622 
Journal of Agricultural Research 
Vol. XXI, No 9 
the mycelium was ground before it was exposed to the light. At 
the end of the period of exposure the powdered hyphae were placed in an 
incubator for 18 hours at 9 0 C. The mycelial powder was then sus¬ 
pended in 25 cc. of distilled water, and after sweet-potato disks of the 
usual type had been added, incubation was carried out at 37.5°. Records 
taken from time to time of the progress of maceration showed that the 
different light intensities used had no influence upon the macerating 
principle. Grinding before exposure to light was likewise without 
effect, maceration being completed in 4.5 hours in all cases. 
Quantity of solution. —It is desirable, other things being equal, 
to employ technic in investigations of this kind which will require the 
least possible time in manipulation. If the volume of the solution whose 
macerating property is to be studied should influence the rate of macera¬ 
tion, a measured quantity would be required for all comparative work. 
This would require time in measuring. Without going into the details 
of the results of this phase of the work it may be stated that there was 
no difference in the time required to macerate sweet-potato disks in a 
solution on which the fungus grew in volumes varying from 25 to 100 cc. 
Concentration of solution. —As would be expected, diametrically 
opposite results were obtained as regards the concentration of the solu¬ 
tion, the rate of maceration being most rapid in the solutions containing 
the largest quantity of enzym powder. 
Optimum temperature for maceration. —It is a well-known fact 
that temperatures below the optimum progressively retard the action 
of enzyms. Above the optimum, action is retarded more rapidly. 
With respect to the macerating principle found in Botryiis cincrea, 
Brown (5) showed that at 65° C. deactivation was practically instan¬ 
taneous. 
The investigations of the writers with respect to this subject were made 
with a solution obtained from six 2-liter flasks on which the fungus had 
grown for 48 hours at 37.5 0 C. The solutions were filtered through two 
thicknesses of cheesecloth and combined into one large receptacle and 
thoroughly mixed. Twenty-five cubic centimeters of this solution were 
pipetted into small flasks and exposed for 1 hour at 9 0 , 20°, 30°, 40°, 45 0 , 
50°, 55°, and 6o°, respectively, to bring to constant temperature. Raw 
sweet-potato disks were then added to the flasks, and notes were taken 
from time to time of the degree of maceration. At 9 0 maceration was 
completed in 3.5 hours, and the time was progressively shortened with 
an increase of the temperature up to the macerating optimum. At 6o° 
the enzym was completely deactivated and no maceration took place. 
The optimum temperature has been difficult to establish, but it lies 
somewhere between 45 0 and 55°, and probably nearer 45 0 than 55 0 . If 
more refined methods were at hand for determining the end point the 
optimum might probably be more nearly established. Above 55 0 
