Pepsin

Pepsin has been already discussed (in the article DIGESTION) as one of the essential constituents of the gastric juice. Various modes of extracting it from the walls of the stomach of the calf, sheep, and pig have been proposed by different chemists. It has not been satisfactorily isolated, and its chemical constitution is unknown. 'At present the manifestation of peptic powers is our only test of the presence of pepsin' (M. Foster). This substance, either in powder or in solution, has been employed of late years to a considerable extent in medical practice, in cases of disorders of digestion due to deficient or imperfect secretion of gastric juice, and of convalescence from typhoid and other debilitating fevers. It is an ingredient in most of the digestive preparations now in the market.