36
OURDON A. KILEY
Commonly 30-60y0 or more of the total material in surface collections was hydrolyzed, although in one cruise the mean was only 10%.
In deep samples, comprising a total of about one hundred analyses,
cruise averages varied from 19-26y0. Hydrolyzed material was examined microscopically after treatment with the usual histochemical
stains. Protein was largely removed, but the carbohydrate was not
noticeably altered.
As Gordon pointed out, the digestive processes of filter feeders may
be more effective in the hydrolysis of this material than the simple in
vitro treatment. How much of the organic matter can really be used
remains obscure. Earlier work by Parsons and Strickland ( 1 962a) suggested that the percentage might be very much higher. Their values for
crude fibre averaged about 25% of the total, and the composition of the
remainder suggested that most of it might be assimilable. The later
work by Holm-Hansen et al. (1966), as described above, was more nearly
in line with the concept that a large fraction of the total might be biologically inert. This is another case in which it is impossible, in the
present state of our knowledge, to distinguish clearly between differences in methodology and real differences in composition of the organic
matter.
It is tempting at this point to suggest that the different kinds of
substances described by Handa and by Degens may be largely segregated morphologically into the two major types of non-living particles
that have been observed in the sea. There are indications that amorphous aggregates may represent a conglomeration of refractory remains
of phytoplankton and other detrital material and that bacteria living
on these particles may be dependent primarily upon dissolved organic
matter rather than the aggregates themselves for their sustenance.
On the other hand, the proteinaceous substances described by Degens
and ranging in size from macromolecules to flakes would appear to
be not only more usable metabolically but also chemically more susceptible to polymerization and cementing into flake-sized particles. The
proposition probably is stated more categorically than is fully deserved
but present information and experimental evidence to be introduced
later suggest that there is some validity in the generalization.
C. Relationships of organic and inorganic materials
Wangersky (1965) remarked. that " aggregates are called organic
only by courtesy and precedent, since their organic fraction seldom
exceeds 30% ". This is quite true. Biologists have recognized for some
time that organic matter is a minor fraction of the total particulate
matter in sea water, but they took little interest in the inorganic fraction.
OURDON A. KILEY
Commonly 30-60y0 or more of the total material in surface collections was hydrolyzed, although in one cruise the mean was only 10%.
In deep samples, comprising a total of about one hundred analyses,
cruise averages varied from 19-26y0. Hydrolyzed material was examined microscopically after treatment with the usual histochemical
stains. Protein was largely removed, but the carbohydrate was not
noticeably altered.
As Gordon pointed out, the digestive processes of filter feeders may
be more effective in the hydrolysis of this material than the simple in
vitro treatment. How much of the organic matter can really be used
remains obscure. Earlier work by Parsons and Strickland ( 1 962a) suggested that the percentage might be very much higher. Their values for
crude fibre averaged about 25% of the total, and the composition of the
remainder suggested that most of it might be assimilable. The later
work by Holm-Hansen et al. (1966), as described above, was more nearly
in line with the concept that a large fraction of the total might be biologically inert. This is another case in which it is impossible, in the
present state of our knowledge, to distinguish clearly between differences in methodology and real differences in composition of the organic
matter.
It is tempting at this point to suggest that the different kinds of
substances described by Handa and by Degens may be largely segregated morphologically into the two major types of non-living particles
that have been observed in the sea. There are indications that amorphous aggregates may represent a conglomeration of refractory remains
of phytoplankton and other detrital material and that bacteria living
on these particles may be dependent primarily upon dissolved organic
matter rather than the aggregates themselves for their sustenance.
On the other hand, the proteinaceous substances described by Degens
and ranging in size from macromolecules to flakes would appear to
be not only more usable metabolically but also chemically more susceptible to polymerization and cementing into flake-sized particles. The
proposition probably is stated more categorically than is fully deserved
but present information and experimental evidence to be introduced
later suggest that there is some validity in the generalization.
C. Relationships of organic and inorganic materials
Wangersky (1965) remarked. that " aggregates are called organic
only by courtesy and precedent, since their organic fraction seldom
exceeds 30% ". This is quite true. Biologists have recognized for some
time that organic matter is a minor fraction of the total particulate
matter in sea water, but they took little interest in the inorganic fraction.