POPULAR MISCELLANY. 



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ited. A pyrometer of platinum, in which 

 was measured the electrical resistance of 

 the metal when exposed to high tempera- 

 tures, was shown by Mr. Callendar. The 

 display of electrical apparatus also included 

 a very fine high-resistance galvanometer de- 

 signed by Prof. Oliver Lodge for physio- 

 logical work ; and a magnetic curve-traces 

 contributed by Prof. Ewing. An instrument 

 invented by Mr. John Anderton for project- 

 ing solids on a screen attracted much atten- 

 tion. Prof. Boys exhibited photographs of 

 flying bullets, and Dr. Isaac Roberts some 

 admirable photographs, chiefly of nebuliB, 

 showing the probable formation of heavenly 

 bodies. The marked success of the exhibi- 

 tion may lead to like collections being dis- 

 played at future meetings of the American 

 Association. 



Diversity of Forms and Conditions of 

 Animal Life. In a paper presented to the 

 Convention of the College Association of the 

 Middle States and Maryland, Dr. Spencer 

 Trotter, speaking of the diversity of life on 

 the earth's surface, remarks upon its corre- 

 spondence, in a broad way, with the diver- 

 sity of surroundings. Aquatic animals, like 

 fishes, crayfish, and many insects, inhabit the 

 waters of ponds, lakes, and streams. Frogs 

 and other amphibious creatures are denizens 

 of bays and streams. Some snakes and tur- 

 tles are aquatic, while others are wholly lov- 

 ers of the dry land. Birds are found in 

 every situation: ducks and divers on the 

 lakes and rivers; herons and bitterns in 

 marshy fens ; gulls and petrels on the open 

 sea ; sandpipers along the shores ; eagles 

 on lofty mountain peaks ; while a host of 

 species enliven the woods and fields. The 

 haunts of mammals are no less diversified. 

 The tree-loving squirrels, the burrowing 

 ground hog, the mole digging out its long 

 subterranean galleries, the water-loving bea- 

 ver and otter, are each and all associated 

 in the mind with their favorite surroundings. 

 The idea of the animal and its particular 

 home is not new. The story is told in pecul- 

 iar language in Psalm civ : " The cedars of 

 Lebanon, which he hath planted ; where the 

 birds make their nests : as for the stork, the 

 fir trees are her house. The high hills are a 

 refuge for the wild goats ; and the rocks for 

 the conies." If this diversity of life is so 



apparent in a limited area, it is far more so 

 when we come to journey over an extended 

 portion of the earth's surface. As the hori- 

 zon widens newer and more significant fea- 

 tures rise into view. Lofty mountain ranges, 

 broad seas, trackless deserts, treeless plains, 

 and vast forests successively present them- 

 selves. Climate and vegetation change from 

 one region to another, and it is not a matter 

 of surprise to find corresponding changes in 

 animal life. Many kinds of animals are 

 limited to particular regions, while others 

 range through wide areas of country under 

 a variety of physical changes. A traveler 

 starting on the Atlantic seaboard of the 

 United States and journeying westward along 

 the fortieth parallel will pass successively 

 through a number of distinct regions, each 

 characterized by certain conditions of cli- 

 mate, vegetation, and peculiar animals. A 

 number of familiar forms will, however, be 

 found throughout the entire extent of the 

 journey across the continent. If the traveler 

 cross the Pacific to Japan, he will find forms 

 of familiar types, though the species are all 

 different from those he knew in America. 

 Should he sail westward by the shortest route 

 to England, he would pass the shores of 

 countries wholly different from those he had 

 left and from each other, each tenanted by 

 strange forms of life beasts, birds, reptiles, 

 insects, and vegetation distinct from any he 

 had previously seen. In England, he would 

 be struck by the likeness of the birds to 

 those of Japan, while he would see none of 

 the familiar species of North American birds. 

 We learn from a survey of these conditions 

 how intimately related an animal is to the 

 earth, and how each species is fitted to the 

 special conditions of the region it inhabits. 



Crocodiles, Alligators, and the Heloderm. 



Crocodiles from the Nile, India, and Ceylon 

 share the tanks at the London Zoological Gar. 

 dens with the alligators from America. The 

 crocodile, says an English writer who has ob- 

 served them, evidently bears the same anal- 

 ogy to the alligator as the frog to the toad. 

 It is lighter in color and in build, and a more 

 active as well as a more malicious creature. 

 It is not so entirely hideous, though the lower 

 jaw shows projecting tusks like those of a 

 wild boar. The creature's eyes, celebrated 

 in connection with the "crocodile tears" 



