19 
with V. 7. an increase of more than 34°/, 
N. | Oo 
We have previously remarked, that the increased respiratory 
exchange at a higher temperature cannot be attributed to this, 
seeing that the determination had not been made, until an equilibrium 
had presumably been established between internal and external gas- 
exchange. Indeed, the O,-consumption and the CO,-elimination in- 
creased more considerably than the tidal air. 
Our experimental evidence seems to show that muscular work at 
a high temperature is less economical than at a low temperature, 
and also that this difference is more marked with one subject than 
with another. 
The increase of gas-exchange parallel to the rise of temperature 
was not gradual. but sudden at 21°—22°. 
Physiology. — “The influence of the reaction upon the action of 
ptyalin”. By Dr. W. E. RiNcer and H. v. Trier. 
(Communicated by Prof. CG. A. PeKerLHARING in the meeting of November 30, 1912). 
One of us (v. Tr.) has for some time been studying the effect of 
diet on the action of the diastatic enzyme of the saliva, to which 
the name ptyalin has been applied. The results of other researchers 
into this subject are tu some extent conflicting with each other’). 
Nor do van Triet’s experiments positively demonstrate an influence 
of diet. Though, taking one with another, they seemed to point to 
an mfluence, occasionally there appeared striking deviations without 
our being able to fix upon the cause, so that we did not know 
what to make of the results. 
This experimentation was conducted as follows: saliva was added 
‘to amylum solutions and after some time the reducing power of 
the solutions was determined. This method involves the risk of fluc- 
tuations in the reaction of the fluids, e.g. such as are brought 
about by the flask-wall or by carbon dioxide from the air, since in 
approximately neutral fluids without regulating-mixtures the reaction | 
may be considerably shifted by a trifling disturbance. This would 
account for the striking deviations mentioned just now, recent researches 
having shown that slight modifications of the reaction markedly 
affect the activity of enzymes. 
Now if, in proseecting our experiments, due care being taken all 
1) Cf. HAMMARSTEN's Lelirbuch der physiologischen Chemie. 
