Aug. I, 1931 
Studies in the Physiology of Parasitism 
619 
tion to determine whether they altered the macerating power of the 
enzym, and if so, to what degree. 
Washing the myceeium. —The first step in the treatment of the 
fungous growth as finally adopted consisted in washing the felt in run¬ 
ning tap water for about 15 minutes, squeezing out the water, and 
subsequently treating it with acetone and ether. Washing in water for 
this length of time did not remove any of the macerating principle from 
the mycelium, as is shown by the following experiments. Several 
fungous mats (two days’ growth) about 6 inches in diameter were removed 
from the culture flasks and rinsed for 2 or 3 seconds in running water 
to remove some of the adhering culture fluid. The felts were then 
cut into two parts, one of which was washed for 15 minutes in flowing 
water. Both lots were subsequently treated with acetone and ether in 
the usual way. A comparison of the macerating power of the two lot 
of material was made by using 0.25 gm. of the fungous hypliae ground 
in sand and suspended in 25 cc. of distilled water. Several sweet- 
potato disks (1 by 15 mm.) added to the systems and incubated at the 
same temperature were macerated in an equal length of time. 
Acetone-ether treatment. —The treatment of the mycelium with 
acetone and ether did not influence the macerating power of the hypliae, 
as was shown by a comparison of the corresponding halves of the same 
felts, one of which was dried over calcium chlorid in partial vacuum for 
five hours and the other treated in the usual way with acetone and 
ether. After the felts of each set were thoroughly dried they were 
mixed into a compound sample, and 0.5 gm. of the powdered mycelium 
of each was suspended in 25 cc. of distilled water. Sweet-potato disks 
(1 by 15 mm.) were macerated in equal time in an enzym powder of the 
same concentration for the two samples. From these results it would 
seem that the treatment of the mycelium with acetone and ether in no 
way influences the macerating power of the liyphae. 
Probably the chief virtue in the acetone-ether method lies in the ease 
with which the dried mycelium can be handled subsequently. Rhizopus 
forms a very compact, leathery mat which is difficult to handle if allowed 
to dry before the threads are torn apart. The practice has been to pull 
the hyphal threads apart while the material is submerged in the acetone 
and ether, so that by the time the treatment is finished the threads are 
well separated and broken into short lengths. When dried the material 
is loose and cottony in general appearance, so that a quick and accurate 
weighing is possible. 
Grinding The hyphae by sand. —A comparison of the rate of mace¬ 
ration by mycelium ground in sand with mycelium not so ground showed 
that, everything else being identical, the disks in the suspension of 
ground hyphae reached complete maceration a little ahead of those in 
the solutions with unground hyphae. 
