NITROGENOUS ORGANIC COMPOUNDS OF PLANTS 2 19 



shake vigorously ; let stand for half an hour or until the next day. 

 Filter (if not clear refilter) and make the following tests with 

 separate portions of the filtrate, (i) To 5 cc. add a few drops of 

 tannic acid. (2) To 5 cc. add a few drops of lead acetate. 



Questions. ( i ) What were the results when tannic acid and lead 

 acetate were added ? (2) Do the tests indicate any large amount 

 of albumin? (3) How do these tests compare with those of the 

 preceding experiment ? 



301. Globulins form a group of proteids insoluble in 

 water, but soluble in dilute salt solution. When animal 

 or vegetable substances, as meat, eggs, wheat, rye or oats, 

 are treated with dilute salt solutions (NaCl), after re- 

 moval of the albumins, soluble proteid substances called 

 globulins are obtained which are coagulated by heat. 

 There are a large number of vegetable globulins. The 

 chief globulin of meat is myosin. When meat is soaked 

 in a dilute salt solution, and then cooked as food, the 

 myosin is extracted and lost. In strong salt solution, 

 myosin and other globulins are insoluble ; hence the use 

 of strong brine in the curing of meats. In the blood, 

 v there are globulins present, and in the yolk of an egg, a 

 globulin-like body, vitellin is found. As a rule, globulins 

 do not make up a very large proportion of the proteids of 

 foods. 



Experiment 60. Obtaining globulin from oats. To the residue 

 left in the flask from Experiment 59, add 2 grams of salt and 50 cc. 

 water. Shake vigorously and, after one hour, filter and make the 

 same tests as in Experiment 59. Save the residue in the flask for 

 Experiment 65. 



Questions. ( i ) What results were obtained when the solution 

 was tested with lead acetate and tannic acid? (2) What do these 

 results indicate ? (3) What are globulins ? 



