METABOLIC PROCESSES IX THE PLANT. 255 



cell -sap, and since the crystals produced (belonging to the 

 rhombic system), especially those which appear in the form of 

 rhombic tables with an obtuse angle of 129 18', are of large size 

 suid characteristic form, it is possible in this way to demonstrate 

 mirrochemically the presence of the acid amide in cells 2 (see Fig. 

 !L>). 



\Ve place the sections (which must be more than one cell thick, 

 so that all the cells are not opened) in a watch-glass containing 

 absolute alcohol, rapidly shake them about in the fluid, and 

 examine them. If only a very small quantity of asparagin is 

 present in the cells, it is best to treat the sections on the slide 

 with absolute alcohol, lay on the cov r er-glass, and examine the 

 preparation after drying. 



To avoid confusing the separated crystals of asparagin with 

 other bodies, e.g. crystals of Potassium nitrate, we subsequently 

 treat the sections with a saturated solution of asparagin. If the 

 crystals obtained with alcohol actually consist of asparagin, they 

 will not dissolve. Crystals of other substances are, on the other 

 hand, absorbed by the asparagin solution. 



1 See Detmer, Vergleichende Physioloqie d. Keimungsprocesses der Samen, 

 1880, Pringsheim's Jahrbiicher, Bd. 12, Wollny's Forschtingen auf d. Gebiete d. 

 Agriculturphysik, Bd. 5, and LehrbncJt d. Pflanzenphysioloyie, 1883. 



2 See Pfeffer, Pringsheim's Jahrbiicher, Bd. 8, p. 533, and Borodin, Ilotan. 

 Zcitung, 1878, p. 804. 



99. The Quantitative Determination of the Total Amount of 

 Nitrogen and of the Nitrogen Present in the Proteids 

 and Acid Amides in Seedlings. 



From a large quantity of seeds of Lupinus luteus are selected 

 about 300, very normal and alike in development. We deter- 

 mine the average weight of a single seed, and estimate the dry 

 weight of the material (see 1). The seeds are now put to soak 

 for twenty-four hours in water. We then thoroughly moisten some 

 sawdust with water, and fill it into large flower-pots or zinc boxes, 

 rubbing it between the hands, and letting it fall into the pots or 

 zinc boxes so as to form a very loose bed. In this the seeds are 

 laid, covered over w r ith the moist sawdust, and put aside in the 

 dark, at a temperature of say 20 C. It only remains to take 

 care to replace the water lost by evaporation. 



