93 



SCIENTIFIC SIDE-LIGHTS 



Chance 

 Change 



by Pressure. In order to produce chemical 

 changes in bodies, it is usually necessary 

 that one at least be a liquid or be in a state 

 of solution, and the combinations that occur 

 lead to the production of bodies having 

 quite different properties from either of 

 their components. Similar results occur 

 when metals are mixed together, forming 

 alloys. Thus a mixture in certain propor- 

 tions of lead, tin, bismuth, and cadmium 

 produces an alloy which melts in boiling 

 water, while the component metals only 

 melt at double that temperature or more. 

 Again, the strength of gold is doubled by 

 the addition of one-five-hundredth part of 

 the rare metal zirconium, indicating that 

 the alloy must have a new arrangement of 

 the molecules. But the interesting point is 

 that alloys can be produced without melting 

 the metals, for mere pressure often produces 

 an alloy at the surfaces of contact; while 

 in other cases, if fine filings of the com- 

 ponent metals are thoroughly mixed to- 

 gether and then subjected to continued pres- 

 sure, true alloys are produced. WALLACE 

 The Wonderful Century, ch. 7, p. 56. (D. 

 M. & Co., 1899.) 



460. CHANGE OF CLIMATE OF NORTH 

 AMERICA Once the Home of Mastodon, Mam- 

 moth, and Camel. Of the remains of verte- 

 brates, the bones of the mastodon or mam- 

 moth, and of the ox, camel, and horse, have 

 been found in the sediments of Lake Lahon- 

 tan, together with a single undetermined 

 fish. The bones of a musk-ox were obtained 

 near Salt Lake City under such conditions 

 that it is believed they were buried in the 

 upper strata of the Bonneville sediments. 

 . . . The mastodon and mammoth roamed 

 over nearly the whole of North America 

 during Pleistocene times, but have since be- 

 come extinct. The camel is no longer found 

 on this- continent, and the horse was ex- 

 tinct before the coming of the white man. 

 The musk-ox is now found only far to the 

 north. The extinction of some of these large 

 animals, and the scattering of others to dis- 

 tant regions, suggests the lapse of a long 

 period of time since they lived together 

 where their remains are now found, and also 

 points to great changes in climatic and 

 other elements of their environment. RUS- 

 SELL Lakes of North America, ch. 6, p. 114. 

 (G. &Co., 1895.) 



461. CHANGE OF COLOR AS THE 

 EFFECT OF SIGHT The Chameleon Flat- 

 fish Variable Protective Coloring. [In 

 some cases] the change [of color] is caused 

 by reflex action set up by the animal seeing 

 the color to be imitated, and the change pro- 

 duced can be altered or repeated as the ani- 

 mal changes its position. . . . The most 

 striking example ... is that of the 

 chameleon, which changes to white, brown, 

 yellowish, or green, according to the color of 

 the object on which it rests. This change is 

 brought about by means of two layers of 

 pigment cells, deeply seated in the skin, and 



of bluish and yellowish colors. By suitable 

 muscles these cells can be forced upwards so 

 as to modify the color of the skin, which, 

 when they are not brought into action, is a 

 dirty white. These animals are excessively 

 sluggish and defenseless, and the power of 

 changing their color to that of their imme- 

 diate surroundings is no doubt of great serv- 

 ice to them. Many of the flatfish are also 

 capable of changing their color according to 

 the color of the bottom they rest on. WAL- 

 LACE Darurinism, ch. 8, p. 133. (Hum., 1889.) 



462. CHANGE OF EYES TO SUIT EN- 

 VIRONMENT IN DEEP-SEA ORGANISMS 



If the animals that now live in the depths 

 of the sea are descended from the shallow- 

 water forms of bygone epochs, they must 

 have passed through many different habi- 

 tats with diminished light until they 

 reached their present dark abode in the 

 abyss. In every new region they came to, 

 the forms with larger and better eyes would 

 be at an advantage in the fainter light, and 

 would be more likely to survive and trans- 

 mit their favorable variation in this respect 

 to their offspring, than their less fortunate 

 neighbors. Thus down to the depth of the 

 limit of sunlight we should expect to find, 

 as we do find in fishes, large-eyed species. 

 HICKSON Fauna of the Deep Sea, ch. 4, p. 

 74. (A., 1894.) 



463. CHANGE OF FORMS FROM AN- 

 CIENT TO MODERN The Chambered Nau- 

 tilus. The chambered nautilus is familiar 

 to all, since, from the exquisite beauty of its 

 shell, it is especially sought for by con- 

 chologists ; but it is nevertheless not so com- 

 mon in our days as the squids and cuttle- 

 fishes, which are the most numerous modern 

 representatives of the class. In the earliest 

 geological days, on the contrary, those with 

 a shell predominated, differing from the 

 later ones, however, in having the shell per- 

 fectly straight instead of curved, tho its 

 internal structure was the same as it is now 

 and has ever been. Then, as now, the ani- 

 mal shut himself out from his last year's 

 home, building his annual wall behind him, 

 till his whole shell was divided into suc- 

 cessive chambers, all of which were con- 

 nected by a siphon. Some of the shells of 

 this kind belonging to the Silurian deposits 

 are enormous: giants of the sea they must 

 have been in those days. They have been 

 found fifteen feet long, and as large round 

 as a man's body. AGASSIZ Geological 

 Sketches, ser. i, ch. 2, p. 49. (H. M. & Co., 

 1896.) 



464. CHANGE OF HABITS IN A BIRD 



The Kea (Parrot) of New Zealand. The 

 kea (Nestor notabilis) is a curious parrot 

 inhabiting the mountain ranges of the Mid- 

 dle Island of New Zealand. It belongs to 

 the family of brush-tongued parrots, and 

 naturally feeds on the honey of flowers and 

 the insects which frequent them, together 

 with such fruits or berries as are found in 



