PHYSIOGNOMY OF PLANTS. 19 



of a forest of tree mosses to its discoverer. Tlie absolute 

 size and the degree of development attained by organic 

 forms of the same family (whether plants or animals), de- 

 pend on laws which are still unknown to us. In each of 

 the great divisions of the animal kingdom, insects, Crustacea, 

 reptiles, birds, fishes, or mammalia, the size of the body 

 oscillates between certain extreme limits. But these limits, 

 which have been established by observation as far as it has 

 yet gone, may be corrected by the discovery of species with 

 which we are still unacquainted. 



In land animals the higher temperatures of the low 

 latitudes appear to have favoured organic development. 

 The small and slender form of our lizards is exchanged in 

 the south for the gigantic, heavy, and cuirassed bodies of 

 crocodiles. In the formidable tiger, lion, and jaguar, we 

 see repeated, on a larger scale, the form of the common cat. 

 one of the smallest of our domestic animals. If we penetrate 

 into the interior of the earth, and search the cemeteries in 

 which the plants and animals of the ancient world lie 

 entombed, the fossil remains which we discover not only 

 announce a distribution inconsistent with our .present 

 climates, they also disclose to us gigantic forms that 

 contrast no less with those which now surround us, than 

 does the simple heroism of the Greeks with the character of 

 human greatness in modern times. Has the temperature 

 of our planet undergone considerable changes, possibly 

 of periodical recurrence ? If the proportion between land 

 and sea, and even the height , of the aerial ocean and its 

 pressure, ( 14 ) have not always been the same, the pliysiog- 



