40 
It is to be expected, that the enzyme molecules will not all decay 
at the same time. At the end of the hydrolysis, when the action on 
the rest of the urea has become very slow, and on the other hand 
the concentration of the reaction products has grown correspondingly, 
it may happen, that a sufficient proportion of the enzyme particles 
is in the decaying state to cause the synthetic action, having a higher 
concentration of substrate at its disposal, to predominate over the 
slow action of the unchanged enzyme on the relatively very diluted 
urea solution. During such a period the total effect will be reversed, 
returning to its normal course as soon as the unchanged enzyme 
particles prevail over the decaying ones, which may be occasioned 
by a further weakening or total decay. 
Figure 11 shows the results of an experiment of Jan. 2rd 1916, 
like that of Nov. 28th, 1915, which shows the same phenomenon 
in a smaller degree. y 
In the phosphate solutions of high py also the reversion sometimes 
became manifest. 
First a regular experiment of April 6, 1917 may be recorded. 
TABLE 20. 
0.25 gr. Soja + 50 c.c. water + 3.64 gr. Na, HPO,2aq. + 1.16 gr. KH,PO4 
10 cc. filtrate mixed with 11.52 gr. Na, HPO, 2aq. + 120 c.c. water. 
pH = 8.13 0.01 °/, urea 
0.0073 4 de 0.01 
t (minutes) yp ; oe ly ae wales 
mn = 
t 
80 O5 0.000029 
140 0.305 0.000030 
200 0.39 0.000027 
260 0.52 0.000028 
321 0.625 0.000030 
In this case little or no destruction had taken place during this 
interval; for 10 c.ec. of the extract, left alone for 320 minutes in 
the same bath at 27° and then mixed with 2 e.e. urea (0.06 °/,) 
gave in 80 minutes 0.3 c.c. NH, #4 N, which makes m = 0.000026. 
April 10% 1917. The same arrangement as on April 6 but now 
with longer time intervals. Part of the same mixture left in the 
bath at 27° till the next day, when 10 c.c. with 2 c.c. urea solu- 
tion of 0.06 °/, gave in 260 minutes only y=0.1 (against y about 
0.45 originally). Thus evidently a considerable decay of the enzyme 
had taken place. 
