Calcium and Phosphorus Metabolism of P. vigil — Sather 
199 
Fig. 9. Percent composition of the exuvia of 
P. vigil (values based on dry weight). 
matter in the carapace was greater than that 
in the entire exuvia. 
To determine whether larger crabs were able 
to resorb the same amount of calcium as smaller 
crabs, the amount of calcium in the exuviae was 
plotted against exuvial carapace width. (The 
data were then statistically analyzed for regres- 
sion and the slope was fitted by the least squares 
method.) Figure 10 clearly indicates that as the 
crabs increased in size the amount of resorbed 
calcium decreased, and the regression analysis 
showed that the calculated slope was 0.082 
(P <0.001). 
DISCUSSION AND CONCLUSIONS 
Weight Changes During the Molt Cycle 
Changes in weight of Crustacea during ecdy- 
sis are due to absorption of water (Baumberger 
and Olmsted, 1928; Drach, 1939; Needham, 
1946; Guyselman, 1953; Travis, 1954). The 
alterations of body weight and water content of 
P. vigil have been reported elsewhere (Sather, 
Fig. 10. Regression of calcium content of exuviae on exuvial carapace widths of P. vigil, b = 0.082 
(P < 0.001). Upper and lower curves represent the 95% confidence limits. 
