126 BOTANICAL GAZETTE [aucust 
the shriveled cotyledons make up so large a percentage of the dry 
weight. : 
The experiment described above shows that proteolysis actually 
does occur as a step in the process of the utilization of the stored 
proteid. It is of interest in this connection to see if this process 
occurs when the cotyledons are removed from the young seedlings 
and kept under sterile conditions. A series of preliminary tests 
showed that if the cotyledons of germinating beans are treated for 
twenty minutes with a 0.5 per cent. solution of mercuric chloride and 
then repeatedly washed with sterile water and kept in sterile tubes 
they will remain free from bacterial or fungal infection. The pro- 
cedure kills the peripheral cells of the cotyledons, as shown by the 
fact that they do not turn green if kept in the light; whereas unsteril- 
ized cotyledons show a gradual development of chlorophyll under the 
same conditions of light and moisture. Comparative tests of the 
sterilized and unsterilized cotyledons showed that both contained 
ereptase, but that there was a noticeably smaller amount in the ones 
treated with mercuric chloride. It is probable that the poison not 
only killed the outer layer of cells, but also destroyed the enzymes 
contained in them. 3 
Three-day old seedlings of Phaseolus were removed from the soil 
and the cotyledons separated. A quantity of these were washed, 
dried between 70° and 80° C., and ground in the mill, yielding prep® 
ration C, Ninety other perfectly sound cotyledons were selected 
forty-five placed in each of two previously sterilized flasks, and kept 
covered with 0.5 per cent. mercuric chloride solution for twenty 
minutes. After pouring off the sublimate solution the cotyledon 
Were washed five times with sterile water in quantities as great % 
that of the mercuric chloride solution used. In pouring off the last 
wash water sufficient was left in the flasks to keep the cotyledons 
moist. The flasks were closed with sterile corks and kept at room 
temperature—about 20° C. After three days one flask was opened 
a 
3 
ee a 
re ae LAIST pe eee orn REN pA EE fe RT Mee ie Pa ie 
and the contained cotyledons dried and ground, giving preparation 
D. The contents of the flask were judged to be sterile by the absenct 
- any foreign growth and by the results of a transfer of a drop of the 
fluid from the bottom of the flask to a sterile agar tube. The second 
- was kept unopened for five days longer and then the cotyledons 
m It were treated as the other portion, yielding preparation E. 
. 
