Calcium and Phosphorus Metabolism of P. vigil — Sather 
201 
between the A 1 . 2 and B ± _ 2 values. During the 
last two postecdysial stages, the water content 
decreased to 77.78%. Because the "remainder” 
was largely composed of exoskeleton, this curve 
follows the same general pattern as the cara- 
pace. The increase in hydration following ec- 
dysis was probably due to a greater extracellular 
fluid volume of the exoskeletal tissues. During 
calcification, the extracellular water was un- 
doubtedly replaced by calcium salts. 
The water content of the whole blood during 
the premolt stages of P. vigil was not deter- 
mined. Water is not absorbed during the first 
three proecdysial stages (Sather, 1966). Travis 
(1954, 1955 b) demonstrated that the premolt 
water uptake by Panulirus argus was limited to 
15 minutes just prior to ecdysis. However, as 
can be seen in Figure 1 , P. vigil becomes desic- 
cated during proecdysis. The water content of 
the intermolt blood was found to be 94.14%. 
The value for the A x . 2 stages was 93.98% ; at 
91.46%; and at the period, 93.88%. 
Because the greatest absorption of water occurs 
during the period immediately following ecdysis, 
it would be expected that the blood at the A 1 _ 2 
duration would be somewhat diluted (to be ex- 
plained below). Travis (1955 b) found that 
the blood calcium and phosphorus concentra- 
tions of P. argus were decreased following molt. 
Robertson (I960) reported that in C. maenas 
the concentrations of blood constituents were 
reduced during the early postmolt stages. Both 
authors attributed their findings to the uptake 
and retention of water. 
Proecdysial and early postecdysial P. vigil 
exhibit significant alterations in water content. 
This phenomenon offers a fine thesis problem 
on the osmoregulatory mechanisms and modes 
employed by the crab during this "stressed” 
duration. 
Organic Content of Four Organs Throughout 
the Molt Cycle 
The organic content of the carapace, gills, 
muscle, and mid-gut gland are plotted in Figure 
2. Analysis of variance illustrated that the 
organic content of the organs did not uni- 
formly fluctuate. 
A great variability is seen in the organic con- 
tent of the carapace, but none of the alterations 
was found to be significant from the intermolt 
content of 35.76%. 
The organic composition of the mid-gut 
gland increased from an intermolt value of 
about 10% to approximately 25% at the pre- 
molt stages. This accounts for the hyperglycemia 
reported for proecdysial Panulirus japonicus by 
Scheer and Scheer (1951). After ecdysis, the 
organic value dropped to 16.15%, which can 
be similarly attributed to the loss of reserves 
utilized for the active process of molting and 
for the tanning of the pigmented layer, espe- 
cially as the crabs do not feed until the late B 
stage. The value found at the C ± _ 2 period was 
not significantly different from that of the pre- 
vious period, but it was greater than that of the 
C 3 _ 4 stages. During the early C stages, P. vigil 
becomes voracious, obviously to compensate for 
the loss which occurred during ecdysis. 
The alterations in the organic content of the 
muscle were similar to those of the mid-gut 
gland. From an intermolt level of 11.66%, the 
organic content increased to about 20% during 
proecdysis. The significant increase in organic 
material during these periods probably is due 
largely to the accumulation of glycogen to serve 
as an energy source for the epidermal cells 
which form the proecdysial tissues and the molt- 
ing fluid. It is quite possible that the muscle 
organic constituents would be at a high level 
just prior to ecdysis, as the active process of 
exuviation would require a great amount of 
energy. In addition, crabs in the early D 3 stage 
did feed and the resulting energy would hive 
to be stored either in the mid-gut gland or in 
some other tissue. Undoubtedly, the former has 
a saturation level and the most likely tissue, 
therefore, would be the muscle because of its 
adequate blood supply. 
The lowest curve in Figure 2 illustrates the 
changes in the organic content of the gills. The 
minimum concentration of organic materials 
occurred in the intermolt period (6.51%) and 
the highest (10.45%) was found to occur in 
the D 3 _ 4 stages. The premolt gains were sig- 
nificantly greater than the intermolt value. 
During the postecdysial stages, the gill organic 
content decreased to the original intermolt con- 
tent. 
One possible explanation for the observed 
increase in gill organic content at D 3 . 4 would be 
