he did not distinguish, and of the position of leaves on the
stem. Bonnet's view of the functions of leaves, foolish as
it is, is historically important and therefore required to be
noticed, because it was really accepted during many years
in preference to the older and better ideas, and because it
shows how the power of judging of such matters had fallen
off since Malpighi's time. It appears to have been the praise
lavished on Bonnet by his contemporaries that made later
physiologists, who might have known better, take him for
an authority on the nutrition of plants. His experiments on
the growth of plants in another material than earth are if
possible more worthless than those with cut leaves. Here too
the idea was not his own; for hearing that land-plants had
been grown in Berlin in moss instead of earth, he made
numerous experiments of the kind, and found that many
plants grow vigorously in this way, and bloom and bear seed.
But the theory of nutrition gained nothing by these experiments, which were only a childish amusement. The few pages
which Malpighi wrote on the nutrition of plants are worth
more than all Bonnet's book on the use of leaves; the former
by the help of some simple considerations and conclusions
from analogy really discovered the use of leaves; Bonnet on
the faith of many unmeaning experiments ascribed to them
another function than the true one.
We are unable to pass a much more favourable judgment on the views respecting the nutrition of plants of another writer, who otherwise did good service to vegetable physiology, and to whom we shall return in our last chapter. It is true that Du Hamel[1], of whom we speak, was not an investigator of
- ↑ Henri Louis du Hamel du Monceau was born at Paris in 1700 and died in 1781. He had an estate in the Gatinais, and turned his studies in physics, chemistry, zoology, and botany to account in the composition of a number of treatises on agriculture, the management of woods and forests, naval affairs, and fisheries. He was made Member of the Academy in 1728
