Marcello Malpighi was an Italian biologist and physician who had a wide knowledge of both plants and animals, and made contributions to the scientific study of both. He founded the sciences of microscopic anatomy and histology. He studied animal tissues extensively for 40 years, using microscopes that he had made himself. Malpighi was the first person to see capillaries in animals. He discovered the link between arteries and veins that had eluded William Harvey. Malpighi was also the earliest person to observe red blood cells under a microscope. He is noted for his studies on the structure of glands. In his treatise De polypo cordis published in 1666, Malpighi explained blood composition, as well as how blood clots are formed. His research provided a foundation for later advances in physiology, embryology, and practical medicine.