244 



table will-o'-the-wisp, leading investigators 

 into a bog where their labors and their 

 thinking were alike futile. For as a sign 

 of what is going on within, the respiratory 

 quotient is absolutely valueless, however 

 interesting the facts in themselves may be. 

 I could cite an indefinite number of in- 

 vestigations to indicate this. I select a few 

 cases. 



As long ago as 1885 Rubner showed* 

 that the respiratory ratio varied in resting 

 muscles at different temperatures. 



At 8.4° = 3.28 



'-'2 



28.2 1.01 



n.-J.S 1.18 



38.8 ; . . . 0.91 



Von Frey and Gruberf showed that in a 

 dog's muscle, with artificial circulation, 

 contractions are accompanied by an in- 

 crease in the carbon dioxid added to the 

 blood, but they found this increase variable 

 (46-10 per cent.) and less than the corre- 

 sponding absorption of oxygen, so that the 

 respiratory ratio became lowered during 

 contraction. Tissot| showed that the pro- 

 duction of carbon dioxid in excised mus- 

 cles was increased if the muscle were killed 

 by heat or were fatigued by prolonged 

 stimulation. The output of carbon dioxid 

 in such eases was not related to the rate 

 of ahsorption of oxygen. Six years ago 

 Fletcher,^ using Blackman's apparatus, 

 the most intricate and accurate apparatus 

 yet devised for following gaseous ex- 

 changes, showed that the evolution of car- 



* ' Versnche fiber den Einfliiss dor Teniperatur 

 auf (lie Respiration des rnhcndes Muskels.' Du- 

 BoiH-Rcijm. Archiv. fur Physiol. 1885: 38-06. 



t ' Versnche iiber den Stoffwoclisel des Muskels.' 

 DuBois-Kcym. .Arch fur Physiol. 1885: 533-.562. 



J ' Reclierclies siir la re.spiration miisRiiliiiie,' 

 Arch, de Phys. norm, ct Path. V. 6: 838-844. 

 1894. Also ' Variation dps echanges gazeux d'un 

 muscle extrait du corjis." Oji. ct .^cr. cit. 7: 641- 

 653. 189"). 



§' Survival respiiatioii of muscle.' Jour. 

 Physiol. 23: 10-99. 1898. 



[N. S. Vol. XXI. No. 529. 



bon 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 oxy- 

 gen ; and second, a long continued evolu- 

 tion of carbon dioxid 'due to chemical 

 processes occurring spontaneously within 

 the muscle, in which complex molecules are 

 replaced by simpler ones, with the con- 

 spicuous results of the appearance of [sar- 

 colactic] acid and of free carbon dioxid.' 

 He adds : ' Under suitable conditions the 

 occurrence of active contractions in an ex- 

 cised muscle is not accompanied by an in- 

 crease in the rate at which carbon dioxid 

 is yielded by the muscle, ' though oxygen is 

 abundantly supplied then by the blood. 

 ?Ie does find, however, an increased forma- 

 tion 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.* 



A great number of researches of the 

 same tenor can be found in botanical lit- 

 erature. A single example must suffice. 

 In an elaborate paper Purjewicz showsf 

 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 di- 

 oxid I'anging within far wider limits than 

 the oxygen. Thus, the carbon dioxid va- 

 ried from — 14 to 120 per cent, of the 

 average; the oxygen varied from to 48 

 per cent, of the average. Purjewicz, in- 

 deed, expre.sses his conviction that the res- 



* ' Lc coellicients de I'activit^ nutritive et respira- 

 toirc des nuiscles.' Compt. Rend. Acad. Sci. France 

 104: 1126-1132. 1887. 



t ' Phy«iol. Ilnters. iiber Pflanzenatmung.' Jahrb. 

 /r/.s.s'. Hot. 35: 573-610. 1900. 



SCIENCE. 



