From the "hungry acid" to pepsinogen: a journey through time in quest for the stomach's secretion.

The stomach's secretion has been a mystery for centuries. Even after the first indications of its function and role appeared, every formulated idea on the nature of the gastric liquid remained open to controversy. After the ancient Greek perceptions which identified acids as bitter-sour liquids, the physicians of the Iatrochemical School, under the influence of Paracelsus and the alchemists, were the first to point out the physiologic chemistry of secretion. Experiments on animals and humans during the 17th-18th centuries, which mainly included swallowing various substances and observing the process, enhanced knowledge, with Stevens and Spallanzani playing the leading part. Any existing objections ceased in 1823, when Prout clearly identified hydrochloric acid as the acid agent of the stomach. Later on, the role of pepsin and pepsinogen was also judged to be important in digestion. In addition, the tremendous contribution of French scientists, experienced in the science of nutrition, must not be underestimated. It took centuries of research, and the involvement of many notable figures from many nations and countries, to form modern concepts of gastric secretion

Ludovico Maria Barbieri (1662-1728), the unknown 17th century physician.

During the 17th century, Ludovico Maria Barbieri from Imola, Italy, discussed the requirement of a gas, seemingly oxygen, for living beings to function. On 6 December 1680, he published his only known work 'Spiritus nitro-aerei operations in microcosmo' in which he reviewed the function of oxygen and the apparatus he used based on the use of experiments rather than just theory. The scarcity of information about his life and work has resulted usually in him being a neglected figure in Italy. In this manuscript we uncover the extant information about his life and reveal that he had been a restless spirit and a great example to the 17th century scientific method