POPULAR MISCELLANY. 



709 



rising. Dr. W. Weiss read a paper before 

 the Berlin Geographical Society at a recent 

 meeting, in which he advanced the theory, 

 founded on a comparison of observations 

 which had been made at the mouths of riv- 

 ers, that the continent is rising. The Isthmus 

 of Panama seems to be rising, and signs of 

 elevation are apparent on the north coast of 

 the continent. The delta of the Magdalena 

 River has suffered notable changes within 

 comparatively recent times. The tertiary 

 highland of Turbaco, which extends from 

 Carthagena to Sabanilla, was once an island 

 in front of the stream, as is indicated by 

 the forking of the river. One arm of the 

 river empties toward the west near Cartha- 

 gena, the other arm forms the present mouth 

 with its branches in the lagoon of Santa 

 Marta ; ships formerly sailed into the west- 

 ern arm, which is not now navigable. The 

 closing of this branch is generally ascribed 

 to the luxuriant vegetation, but it is more 

 than probable that other causes were com- 

 bined with it. A small elevation would be 

 enough to stop the flow of water, and the 

 fact that such an elevation has taken place 

 is shown by the discovery of recent shell- 

 beds in a part of the lagoon. The bay of 

 Santa Marta, with its monotonous sand-flats 

 between steep, bald cliffs and island-like up- 

 rising knobs, produces the impression of a 

 recently dried sea-bottom. Similar appear- 

 ances are presented farther east, to such an 

 extent that it was believed in the sixteenth 

 century that the sea had retreated. The 

 region of the lagoon of Maracaybo, and in- 

 deed the whole coast of Venezuela, appears 

 to have taken part in a movement of up- 

 rising. The existence of the delta of the 

 Orinoco favors the theory of elevation, for, 

 though it can not be held that deltas are 

 not formed except where the ground is rising, 

 it is nevertheless true that elevation is most 

 favorable to their formation. The observa- 

 tions along the coast of the British, French, 

 and Dutch possessions are contradictory ; 

 but as a whole they seem to indicate that 

 the land is gaining on the sea. The charac- 

 ter of the changes that are taking place at 

 the mouth of the Amazon is generally sup- 

 posed to indicate a sinking of the land, but 

 there are circumstances that favor the op- 

 posite view. The signs that the upper part 

 of the bed of the river is rising are numer- 



ous, and all the phenomena of washing away 

 at the mouth which are generally considered 

 evidences of a depression can be accounted 

 for by supposing that the interior is rising 

 faster than the coast. Indications of a re- 

 cent elevation may be seen all along the 

 coast from Cape St. Roque to the La Plata, 

 in the hardened shore-ridge3 of the Rio 

 Grande do Norte, Parahyba, and Pernam- 

 buco, the elevated shore-lines of Rio Ver- 

 miglio, Bahia, and Rio Jequitinhonha, the 

 coral reefs of the Abrolhos, the holes of the 

 sea-urchin found above the level of the sea 

 near Cape Frio, the new formations near 

 Rio de Janeiro, the deterioration of the har- 

 bors of Santa Catarina, Porto Alegre, and 

 other places. Darwin proved by the discov- 

 ery of recent shell-deposits that the region 

 of the La Plata was rising ; since then some 

 facts have been adduced pointing to a sink- 

 ing, but the La Plata affords relations simi- 

 lar to those which have been referred to in 

 the case of the Amazon. A lake in the 

 Straits of Magellan containing marine ani- 

 mals, but situated at a higher level than 

 that of the sea, is cited by Agassiz in proof 

 that a rise of the land has taken place there. 

 On the west coast signs of a sinking appear 

 in the Chonos Archipelago, but they give 

 way to trustworthy evidences of elevation 

 in southern Chili. These continue to Callao 

 and Lima, where a sinking is suddenly indi- 

 cated. The land at Callao consists of grav- 

 el-beds, which may be considered as river and 

 shore formations. "Washings away from be- 

 neath, assisted by earthquakes, might readi- 

 ly have caused slight local falls, without 

 making it necessary to invoke a sinking of 

 the land. Not enough is known of the 

 coasts north of Callao to justify a definite 

 expression of opinion. 



The Law of Mutual ITelp. At the Con- 

 gress of Russian Naturalists and Physicians, 

 held in January last, Professor K, Kessler 

 delivered an address on the law of mutual 

 help, which he urged was entitled to a place 

 by the side of Darwin's law of the struggle 

 for existence. Having given a brief sketch 

 of the theory of the struggle for existence, 

 Professor Kessler remarked that it did not 

 play the only part in organic development. 

 By the operation of the reproductive in- 

 stinct, there was developed in the different 



