iisar- 



SCIENTIFIC SIDE-LIGHTS 



375. BLACKNESS OF ATLANTIC 

 DEPTHS Reflection Necessary To Give Color 

 Solid Particles in Suspension Give the 

 Green Hue to Shoal Water. If, then, we 

 render water sufficiently deep to quench all 

 the light, and if from the interior of the 

 water no light reaches the eye, we have the 

 condition necessary to produce blackness. 

 Looked properly down upon there are por- 

 tions of the Atlantic Ocean to which one 

 would hardly ascribe a trace of color: at 

 the most a tint of dark indigo reaches the 

 eye. The water, in fact, is practically black, 

 and this is an indication both of its depth 

 and purity. But the case is entirely 

 changed when the ocean contains solid par- 

 ticles in a state of mechanical suspension, 

 capable of sending light back to the eye. 

 Throw, for example, a white pebble into the 

 blackest Atlantic water; as it sinks it be- 

 comes greener and greener, and, before it 

 disappears, it reaches a vivid blue green. 

 Break such a pebble into fragments, these 

 will behave like the unbroken mass ; grind 

 the pebble to powder, every particle will 

 yield its modicum of green; and if the par- 

 ticles be so fine as to remain suspended in 

 the water, the scattered light will be a uni- 

 form green. Hence the greenness of shoal 

 water. You go to bed with the black water 

 of the Atlantic around you. You rise in the 

 morning, find it a vivid green, and correctly 

 infer that you are crossing the bank of 

 Newfoundland. Such water is found charged 

 with fine matter in a state of mechanical 

 suspension. The light from the bottom may 

 sometimes come into play, but it is not nec- 

 essary. The subaqueous foam generated by 

 the screw or paddle-wheels of a steamer also 

 sends forth a vivid green. The foam here 

 furnishes a reflecting surface, the water be- 

 tween the eye and it the absorbing medium. 

 TYNDALL Lectures on Light, lect. 1, p. 35. 

 (A., 1898.) 



376. BLINDNESS OF INSTINCT 



Squirrel Burying Nut. [The following] in- 

 stance is given by Dr. H. D. Schmidt, of 

 New Orleans, in the " Transactions of 

 American Neurological Association," vol. i, 

 p. 129 (1875) : " I may cite the example of 

 a young squirrel which I had tamed, a num- 

 ber of years ago, when serving in the army, 

 and when I had sufficient leisure and oppor- 

 tunity to study the habits of animals. In 

 the autumn, before the winter sets in, adult 

 squirrels bury as many nuts as they can col- 

 lect, separately, in the ground. Holding the 

 nut firmly between their teeth, they first 

 scratch a hole in the ground, and, after 

 pointing their ears in all directions to con- 

 vince themselves that no enemy is near, 

 they ram the head, with the nut still be- 

 tween the front teeth, serving as a sledge- 

 hammer the nut into the ground, and then 

 fill up the hole by means of their paws. 

 The whole process is executed with great 

 rapidity, and, as it appeared to me, always 

 with exactly the same movements; in fact, 



it is done so well that I could never dis- 

 cover the traces of the burial-ground. Now, 

 as regards the young squirrel, which, of 

 course, never had been present at the burial 

 of a nut, I observed that, after having eaten 

 a number of hickory-nuts to appease its ap- 

 petite, it would take one between its teeth, 

 then sit upright and listen in all directions. 

 Finding all right, it would scratch upon the 

 smooth blanket on which I was playing 

 with it as if to make a hole, then hammer 

 with the nut between its teeth upon the 

 blanket, and finally perform all the motions 

 required to fill up a hole in the air; after 

 which it would jump away, leaving the nut, 

 of course, uncovered." JAMES Psychology, 

 vol. ii, ch. 24, p. 400. (H. H. & Co., 1899.) 



377. BLOOD-BROTHERHOOD A Sym- 

 bol of Duty and Truth Owed Only to 

 Kindred. In the old days, before there were 

 lawyers and law-books, solemn acts and 

 rights were made plain to all men by pic- 

 turesque ceremonies suited to lay hold of 

 unlettered minds. Many of these old cere- 

 monies are still kept up and show their 

 meaning as plainly as ever. For example, 

 when two parties wish to make firm peace 

 or friendship, they will go through the cere- 

 mony of mixing their blood, so as to make 

 themselves blood-relations. Travelers often 

 now ally themselves in such blood-brother- 

 hood with barbarous tribes; an account of 

 East Africans performing the rite describes 

 the two sitting together on a hide so as to 

 become " of one skin," and then they made 

 little cuts in one another's breasts, tasted 

 the mixed blood, and rubbed it into one an- 

 other's wounds. Thus we find still going on 

 in the world a compact which Herodotus 

 describes among the ancient Lydians and 

 Scythians, and which is also mentioned in 

 the sagas of the old Northmen and the an- 

 cient Irish legends. It would be impossible 

 to put more clearly the great principle of 

 old-world morals, that a man owes friend- 

 ship not to mankind at large, but only to his 

 own kin, so that to entitle a stranger to 

 kindness and good faith he must become a 

 kinsman by blood. With much the same 

 thought even rude tribes hold that eating 

 and drinking together is a covenant of 

 friendship, for the guest becomes in some 

 sort one of the household, and has to be 

 treated as morally one of the family. This 

 helps to explain the vast importance people 

 everywhere give to the act of dining to- 

 gether. TYLOR Anthropology, ch. 16, p. 423. 

 (A., 1899.) 



378. BLOOD, CAUSE OF COLOR OF 



Work of the Red Corpuscles " The Life of 

 All Flesh Is the Blood" (Lev. xvii, 14). 

 When a very thin film of blood is placed 

 under a microscope of sufficient power, we 

 observe that, so far from being a uniformly 

 red fluid, blood is really as colorless as 

 water. This apparent "paradox between 

 what we see with the unassisted sight and 





