On the physiology and biochemistry of the scalp and hair lipids.

Analyses were made of the scalp and hair lipids of 67 test persons. These were the most important results: 1. Seborrhoea is caused on one hand by a high secretion performance of the sebaceous glands. A further cause is that a longer period of time passes before a constant lipid amount is established. 2. There was an average of 19.32% of free fatty acids in the scalp and hair lipids on the 1st day after the hair was washed, and 38.68% on the 10th day. These results allow an assessment of the physiological significance of microbial lipolysis outside the secretory ducts of the sebaceous glands. 3. On the hairy head the percentage of free fatty acids in the scalp and hair lipids is independent of the amount of lipids. Such a difference in the concentration of fatty acids as is found between seborrhoea oleosa and seborrhoea sicca on hairless skin can not be found on the hairy head.