Stern also invented a theory to account for the therapeutic effects of his inventions, namely, the theory of phlebostasis. Instead of pumping air out of a device, Stern pumped air into a device, for the same purpose of removing a portion of blood from the general circulation. His "phlebostate," manufactured by Kny-Scheerer of New York, was quite similar to a sphygmomanometer. It consisted of a set of cuffs that fit about the thighs, rubber tubes, a manometer, and a suction bulb or an electric force pump. For stubborn cases, such as migraine headaches, Stern recommended using the cuffs for 30 minutes or more. To facilitate the application of the cuffs, Stern invented a "phlebostasis chair," one of the most complex "cupping" devices ever made. Like an electric chair, the phlebostasis chair was supplied with cuffs for both arms and legs. Air was pumped into the cuffs by means of an electric motor. According to Stern, compression of the upper segment of both arms withheld 300 cc of blood from circulation, while compression of the thighs withheld as much as 600 cc.[170] In addition to these sophisticated devices, simple cupping, especially dry cupping, continued well into the 1930s. Although cupping was no longer generally recommended by physicians, most surgical companies advertised cups, scarificators, and cupping sets in the 1920s and even the 1930s. The last bastions of cupping in the United States were the immigrant sections of large cities. In the lower East Side of New York, in particular, cupping was still flourishing in the 1920s. By then cupping was no longer performed by the physician, but had been relegated back to the lowly barber, who advertised in his shop window, "Cups for Colds."[171] Leeching _Leeches_ The word "leech" derives from the Anglo-Saxon _loece_, "to heal." Thus, the Anglo-Saxon physician was called a "leech" and his textbook of therapeutic methods a "leechdom." The animal itself was already known to the ancients under its Latin name _hirudino_. It appears, however, that the introduction of leeches into Western medicine came somewhat later than that of phlebotomy or cupping, for Hippocrates made no mention of them. The earliest references to the use of leeches in medicine are found in Nicander of Colophon (2nd century B.C.) and in Themison (1st century B.C.). Thereafter they were mentioned by most Greek, Roman, and Arabic medical writers.[172]