241 



SCIENTIFIC SIDE-LIGHTS 



xtremes 



rays of sunlight do penetrate even to the 

 greatest depths of the ocean a view mainly 

 based on the fact that so many deep-sea ani- 

 mals possess extremely perfect and compli- 

 cated eyes and very brilliant color. . . . 

 There seem to me to be very slight grounds 

 for this view. HICKSON Fauna of the Deep 

 Sea, ch. 2, p. 23. (A., 1894.) 



1176. 



Difference in Dif- 



ferent Zones. In the majority of cases [of 

 deep-sea animals] we find that the eyes are 

 either very large or very small. Only in a 

 small minority of cases do we find that the 

 eyes are recorded to be moderate in size. 

 The relation between the large-eyed forms 

 and the small-eyed forms is not the same in 

 all the regions of deep seas. In depths of 

 300 to 600 fathoms the majority are large- 

 eyed forms. In depths of over 1,000 fath- 

 oms, the small-eyed and blind forms are in 

 a majority, altho many large-eyed forms are 

 to be found. HICKSON Fauna of the Deep 

 Sea, ch. 4, p. 68. (A., 1894.) 



1177. FABLE FOUNDED ON FACT 



Story of the Avernian Lake Deadly Exha- 

 lations of Volcanoes. Many volcanoes, which 

 have sunk into a state of quiescence or ex- 

 tinction like the Solfatara of Naples, exhibit 

 the same tendency to give off great quanti- 

 ties of the powerfully acid gases which act 

 upon the surrounding rocks. . . . At 

 the so-called Grotto del Cane, beside the 

 Lago Agnano, it is the custom to show the 

 presence of this heavy and poisonous gas by 

 thrusting a dog into it, the poor animal 

 being revived before life is quite extinct by 

 pouring cold water over it. At the Biidos 

 Hegy, or " stinking hill," of Transylvania, 

 carbonic acid and sulfureted hydrogen are 

 emitted in considerable quantities, and it is 

 possible to take a bath of the heavy gas, the 

 head being kept carefully above the constant 

 level of the exhalations. 



Altho the stories of the ancient Avernian 

 lake, across which no bird could fly without 

 suffocation, and of the Guvo Upas, or 

 " Poison Valley," of Java, which it has been 

 said no living being can cross, may not im- 

 probably be exaggerations of the actual 

 facts, yet there is a basis of truth in them 

 in the existence of old volcanic fissures and 

 craters which evolve the poisonous sulfu- 

 reted hydrogen and carbonic acid gases. 

 JUDD Volcanoes, ch. 8, p. 214. (A., 1899.) 



1178. FABLES ABOUT ORANG The 



orang never stands on its hind legs, and all 

 the pictures representing it as so doing are 

 as false as the assertion that it defends it- 

 self with sticks and the like. HUXLEY 

 Man's Place in Nature, p. 207. (Hum.) 



1179. FACILITY BECOME A SNARE 



Body Holds Perverted Habit The Motor 

 Memory a Source of Difficulty as well as of 

 Advantage. It is by means of the motor 

 memory that we are able to walk, ride, and 

 skate with ease, and if it were not for it we 

 should have the movement cease directly 



the attention was suspended or temporarily 

 transferred to some other object. Occa- 

 sionally, the motor memory is found incon- 

 venient, on account of its having become so 

 firmly established in an erroneous direction 

 as to require every effort of the will to over- 

 come it and establish a new action. Every 

 teacher of dancing, riding, or boxing knows 

 how difficult it is to break a pupil of any 

 habit he may have formed. A boxer, for 

 instance, who has for some_considerable time 

 raised his right arm every time he strikes 

 with the left, will find the greatest difficulty 

 in striking with the left and keeping the 

 right still. Examples might be given from 

 all classes of coordinated actions, there be- 

 ing often more trouble in unlearning some 

 erroneous movement than would have been 

 required to learn the new one two or three 

 times over. ELDRIDGE-GREEN Memory and 

 Its Cultivation, pt. i, ch. 4, p. 26. (A., 

 1900.) 



1180. FACT NEEDED TO CORRECT 

 THEORY Descartes Supposed Transmission 

 of Light Instantaneous Ingenious Illustra- 

 tion of a Staff. Descartes imagined space 

 to be filled with something that transmitted 

 light instantaneously. Firstly, because, in 

 his experience, no measurable interval was 

 known to exist between the appearance of 

 a flash of light, however distant, and its 

 effect upon consciousness; and secondly, 

 because, as far as his experience went, no 

 physical power is conveyed from place to 

 place without a vehicle. But his imagina- 

 tion helped itself farther by illustrations 

 drawn from the world of fact. " When," 

 he says, " one walks in darkness with staff 

 in hand, the moment the distant end of the 

 staff strikes an obstacle the hand feels it. 

 This explains what might otherwise be 

 thought strange, that the light reaches us 

 instantaneously from the sun. I wish thee 

 to believe that light in the bodies that we 

 call luminous is nothing more than a very 

 brisk and violent motion, which, by means 

 of the air and other transparent media, is 

 conveyed to the eye exactly as the shock 

 through the walking-stick reaches the hand 

 of a blind man. This is instantaneous, and 

 would be so even if the intervening distance 

 were greater than that between earth and 

 heaven. It is therefore no more necessary 

 that anything material should reach the eye 

 from the luminous object than that some- 

 thing should be sent from the ground to 

 the hand of the blind man when he is con- 

 scious of the shock of his staff." The cele- 

 brated Robert Hooke first threw doubt upon 

 this notion of Descartes, but afterwards sub- 

 stantially espoused it. The belief in instan- 

 taneous transmission was destroyed by the 

 discovery of Homer [of the measurable ve- 

 locity of light]. TYNDALL Lectures on 

 Light, lect. 2, p. 44. (A., 1898.) 



1181. FACT SURPASSES THEORY 



Life in Torrid Heat and Arctic Cold Life 

 in Other Worlds. For instance, if we did 



