126 



LECTURES ON 



Fig. 7. 



air for some days in a warm place, it disappears or dissolves; if now 



the liquid be heated to near boiling, a 

 coagulum separates, having all the char- 

 acters of albumin. After removing the 

 albumin, the addition of an acid causes 

 another coagulation, separating a body 

 ^)C)^jClDCZy^l % * na * a » rees i n ^ s properties with casein. 

 n^flM/]fiyyyii/lfti!M,yMfl c As has been already stated, the albu- 

 minoid bodies form the lining membrane 

 of the young cell and are diffused in the 

 dissolved state throughout its liquid con- 

 tents. In those parts of the plant where 

 these bodies accumulate, they are found 

 nearly filling entire cells and series of cells. 



(e, fig. 7.) 



According to Hartig (Entwickelungsgeschichte des Planzen Keims) 



the albuminoids exist in the seed in an organized form, usually in 



grains that are scarcely to be dis- 

 tinguished from starch by the eye, 

 (A, fig. 8) often, however, in per- 

 fect polyhedral crystals. (Fig. 8, 

 B and C.) This aleuron, as Hartig 

 terms it, is not a pure albuminoid; 

 according to an analysis made 



from material prepared by him, 

 it contains but 9.4G per cent, of 

 nitrogen. The aleuron grains dur- 

 ing the life of the plant suffer 

 metamorphosis into starch and 

 other organized matters, of course 

 undergoing radical chemical chan- 

 ges at the same time. 

 While the two great classes of organic proximate elements, just 

 considered, make up the larger share of vegetation, and suffice to 

 show in the most beautiful manner how the single cell represents 

 the whole plant, both structurally and chemically, we should stop 

 short of the object of these lectures did we not consider some other 

 vegetal principles of great importance both to the vegetable and ani- 

 mal economy, which agree with the cellulose group in consisting only 

 of carbon, hydrogen, and oxygen, but differ again from the carbo-hy- 

 drates in the fact that their hydrogen and oxygen are not in the pro- 

 portions to form water. 



We may notice these substances under three divisions, viz: 

 Pectose and its derivatives. 

 The vegetal acids. 

 The oils and fats. 



The lactose group includes pectose, pectin, pectosic, and pectic 

 acids. These bodies exist principally in fleshy fruits and berries, 

 and in the roots of the turnip, beet, and carrot. They are an important 

 part of the food of men and domestic animals. 



Pectose is the designation of a body which occurs with cellulose in 



