questions of the nature of 

 the earth's interior and the cause of the 

 high temperatures which produce volcanic 

 phenomena are still open ones. We have not 

 yet got beyond the stage of endeavoring to 

 account for the facts observed by means 

 of tentative hypotheses. Some of these, as 

 we have seen, agree with the facts, so far 

 as they are at present known, much better 

 than others; but the decision between them, 

 or the rejection of the whole of them in 



favor of some new hypothesis, must depend 

 on the results of future observation and 

 inquiry. JUDD Volcanoes, ch. 12, p. 352. 

 (A., 1899.) 



2741. Vain Search for 



Intra - Mercurian Planet Perturbations of 

 Mercury Still Unexplained. Intra - Mer- 

 curian planets have . . . been diligently 

 searched for when the opportunity of a to- 

 tal eclipse offered, especially during the 

 long obscuration at Caroline Island. Not 

 only did Professor Holden " sweep " in the 

 solar vicinity, but Palisa and Trouvelot 

 agreed to divide the field of exploration, 

 and thus make sure of whatever planetary 

 prey there might be within reach; yet 

 with only negative results. Belief in the 

 presence of any considerable body or bodies 

 within the orbit of Mercury is, accordingly, 

 now at a low ebb. Yet the existence of the 

 anomaly in the Mercurian movements indi- 

 cated by Le Verrier has been made only 

 surer by further research. Its elucidation 

 constitutes one of the " pending problems " 

 of astronomy. CLERKE History of Astrono- 

 my, pt. ii, ch. 7, p. 308. (BL, 1893.) 



2742. PROCESS OF CRYSTALLIZA- 

 TION SEEN BY MEANS OF SOLAR MI- 

 CROSCOPE Cleansing perfectly a glass 

 plate, the solution of the chlorid [common 

 sal ammoniac, or ammonium, dissolved in 

 water] is poured over the glass, to which, 

 when the plate is set on edge, a thin film 

 of the liquid adheres. Warming the glass 

 slightly, evaporation is promoted, but by 

 evaporation the water only is removed. The 

 plate is then placed in a solar microscope, 

 and an image of the film is thrown upon a 

 white screen. The warmth of the illumina- 

 ting beam adds itself to that already im- 

 parted to the glass plate, so that after a 

 moment or two the dissolved salt can no 

 longer exist in the liquid condition. Mole- 

 cule then closes with molecule, and you 

 have a most impressive display of crystal- 

 lizing energy overspreading the whole screen. 

 You may produce something similar if you 

 breathe upon the frost-ferns which over- 

 spread your window-panes in winter, and 

 then observe through a pocket-lens the sub- 

 sequent recongelation of the film. In this 

 case the crystallizing force is hampered by 

 the adhesion of the film to the glass; never- 

 theless, the play of power is strikingly beau- 

 tiful. TYNDALL Lectures on Light, lect. 3, 

 p. 103. (A., 1898.) 



2743. PROCESS SUCCESSFULLY 

 USED, WHILE REASON UNKNOWN Real 

 Cause of Fermentation Discovered by Pas- 

 teur: It was Pasteur who in 1857 first pro- 

 pounded the true cause and process of fer- 

 mentation. The breaking - down of sugar 

 into alcohol and carbonic acid gas had been 

 known, of course, for a long period. Since 

 the time of Spallanzani (1776) the putre- 

 factive changes in liquids and organic mat- 

 ter had been prevented by boiling and 

 subsequently sealing the flask or vessel con- 



