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488 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, of whom we speak, was not an investigator of