14 
ing readings were obtained for these several solutions at the tempera- 
tures and intervals indicated above: 
Time. 
Tempera- 
ture. 
Readings 
on colori- 
meterscale. 
Standard. 
15 minutes 
°C. 
2 
10. 5 
5 
Do 
14 
4.6 
5 
Do 
39 
3.1 
5 
1 hour 
2 
3.8 
5 
Do 
14 
2.8 
5 
Do 
39 
3.6 
5 
It will be observed, therefore, especially for the shorter interval, 
that a rise of temperature causes an increase in the amount of phe- 
nolphthalin oxidized, the apparently low result reached at 39° C. for 
one hour being due to a gradual fading out of color of the phenol- 
phthalein in alkali, a change which also probably takes place more 
rapidly with rise of temperature and which will be more fully dis- 
cussed in a subsequent portion of this communication. Up to this time 
our experiments have been carried on at room temperature which has 
varied within a range of ten degrees or more, during the time that this 
investigation has been in progress. Hence, we see that only the results 
of any one series of experiments are strictly comparable among them- 
selves, for the reason that it has proven practicable to carry out only 
one series of experiments at any particular time and da} 7 . 
Up to the present time the peroxidase activity of the blood of forty- 
seven different persons has been determined in the manner above 
described with the following results: 
