Organisms 

 Organs 



SCIENTIFIC SIDE-LIGHTS 



502 



bors. This occurs apparently in the self- 

 purification of rivers, as well as in polluted 

 soils. NEWMAN Bacteria, ch. 1, p. 33. (G. 

 P. P., 1899.) 



2469. ORGANISMS, LOWER, HELP 



HIGHER Microbes Fix Nitrogen for Plants 

 Nitrates. Until comparatively recently 

 it was held that plant life could not be 

 maintained in a soil devoid of nitrogen or 

 compounds thereof. But it has been found 

 that certain classes of plants (the Legu- 

 minosce, for example), when they are grown 

 in a soil which is practically free from ni- 

 trogen at the commencement, do take up 

 this gas into their tissues. One explanation 

 of this fact is that free nitrogen becomes 

 converted into nitrogen compounds in the 

 soil through the influence of micro-organ- 

 isms present there. Another explanation 

 attributes this fixation of free nitrogen to 

 micro-organisms existing in the rootlets of 

 the plant. . . . The main supply of this 

 gas, absolutely necessary to the existence of 

 vegetable life upon the earth, is drawn not 

 from the nitrogen of the atmosphere, but 

 from that contained in nitrogen compounds 

 in the soil. The most important of these 

 are the nitrates. Here, then, we have the 

 necessary food of plants expressed in a sen- 

 tence: water, gases, salts, the most impor- 

 tant and essential gas and some of the salts 

 being combined in nitrates. NEWMAN Bac- 

 teria, ch. 5, p. 147. (G. P. P., 1899.) 



2470. ORGANISMS, MICROSCOPIC, 

 INCONCEIVABLY NUMEROUS -Protected 

 Infusions Void of Life. Sixty flasks filled, 

 boiled, and sealed [hermetically], and con- 

 taining strong infusions of beef, mutton, 

 turnip, and cucumber, are carefully packed 

 in sawdust, and transported to the Alps. 

 . . . We open our box at the Bel Alp 

 and count out fifty- four flasks, with their 

 liquids as clear as filtered drinking-water. 

 In six flasks, how r ever, the infusion is found 

 muddy. We closely examine these, and dis- 

 cover that every one of them has had its 

 fragile end broken off in the transit from 

 London. Air has entered the flasks, and 

 the observed muddiness is the result. . . . 

 Examined with a pocket lens, or even with 

 a microscope of insufficient power, nothing 

 living is seen in the muddy liquid; but 

 regarded with a magnifying power of a 

 thousand diameters or so, what an aston- 

 ishing appearance does it present ! Leeuwen- 

 hoek estimated the population of a single 

 drop of stagnant water at 500,000,000: 

 probably the population of a drop of our 

 turbid infusion would be this many times 

 multiplied. The field of the microscope is 

 crowded with organisms, some wabbling 

 slowly, others shooting rapidly across the 

 microscopic field. They dart hither and 

 thither like a rain of minute projectiles; 

 they pirouette and spin so quickly round 

 that the retention of the retinal impression 

 transforms the little living rod into a twirl- 

 ing wheel. And yet the most celebrated 



naturalists tell us they . are vegetables. 

 From the rod-like shape which they so fre- 

 quently assume, these organisms are called 

 " bacteria " a term, be it here remarked, 

 which covers organisms of very diverse 

 kinds. TYNDALL Floating Matter of the 

 Air, essay 3, p. 292. (A., 1895.) 



2471. ORGANISMS NEITHER PLANT 

 NOR ANIMAL Moving Plants among Rooted 

 Animals Animals Secreting Chlorophyl 

 Plants Eating Insects. There is a limbo 

 filled with organisms which never rise high 

 enough in the scale to be manifestly either 

 animal or plant, unless it may be said of 

 some of them that they are each in turn and 

 neither long. There are undoubted animals 

 which produce the essential material of 

 vegetable fabric, or build up a part of their 

 structure of it, or elaborate the character- 

 istic leaf-green [chlorophyl] which, under 

 solar light, assimilates inorganic into or- 

 ganic matter, the most distinguishing func- 

 tion of vegetation. On the other hand, there 

 are plants microscopic, indeed, but unques- 

 tionable which move spontaneously and 

 freely around and among animals that are 

 fixed and rooted. And, to come without 

 further parley to the matter in hand, while 

 the majority of animals feed directly upon 

 plants, " for 'tis their nature to," there are 

 plants which turn the tables and feed upon 

 them. Some, being parasitic upon living 

 animals, feed insidiously and furtively; 

 these, altho really cases in point, are not 

 so extraordinary, and, as they belong to the 

 lower orders, they are not much regarded, 

 except for the harm they do. There are 

 others, and those of the highest orders, 

 which lure or entrap animals in ways which 

 may well excite our special wonder, all the 

 more so since we are now led to conclude 

 that they not only capture but consume 

 their prey. GRAY Darwiniana, art. 10, p. 

 289. (A., 1889.) 



2472. ORGANISMS, SOCIAL, IN 

 ECONOMY OF NATURE Coral Reefs and 

 Islands. As minute social organisms, the 

 corals play an important part in the gen- 

 eral economy of Nature, altho they do not, 

 as people began to believe after Captain 

 Cook's voyages of discovery, build up is- 

 lands or enlarge continents from almost 

 unfathomable depths of the ocean. They 

 excite the liveliest interest, whether regard- 

 ed as physiological objects, and as illustra- 

 ting the various gradations of animal form, 

 or in connection with the geography of 

 plants and the geognostic relations of the 

 earth's crust. According to the comprehen- 

 sive views of Leopold von Buch, the whole 

 Jura-formation consists of " large elevated 

 coral-banks of the ancient world, surround- 

 ing at a certain distance the old mountain 

 chains." HUMBOLDT Views of Nature, p. 

 252. (Bell, 1896.) 



2473. ORGANIZATION NOT THE 

 CAUSE OF LIFE Vital Force Organizes 

 Matter. We never see the phenomena of 



