fferences 



SCIENTIFIC SIDE-LIGHTS 



168 



copious dews, which in forests would form 

 torrents of rain by the rapid condensation 

 on the leaves. WALLACE The Wonderful 

 Century, ch. 9, p. 78. (D. M. & Co., 1899.) 



8 2O. DIFFERENCE IN HABITS OF 

 MALE AND FEMALE Mother-bird Seeks 

 Protection in Silence. A scarlet-breasted 

 troopial of La Plata perches conspicuously 

 on a tall plant in a field, and at intervals 

 soars up vertically, singing, and, at the 

 highest ascending point, flight and song end 

 in a kind of aerial somersault and vocal 

 flourish at the same moment. Meanwhile, 

 the dull-plumaged female is not seen and 

 not heard: for not even a skulking crake 

 lives in closer seclusion under the herbage 

 so widely have the sexes diverged in this 

 species. Is the female, then, without an in- 

 stinct so common? has she no sudden fits 

 of irrepressible gladness ? Doubtless she has 

 them, and manifests them down in her place 

 of concealment in lively chirpings and quick 

 motions the simple, 'primitive form in 

 which gladness is expressed in the class of 

 birds. In the various species of the genus 

 Cnipolegus . . . the difference in the 

 sexes is just as great as in the case of the 

 troopial; the solitary, intensely black, sta- 

 tuesque male has . . . a set and highly 

 fantastic performance; but on more than 

 one occasion I have seen four or five females 

 of one species meet together and have a lit- 

 tle simple performance all to themselves 

 in form a kind of lively mock-fight. HUD- 

 SON Naturalist in La Plata, ch. 19, p. 283. 

 (C. & H., 1895.) 



821 . DIFFERENCE IN WEARING OF 

 ROCKS BY ICE AND BY WATER Na- 

 ture's Distinctions also Those of Science. 

 The leveling and abrading action of water 

 on rock has an entirely different character 

 [from glacier action]. Tides or currents 

 driven powerfully and constantly against a 

 rocky shore, and bringing with them hard 

 materials, may produce blunt, smooth sur- 

 faces, such as the repeated blows of a ham- 

 mer on stone would cause; but they never 

 bring it to a high polish, because the grind- 

 ing materials are not held steadily down in 

 firm permanent contact with the rocky sur- 

 faces against which they move, as is the case 

 with the glacier. On the contrary, being 

 dashed to and fro, they strike and rebound, 

 making a succession of blows, and never a 

 continuous, uninterrupted pressure and fric- 

 tion. The same is true of all the marks 

 made on rocky shores against which loose 

 materials are driven by water-currents. They 

 are separate, disconnected, fragmentary; 

 whereas the lines drawTi by the hard ma- 

 terials set in the glacier, whether light and 

 fine or strong and deep, are continuous, often 

 unbroken for long distances and rectilinear. 

 AGASSIZ Geological Sketches, ser. ii, p. 35. 

 (H. M. &Co, 1896.) 



822. DIFFERENCE OF DEVELOP- 

 MENT PRODUCES DIFFERENCE OF 

 CHARACTER Among Bees, Workers Are 



But Undeveloped Queens. The " workers " 

 among hive-bees are not really "neuters," 

 but are undeveloped females; every one of 

 them being originally a potential queen. 

 They differ from the queen, or fertile female, 

 however, not merely in the non-development 

 of the reproductive organs (which shows it- 

 self in the inferior length of the abdomen ) , 

 but also in the possession of the " pollen- 

 baskets " on the thighs, which are used in 

 the collection of pollen and propolis, and in 

 the conformation of the jaws and antennae. 

 But they differ yet more in their instincts, for 

 whilst the life-work of the queen is to lay 

 eggs, that of the workers is to build cells 

 for their reception, to collect and store up 

 food, and to nurture the larvae this nur- 

 turing process being continued as a sort of 

 incubation during the pupa-state. The 

 worker- larvae, which come forth from the 

 eggs that are laid in ordinary cells, are fed 

 for three days upon a peculiar substance of 

 jelly like appearance, prepared in the stom- 

 achs of the workers; but afterwards upon 

 " bee-bread " composed of a mixture of honey 

 and pollen. The queen-larvae, on the other 

 hand, are reared in larger royal cells of pe- 

 culiar construction; and they are fed dur- 

 ing the whole of the larva-period upon the 

 substance prepared by the workers, which is 

 hence known as " royal jelly." The length 

 of time occupied in their development is dif- 

 ferent; the preliminary stages of the queen 

 being passed through in sixteen days, whilst 

 those of the worker require twenty-one. 



Now it sometimes happens that, from 

 some causes not understood, there is a fail- 

 ure in the production of young queens, so 

 that there are none forthcoming when 

 wanted. The workers then select either 

 worker-eggs or worker-larvae not yet three 

 days old, and around these they construct 

 " royal cells," by throwing together several 

 adjacent worker-cells and destroying the 

 larvae they contain. The selected larvae are 

 fed with the " royal jelly," and are treated 

 in every respect as queen-larvae; and in due 

 time they come forth as perfect queens 

 thus having had not only their bodily or- 

 ganization, but their psychical nature, essen- 

 tially altered by the nurture they have re- 

 ceived. CARPENTER Mental Physiology, ch. 

 2, p. 61. (A., 1900.) 



823. DIFFERENCE OF QUANTITY, 

 NpT OF QUALITY- Similarity of Feeble and 

 Violent Volcanic Eruptions. We are thus 

 led to the conclusion that the grand and ter- 

 rible appearances displayed at Vesuvius and 

 other volcanoes in a state of violent erup- 

 tion do not differ in any essential respect 

 from the phenomena which we have wit- 

 nessed accompanying the miniature out- 

 bursts of Stromboli. And we are convinced, 

 by the same considerations, that the forces 

 which give rise to the feeble displays in the 

 latter case would produce, if acting with 

 greater intensity and violence, all the mag- 

 nificent spectacles presented in the former. 

 In Vesuvius and Stromboli alike, the active 



