CASTLE1 concluded from the observations of Zophoniasson that the yellow fat appearing in some Icelandic sheep is due to a simple recessive character in inheritance. I have recently examined the chemical nature of the yellow pigments in the adipose tissue of some Irish sheep. The yellow fat was rendered from the adipose tissue by heating in an oven at 60°C. One hundred and fifty grams were saponified by heating with 300 ml. of 20 per cent alcoholic potassium hydroxide. After dilution with 900 ml. of water the pigments were extracted using 1,200 ml. of diethyl ether. Complete extraction was accomplished by using 600-ml. portions of ether in two or three subsequent extractions. After washing with water and drying over anhydrous sodium sulphate the ether was distilled off under nitrogen on a water bath. The residue of crude pigments and cholesterol was dissolved in 5 ml. of hexane and chilled. After filtration, from unsaponified material deposited during chilling, the pigment extract was made up to 50 ml. using hexane.