Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
What to the Slave Is the Fourth of July? What to the Slave Is the Fourth of July? "What to the Slave Is the Fourth of July?" is the title now given to a speech by Frederick Douglass delivered on July 5, 1852, in Corinthian Hall, Rochester, New York, addressing the Rochester Ladies' Anti-Slavery Society. The speech is perhaps the most widely known of all of Frederick Douglass' writings save his autobiographies. Many copies of one section of it, beginning in para. 32, have been circulated online. Due to this and the variant titles given to it in various places, and the fact that it is called a July