430
N . BALAKRISHNAN NAIR AND M . SARASWATHY
present study that glycogen in N . hedleyi not only changes seasonally,
but also between gravid and non-gravid individuals. It seems probable
that glycogen, though a storage material in both sexes, is rapidly used
up in the female for the formation of ovocytes. It was interesting to
note that the minimum concentration of glycogen is in females at the
end of the breeding season. Contrary to the results obtained by
Sreenivasan (1963a) in Martesia fragilis, the glycogen content is, on an
average, higher in males than in either the indeterminate forms or in
the females. However, a similar result with comparatively high values
of glycpgen has also been obtained from the shrunken, spent male gonad
of the chitons Katherina tunicata (Giese and Araki, 1962) and Cryptochiton stelleri (Tucker and Giese, 1962). Generalization is, however,
difficult owing to the paucity of information since Lane et al. (1952)
do not give any data with reference to sex and maturity. An increase
in glycogen content is also evident with an increase in weight. A
similar observation has also been reported for the Miami species by
Lane et al. (1952) and Greenfield (1953). Detailed histochemical studies
may throw further light on the distribution of glycogen. Lane
et al. ( 1 952) have reported considerable concentration of glycogen in the
muscles and also in the gill and in the imbedded larvae. I n the pholad,
Martesia striata Nagabhushanam ( 196 la) estimated that glycogen
forms about 3% on the basis of dry weight of adult specimens. This
was chiefly concentrated in the gonad and the muscles. A decrease of
about 62% was noted in animals kept in plankton-free sea water for
10 days. He found no seasonal variation of glycogen in this borer.
In N . hedleyi the protein content was generally high from June to
January. The total nitrogen values were apparently steady both during
breeding and non-breeding periods. The values for non-protein
nitrogen indicate that in general this was poor during a major part of
the breeding season. It has been reported (Lasker and Lane, 1953;
Greenfield, 1953) that the nitrogen content of adult Teredo is generally
very low and this has been attributed to a dominant cellulose diet. This
generalization seems to be justified and our studies indicate that the
values for total nitrogen are generally low. However, it may be noted
that in Nausitora hedleyi, though the total nitrogen content (5.16) is
higher than that in Teredo pedicellata (2.17), it is much less than in
other molluscs such as Martesia fragilis (Sreenivasan, 1963b) in which a
value as high as 11.7 has been recorded. The higher nitrogen content
noticed in this species is perhaps due to its habitat in highly productive
estuarine areas. The greater amounts in smaller specimens of this
species has been noticed in Teredo pedicellata also (Greenfield, 1953).
Similarly in both Martesia striata and M . fragilis the unit nitrogen con-
N . BALAKRISHNAN NAIR AND M . SARASWATHY
present study that glycogen in N . hedleyi not only changes seasonally,
but also between gravid and non-gravid individuals. It seems probable
that glycogen, though a storage material in both sexes, is rapidly used
up in the female for the formation of ovocytes. It was interesting to
note that the minimum concentration of glycogen is in females at the
end of the breeding season. Contrary to the results obtained by
Sreenivasan (1963a) in Martesia fragilis, the glycogen content is, on an
average, higher in males than in either the indeterminate forms or in
the females. However, a similar result with comparatively high values
of glycpgen has also been obtained from the shrunken, spent male gonad
of the chitons Katherina tunicata (Giese and Araki, 1962) and Cryptochiton stelleri (Tucker and Giese, 1962). Generalization is, however,
difficult owing to the paucity of information since Lane et al. (1952)
do not give any data with reference to sex and maturity. An increase
in glycogen content is also evident with an increase in weight. A
similar observation has also been reported for the Miami species by
Lane et al. (1952) and Greenfield (1953). Detailed histochemical studies
may throw further light on the distribution of glycogen. Lane
et al. ( 1 952) have reported considerable concentration of glycogen in the
muscles and also in the gill and in the imbedded larvae. I n the pholad,
Martesia striata Nagabhushanam ( 196 la) estimated that glycogen
forms about 3% on the basis of dry weight of adult specimens. This
was chiefly concentrated in the gonad and the muscles. A decrease of
about 62% was noted in animals kept in plankton-free sea water for
10 days. He found no seasonal variation of glycogen in this borer.
In N . hedleyi the protein content was generally high from June to
January. The total nitrogen values were apparently steady both during
breeding and non-breeding periods. The values for non-protein
nitrogen indicate that in general this was poor during a major part of
the breeding season. It has been reported (Lasker and Lane, 1953;
Greenfield, 1953) that the nitrogen content of adult Teredo is generally
very low and this has been attributed to a dominant cellulose diet. This
generalization seems to be justified and our studies indicate that the
values for total nitrogen are generally low. However, it may be noted
that in Nausitora hedleyi, though the total nitrogen content (5.16) is
higher than that in Teredo pedicellata (2.17), it is much less than in
other molluscs such as Martesia fragilis (Sreenivasan, 1963b) in which a
value as high as 11.7 has been recorded. The higher nitrogen content
noticed in this species is perhaps due to its habitat in highly productive
estuarine areas. The greater amounts in smaller specimens of this
species has been noticed in Teredo pedicellata also (Greenfield, 1953).
Similarly in both Martesia striata and M . fragilis the unit nitrogen con-