A simple method for preparing serial blocks of tissue.

The organ or tissue, e.g., extrinsic eye muscle (Fig. 1), a vermiform appendix (Fig. 2), or a length of blood vessel, is fixed in formalin and impregnated with paraffin wax in the ordinary way. It is removed from the molten wax, laid on a smooth surface, straightened by hand, and allowed to cool. As soon as the wax has become firm a series of transverse cuts are made with a very sharp knife so that the tissue is divided into a series of small segments each about 3 mm. thick. The usual embedding box of two metal "4squares" is arranged on a flat metal plate. A very little melted paraffin wax is poured in and the base warmed over a flame until