1. Methods of analysis of muscle are discussed, particularly in regard to ashing and extraction procedures for inorganic ions and the determination of chloride.
2. Simultaneous analyses have been made of blood and muscle for the following ions: Na, K, Ca, Mg, Cl, SO4, inorganic and total trichloracetic acid soluble P (inorganic and organic phosphates).
3. In Myxine muscle the ions analysed make up 39-47% (average 42%) of the total osmotic concentration, assuming it to be that of the blood-serum: 491 mg. ions/kg. water content compared with 1181 mg. ions/kg. water in the serum. The latter is practically isosmotic with the surrounding sea water of 1208 mg. ions. Potassium and phosphate are the only ions higher in concentration in the muscle than in the serum, but the muscle concentration of sodium exceeds that of potassium. Low calcium concentrations of 1.8-2.2 mg. ions/kg. water in the muscle and 5.5-7.1 mg. ions in the blood serum, compared with 11.1 mg. ions in the sea water, are correlated with the absence of a calcified skeleton.
4. Muscle ions in Muraena come to 308 mg. ions/kg. water content, about 72% of the osmotic concentration of the plasma; the latter is about one-third that of the surrounding sea water. Potassium, calcium, magnesium and phosphate ions in muscle exceed their respective concentrations in the plasma, while the remaining sodium, chloride and sulphate ions are below the plasma values.
5. Cation-anion balance of the analysed constituents of Myxine muscle is satisfactory, but there is a considerable anion deficit in Muraena muscle, probably made up in part by lactate and bicarbonate ions.