● It is interesting to learn about those `color{violet}"simple experiments"` that led to a `color{violet}"gradual development"` in our understanding of photosynthesis.

● `color{Brown"Joseph Priestley"` (1733-1804) in 1770 performed a series of experiments that revealed the `color{violet}"essential role of air"` in the growth of green plants.

● `color{violet}"Priestley"`, `color{Brown}"discovered oxygen"` in 1774.

● Priestley observed that a `color{violet}"candle burning"` in a `color{violet}"closed space"` – a bell jar, soon gets `color{violet}"extinguished"`.

● Similarly, a `color{violet}"mouse would soon suffocate"` in a closed space.

● He concluded that a `color{violet}"burning candle or an animal"` that breathe the air, both somehow, `color{violet}"damage the air"`.

● But when he placed a `color{violet}"mint plant"` in the same bell jar, he found that the `color{violet}"mouse stayed alive"` and the `color{violet}"candle continued to burn"`.

● `color{violet}"Priestley hypothesised"` as follows:

● `color{violet}"Plants restore to the air"` whatever breathing animals and burning candles `color{violet}"remove"`.

● Using a `color{violet}"similar setup"` as the one used by Priestley, but by placing it `color{violet}"once in the dark"` and `color{violet}"once in the sunlight"`, `color{Brown}"Jan Ingenhousz"` (1730-1799) showed that `color{violet}"sunlight is essential"` to the plant process that somehow `color{violet}"purifies the air"` fouled by burning candles or breathing animals.

● Ingenhousz in an elegant experiment with an `color{Brown}"aquatic plant"` showed that in `color{violet}"bright sunlight"`, `color{violet}"small bubbles"` were formed around the `color{violet}"green parts"` while in the dark they did not.

● Later he `color{violet}"identified these bubbles"` to be of `color{Brown}"oxygen"`.

● Hence he showed that it is `color{violet}"only the green part"` of the plants that could `color{violet}"release oxygen"`.

● It was not until about `color{violet}"1854"` that `color{Brown}"Julius von Sachs"` provided evidence for `color{violet}"production of glucose"` when plants grow.

● `color{Brown}"Glucose"` is usually `color{violet}"stored as starch"`.

● His later studies showed that the `color{violet}"green substance"` in plants (`color{Brown}"chlorophyll"` as we know it now) is located in `color{violet}"special bodies"` (later called `color{Brown}"chloroplasts"`) within plant cells.

● He found that the `color{violet}"green parts in plants"` is where `color{violet}"glucose"` is made, and that the glucose is usually `color{violet}"stored as starch"`.