A YO UNG NA TURALIST. 1 6 S 



great catastrophes is past. The molten matter solidified on the 

 surface, as it became cool, and then water made its appearance, 

 and transformed and rendered habitable the thin crust on which 

 we live, the thickness of which is so inconsiderable when com- 

 pared with the bulk of the globe." 



" What is this molten matter composed of which is burning 

 under our feet ? " 



" The same substances which we see around us — granite, por- 

 phyry, and basalts, which are called igneous or Vulcanian rocks, 

 as contrasted with the Neptunmn rocks, such as gypsum or lime, 

 clay and sandstone, the agglomeration of which is attributed to 

 water. The science which deals with these subjects is called 

 geology, a study with which, some day, you will be delighted." 



" Then all Vulcanian rocks can be melted 1 " 



" Yes, if they were subject to as great a heat as that existing 

 in the centre of the earth, which reaches an intensity at whicli 

 the imagination recoils. But to return to the subject of caves. 

 Some have been produced by the dissolving action of water. 

 Thus, at some future date, the spring which we saw gushing out 

 from the fallen mountain might dry up or^alter its direction, and 

 leave for the curiosity of future travellers the sight of chambers 

 full of stalactites such as we have inspected." 



Our geological chat was interrupted by an exclamation from 

 I'Encuerado, who had just discovered a tree which the Mexicans 

 call " the tree of St Ignatius." Its fruit is of a brown colour, 

 with a woody husk, something like small melons, which, as they 

 hang on the tree, strike against one another with a sharp sound. 

 L'Encuerado informed Lucien that this fruit is in the habit of 

 bursting suddenly with a loud explosion, and that the flat beans 

 which they contain are much used as medicine. 



Sumichrast led the way through the forest, where we were 

 sheltered under the tall trees. After a somewhat long ramble, 

 during which we met with nothing but magpies, I requested 

 I'Encuerado to guide us back to our bivouac. All of a sudden, 

 my friend enjoined silence ; an opossum, followed by five young 

 ones, was coming near us on our left. The animal indolently 

 approached a tree of middling size, which it climbed, aided 



