364 CHANGES OF ORGANIC MATTER IN THE PLANT. 



soluble in a solution of basic potassic phosphate. Their ultimate 

 composition is nearly the same as that of the group just men- 

 tioned. 



Gelatin of plants. The associated matters are (1) Gliadin, 

 (2) Mucedin, (3) Gluten-fibrin. These bodies are -soluble in 

 alcohol, and in water containing a small amount of acid or 

 alkali. In their fresh state they are tough, viscid masses, only 

 slightly soluble in water. 1 



958. Weyl does not accept Ritthausen's classification, but 

 holds that legumin is a mixture of vegetable vitellin and casein ; 

 and further, that there is no true casein in seeds, the sub- 

 stance called by this name being a product of secondar}' changes 

 in the laboratory. 



959. Products containing nitrogen. II. Asparagin (C 4 H 8 N 2 O 3 ). 

 This substance occurs in the shoots of Asparagus officinalis and 

 many other plants, from which it can be obtained in the form of 

 transparent crystals of the orthorhombic system. It is merely 

 necessary to evaporate the juice of the plants to the consist- 

 ence of a thin syrup, and after allowing it to stand for a time 

 the crystals will separate, and may be purified by recrystalliza- 

 tion. Pfeffer describes the following useful method of preparing 

 them upon the slide of the microscope : A moderately thick sec- 

 tion of the tissue suspected of containing asparagin is placed on 

 a slide, covered with a bit of glass, and treated with absolute 

 alcohol, when the crystals will be thrown down in the cells, or 

 will form in the alcohol outside of the specimen. The character 

 of the crystals can be known certainly b}* their insolubilfty in a 

 concentrated aqueous solution of the same substance (see 46) . 



The amount of asparagin in certain plants has been given as 

 follows : 



Name of Plant. Per cent of Asparagin. Observer. 



Roots of Althaea .... 2. ... Plisson and Henry. 



Vetch germs 1.5 ... Piria. 



Radicles of a germinating 



plant dried at 100 C. . . 10.5 . . . Beyer. 



960. Asparagin possesses its chief interest from the part 

 which it probably pla^ys in the transfer of nitrogenous matters 

 through the plant. According to Pfeffer, although it cannot be 

 detected with certainty in the seeds of the vetch and pea, it 

 appears in the young parts, especially in the lines of transfer (for 



1 Hunt has called attention to a curious relation between the composition 

 of animal gelatin and that of starch to which ammonia is added. 



