118 
Proceedings of the Royal Society of Edinburgh. [Sess. 
more liquid could be expressed, and the extract was finally made up with 
distilled water to 350 c.c. 
The liquid was freed from suspended particles by means of a centrifuge, 
and was thereafter divided into two portions, one of which was mixed with 
a solution of Pepton Witte in such quantities as to give a concentration of 
2 per cent, peptone, whilst 10 per cent, of Pepton Roche was dissolved in 
the other. 
The liquids were then placed, in quantities of 10 c.c., in a number of 
small bottles, each of which received in addition T c.c. of chloroform. 
Excess of tannic acid and a trace of sodium acetate were added to half of 
those bottles containing Pepton Witte, while the remainder of these and all 
those containing Pepton Roche were placed in an incubator at 35° C. 
The Pepton Witte digestions were withdrawn after forty-eight hours’ 
incubation, precipitated with tannic acid and sodium acetate, and, along 
with the controls, which were precipitated before digestion, filtered and * 
used for determining the amount of nitrogen contained in 5 c.c. of the 
filtrate, Kjeldahl’s method being employed. 
The increase in nitrogen, expressed in cubic centimetres of N/10 
alkali, was, as before, taken as an indication of the amount of peptolytic 
activity during digestion. 
This difference was, in all cases where ungerminated barley was em- 
ployed, within the limits of experimental error, and the resting seed of 
barley may therefore be regarded as containing only in extremely small 
quantities, if at all, a peptase capable of catalysing the hydrolysis of the 
polypeptids contained in Pepton Witte. 
A peptase of this nature was, however, found to be rapidly produced 
during germination, as will be seen below. 
In the following tables, the first column shows the number of days from 
the time when the barley was steeped in water to the time when the 
sample was withdrawn for examination, while the second column gives the 
degree of peptolytic activity expressed in cubic centimetres of N/10 acid 
neutralised by the ammonia formed during the Kjeldahl process, and in 
each case corrected for the amount of moisture contained in the sample. 
The Pepton Roche digestions were examined from day to day, and a 
note was made of the minimum number of days within which a deposit of 
tyrosin was formed. 
Although there is no experimental evidence to show that under the 
conditions of the experiment, and especially considering its duration, the 
time required to produce a precipitate is inversely proportional to the 
degree of activity, it is nevertheless obvious that, the greater the peptolytic 
