39 
causes synthesis in the neighbouring cells; as soon as enzyme and 
substrate are brought together, the hydrolytic action prevails almost 
exclusively. 
This conception of enzyme activity is borne out by experiment in 
different ways. 
The weakening of the radiation may be occasioned, as observed 
above, not only by spreading, but also by other factors, e.g. by the 
deteriorating action of temperature and acids or alcalis in a shorter 
or longer time. As will be seen, in what follows, several times a 
reversion of the hydrolysis of urea was observed, which could be 
explained by a decay of the urease. 
Nov. 18 1915 an experiment was carried out with ammonium- 
carbonate as a buffer, in which this reversion at the end of the 
hydrolysis manifested itself clearly. See figure 10, p. 10. 
i Figure 11. 
20 40 60 80 100 120 140 160 
minutes. 
