Cnapter 21 



LATEX-PRODUCING PLANTS 



In many plants there occurs a white or colored emulsion 

 known as latex, which consists of a watery liquid holding in sus- 

 pension within it a variety of minute particles or globules of 

 other chemical substances. When exposed to the air, or subjected 

 to chemical treatment, these latex substances usually separate 

 or coagulate. Their actual value to the plant has not been 

 definitely determined, but since latex coagulates upon exposure 

 to air, which happens only when wounding of the plant occurs, 

 it may well be a protective device which prevents drying of plant 

 tissues and entrance of parasitic organisms under such conditions. 



Rubber is by far the most important latex product known to 

 man at the present time. Over fifty species of plants are known 

 to yield rubber, not all of them in the form of latex, as will be 

 pointed out later; but only a few species are of commercial im- 

 portance at present. Rubber is the youngest of the world's major 

 crop plants; it has been under cultivation for only a little over 

 fifty years, and has been used industrially for only one hundred 

 years. British possessions, Malaya, Ceylon, India and Borneo, 

 and the Dutch East Indies are the world's rubber producing 

 centers today. 



Rubber was first brought to the attention of European 

 civilization when Columbus reputedly brought back crude 

 bouncing balls fashioned out of it by West Indian natives. Later, 

 Brazilian natives were found waterproofing footwear with coats 

 of latex. It was not until the middle of the eighteenth century 

 that French explorers discovered the source of rubber in South 

 America to be the now famous Brazilian rubber tree. The early 

 French name for rubber was "caoutchouc," a French rendition 

 of the Indian "cahuchu" or weeping tree, so called because of 

 its tear-like exudations of latex. The present day term rubber 



359 



