Some observations on the electron microscopy of lipids

SYNOPSIS The preservation and identification of free lipids is most difficult because they are very readily dissolved by the usual embedding media. At present only unsaturated triglycerides fixed by postchromation and lipofuscins can survive this extraction. There is no general fixative for lipids. A few unusual embedding media will preserve small droplets of lipids, but they are technically far from satisfactory. Included in this group is a new medium—urea‐formaldehyde. Some general stains for lipids have been developed; the results are, again, usable but rather unsatisfactory.