98 SECRETION. 



104. The second class containing juices in which 

 Caoutchouc predominates, includes those plants yielding 

 Indian Rubber, as Siphonia cahuca, etc. ; but this 

 substance is also found in the juice of many other 

 plants, though in less quantity, as in Papavaracece, Com- 

 positce, etc. It has been shown that in the juice of the 

 young branches of Ficus elastica, instead of caout- 

 chouc, Viscin is found, whilst in the other parts of the 

 tree no viscin, but caoutchouc is seen. It is probable 

 that this viscin is an incomplete state of caoutchouc, 

 containing a considerable quantity of water, which af- 

 terwards becomes converted into the latter substance at 

 the leaves. A substance closely resembling it is to be 

 found in the common Fig. 



105. The third class whose juices contain consider- 

 able quantities of vegetable albumen and wax, is well 

 represented by the juices of the famous Cow Tree and 

 Papaya, interesting accounts of which will be found in 

 the travels of Baron Humboldt. 



Products composed of Oxygen, Hydrogen, and Carbon, 

 the Oxygen and Hydrogen being in the proportions to 

 form water. 



106. Fecula, or starch, exists in great quantity in the 

 vegetable kingdom, both in the higher and lower orders 

 of plants. In the stems of some Ferns it is so abun- 

 dant that a sort of bread can be prepared from it, 

 and as obtained from the higher orders of plants, it is 

 in daily use. Without dwelling on the well-known uses 

 of the seeds of the cereal grasses, which, however, de- 

 pend very much for the nutritive property of their 

 Fecula upon its combination with gluten, we may re- 

 mark that amylaceous matter exists in abundance in the 

 seeds of all plants, in tuberous roots, and the en- 

 largements at the base of Monocotyledonous stems. 

 From the pith of some trees it is obtained in considera- 



