“…thick, were cut in a microtome cryostat at -25°C , were air-dried on to slides and stained for one of the following lipids, using the necessary controls : neutral lipids, using oil red O (Chayen, 1968;Pearse, 1968); unsaturated lipids, using the brominesilver technique (Norton, Korey & Brotz, 1962); phospholipids using the method of Kennedy, Soper & Lunn (1970) ; and free fatty acids, using Fischler's method (Luna, 1968), and counterstained as required.…”