METABOLIC PROCESSES IX THE PLANT. 257 



iny the solution when perfectly cold with 25 c.c. of Bromine). 

 \\Y require for the purpose 10 c.c. of the fluid. The volume of 

 Xitrogen found is reduced to C. and 76Q mm. barometric 

 pressure, and it is then easy to calculate the weight of the 

 Xitrogen, and thence the quantity of anhydrous asparagin 

 <( 1 4 H 8 O 3 N 2 ) present. Seedling extracts frequently contain 

 small quantities of a body which at once yields Nitrogen, with- 

 out previous boiling with Hydrochloric acid, on treatment with 

 I nominated soda solution. It is therefore necessary to shake up 

 10 c.c. of the extract in the azotometer with the soda solution 

 <lirectly, and to subtract the Nitrogen which may be found from 

 that obtained after boiling the extract with H Cl. 1 The Nitrogen 

 of the acid amides can in the above manner be determined very 

 accurately. The calculation of this Nitrogen as asparagin is only 

 in some measure permissible when the material, as is the case 

 with lupins, contains only trifling quantities of amides other than 

 asparagin. 



1 See Sachsse, Die Chemic und Physiologic d. Farlstoffe, etc., 1877, p. 257, 

 and Detmer, Pliysiol.-chemische Untersuchungen iiber die Keimung, etc., 1875, 

 p. 74. 



100. Behaviour of Asparagin in Plants. 



If it is required to obtain information as to the physiological 

 function of asparagin, very suitable material for investigation is 

 provided by seedlings of Lupinus luteus. In the germination of 

 lupins the hypocotyl elongates very considerably, the cotyledons 

 are raised above ground, quickly strip off the seed-coat, and 

 function as organs of assimilation. The epicotyl then at once 

 elongates also, and the first foliage leaves unfold. The hypocotyl 

 has developed a thick cortical parenchyma, which surrounds the 

 circle of vascular bundles and the pith. In the stalks of the 

 Cotyledons the vascular bundles are arranged in the form of a 

 half-moon. The ground tissue of the cotyledons is only rich in 

 chlorophyll grains in the peripheral region. According to the 

 microchemical researches of Pfeffer, of which I have repeated a 

 large number, the distribution of asparagin in the seedling of 

 Lupinus developing under normal conditions, in sunlight, is as 

 follows. The seeds contain no asparagin. When the root has 

 Attained a length of 12 mm., and the hypocotyl a length of 



P.P. S 



