June, 1922] SMITH COMPARATIVE STUDIES ON RESPIRATION 
ration effect" was determined for distilled water for each individual experi- 
ment, and allowance was made for this in drawing the curve. In no case 
did this preliminary lag in distilled water endure for more than 10 minutes, 
and it was shown, by introducing the lactic acid into the system in a sepa- 
rate tube, that it had no more buffer effect than the same volume of distilled 
water. 
The lactic acid was used in the following concentrations: o.oo25ikr, 
o.oosM, o.oi ikf, 0.02M, o.04Af, o.iM, 0.2M, o.sM, and 271^". This range 
was sufficiently close to give a good series of curves. 
With lactic acid 0.002571^", the first effect was a rise in the rate of respi- 
ration, which reached a maximum of 168 percent in 24 minutes after begin- 
ning the exposure to the acid. In 27 minutes the rate reached normal 
again, and then proceeded to fall below it. In 2 hours the rate had 
fallen to 68 percent. 
With a concentration of o.oi ikf, a maximum of 153 percent was reached 
in 21 minutes from the first exposure. The rate remained above normal 
for 30 minutes, and then fell to 61 percent in 2 hours. 
With o.04ikf lactic acid, the initial rise was smaller, and the time above 
normal was less. Thus, the maximum of 130 percent was reached in 18 
minutes, and the rate returned to normal in 21 minutes. After 2 hours 
the rate was 55 percent. 
With o. I ikf lactic acid, there was no rise apparent. The rate fell steadily, 
at first rapidly and then more slowly, reaching 40 percent in 30 minutes, 
28 percent in one hour, and 24 percent in two hours. After 4 hours the 
rate was reduced to 16 percent. 
With intermediate strengths the results were intermediate and similar 
to those given. The figures represent the mean of several closely agreeing 
experiments. 
In order to determine whether the osmotic pressure or the pH value of 
the lactic acid was contributing to the results obtained, experiments were 
made with sulphuric acid of the same pH value (about pH 3) as the o.iikf 
lactic acid. It was found that the sulphuric acid had no more effect than 
the same volume of distilled water. In the same way a 3 percent solution 
of dextrose, which was known to have a greater osmotic pressure than the 
o.iikf lactic acid, was found to have very little more effect than distilled 
water: and the "saturation effect" lasted only a few minutes longer. 
It was thus reasonably certain that the observed results were really due 
to some specific action of the lactic acid. 
Recovery experiments were made with the 0.1 M, 0.2 M, and 2M acid. 
In all cases the seeds recovered completely on removal to distilled water, 
if sufficient time was allowed. Recovery was possible even if the rate had 
been reduced to 25 percent of the normal. 
In these experiments there was no evidence of any permanent increase 
in the rate of production of carbon dioxide. This would seem to indicate 
