PECULIAR JUICES. 93 



great and mysterious secret, life performs a less impor- 

 tant part in the vegetable than in the animal economy. 



The secretions separated from the cambium by the 

 glands are of two descriptions : the one, destined to re- 

 main in the plant, is distinguished by the name of inter- 

 nal secretions, and is elaborated by glands of a cellular 

 form ; the other, intended to be conveyed out of the plant 

 as useless or detrimental to it, is for this purpose se- 

 creted by glands of a vascular form. 



The internal secretions are milk, resins, gums, gum 

 resins, manna, essential oils, and fixed oils. 



Emily. These are substances with which we are in 

 some measure acquainted, as I believe you explained 

 their chemical composition in our Conversations on 

 Chemistry. j 



Mrs. B. True ; but we are now to examine them rather 

 in a different point of view ; and I do not think I then 

 mentioned the secretion of vegetable milk. There are 

 three species of this fluid : the first is that which contains 

 opium, and is extracted from the juice of poppies, lettu- 

 ces, and some other plants ; it is almost always white, 

 but sometimes assumes a reddish or yellowish tint. 



The second contains caoutchouc, or elastic gum; which, 

 however different in appearance in the artificial state in 

 which we are acquainted with it, is naturally white and 

 liquid. i 



It is obtained from several different species of trees in 

 tropical climates, but principally from that which bears the 

 name of Hevea. 



When an incision is made in the stem, it flows from the 

 wound, and is collected on the surface of small moulds 

 of clay in the form of bottles, to which, being of a glu- 

 tinous nature, it adheres. It acquires consistence and 

 blackens in drying, and, when the coating of caoutchouc 

 is of a sufficient thickness, it is beaten to pulverise the 

 mould, which is then shaken out. 



507. Why is the chemistry of vegetables more advanced than that of 

 the animal kingdom! 508. The secretions separated from the cam- 

 bium are of two descriptions what is said of them! 509. What 

 are the internal secretions! 510. How many kinds of vegetable milk 

 are there! 511. Which is the first! 512. What is the second 

 kind! 513. From what is it obtained! 514. How is it obtained 

 and prepared! 



