274 PHYSIOGNOMY OF PLANTS. 



artifices and modes of capture among nations who are entirely un- 

 connected with each other. 



Although, as we have already remarked, the zone included 

 between 22 or 24 degrees of latitude on either side of the equator, 

 appears to be the true region of the calcareous saxigenous litho- 

 phytes which raise wall-like structures, yet coral reefs are also found, 

 favored it is supposed by the warm current of the Xrulf Stream, in 

 lat. 32 23', at the Bermudas, where they have been extremely well 

 described by Lieutenant Nelson. (Transactions of the Geological 

 Society, 2d Series, 1837, vol. v. pt. i. p. 103.) In the southern 

 hemisphere, corals (Millepores and Cellepores) are found singly as 

 far south as Chiloe, the Archipelago of Ohonos, and Tierra de Fuego, 

 in 53 lat. ; and Retepores are even found in lat. 72 J. 



Since the second voyage of Captain Cook there have been many 

 defenders of the hypothesis put forward by him as well as by Rein- 

 hold and George Forster, according to which the low coral islands 

 of the Pacific have been built up by living creatures from the depths 

 of the bottom of the sea. The distinguished investigators of nature, 

 Quoy and Graimard, who accompanied Captain Freycinet in his 

 voyage round the world in the frigate Uranie, were the first who 

 ventured, in 1823, to express themselves with great boldness and 

 freedom in opposition to the views of the two Forsters (father and 

 son), of Flinders and of Pe*ron. (Annales des Sciences Naturelles, 

 t. vi. 1825, p. 273.) "En appelant 1' attention des naturalistes sur 

 les animalcules des coraux, nous esperons de"montrer que tout ce 

 qu'on a dit ou cru observer jusqu'& ce jour relativement aux im- 

 menses travaux qu'il sont susceptibles d'ex&juter, est le plus souvent 

 inexact et toujours excessivement exagere. Nous pensons que les 

 coraux, loin d' Clever des profondeurs de I'oc&in des murs perpendicu- 

 laires, ne forment que des couches ou des encroutemens de quelques 

 toises d'e*paisseur." Quoy and Graimard also propounded (p. 289) 

 the conjecture, that the Atolls (coral walls enclosing a lagoon) pro- 

 bably owed their origin to submarine volcanic craters. Their 

 estimate of the depth below the surface of the sea at which the 

 animals which form the coral reefs (the species of Astraea, for 

 example) could live, was doubtless too small, being at the utmost 

 from 25 'to 30 feet (26| to 32 E). An investigator and lover of 



