THE VOLATILE PAST OF PLANTS. 87 



ishes as they ripen, and in the sugar-cane the quantity 

 of wax is said to be largest when the sugar is least abund- 

 ant, and vice versa. In germination the oil of the seed 

 is converted back again into starch, sugar, etc. 



The Estimation of Fat (including wax) is made by warming the pul- 

 verized and dry substance repeatedly with renewed quantities of ethef , 

 or sulphide of carbon, as long as the solvent takes up anything. On 

 evaporating the solutions, the fat remains, and after drying thorough- 

 ly, may be weighed. The ether extract thus obtained is usually accom- 

 panied by a small amount of other substances, especially chlorophyll 

 and lecithin, and is hence properly termed crude fat. 



PROPORTIONS OF CRUDE FAT EN VARIOUS VEGETABLE PRODUCTS. 



Per cent. Per cent. 



Meadow grass 0.8 Turnip 0.1 



Red clover (green) 0.7 Wheat kernel 1.6 



Cabbage 0.4 Oat 



Meadow hay 3.0 Maize 



Clover hay 3.2 Pea 



1.6 

 7.0 

 .3.0 

 Wheat straw 1.5 Cotton se d 34.0 



Oat straw 2.0 Flax 



Wheat bran 1.5 Colza 



Potato tuber 0.3 



.34.0 

 .45.0 



6. THE ALBUMINOIDS OR PROTEIDS. The bodies of 

 this class essentially differ from those of the groups hith- 

 erto noticed, in the fact of their containing, in addition 

 to carbon, oxygen, and hydrogen, 15 to 18 per cent of 

 nitrogen, with a small quantity of sulphur, and, in some 

 cases, perhaps phosphorus. 



These bodies, though found in some proportion in all 

 parts of plants, being everywhere necessary to growth, 

 are chiefly accumulated in the seeds, especially in those 

 of the cereal and leguminous grains. 



The albuminoids or proteids* that occur in plants are 

 so similar, in many characters, to those which constitute 

 a large portion of every animal organism, that we may 

 advantageously consider them in connection with the 

 latter. 



* The nomenclature of these substances is unavoidably confused. 

 They are often termed nitrogenous or nitrogenized bodies, also albu 

 minous bodies, and protein bodies. The term albuminoids has been 

 latterly restricted, by some authors, to the substances of which gel 

 tine is a type. The word albuminates is applied to syiitouin an<J 

 casein. 



