The Air Turbine Ultracentrifuge, together with some Results upon Ultracentrifuging the Eggs of Fucus serratus

GENERALLY, the force of gravity has little or no effect upon the distribution of the various materials within cells, although they may differ considerably in their relative specific gravity. However, by means of the centrifuge forces can be obtained many times greater than gravity, which otherwise exist only on the very largest planets. Because of this fact, the centrifuge has proved to be a very valuable instrument in the study of many problems of biology. For instance, in experimental cytology and embryology, the subjects with which we are here concerned, it has been used extensively to bring about a redistribution of the various materials within the animal egg, such as the yolk, the pigment, the protoplasm and the fat. From such experiments the role of these various substances as possible organ-forming materials and as affecting cellular differentiation has been studied. Other problems such as fragmentation of the egg, viscosity of the protoplasm, membrane strengths, influence of gravity upon development, differential injury to eggs, molecular weight determinations, polarity, and the cytoplasmic components and inclusions have all been profitably investigated by means of the centrifuge. The types of devices that have been used to generate centrifugal force in biological experiments are many and varied. For instance, we find a gradual evolution from a simple wagon-like wheel used by Knight in 1815 to study the effect of centrifugal force upon developing plants, to various types of hand centrifuges with high gear ratios, to the fly-wheel of an engine as used by Morgan (1902), to electric and water driven centrifuges, to the Sharples supercentrifuge which develops forces upward to 62,000 times gravity, to the Svedberg oil turbine centrifuge capable of developing forces upward to 400,000 times gravity, and finally to the recently