Abstract
It has recently been shown that the eggs of Ascaris suum and A. megalocephala (Beams and King 1 2 ) Fucus eggs (Beams 3 ), cancer cells of rat (Guyer and Claus 4 ) and the cells of the adrenal cortex of rat (Dornfeld 5 ) are not killed when subjected to very great centrifugal force. The significance of these experiments rests in the fact that the behavior of protoplasm to high speed centrifuging seems to differ markedly from that of many non-living colloidal systems (Svedberg 6 7 ).
In an effort to extend further these studies on the effect of ultracentrifuging upon protoplasm, the tissue culture method has been employed here. Cultures were made of embryonic chick hearts (of 9 days' incubation) by the usual Carrel hanging drop technique; 4 parts chick plasma and 3 parts embryonic extract being used as medium. The extract was in every case centrifuged twice, in order that no confusion between growth from the explanted material and growth from tissue fragments introduced along with the extract should arise. After the heart was removed, the ventricle was divided into 2 parts, one of which was placed in Tyrode solution in the rotor of the ultracentrifuge where it was centrifuged at either 150,000 or 400,000 times gravity for one-half hour; the other half being left standing in Tyrode solution at room temperature. Contamination of the experimental material was avoided by handling the sterilized rotor with a large hemostat. Cultures of both experimental and control tissue were then made at nearly the same time under identical conditions.
One hundred percent growth was obtained in both control and experimental cultures and although no quantitative determinations of actual growth were made, no difference was observed in the amount and rate of growth in the centrifuged and control material.
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