1. FATTY ACID OCCURRENCE AND DISTRIBUTION
5
in some specimens of Duboisia myoporoides and of hyoscyamine in
other specimens (9).
In one specimen of Daphnandra micanthra the bark alkaloids were
found to consist mainly of daphnandrine and daphnoline with traces of
micanthrine (JO) whereas in another specimen micanthrine alone was
present (11).
In microorganisms it is perhaps significant that the presence of
strains in a particular culture may mean wide variations in the elaboration of constituents, as in penicillin-producing mold; or variations may
be observed in the color of the microorganisms showing chemical
modifications within a particular species (12).
In spite of the anomalies mentioned above, a study of chemical
constituents can be useful as a guide to the classification of species.
Bate-Smith (13) in considering the distribution of phenolic substances
in plants has remarked: "It is therefore extremely encouraging to find
the divisions of plants indicated by the pattern of distribution of
phenolic substances so seldom at variance with the generally accepted
systems of taxonomic classification." More recently Micks has used
Chromatographie techniques to assist in the solution of taxonomic problems in insects (14), particularly in regard to the classification of types
of mosquitoes (15).
In the field of fats the evidence almost certainly points toward the
occurrence of specific fatty acids in some species, especially in the
vegetable kingdom, but the possibilities of variations within morphologically identical species cannot be overlooked.
In defining relationships between the occurrence of specific fatty
acid types and the classification of species, it is desirable to eliminate
the effect of environment. In animals, for example, it is obvious that
the kinds and proportions of the fatty acids in the depot fats are influenced by those of the dietary fats. In extreme cases when the diet
includes a high proportion of fat, the depot fats and the dietary fats
may be very similar in composition. On the other hand, there is little
evidence to show that wool or hair lipids are markedly changed by the
diet or that the dietary fatty acids are incorporated into these lipids to
any great extent. It is therefore possible that such lipid secretions are
more characteristic of the species than are their depot fats.
Specific modifications may be imposed on the ingested fats that
serve to characterize a class or a species. Thus it is found that in ruminants the dietary unsaturated fatty acids are partially hydrogenated,
giving rise to trans and positional isomers of the ingested unsaturated
fatty acids. These acids are not found to occur naturally elsewhere.
Information on the relationships between fatty acid occurrence and
5
in some specimens of Duboisia myoporoides and of hyoscyamine in
other specimens (9).
In one specimen of Daphnandra micanthra the bark alkaloids were
found to consist mainly of daphnandrine and daphnoline with traces of
micanthrine (JO) whereas in another specimen micanthrine alone was
present (11).
In microorganisms it is perhaps significant that the presence of
strains in a particular culture may mean wide variations in the elaboration of constituents, as in penicillin-producing mold; or variations may
be observed in the color of the microorganisms showing chemical
modifications within a particular species (12).
In spite of the anomalies mentioned above, a study of chemical
constituents can be useful as a guide to the classification of species.
Bate-Smith (13) in considering the distribution of phenolic substances
in plants has remarked: "It is therefore extremely encouraging to find
the divisions of plants indicated by the pattern of distribution of
phenolic substances so seldom at variance with the generally accepted
systems of taxonomic classification." More recently Micks has used
Chromatographie techniques to assist in the solution of taxonomic problems in insects (14), particularly in regard to the classification of types
of mosquitoes (15).
In the field of fats the evidence almost certainly points toward the
occurrence of specific fatty acids in some species, especially in the
vegetable kingdom, but the possibilities of variations within morphologically identical species cannot be overlooked.
In defining relationships between the occurrence of specific fatty
acid types and the classification of species, it is desirable to eliminate
the effect of environment. In animals, for example, it is obvious that
the kinds and proportions of the fatty acids in the depot fats are influenced by those of the dietary fats. In extreme cases when the diet
includes a high proportion of fat, the depot fats and the dietary fats
may be very similar in composition. On the other hand, there is little
evidence to show that wool or hair lipids are markedly changed by the
diet or that the dietary fatty acids are incorporated into these lipids to
any great extent. It is therefore possible that such lipid secretions are
more characteristic of the species than are their depot fats.
Specific modifications may be imposed on the ingested fats that
serve to characterize a class or a species. Thus it is found that in ruminants the dietary unsaturated fatty acids are partially hydrogenated,
giving rise to trans and positional isomers of the ingested unsaturated
fatty acids. These acids are not found to occur naturally elsewhere.
Information on the relationships between fatty acid occurrence and