THE PHYSIOLOGY OF MUSCULAR WORK 217 



In the above table the sulphur is represented in two divisions ; 

 the first gives the sulphate which can be extracted by water, and 

 the second the total sulphur after incineration. The difference 

 is due to the large quantity of sulphur which is set free by the 

 destruction of the proteins of the muscle. 



Interesting observations upon the distribution of potassium 

 in muscle have been made by Macallum ( n ), who precipitated the 

 potassium as the hexanitrite of cobalt, sodium, and potassium. In 

 striated muscle there is a condensation of the potassium in the 

 dim bands, the rest of the fibre remaining free from the precipitate ; 

 in involuntary muscle it is smaller in amount and is diffused 

 throughout the cytoplasm, and in cardiac muscle it is distributed 

 as in voluntary muscle. Macallum suggests that the potassium 

 is associated with the rapidity of contraction. 



THE PIGMENT OF MUSCLE 



The exact nature of the pigment, which is present in muscle 

 after the blood has been washed out, has given rise to much con- 

 troversy. MacMunn ( 12 ) found associated with haemoglobin in the 

 muscles a pigment which gave a different spectrum ; this he named 

 myohsematin. He observed it in a compressed fresh muscle when 

 it was held before the slit of a spectroscope, and on account of its 

 capacity for oxidation and reduction he considered it to be a 

 respiratory pigment. It was maintained on the other hand by 

 Hoppe Seyler and his pupils that the pigment was either haemo- 

 globin or a derivative produced by putrefaction. After the lapse 

 of some years the subject has been reinvestigated by Morner ( 13 ), 

 who confirms MacMunn's view, and suggests that the pigment 

 differs from hemoglobin in the combination of its haematin with 

 some other protein or in a different linkage of the components. 



THE FERMENTS OF MUSCLE 



Modern investigations have demonstrated the great importance 

 of unorganised ferments in physiological processes ( 14 ) ; the living 

 cell may be compared to an organised ferment which produces 

 unorganised ferments or enzymes. In voluntary muscles there 

 have been found amylolytic, glycolytic, and peptic enzymes, or in 

 other words, ferments which act upon glucose, glycogen, and protein 



