From the earliest examples of the fleam, such as the specimen found at Pompeii, this instrument has been associated with the veterinarian. Since early practitioners, particularly the Roman physician, performed the duties of the surgeon as well as those of the veterinarian, it is possible that they used the same instrument to open blood vessels in humans and animals.[46] In the seventeenth and eighteenth centuries a type of fleam (German _fliete_, French _flamette_), which had a pointed edge at right angles to the handle, was in use in Germany, Holland, and Vienna, Austria.[47] Since the specimens found in museums vary in size, it is likely that this type of fleam was used on both animals and humans. In about the fifteenth century the thumb lancet, also called a _gladiolus_, _sagitella_, _lanceola_, _lancetta_, or _olivaris_, was introduced.[48] It soon became the preferred instrument for opening a vein in any part of the body. The double-edged iron or steel blade was placed between two larger covers, usually made of horn or shell, and all three pieces were united at the base with a riveted screw. The blade could be placed at various angles of inclination when in use. The shape of the blade, whether broad or narrow, determined the ease with which the skin and vein could be penetrated. A long slender blade was essential to pierce a vein located below many layers of fatty tissue.[49] These tiny and delicate thumb lancets were often carried in small flat cases of silver, tortoise shell, shagreen, or leather with hinged tops and separate compartments for each lancet. (Figure 5.) A surgeon was advised to carry lancets of various sizes and shapes in order to be prepared to open veins of differing sizes and in different locations. Even Hippocrates had cautioned bloodletters not to use the different size lancets indiscriminately, "for there are certain parts of the body which have a swift current of blood which it is not easy to stop."[50] For vessels that bled easily, it was essential to make narrow openings; otherwise it would be difficult, if not impossible, to stop the flow of the blood. For other vessels, lancets that made larger openings were required or the blood would not flow satisfactorily. The blood as it spurted from the vein would be collected in a container and measured. When enough blood was removed, the bleeding would be stopped by a bandage or compress applied to the incision. [Illustration: FIGURE 5.--18th-19th century lancets and lancet cases. The cases are made of mother-of-pearl, silver, shagreen, and tortoise shell. (NMHT 308730.10. SI photo 76-9116.)] Teaching a medical student how to bleed has had a long tradition. Before approaching a patient, the student practiced opening a vein quickly and accurately on plants, especially the fruits and stems.[51] The mark of a good venesector was his ability not to let even a drop of blood be seen after the bleeding basin was removed.[52]