AMYLASE IN THE LIVING CELL 121 



sterilising in a steam steriliser. With this starch gelatine a 

 number of cultivation tubes and plates may be prepared in 

 order to determine the production of amylase under difEerent 

 conditions. 



For the determination of the production of amylase by the 

 growing embryo of the barley grain, a small deep Petri dish 

 may be taken, and the starch gelatine poured in to the depth 

 of about ^ inch and allowed to set. By means of a sterile 

 needle or knife blade an embryo may be detached from the 

 grain, previously softened in water, and placed on the surface 

 of the starch gelatine. It can be brought into close contact 

 with the starch gelatine by melting a minute portion of the 

 jelly immediately under the embryo with a warm sterile needle. 

 Several embryos may thus be set up and allowed to remain at 

 a temperature of about 18° C. for a day or two. At the end 

 of that time sections of the jeUy a little wider than the embryo 

 may be cut out so that the jelly immediately below the embryo 

 can be observed. On treating the slices of jeUy with a little 

 dilute iodine solution it will be found that a semicircular space 

 below the embryo is colourless, thus showing that the embryo 

 has secreted amylase, which has saccharified the starch in its 

 immediate vicinity. 



By making similar observations with the other embryos 

 used, at intervals, say, of twenty-four hours, it wiU be seen 

 that the area affected increases as the embryo develops. 



Brown and Morris have shown that embryos separated from 

 the barley graia in this way can be grown on quite a variety 

 of different media. Thus, e.g., barley embryos could be grown 

 in the endosperm of a wheat grain, the embryo of the latter 

 being removed. They can also grow in solutions of sugar or 

 even on moist filter paper, their action in the last two cases 

 being very probably due to the secretion of enzymes other 

 than amylase. Careful experiment has shown that the amy- 

 lase is secreted mainly by cells in the neighbourhood of the 

 scutellar epithelium {b, Plate II (ii)). 



