The natural phenomenon of transpiration was first widely proposed in 1895, and it entails the absorption of water by the plant’s roots; then its subsequent transportation through the stem region due to low pressure; and ultimately its evaporation (into the atmosphere) through the surface of the leaves. And now, researchers have found a similar explanation for this plant-oriented organic occurrence, albeit in notes that are older by more than 225 years. This is because the notes were that of one Isaac Newton, and were penned by the great scientist during his undergraduate years in the 1660’s. The half-a-page description has been assessed by Professor David Beerling (from University of Sheffield), and then published in the journal Nature Plants.
According to the notes, the young Newton wrote –
Suppose a b the pore of a Vegitable filled with fluid mater & that the Globule c doth hitt away the particle b, then the rest of subtile matter in the pores riseth from a towards b & by this meanes juices continually arise up from the roots of trees upward leaving dreggs in the pores & then wanting passage stretch the pores to make them as wide as before they were clogged. which makes the plant bigger untill the pores are too narow for the juice to arise through the pores & then the plant ceaseth to grow any more.
This is very much akin to the aforementioned process of transpiration – a cyclic event brought on by the sunlight. The sun allows for evaporation of water, which then leads to low pressure inside the plant and creates a state of tension. This in turn is utilized by the highly-pressured bottom section of the plant to absorb water from the ground. And quite interestingly, the last part of the process is achieved against Newton’s laws of gravitational force – which were explained in his Principia, published on 5 July 1687.
However, Beerling has mentioned how Newton’s explained ‘pores’ might have been thought of as water-conducting tissues present inside stems, as opposed to the actual stomata found in the epidermis of leaves and stems. But as is often the case, the mystery remains as to why Newton made his analysis on plant juices in the first place. As Beerling says –
We have no idea how long Newton spent thinking about the workings of plants or what prompted these thoughts. Reclusive and secretive, it’s doubtful he gained botanical inspiration from conversations with others at Cambridge University interested in plants.
Image Credit: Cambridge University Library