202 
PACIFIC SCIENCE, Vol. XXI, April 1967 
that a supply of energy would be required to 
regulate the ionic ratio of the internal to ex- 
ternal media. Unfortunately, the glycogen con- 
tent of the gills was not determined. Consider- 
ing the decreased water content of P. vigil 
during late premolt, it appears that the gills 
may be possible sites of water and/or ion efflux. 
This hypothesis is not in agreement with the 
report by Robertson (I960), which stated that 
the antennal glands of C. maenas were the sites 
of water and ionic efflux. One possible method 
for determining the site of water flux in P. 
vigil would be the use of tritiated water. Radio- 
isotopes representing the extracellular ions 
would also verify the sites of ionic flux. 
Because the organic content of premolt blood 
was not determined, it was not possible to fol- 
low the changes throughout the ecdysis cycle. 
The organic constituent during the A 4 _ 2 period 
was 2.93% of the whole blood. The content in 
stages B 4 _ 2 was 4.02%; in the C 4 _ 2 stages, 
2.86%; and in the C 3 _ 4 stages, 2.64%. The ob- 
served increase during the B period may be due 
to the commencement of food ingestion and the 
subsequent loss (during the C stages) by the 
distribution to the mid-gut gland and exo- 
skeleton. 
Inorganic Content of Four Organs Throughout 
the Molt Cycle 
The fluctuations in inorganic content are illus- 
trated in Figure 3. Analysis of variance indi- 
cated that interaction was again present. 
As could be expected, the carapace varied 
much more in inorganic content than did the 
other sampled tissues. The intermolt value was 
determined to be 42.12%. The significant in- 
crease to 52.01% during the D 4 . 2 stages pos- 
sibly can be attributed to the formation and 
tanning of the new epicuticle. However, the 
inorganic constituent in the proecdysial tissues 
is not dominantly calcium (see Fig. 4). The 
finding is in agreement with those of other 
investigators (Drach, 1936, 1939; Krishnan, 
1950; Travis, 1955^, I960, 1963). During the 
D 3 _ 4 stages when resorption was nearly com- 
pleted, the inorganic content was decreased sig- 
nificantly to 43.80%. It becomes apparent that 
the entire carapace is not an area where maxi- 
mum resorption occurs (see introductory re- 
marks). Following ecdysis the inorganic content 
of the carapace was approximately 20%, reflect- 
ing the amount found in the exocuticle. During 
the A x _2 periods, the exocuticle was impregnated 
with calcium salts, with concomitant formation 
of the principal layer. During the B-^ and 
stages, periods of major calcification, the in- 
organic composition was increased to 27.31% 
and 41.28%; both were significant gains. The 
amount during the early C periods approxi- 
mated that of the intermolt content. 
The mid-gut gland’s alterations are plotted 
also in Figure 3. The increased values during 
premolt (D^ = 5.98%, D 3 . 4 = 7.74%) were 
statistically different from each other and also 
from the intermolt value of 4.29%. This was 
probably due to the storage of some constituents 
absorbed from the exoskeleton. Similar storage 
has been reported by Paul and Sharpe (1916) 
for Cancer pagurus ; by von Schonborn (1912) 
and Robertson (1937, I960) for Carcinus 
maenas; by Drach (1939) for Maia squinado ; 
by Kincaid and Scheer (1952) for Hemigrapsus 
nudus; and by Travis (1955^) for Panulirus 
argus. The reduction in inorganic content dur- 
ing the postmolt stages can be attributed to the 
redistribution of the stored elements to the 
hardening exoskeleton. 
The gill inorganic content was found to vary 
slightly. The observed value of 4.15% at the 
D 4 . 2 duration was found to differ significantly 
from those of the other durations. The greater 
inorganic content was due to the formation of 
the proecdysial tissues, which similarly occurred 
in the carapace, i.e., the epicuticle and exo- 
cuticle. 
As expected, the mean per cent inorganic 
composition of muscle did not vary significantly 
between stages (P > 0.05). The average con- 
tent of the inorganic materials was 2.44%, the 
range being 2.14-2.69%. 
The intermolt inorganic composition of the 
whole blood was 3.22%. During the A 4 . 2 pe- 
riod it was 3.09%, and at the B 4 . 2 it was 
4.52%. The former value reflected the absorp- 
tion of sea water, and the latter value was prob- 
ably due to the mobilization of calcium, after 
it was actively transported by the gills to the 
exoskeleton. The blood inorganic content at the 
Ci -2 period was approximately equal to the 
intermolt value, indicating that the sclerotiniza- 
tion process was nearly completed. 
