Lipoid Metabolism in T H E Developing Chick

PLATES 59 AND 60. While working with a chick embryo of nineteen days' incubation, my attention was attracted by the brilliant yellow color of the liver. The color was like that o f the adrenal cortex, or the corpus luteum, and this resemblance impelled me to investigate more closely the condition of the liver cells. A small fragment of the liver was teased and examined between the Nicol prisms of a polarizing microscope. The result is illustrated by figure I. With the Nicol prisms uncrossed the field was filled with many small, rather refrac-tile d,roplets (figure I, A), and these upon crossing the prisms exhibited with great clearness and beauty the phenomenon of double refractivity (figure i, B). Sudan III was now added to the preparation and the droplets gradually stained a vivid yellowish red. It was clear, then, that the liver of the chick embryo of nineteen days incubation contained an abundance of fatty matter of an anisotro-pic lipoidal nature. This discovery was quite surprising, for as far as I am aware, the occurrence of anisotropic lipoids in the paren-chyma cells of the liver has never been described. Much has been written within recent years concerning the physical and chemical properties of the so called lipoids, and a great deal has been learned in regard to their physiological and pathological occurrences in the body. I need not review even the principal contributions to the subject at this time, for the writings of Adami