340 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS variables, 19 out of 20 test persons could be classified correctly. Only one of the "very oily" test persons was classified as "oily." This satisfactory result was achieved with the following variables (in the sequence of their importance): x•5: % wax ester of total lipids X37: ratio of saturated: unsaturated FFA x28: % monoglycerides of hair x•0: % cholesterol ester of total lipids From these variables 2 new variables y• and Y2 were obtained by linear combination (cf. Figure 2). 1.0 0.8 dry ß 189/I medium 0.6 ß 14/I • 0.2 '•. '• 0.0 õ -o. 2 ß 171/2 I,•e/I very greasy J X37 ß I•9/I • ß 163/I 229/I e• 17•/2 e•5/2 I83/2 ß 257/3 ß 239/2 127/1 155/2 ß37/I -0.6 very dry greasy ß58/I I!0/I 264/I -0.8 ß 120/2 -I.0 -I. 0 -0.8 -0.6 -0.• -0.2 0.0 0.2 0.,• 0.6 0.8 1.0 canonical variable Y• Figure 2. Computer-classification of 20 hair samples w.r.t. oiliness according to analytical data of the variables No. 28, 30, 37, and 45. (The arrows in the centre indicate the expected direction of a change in oiliness upon alteration of the variables.) x35 = % wax ester of total lipids x37 = proportion of saturated:unsaturated FFA x28 = % monoglycerides of hair x30 = % cholesterol ester of total lipids y• = 0.067 x•5 - 1.31 x37 -[- 13.29 x28 - 0.376 X•o + 0.1 y2 = 0.0213 x35 + 1.80 x37 -- 5.90 X28 '4- 0.086 X30 -- 2.1.

HAIR OILINESS 341 Thus each object can be characterized as a point in a plane formed by the coordinates y• and Y2, in which areas of different oiliness are marked by boundary lines (Figure 2). The effect of an increase of the 4 variables can be gathered from the direction of the corresponding arrow in the centre of Figure 2. Thus -- an increasing wax ester content in the lipid -- or a decreasing ratio of saturated/unsaturated free fatty acids -- or an increasing quantity of monoglycerides on the hair -- or a decreasing cholesterol ester content in the lipid are leading to increased hair oiliness when all other parameters are kept constant at the same time. In the case of our 20 test persons there is no strict correlation for each of the 4 single parameters (ref. Tables III, IV, IV) because their influence is weakened or even overcompensated by one or several of the other factors. The general validity of these results should be considered with due care since they were obtained from persons with similar hair type and because a number of 20 test persons may be inadequate for attaining a broad generalization. It may well be that the compositional peculiarities of dry and oily sebum are only of minor importance compared to other factors such as fibre cross-section or hair structure (e.g., curliness) which were, as far as possible, kept constant in our panel. There are, however, some hints in literature which support the following conclusions: -- It is common knowledge that an increasing content of unsaturated FFA or TG in fat decreases its melting point and, accordingly, Korolev (44) found significant differences of the degree of unsaturation of sebum between cases of seborrhea sicca and seborrhea oleosa. Therefore, one might expect a more oily appearance of hair lipid with an increasing proportion of unsaturated:saturated fatty acids. -- The fatty acids and alcohols forming the wax esters originate from fatty acid source in the body other than those of the triglycerides (45), and contain more unsaturated and branched chain fatty acids, which are also known to decrease the melting point of sebum as observed in case of the rump lipids of aquatic birds (46). -- Monoglycerides are surface active agents, which could accelerate the distribution of sebum on hair and thus increase its quantity. It is interesting to note that neither the total quantity of lipids nor the degree of triglyceride hydrolysis, both of which are commonly believed to play a major role in hair oiliness, were identified as main factors of influence. Although it is obvious that there must be a correlation between the amount of sebum and hair oiliness, the chemical composition often seems to be the overriding factor. The discriminant analysis did not reveal the lipid quantity G in the washing solutions (determined by CHC13-extraction ) as variable of major relevance, although the results, compiled in Table VIII (column C), indicate a rather close relationship with hair oiliness. However, this correlation is probably accidental, since the procedure of extraction and determination yielded rather erratic results compared to those calculated from the difference between the 2 ether extracts A and H, which can be considered as reliable. The fact that for the majority of samples the quantity of extract G is