352 GASEOUS ANALYSIS OF MUSCLE. [BOOK I. 



and acidification. This method is technically known as scalding. If 

 an inverted beaker be placed in the large dish of boiling fluid and very 

 accurately filled with the salt-solution or its steam, to the exclusion 

 of all air, the muscle may be thrown at once beneath it, and any gas 

 which escapes from the muscle in the process may be collected. 

 Under these circumstances it appears that scalded muscle, during 

 the process of scalding, loses no appreciable quantity of gases. If 

 the muscle is now reduced to a low temperature, and minced 

 to prevent the mechanical entanglement of gas-bubbles ; and then 

 subjected to the influence of a vacuum ; it is found to yield a small 

 per-centage of gases. If, after a first evacuation, phosphoric acid is 

 added to the minced muscle by tilting the froth-chamber, a further 

 escape of gases follows. In both cases the gas is carbon dioxide. 

 Thus scalded muscle muscle in which the process of rigor has been 

 circumvented, and which may therefore be regarded as presenting the 

 gases of fresh normal muscle contains an extremely small quantity 

 of carbon dioxide, both free (i.e. capable of withdrawal by the air- 

 pump), and fixed (i.e. needing an acid to drive it out). The former 

 may amount to 2'74 per cent., and may be due, in part, to the im- 

 perfect scalding of the central portions of the muscle; for, if the 

 temperature is not high enough, rigor follows, and not instant death ; 

 and rigor is associated with acidification and the production of carbon 

 dioxide. The fixed carbon dioxide may amount to 1*95 per cent. 1 



Gaseous -^ ^ e a ^ ove figures be taken as indicating the gases 



analysis of of fresh normal muscle, we shall observe a marked 

 muscle difference in muscle which is passing into rigor. A con- 



passing into venient method of producing the gases of rigor, and at 

 rigor ' the same time facilitating their liberation from the mus- 



cular substance, is the following. Frogs, whose blood-vessels have 

 been well washed out with *5 per cent, solution of NaCl, are taken 

 into a cold atmosphere, and their belly-muscles and muscles of the 

 hinder limbs (excluding the feet and tendons) are quickly cut away 

 and weighed on a watch-glass. They are then placed, still on the 

 watch-glass, over a freezing mixture until they are frozen to a firm 

 mass ; and afterwards they are minced with cold knives and rubbed 

 up in a cooled mortar. The freezing preserves the normal composition 

 of the muscle more or less perfectly during the mincing and tritura- 

 tion 2 ; and these processes are devised to facilitate the disentangle- 

 ment of the gas during evacuation. 



The frozen and triturated muscle is introduced into the boiling- 

 flask which is filled to the brim with normal NaCl solution at 

 C., the various portions being so quickly dropped in that a constant 

 overflow of salt-solution is kept up. The object of this manoeuvre 

 is to wash away the air-bubbles which are carried into the salt- 



1 Hermann, Op. cit. pp. 115, 116. Expt. 9. 



2 Kuhne, Untersuch.u. das ' Protoplasma, Leipzig, 1864, p. 3. See Hermann, Stoff- 

 wechsel der Muskeln, p. 5. 



