86 BOTANICAL GAZETTE [FEBRUARY 
excised muscles was increased if the muscles were killed by heat or 
were fatigued by prolonged stimulation. The output of carbon 
dioxid in such cases was not related to the rate of absorption of oxygen. 
Six years ago FLETCHER,* using Blackman’s apparatus, the most 
intricate and accurate apparatus yet devised for following gaseous 
exchanges, showed that the evolution of carbon dioxid from excised 
frog’s muscles is independent of the amount of oxygen taken up during 
the period. He distinguished in the production of carbon dioxid, 
first, a short period (about six hours), which he thinks dependent 
upon the presence of oxygen; and second, a long-continued evo- 
lution of carbon dioxid ‘due to chemical processes occurring spon- 
taneously within the muscle, in which complex molecules are replaced 
by simpler ones, with the conspicuous results of the appearance of 
[sarcolactic] acid and of free carbon dioxid.” He adds: “Under 
suitable conditions the occurrence of active contractions in an excised 
muscle is not accompanied by an increase in the rate at which carbon 
dioxid is yielded by the muscle,” though oxygen is abundantly sup- 
plied then by the blood. He does find, however, an increased for- 
mation of other decomposition products. 
CHAUVEAU and KAUFMANN, as long ago as 1887, found that the 
output of carbon. dioxid from the levator muscle of a horse’s upper 
lip was greater during activity than during rest, and contained more 
oxygen than that absorbed in same time.5 
A great number of researches of the same tenor can be found 
in botanical literature. A single example must suffice. In an 
elaborate paper PuryEwIcz shows® that the variations in the carbon 
dioxid produced and the oxygen absorbed during a given period 
under various conditions are not parallel, the amount of carbon 
dioxid ranging within far wider limits than the oxygen. Thus, the — 
carbon dioxid varied from —14 to 120 per cent. of the average; the 
oxygen varied from o to 48 per cent. of the average. PURJEWICZ, 
indeed, expresses his conviction that the respiratory ratio has no value 
as indicating the actual course of respiration, and would separate : 
4 Survival respiration of muscle. Jour. Physiol. 23:10-99. 1898. 
5 Le coefficient de l’activité nutritive et respiratoire des muscles. Compt. Rend. 
Acad. Sci. France 104:1126-1132. 1887. 
oe _ © Physiol. Unters. iber Pflanzenatmung. Jahrb. Wiss. Bot. 35:573-610. 1990- 
