10 



ANALYTICAL CLASS-BOOK. OF BOTANY. 



rise to the surface and coalesce, in the same manner as 

 those of cream, nor can they be reconverted into globules. 

 Caoutchouc abounds in the Nettle-worts, Spurge-worts 

 and Dog-bane tribe. Gutta Percha is a similar product 

 of a tree of the East Indian Archipelago, and is now 

 applied to a great variety of uses. 



63. FIXED OILS. In some plants, the fixed or fatty 

 oils take the place of starch, from which they seem to be 

 derived. They abound in the seeds of many plants, as in 

 those of the Sunflower, Flax, Butternut and Castor-oil 

 plant, and in the fruit of the Olive. 



64. WAX. This substance is nearly allied to the 

 fixed oils. The glaucous bloom on the surface of leaves 

 and fruits is a very thin coating of wax, which not only 

 gives them their rich and beautiful gloss, but preserves 

 them from injury by water. Wax is abundant on the 

 fruit of the Bayberry, from which it may be separated 

 by boiling in water. 



65. CHLOROPHYLLE. The proper sap, as you have 

 seen (54), is wholly destitute of color; but in many 

 cells, as in those of the leaf and flower, the heart of 

 wood and the skin of fruits, we find a variety of brilliant 

 and pleasingliues. These are all owing to the presence 

 of a distinct principle, which most commonly produces 

 green ; and because it associates this most agreeable of 

 all colors chiefly with the leaf, it is called CHLOROPHYLLE, 

 or leaf-green. This substance consists of minute gran- 

 ules of irregular form, which either lie free in the cells, 

 or loosely adhere to their walls. These granules are 

 deposited in parts exposed to the light, which is essential 

 to their formation, as you may see in plants that grow 

 in the dark, for they never have green foliage. The 

 beautiful blue of the Indigo plant is but a modification 

 of leaf-green. In autumn, the chlorophylle undergoes 

 important changes, and becomes red, yellow, or brown. 



66. The substance of all coloring matter not green, 

 as in fruits and the petals of flowers, is called CHROMULE. 



67. VEGETABLE ACIDS. The most important of 

 these are, Malic, Citric, Tartaric and Oxalic acids. 

 Malic acid is obtained from the juice of Apples and Pears; 

 citric acid is found in the juice of Lemons and Oranges ; 

 tartaric acid in the Grape ; and oxalic acid in almost all 

 plants. The latter is abundant in our common Wood- 

 sorrel, and hence the name of the genus, ( Oxalis). Prus- 

 sic acid is found in the leaves, bark and kernel of the 

 Peach, Cherry and Plum, but is most abundant in a 



Fixed Oils, of what do they take the place? In what plants and what 

 parts found? Wax, to what nearly allied? How diffused? Where abun- 

 dant? Chlorophylle. Its effects. Meaning. Of what does it consist ? What 

 essential to their formation ? Chroraule. Most important Vegetable Acids. 

 From what Is Malic Acid obtained ? Citi ic Tartaric Oxalic Prusstc Tan- 



species of Wild Cherry (Cerasus Serotina}. Tannin, 

 or Tannic acid, is the astringent principle which gives to 

 the bark of some trees, as the Oak and Hemlock, their 

 value in tanning leather. It abounds in many old barks, 

 and probably is a result of decomposition in the tissues. 



QUATERNARY PRODUCTS. 



68. ALBUMEH. That substance which is interposed 

 between the embryo and integument, in most seeds, is 

 called the ALBUMEN. It is fleshy in the Cocoa-nut, tough 

 and leathery in the Coffee, floury or farinaceous in the 

 cereal grains, and composes almost the entire mass of 

 many seeds. It has many of the properties of animal 

 albumen, and however poisonous the plant may be, this 

 part never has any noxious qualities. 



69. LEGUMINE. This is a highly nutritive substance, 

 which abounds in seeds of the Bean, Pea, and other 

 leguminous plants. It is identical with caseine, the 

 substance which forms curds, and is the basis of cheese 

 in animal milk. 



70. GLUTEN. This is a tough elastic substance, 

 which remains after the starch is washed off in wheat 

 flour. It exists in many grains, and in the juices of cer- 

 tain plants, but it is a characteristic property of Wheat 

 and Rye, and gives to those grains their peculiar value 

 as breadstuff's. It is the presence of gluten that gives to 

 bread made from those grains tenacity, or that capability 

 of swelling up, which, in culinary terms, we call being 

 " raised." Gluten constitutes more than one quarter, 

 by weight, of the best wheat flour. It is not a simple 

 substance, but is found by analysis to be composed of 

 albumen, fibrine, caseine and glutine. 



71. The three substances last described bear an 

 important part in vegetation, being accumulated in seeds, 

 in order to sustain the vital operations of the Young 

 Plant until it can work for itself. 



72. In the common process of separating the bran 

 from the flour, a large portion of the gluten is rejected, 

 or cast away with the bran. This is clearly illustrated 

 in fig. 4, which represents a delicate cross section from a 

 grain of Rye very highly magnified. It may be seen at 

 a glance that the contents of the outer cells, or those 

 lying next the skin (which may be distinguished by its 

 line of flattened cells) at a, are different from those 

 below. These are chiefly filled with gluten, while, as 

 you proceed downward, starch gradually takes place of 



nin or Tannic Acid? Of what probably a result? Albumen, of what does it 

 consist? What properties in poisonous plants? Legumine. In what plants? 

 With what animal substance identical? Gluten. In what plants? What 

 grains most especially ? What property does it giro to bread ? What propor- 

 tion in the lest wheat flour ? What loss of gluten f 



