418 THE UNIVERSE. 



years. Like the gold of California, this tree has caused 

 great social changes in the countries where it grows. 



In Caracas, in South America, grows the cow-tree, which, 

 when its trunk is wounded, furnishes an abundant supply of 

 milk, of which the traveller can confidently drink freely, for 

 it unites all the qualities of the milk of our domestic animal, 

 which it entirely replaces in some countries of America. 1 



One of the trees which yield our internal economy ser- 

 vices as important as the preceding is the butter-tree. It 

 furnishes the negroes of the Niger with a secretion which 

 they substitute for the ingredient used in our kitchens, and 

 with which they prepare all their food. It is sold abun- 

 dantly in their markets, where it is known as shea-butter. 



Nature offers us in profusion the greatest contrasts. On 

 one side, with generous and beneficent hand she lavishes 

 food and salutary remedies ; on the other, she only distils 

 poison, as though in the laboratory of Medea. 



Here we see opium perspiring like a milky dew from the 

 heads of our poppies, and becoming so indispensable to the 

 art of medicine that Sydenham, the Hippocrates of modern 

 times, said he would renounce his profession were he de- 

 prived of this powerful anodyne. There we behold the 

 poisons of belladonna, datura, and henbane by turns useful 

 and deadly. 



But no tree prepares in its invisible laboratories such 

 precious crystals as the cinchona ; nature offers us no other 



1 As respects the milk or cow-tree, paolo de vaca, as it is called in the country, 

 M. Boussingault, who at Humboldt's request analyzed its products, states that its 

 physical properties are exactly similar to those of cow's milk, except that it is a 

 little more viscous. It is remarkable for containing an enormous quantity of wax. 

 This substance constitutes the half of its weight. 



