OF PLANTS. 189 



South America is the country which supplies the largest 

 quantity of Caoutchouc for this great demand ; but a great 

 deal is also imported from the East Indies, and even 

 Africa might furnish it, if the social condition of the 

 natives did not oppose itself to their availing themselves of 

 their indigenous resources. All the countries which count 

 Caoutchouc among their products, belong to the torrid 

 zone. A. von Humboldt, in his " Ideas of a Geography of 

 Plants," remarked, that the plants yielding milky juices 

 multiply as we approach the tropics. This milky juice 

 of plants it is which contains the peculiar elastic substance. 

 The tropical heat seems to exert a distinct influence in its 

 perfect formation, for it has been remarked, that the same 

 plants which, under the equator, yield abundance of 

 Caoutchouc, contain instead, with us, even in hot-houses, a 

 substance which resembles the bird-lime obtained from our 

 native Misletoe. 



Who among my readers has not seen our indigenous 

 Wolf's-milk or Spurge, the white milky juice of which 

 popular superstition recommends as a remedy against 

 warts ? Who has not in youth at least become acquainted 

 with the Celandine, from the broken stalk and leaf of 

 which, a bright orange-coloured juice runs out ? Who has 

 not observed that the Lettuce, when it has run up to 

 flower, ejects a milk-white fluid at the slightest touch? 

 But the occurrence of milky juices in plants is not limited 

 to these few. The vegetable world presents to us most 

 useful as also poisonous matters in this milky sap, and 

 I will content myself at present with recalling to recollec- 

 tion Opium, the dried milky juice of our large garden 

 Poppy. 



A great number of plants, which principally belong to 

 three great families, namely, the Spurges, the Apocynaceee 



