The comparison of the fertilization of the date palm to the use of the wild fig refers to the practice of Caprification. Theophrastus tells us that there are certain trees, the fig among them, which are apt to shed their fruit prematurely. To remedy this ‘the device adopted is caprification. Gall-insects come out of the wild figs which are hanging there, eat the tops of the cultivated figs, and so make them swell’.[76] These gall-insects ‘are engendered from the seeds’.[77] Theophrastus distinguished between the process as applied to the fig and the date, observing that ‘in both [fig and date] the male aids the female—for they call the fruit-bearing [palm] _female_—but whilst in the one there is a union of the two sexes, in the other things are different’.[78] [76] _Historia plantarum_, ii. 8, i. [77] _Ibid._ ii. 8, ii. [78] _Historia plantarum_, ii. 8, iv. Theophrastus was not very successful in distinguishing the nature of the primary elements of plants, though he was able to separate root, stem, leaf, stipule, and flower on morphological as well as to a limited extent on physiological grounds. For the root he adopts the familiar definition, the only one possible before the rise of chemistry, that it ‘is that by which the plant draws up nourishment’,[79] a description that applies to the account given by the pre-Aristotelian author of the work περὶ γονῆς, _On generation_. But Theophrastus shows by many examples that he is capable of following out morphological homologies. Thus he knows that the ivy regularly puts forth roots from the shoots between the leaves, by means of which it gets hold of trees and walls,[80] that the mistletoe will not sprout except on the bark of living trees into which it strikes its roots, and that the very peculiar formation of the mangrove tree is to be explained by the fact that ‘this plant sends out roots from the shoots till it has hold on the ground and roots again: and so there comes to be a continuous circle of roots round the tree, not connected with the main stem, but at a distance from it’.[81] He does not succeed, however, in distinguishing the real nature of such structures as bulbs, rhizomes, and tubers, but regards them all as roots. Nor is he more successful in his discussion of the nature of stems. As to leaves, he is more definite and satisfactory, though wholly in the dark as to their function; he is quite clear that the pinnate leaf of the rowan tree, for instance, is a leaf and not a branch. [79] _Ibid._ i. 1, ix. [80] _Ibid._ iii. 18, x. [81] _De causis plantarum_, ii. 23. [Illustration: Fig. 8. THEOPHRASTUS From VILLA ALBANI Copy (second century A. D.?) of earlier work]