6 Feeds mid Feeding. 



and sugars there is formed a new group of complex compounds 

 called crude proteins, which, in addition to carbon, hydrogen, and 

 oxygen, found in the carbohydrates, contain nitrogen, sulfur, and 

 sometimes phosphorus. The nitrogenous compounds are the most 

 complex of all plant substances. Osborne of the Connecticut Sta- 

 tion gives the following as the probable molecular composition of 

 legumin, a protein found in the seed of the field pea, and hordein, 

 found in the barley grain : 



Legumin C-igH^ssOossNaiiSa 

 Plordein Ce^sHioiiOio.N.s.S, 



Because of their great variety and complexity, the nitrogenous 

 compounds are the most difficult of all plant substances for study 

 and classification. Able organic chemists are attacking these intri- 

 cate problems with great energy and patience, and important dis- 

 coveries are being made. While it is certain that the old classifica- 

 tion of these compounds must be superseded, it is too early to pre- 

 sent any satisfactory substitute. Since this work sets forth only 

 the briefest and most informal consideration of the matter, it seems 

 best to adopt the following grouping of the nitrogenous compounds 

 of plants, in so doing holding to what has been found in the past 

 and helping toward what is to come. 



Crude protein is the term employed to designate all the nitroge- 

 nous compounds of the plant. The chemist finds that about 16 

 per ct. of the plant proteins is nitrogen. Accordingly, he multi- 

 plies the nitrogen found in any given plant substance by 6.25 

 (100/^^=6.25) and calls the product crude protein. Crude protein 

 embraces two groups of nitrogenous plant compounds, proteins and 

 amids. 



Proteins are the more highly organized forms of crude protein. 

 They are not always soluble and therefore not transportable in the 

 juices of the plant. The life of the plant centers in its protein- 

 containing parts, such as the active leaf cells and the germs of 

 seeds. 



Amids are the nitrogenous, portable building compounds of the 

 plant. They are soluble in its juices and are the common vehicle 

 for conveying nitrogen to needed points thruout the plant struc- 

 ture. Out of the soluble amids the plant constructs its still more 

 highly organized protein compounds. During the active period of 

 the plant's life, amids are constantly l)eing formed out of the ele- 

 ments composing sugar or starch and the nitratos and other min- 



