Eighteen illustrations of various fats under a microscope. Some examples are under polarized light. Dr. Taylor was trying to create a method of analyzing different fat types to be able to judge purity of food against adulteration. See page 8 of the reprint for a description of each figure in the plate.
This reprint is Dr. Thomas Taylor's reply to the magazine "Science" relating to his heavily disputed method of analyzing fats for adulteration. Dr. Thomas (1820-1910) was appointed in 1871 Microscopist to the United States Department of Agriculture until the position was eliminated in 1885.