. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 96 INTRODUCTION this. These will be thoroughly described later on (cf. also p. 67). In this place the various forms of nectary will not be fully considered, but one example may serve to indicate in what variety these organs may occur even within a single family, the Ranunculaceae (Fig. 12). The form of the nectaries is not always the same, even in one and the same species of plant. Herm. Miiller gives in his works two particularly striking examples of the ki
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 96 INTRODUCTION this. These will be thoroughly described later on (cf. also p. 67). In this place the various forms of nectary will not be fully considered, but one example may serve to indicate in what variety these organs may occur even within a single family, the Ranunculaceae (Fig. 12). The form of the nectaries is not always the same, even in one and the same species of plant. Herm. Miiller gives in his works two particularly striking examples of the kind, Ranunculus auricomus ('Fertilisation,' p. 79) and R. pyrenaeus ('Alpenblumen,' p. 133) (see Fig. 13).. Fig. 13. (1-8) Different petals of Ranunculus auricomus with diversely-formed nectaries (w). (9) Petal o^ Erantkis hyemalis. (After Herm. Miiller.) Nedar-covers, which also were frequently mentioned by Sprengel, and which are formed by projecting parts of flowers, processes, hairs, and so forth, serve as a means of protecting nectar from rain. Owing to such shelter nectar is not only saved from dilution, or even from being washed away, but more abundant secretion and accumulation are also rendered possible, with the result that insect visits'are more numerous. On the other hand, since the nectar is sheltered deeper down, numerous of the less industrious insects are debarred from visiting and pollinating the flowers. In order to render more easy the finding of nectar by insects that have been attracted by colour or odour there are, as Sprengel pointed out (see pp. 4-6), many spots or lines on the flower, which by their position or direction indicate the place where the honey is concealed (cf. Fig. 14). These Nectar-guides, however, are naturally only present in such flowers as are visited by insects during the day. They are wanting (see p. 67) in moth flowers, where they would be useless (cf also Sprengel, ' Entd. Geh.,' p. 16). The nectar-guides of one and the same sp
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