THEIR CHEMICAL RELATIONS. 73 



precludes the possibility of separating this substance from the 

 nuclei of the fibre-cells; secondly, the fibre-cells themselves are 

 attacked by the prolonged boiling which is necessary for the 

 purpose of effecting as completely as possible the solution of the 

 connective tissue, (a substance, corresponding to Mulder's tritoxide 

 of protein, dissolving with the gelatin, as Schultze formerly re- 

 marked;) thirdly and lastly, notwithstanding all boiling, the 

 nuclear fibres of the connective tissue remain undissolved (as has 

 been often already mentioned), and even when no true elastic 

 fibres are interspersed amongst the contractile tissue, constitute a 

 residual mass which cannot be regarded as a chemically pure body. 

 The coagulated substance of the smooth muscles does not dissolve 

 readily in alkalies, and cannot, therefore, be very perfectly sepa- 

 rated from the substance of the nuclear fibres, as this also partially 

 dissolves in alkalies, more especially on the application of heat. 

 The quantity of sulphur contained in the contractile fibre-cells 

 cannot therefore be determined with certainty by this method, nor 

 is the method of dissolving the substance in alkalies, and precipi- 

 tating it by acids, to be unconditionally recommended ; if, however, 

 we would analyse for its sulphur the substance after being only 

 boiled in water, without having been previously dissolved in alka- 

 lies, we should in every case find too small a quantity of sulphur ; 

 for the nuclear fibres augment the matter which is free from 

 sulphur, and some of the sulphur of the substance also escapes 

 on boiling it in the air. 



It is better, therefore, for these reasons to endeavour to dissolve 

 the substance of the fibre-cells, and we may employ as a solvent 

 dilute alkaline solutions, moderately dilute acetic acid, or water 

 containing hydrochloric acid. I have found that the most effi- 

 cacious of these three solvents is the very dilute hydrochloric acid 

 (containing from 0*1 to 0'5% of the acid). A dilute solution of 

 soda renders the connective tissue too gelatinous, and very pro- 

 bably also dissolves some of the nuclear substance of the contrac- 

 tile fibre-cells, and makes the determination of the sulphur uncer- 

 tain. Acetic acid is better, but the first of the objections advanced 

 against the use of the soda solution exists also in the case of this 

 acid. The hydrochloric-acid solution must be regarded as a tolera- 

 bly pure solution of the substance of the cells of the contractile 

 tissue, as the connective tissue, the nuclear fibres, and the nuclei 

 of the fibre-cells themselves remain undissolved. The substance 

 of the fibre-cells is thrown down from this solution by careful 

 neutralisation in the form of a soft gelatinous mass, which is 



