A Dope for Embedding Wax

Abstract

ATTENTION has been directed by Higgs1 to the effect of small quantities of petroleum ceresins in causing paraffin wax to cool in a microcrystalline state. It seemed possible that this effect might be valuable in the technique of cutting paraffin sections. During this summer we have been using, for the routine sectioning of early amphibian embryos, a paraffin wax mixture, without addition of beeswax but containing 0.5 per cent of petroleum ceresin which was supplied by Messrs. Shell-Mex and B. P., Ltd. The results have been all that could be desired, the wax cooling with a very fine texture even when the embedding dish was allowed to cool in the air without being immersed in water. It is necessary to use a mixture having a melting point, before the addition of ceresin, slightly lower than is normally appropriate. The electrostatic properties of the wax appear to be unaltered. The dope may be particularly useful in embedding large objects, in which ordinary wax tends to cool too slowly in the centre of the block.