The present review covers only a part of the literature, since the majority of foreign journals have become unavailable in the past year. In a few cases the summaries published in Chemical Abstracts could be used, and this has been indicated in the bibliography. A consider able number of foreign publications had to be omitted.The present period in biochemistry is characterized by an increased emphasis on new tools rather than on definitive results. The possibili ties of the application of stable and radioactive isotopes, of the ultra centrifuge; the electrophoresis apparatus, etc., have occupied the at tention of a great number of workers. It is perhaps indicative of the present trend that the lipid metabolism in plants, unquestionably a fascinating and important subject in comparative biochemistry, is practically not mentioned in this review.
GLYCERIDES AND FATTY ACIDSAbsorption.-Winter & Crandall (1) were unable to demonstrate the direct portal absorption of fatty acids in normal unanesthetized dogs. No significant differences between the fatty acid contents of portal and arterial blood (obtained by the angiostomy technique) were foun d in samples taken before and during fat absorption. A similar conclusion was reached by Little & Robinson (2) .Burr and co-workers (3) studied the absorption and transport of the methyl esters of fatty acids across the intestinal mucosa in adult rats. The acids were characterized by their content of spectroscopi cally distinguishable conjugated compounds produced by partial isom erization with alkali of the corn oil fatty acids. Both the neutral fats and the phospholipids of the mucosa were examined. In the first half hour of absorption more than 50 per cent of the acids of the neutral fat had exchanged, in contrast to only 3 per cent of the phosphatide fatty acids. The amount of tagged fatty acids in the neutral fat re mained fairly constant between one-haH hour and eight hours after absorption; the entry of fatty acids into the phospholipid fraction took place gradually and reached a maximum eight hours after absorption.
235Annu. Rev. Biochem. 1942.11:235-256. Downloaded from www.annualreviews.org Access provided by University of Saskatchewan on 02/05/15. For personal use only.Quick links to online content Further ANNUAL REVIEWS