The study of the cellular structure of effusions is a valuable laboratory procedure. The most satisfactory method of study is that devised by Mandlebaum.1 The fluid is placed in a large Erlenmeyer flask and allowed to stand over night in the icebox. The supernatant fluid is decanted and the sediment poured in a large 50 cc. centrifuge tube and centrifugated for at least twenty minutes at a moderate speed. The supernatant fluid is again decanted and the sediment hardened with a diluted solution of formaldehyde, U. S. P. (1: 10) or Zenker's fluid for twenty-four hours. The fixed sediment is then treated as ordinary tissue by running through alcohols, embedding in paraffin and staining with hematoxylin eosin. The tissue is cut from above down so as to include all the cellular elements.
This report is based on the study of fifty effusions prepared by this method from serous fluids