[1]. "Anal Fissure," 1868, p. 45.
[2]. "Principles and Practice of Surgery," vol. i, p. 416.
[3]. "Intestinal Diseases of Children," p. 295.
[4]. Andrews, "Rectal and Anal Surgery," Chicago, 1889, p. 69.
[5]. Op. cit., p. 69.
[6]. Ball, "The Rectum and Anus," Philadelphia, 1887, pp. 128-129.
[7]. Op. cit., pp. 69-70.
[8]. Bodendamer (op. cit., p. 58) calls attention to a fact of some importance as bearing upon this point—to wit, that in some cases of constipation, while the diaphragm and other abdominal muscles act with considerable energy, the anal sphincters remain more or less contracted, and yield but slowly, so that the indurated feces contuse and abrade the surface of one or more points of the mucous membrane, which abrasions, if they do not heal, lay the foundation of the disease.
[9]. Instances of this condition as the cause of anal fissures are mentioned by T. B. Curling in his "Observations on the Diseases of the Rectum," second edition, London, 1855.