613 



SCIENTIFIC SIDE-LIGHTS 



Sea 

 Seed-dispersal 



cessful application of the spectroscope to 

 comets was by Donati in 1864. A comet dis- 

 covered by Tempel, July 4, brightened until 

 it appeared like a star somewhat below the 

 second magnitude, with a feeble tail 30 in 

 length. It was remarkable as having, on 

 Augtist 7, almost totally eclipsed a small 

 star a very rare occurrence. On August 5 

 Donati admitted its light through his train 

 of prisms, and found it, thus analyzed, to 

 consist of three bright bands yellow, green, 

 and blue separated by wider dark inter- 

 vals. This implied a good deal. Comets 

 had previously been considered, as we have 

 seen, to shine mainly, if not wholly, by re- 

 flected sunlight. They were now perceived 

 to be self-luminous, and to be formed, to a 

 large extent, of glowing gas. The next step 

 was to determine what kind of gas it was 

 that was thus glowing in them; and this 

 was taken by Dr. Huggins in 1868. . . . 

 All the eighteen comets tested by light- 

 analysis, between 1868 and 1880, showed the 

 typical hydrocarbon spectrum common to 

 the whole group of those compounds, but 

 probably due immediately to the presence of 

 acetylene. CLERKE History of Astronomy, 

 pt. ii, ch. 10, p. 414. (Bl., 1893.) 



3030. SECRETS REVEALED For- 

 eign Substances in the Body Shown by 

 Roentgen Rays The Mercy of Civilization. 

 Flesh and skin are transparent in moder- 

 ate thicknesses, while bone is opaque. Hence, 

 if the rays [Roentgen] are passed through 

 the hand the bones cast a shadow, tho an 

 invisible one; and as, most fortunately, the 

 rays act upon photographic plates almost 

 like ordinary light, hands or other parts of 

 the body can be photographed by their 

 shadows, and will show the bones by a much 

 darker tint. Hence their use in surgery, to 

 detect the exact position of bullets or other 

 objects embedded in the flesh or bone. A 

 needle which penetrated the knee-joint and 

 then broke off, leaving a portion embedded 

 which set up inflammation, and might have 

 necessitated the loss of the limb, was shown 

 so accurately that a surgeon cut down to it 

 and got it out without difficulty. WALLACE 

 The Wonderful Century, ch. 5, p. 40. (D. 

 M. & Co., 1899.) 



3031. SECURITY BY PRECAUTION 



Disinfection of Milk Possible Sterilizing 

 by Heat. If for practical purposes we 

 look upon all milk derived from tubercular 

 udders as highly infective, we may adopt a 

 comparatively simple and efficient remedy. 

 To avoid all danger it is sufficient to bring the 

 milk to a boil for a few minutes before it is 

 consumed; in fact, the temperature of 85 

 C. (160 F.) prolonged for five minutes kills 

 all bacilli. The common idea that boiled 

 milk is indigestible, and that the boiling 

 causes it to lose much of its nutritive value, 

 is largely groundless. NEWMAN Bacteria, 

 ch. 6, p. 197. (G. P. P., 1899.) 



3032. SECURITY FROM INFECTION 



Putrefaction within the Law of Cause and 

 Effect Bacteria. Our knowledge here, as 

 elsewhere in connection with this subject, 

 has been vastly extended by Professor Cohn, 

 of Breslau. "No putrefaction," he says, 

 " can occur in a nitrogenous substance if its 

 bacteria be destroyed and new ones prevent- 

 ed from entering it. Putrefaction begins 

 as soon as bacteria, even in the smallest 

 numbers, are admitted either accidentally 

 or purposely. It progresses in direct pro- 

 portion to the multiplication of the bacteria, 

 it is retarded when they exhibit low vitality, 

 and it is stopped by all influences which 

 either hinder their development or kill them. 

 All bactericidal media are therefore anti- 

 septic and disinfecting." TYNDALL Floating 

 Matter of the Air, essay 5, p. 287. (A., 

 1895.) 



3033. SEED-DISPERSAL Compensa- 

 tions for Vegetable Immobility Children 

 Given a New Start in Life. If each seed 

 fell where it grew, the spread of the species 

 would shortly be at an end. But Nature, 

 working on the principle of cooperation, is 

 once more redundant in its provisions. By 

 a series of new alliances the offspring are 

 given a start on distant and unoccupied 

 ground ; and so perfect are the arrangements 

 in this department of the struggle for the 

 life of others that single plants, immovably 

 rooted in the soil, are yet able to distribute 

 their children over the world. By a hun- 

 dred devices the fruits and seeds when ripe 

 are entrusted to outside hands provided 

 with wing or parachute and launched upon 

 the wind, attached by cunning contrivances 

 to bird and beast, or dropped into stream 

 and wave and ocean-current, and so trans- 

 ported over the earth. DRTJMMOND Ascent 

 of Man, ch. 7, p. 237. (J. P., 1900.) 



3O34. Seed Distributor 



Rolled by Wind The Russian Thistle. The 

 Russian thistle begins its yearly growth in 

 a simple, inoffensive way. The young plants 

 are slender and succulent, but as they grow 

 older they harden and spread out, becoming 

 densely covered with sharp spines. When 

 full grown they often reach a diameter of 

 four or five feet, a majority of the specimens 

 being distinctly rounded in outline. After 

 the seeds have matured the stem twists 

 around and breaks off, thus leaving the 

 plant to roll wherever the wind blows it, 

 dropping its seeds as it goes along. As one 

 large plant sometimes produces 200,000 

 seeds, and may be blown for miles, one can 

 readily imagine how soon a prairie region 

 might be overrun by the pest, which grows 

 so vigorously that it crowds out practically 

 all plants with which it comes in competi- 

 tion. WEED Seed Travellers, pt. i, p. 23. 

 (G. & Co., 1899.) 



3O35. 



Seeds Carried by 



Birds The Holly The American Currant. 

 What holly loses in the size of its clusters, 

 it gains in the brightness of its berries. 



