78
F. B. SHORLAND
sterol). Glycerides are probably absent. In human hair fat, Nicolaides
and Foster (333) have shown that in addition to free fatty acids there
are present mono-, di-, and triglycerides and waxes. In addition, the
acids combined as waxes possess a somewhat higher iodine value than
those combined as glyceride or present in the free form.
The inverse relationship between the free fatty acids and total
glyceride contents suggests that the free fatty acids, mono- and triglycerides, represent more or less complete stages of hydrolysis of triglycerides. On the other hand the fatty acids of the sebum of the
rodents (304) shown in Table XXVIII were mainly present in the combined form as wax or sterol esters, and not more than traces of glycerol
were formed on saponification. The analysis of the sebum of the rodents
refers to the total fatty acids, but in the human sebum the values recorded in Table XXVIII are for the free acids only (305).
These values are not unlike those obtained earlier by Weitkamp et dl.
(334) for the free fatty acids of human hair fat. However, James and
Wheatley (305) used gas-liquid chromatography, which permitted a
sharper resolution than ester fractionation, thereby revealing the presence of small amounts of branched-chain fatty acids in addition to the
odd- and even-numbered n-saturated and unsaturated acids reported by
Weitkamp et al. (334).
The presence of unsaturated acids with double bonds mainly in the
6,7-position, and to a lesser extent in the 8,9-position, shows that human sebum is different from the depot fat, where the 9,10-position (of
oleic acid) is the most common one (334). In the Ci 8 unsaturated acids
of human sebum, however, oleic acid is still the most abundant unsaturated acid.
The unsaturated acids of the sebum of rodents have not been examined in detail. Taking the results as a whole it will be seen from
Table XXVIII that not only are the sebum fatty acids markedly different in composition between different species, but they are also markedly
different in composition from their depot fats.
Considering the n-saturated acids, these are represented to the extent of about 8% in wool grease and consist chiefly of C 14 and C 16 acids
with lesser amounts of C 24 and C 26 acids. On the other hand the
n-saturated acids of human sebum form about 50% of the total and
cover a range from Cio to 0 Χ8 with Ci 6 predominating. The saturated
acids of the sebum of the guinea pig, mouse, and rat are present in
lesser amounts than in the human sebum. The mouse sebum stands
apart in containing predominantly the higher molecular weight n-saturated acids from C 14 to C 2 i.
n-Unsaturated acids are apparently absent from wool grease, while
F. B. SHORLAND
sterol). Glycerides are probably absent. In human hair fat, Nicolaides
and Foster (333) have shown that in addition to free fatty acids there
are present mono-, di-, and triglycerides and waxes. In addition, the
acids combined as waxes possess a somewhat higher iodine value than
those combined as glyceride or present in the free form.
The inverse relationship between the free fatty acids and total
glyceride contents suggests that the free fatty acids, mono- and triglycerides, represent more or less complete stages of hydrolysis of triglycerides. On the other hand the fatty acids of the sebum of the
rodents (304) shown in Table XXVIII were mainly present in the combined form as wax or sterol esters, and not more than traces of glycerol
were formed on saponification. The analysis of the sebum of the rodents
refers to the total fatty acids, but in the human sebum the values recorded in Table XXVIII are for the free acids only (305).
These values are not unlike those obtained earlier by Weitkamp et dl.
(334) for the free fatty acids of human hair fat. However, James and
Wheatley (305) used gas-liquid chromatography, which permitted a
sharper resolution than ester fractionation, thereby revealing the presence of small amounts of branched-chain fatty acids in addition to the
odd- and even-numbered n-saturated and unsaturated acids reported by
Weitkamp et al. (334).
The presence of unsaturated acids with double bonds mainly in the
6,7-position, and to a lesser extent in the 8,9-position, shows that human sebum is different from the depot fat, where the 9,10-position (of
oleic acid) is the most common one (334). In the Ci 8 unsaturated acids
of human sebum, however, oleic acid is still the most abundant unsaturated acid.
The unsaturated acids of the sebum of rodents have not been examined in detail. Taking the results as a whole it will be seen from
Table XXVIII that not only are the sebum fatty acids markedly different in composition between different species, but they are also markedly
different in composition from their depot fats.
Considering the n-saturated acids, these are represented to the extent of about 8% in wool grease and consist chiefly of C 14 and C 16 acids
with lesser amounts of C 24 and C 26 acids. On the other hand the
n-saturated acids of human sebum form about 50% of the total and
cover a range from Cio to 0 Χ8 with Ci 6 predominating. The saturated
acids of the sebum of the guinea pig, mouse, and rat are present in
lesser amounts than in the human sebum. The mouse sebum stands
apart in containing predominantly the higher molecular weight n-saturated acids from C 14 to C 2 i.
n-Unsaturated acids are apparently absent from wool grease, while