L gnosticism 



SCIENTIFIC SIDE-LIGHTS 



22 



sometimes in alternate layers, as special 

 causes may have determined successive de- 

 posits of lighter or heavier materials at 

 some given spot. AGASSIZ Geological 

 Sketches, ser. i, ch. 1, p. 5. (H. M. & Co., 

 1896.) 



105. AGENCY, UNCONSCIOUS In- 

 sects Allured by Nectar Carry Away Ad- 

 hering Pollen Narrow Self-seeking Ful- 

 fils Wide Design. Small insects alight on 

 the labelluin of the Listera ovata for the 

 sake of the nectar copiously secreted by it; 

 as they lick this they slowly crawl up its 

 narrowed surface until their heads stand 

 directly beneath the overarching crest of the 

 rostellum ; when they raise their heads they 

 touch the crest ; this then explodes, and the 

 pollinia are instantly and firmly cemented 

 to their heads. As soon as the insect flies 

 away, it withdraws the pollinia, carries 

 them to another flower, and there leaves 

 masses of the friable pollen on the adhesive 

 stigma. DARWIN Fertilization of Orchids, 

 eh. 4, p. 119. (A., 1898.) 



106. AGENT LOST IN RESULT 



Heat Disappears in Work. We can raise a 

 weight by heat; and in this agent we pos- 

 sess an enormous store of mechanical power. 

 A pound of coal produces by its combination 

 with oxygen an amount of heat which, if 

 mechanically applied, would suffice to raise 

 a weight of 100 pounds to a height of 

 twenty miles above the earth's surface. 

 Conversely, 100 pounds falling from a 

 height of twenty miles, and striking 

 against the earth, would generate an 

 amount of heat equal to that developed by 

 the combustion of a pound of coal. Wher- 

 ever work is done by heat, heat disappears. 

 A gun which fires a ball is less heated than 

 one which fires blank cartridge. The quan- 

 tity of heat communicated to the boiler of 

 a working steam-engine is greater than that 

 which could be obtained from the reconden- 

 sation of the steam, after it had done its 

 work; and the amount of work performed 

 is the exact equivalent of the amount of 

 heat lost. TYNDALL Fragments of Science, 

 vol. i, ch. 16, p. 373. (A., 1897.) 



1 7 . AGENT . OF DESTRUCTION VAN- 

 ISHES, RUIN REMAINS Explosion of Vol- 

 cano Likened to Bursting of a Boiler. We 

 may compare the explosion of a volcano to 

 the action of a bursting boiler, when in a 

 moment the rupturing agent disappears in 

 the air, leaving only the fragments of the 

 vessel which contained it and which it has 

 torn to pieces. SHALER Aspects of the 

 Earth, p. 65. (S., 1900.) 



1O8. AGE OF DEEP-SEA ORGANISMS 



Oldest Genera at Greatest Depths. Agas- 

 siz points out that all those genera that have 

 the greatest bathymetrical range, extending 

 from the littoral to the abysmal region, are 

 at the same time genera which date back 

 to the cretaceous period, while those having 

 a somewhat more limited range go back to 



the tertiaries, and those that extend only 

 slightly beyond the littoral area go back 

 only to the later tertiaries. 



This interesting generalization brings 

 home to our minds the enormous length of 

 time that it must have taken these animals 

 to migrate from the shallow to the deep sea. 

 In the struggles for existence between ma- 

 rine animals it must always have been the 

 last resort of those unable to compete with 

 the younger generations in shallow water 

 to migrate into the deeps. 



The scarcity of food, the darkness, and 

 the pressure of these regions can never be 

 so favorable for the support of animals as 

 the conditions of the shores. We can well 

 imagine that a species would take every op- 

 portunity that is afforded to return from 

 such inhospitable habitats, and that only 

 when, as it were, every door is closed, when 

 no island, continent, or cape can afford it a 

 free scope for life in shallow water, does it 

 become a true deep-sea species. HICKSON 

 Fauna of the Deep Sea, ch. 5, p. 103. (A., 

 1894.) 



109. AGE OF SEQUOIAS Brevity of 

 Human Life and Fame. So far as we can 

 judge from the actual counting of the layers 

 of several trees, no sequoia now alive sen- 

 sibly antedates the Christian era. . . . 

 That the more remarkable of these trees 

 should bear distinguishing appellations 

 seems proper enough; but the tablets of 

 personal names which are affixed to many 

 of them in the most visited groves as if 

 the memory of more or less notable people 

 of our day might be made enduring by the 

 juxtaposition do suggest some incongruity. 

 When we consider that a hand's breadth at 

 the circumference of any one of the vener- 

 able trunks so placarded has recorded in 

 annual lines the lifetime of the individual 

 thus associated with it, one may question 

 whether the next hand's breadth may not 

 measure the fame of some of the names thus 

 ticketed for adventitious immortality. 

 Whether it be the man or the tree that is 

 honored in the connection, probably either 

 would live as long, in fact and in memory, 

 without it. ASA GRAY Danoiniana, art. 5, 

 p. 207. (A., 1889.) 



110. AGE OF TREES Yew, Linden, 

 and Eucalyptus Relative Brevity of Hu- 

 man Life. Decandolle finds that of all 

 European species of trees the yew attains 

 the greatest age; and according to his cal- 

 culations thirty centuries must be assigned 

 as the age of the Taxus baccata of Braburn 

 in Kent, from twenty-five to twenty-six to 

 the Scotch yew of Fortingal, and fourteen 

 and one-half and twelve respectively to 

 those of Crowhurst in Surrey and Hipon 

 (Fountains Abbey) in Yorkshire. Endlicher 

 remarks that " another yew-tree in the 

 churchyard of Grasford, North Wales, which 

 measures more than fifty feet in girth below 

 the branches, is more than 1,400 years old, 

 whilst one in Derbyshire is estimated at 



