THE BEHAVIOR OF ISOLATED HEARTS OF THE GRASSHOPPER, CHORTOPHAGA VIRIDIFASCIATA, AND THE MOTH, SAMIA WALKERI, IN SOLUTIONS WITH DIFFERENT CONCENTRATIONS OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM

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Abstract
The blood of Chortophaga viridifasciata was found to contain the following (concentration in mg %): Na 250.66; K, 13.52; Ca, 11.40; Mg, 51.15; protein N, 253.4; and non-protein N, 140.0. The osmotic pressure at 0[degree] C is 10.7 atmospheres. The blood of Samia walkeri has an osmotic pressure of 13.36 atmospheres at 0[degree]C. Its protein N is 628.58, and its non-protein N, 441.20 mg %. The ratio of Na to K in milligram percent necessary for maintaining the normal heart beat of C. viridifasciata is 3 - 1, but it may be increased to at least 34-1 without appreciable effects. The ratio of K to Ca necessary for maintaining the normal heart beat of this insect is 1 - 1, and may be increased to as much as 3 - 1. The ratio of Na to K needed for the normal heart beat of S. walkeri was found to be equal to or to exceed 1 - 13.8. However, the Na content may be increased so that the ratio is 34 - 1 without toxic effects. The ratios of K to Ca required for the heart beat of this insect may be 1 - 1, 2 - 1, or 3-1. The hearts of the grasshopper beat normally in isotonic solutions having an osmotic pressure of 10.7 atmospheres. They beat equally well in solutions having an osmotic pressure of 13.4 atmospheres. The hearts of the cynthia pupae beat normally in isotonic solutions having an osmotic pressure of 13.36 atmospheres. However, they also beat normally in solns. having an osmotic pressure of 10 atmospheres.