338 WHAT LATEX IS; [BOOK n. 



them. These vessels pass through and round the different 

 organs, particularly the cells of the secreting organs, like 

 a fine spider's web, and are visible in many plants, for 

 example, in the species of Caladium and Arum, even after 

 maceration." 



3. The latex is a highly elaborated and highly organised 

 juice, which is not formed immediately from the fluid nu- 

 trient matter absorbed from without. It is usually viscid, 

 insoluble in water, often opake, coloured white, yellow, red, 

 brown, and is also often transparent and colourless; differ- 

 ences that result from the nature of the organised globules 

 it contains, which, according to M. Schultz, constitute the 

 living part of the latex. These globules have an oscillating 

 motion, and, like the globules of blood, they coagulate, and 

 the liquid part becomes transparent. In many plants which, 

 when old, have a milky latex, it is colourless when they are 

 young ; this depends upon the degree of concentration of the 

 latex. Upon exposure to the air, latex separates into a 

 coagulum of a tenacious elastic quality, and a serum, the 

 former being sometimes analogous to caoutchouc. This pro- 

 perty is not found in any other vegetable secretions. If we 

 consider the organisation of the latex, the globules it con- 

 tains, its property of coagulating and separating into serum 

 and a sort of fibrin e, we are tempted to believe that there 

 exists a considerable analogy between it and the blood of 

 animals. By these marks the latex may be known from 

 ethereal oil, resin, gum, and other secretions sometimes found 

 in the interior of parenchyma, and which are always trans- 

 parent and destitute of globules. Nevertheless, Link has 

 unaccountably confounded with cinenchyma the turpentine 

 vessels of Conifers. (Elementa, ed. 2., i. 196.) 



4. The latex itself originates in the sap, which rises by the 

 tissue of the wood, and introduces itself into the foliaceous 

 organs, thence, after being elaborated, passing into the bark, 

 where it is deposited in the vessels in its mature form. De 

 la Baisse caused a Euphorbia to pump up water coloured red ; 

 the liquid ascended in the wood, reached the leaves, tinged 

 the latex, and the colour spread from above downwards in 

 the bark : but M. Schultz only twice succeeded, after many 

 attempts, at obtaining this result. 



