Biology: Concepts and Investigations 2nd Edition by Mariëlle Hoefnagels

Exercise 50

In the early 1600s, Jean Baptista van Helmont investigated how plants acquire new mass as they grow. He weighed and planted a willow shoot into soil that he had also weighed. After 5 years of adding nothing but water to the plant, he found that the soil had lost only a little weight, while the plant had grown from 2 kilograms to about 76 kg. He therefore concluded, incorrectly, that water was the sole source of the added plant material. What other source did he fail to consider in his experiment?