The origin and significance of the gelatinous material found in tumors designated colloid carcinoma has long been a subject of interest. Colloid has been described as a product of degeneration taking place in a tumor; it has probably been derived either from epithelial or connective tissue, or both. It is now agreed that it is secretory in origin and derived from the epithelial cells of tumors arising from any of the glandular epithelial structures. Accordingly, Broders1 has defined colloid carcinoma as adenocarcinoma with a tendency to differentiate to the extent that a mucus-like substance is produced, and Robertson2 affirmed that a colloid carcinoma is so-called because it is really a collection of mucus large enough to be appreciable to the eye. A distinction between mucus and colloid is no longer maintained; they are usually considered identical substances. Wells,3 however, made such a distinction. He submitted a definite chemical composition for