The original conception regarding the manner in which gastric juice exerts its solvent power on proteid foods was apparently limited to simple solution; chemical solution if you choose, brought about by catalytic action, but without any hint as to the possible nature of the soluble products formed. Mialhe,[14] however, recognized the fact that this transformation, by which insoluble and non-diffusible proteid matter was converted into a soluble and diffusible product, was a form of hydration, comparable to the change of insoluble starch into soluble sugar, and he named the hypothetical product albuminose. Mialhe’s study of the matter in 1846 was followed by Lehmann’s[15] investigation of the subject, and the coining of the word peptones as an appropriate name for the soluble products of gastric digestion. The peptones isolated by Lehmann were described as amorphous, tasteless substances, soluble in water in all proportions and insoluble in alcohol. They were likewise precipitated by tannic acid, mercuric chloride, and lead acetate, and were considered as weak acid bodies, having the power of combining with bases to form salts of a more or less indefinite character. Twelve years later, in 1858, Mulder[16] gave a more complete description of peptones, but his study of the subject failed to advance materially our knowledge of the broader questions regarding the nature of the process, or processes, by which the so-called peptones were formed. A year later, in 1859, Meissner[17] brought forward the first of his contributions, and during the following three or four years several communications were made representing the work of himself and pupils upon the question of gastric digestion, or more especially upon the character of the products resulting from the digestive action of pepsin-hydrochloric acid. [14] Canstatt’s Jahresbericht d. Pharm., 1846, p. 163. [15] Lehmann’s Physiologische Chemie, Band 2, p. 318. [16] Archiv f. d. Holländ. Beitr., 2, 1858. [17] Zeitschr. f. rat. Med., Band 7, 8, 10 und 14. The general tenor of Meissner’s results is shown in the description of a row of products as characteristic of the proteolytic action of pepsin-acid on proteid matter. In other words, there was a clear recognition of the fact that proteid digestion in the stomach, through the agency of the ferment pepsin, is something more than a simple conversion of the proteid into one or two soluble products. The several bodies then isolated were named parapeptone, metapeptone, dyspeptone, α, β, and γ peptone; names now seldom used, but significant as showing that at this early date there was a full appreciation of the fact that digestive proteolysis as accomplished by the ferment pepsin is an intricate process, accompanied by the formation of a series of products which vary more or less with the conditions under which the digestion is conducted.