NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 221 



was added to the syntonin solution? (2) What was used in the 

 preparation and what as the solvent for syntonin. (3) What is 

 syntonin? (4) What are the properties of syntonin? 



Experiment 63. Preparation of vegetable casein from peas. 

 Place in an evaporator, i gram of pea meal, 100 cc. H 2 O, and 3 cc. 

 NaOH. Heat on the sand-bath, occasionally stirring. Filter. If 

 the filtration is slow, pour off and use some of the clear solution. 

 Neutralize with HC1 and observe. 



Questions. ( I ) To what class of proteids does vegetable casein be- 

 long ? (2) What was used as the solvent for extracting the vegetable 

 casein? (3) What effect had HC1 ? (4) How does vegetable 

 casein resemble that from milk in solubility and other properties ? 



303. Peptones and Proteoses are closely related 

 groups of proteids present in animal and vegetable bodies. 

 When any proteid material is acted upon by the peptic 

 and tryptic ferments, peptones are formed. These are 

 soluble in water, and are not coagulated by heat or 

 precipitated by acids or alkalies. They are derived from 

 other proteids by ferment action, and are the first prod- 

 ucts formed when the proteids of the food undergo diges- 

 tion. In prepared or peptonized foods, the peptonizing 

 process is carried on artificially. When meat undergoes 

 the curing or ripening process, a small amount of peptones 

 is produced. Peptones are naturally present in milk and 

 also in traces in nearly all cereal products. When seeds 

 germinate, proteoses are formed. These compounds are 

 never present in ordinary foods in any appreciable amount. 



Experiment 64. Tests with peptones. Measure into separate 

 test-tubes, three 5 cc. portions of peptone solution. To the first, 

 apply heat and, when cool, add a few drops of tannic acid. To the 

 second, add a few drops of alum solution. To the third, add 5 cc. 

 alcohol. The peptone solution is prepared by treating coagulated 



