Note 26 — Chapter XII · THE PHYSIOLOGY OF PLANTS
Reading edition
From “Nat. Hist. of Plants,” p. 554: “It has been proved experimentally that seeds which have been deprived by calcium chloride of as much water as possible are not killed even at the boiling point of water.” Careful experiment has shown that there are three stages of activity in the life and work of a plant—(1) A minimum or zero, at which the processes are just possible; (2) a medium stage or optimum point where the activity is the greatest; and (3) a maximum stage of heat where growth is arrested. So that we learn that plant-life can suffer from too high a temperature as well as that which is too low.