A particular focus of interest in the study of living organisms is the way in which life is sustained by nutrients, and how the organisms process these nutrients to provide energy for their necessary functions. Understanding these processes involves more than a simple examination of the anatomy of the organisms and requires a more experimental approach to studying their physiology—the way they function. A pioneer in this method of experimental biology was Santorio Santorio, who from the 1580s conducted an experiment that lasted some 30 years: he meticulously weighed himself, all his food and drink, and all the urine and feces he excreted, observing the difference between these amounts. He concluded that some “insensible perspiration” must account for the discrepancy. His experiment prompted further study of the way animals extract energy from food, a process that later was likened, by Antoine Lavoisier, to the burning of fuel in air.
Early in the 17th century, Jan van Helmont took a similarly methodical approach to studying the processes of nutrition and growth in plants, measuring the mass of a willow tree and the soil and water it stood in, and observing that the tree grew by absorbing water. In the 1770s and 1780s, experiments by Jean Senebier showed that plants also use carbon dioxide (CO₂) to grow and Jan Ingenhousz and Joseph Priestley revealed that plants give off oxygen as a by-product. Most importantly, however, Ingenhousz demonstrated that sunlight is also a factor in the process, giving a foundation for the idea of photosynthesis.
0 Comments