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Show 184 NEMOPHILA INSIGNIS. CHAP. v. The plants were first measured to the tips of their loaves, before they had flowered and when the crossed were under a foot in height. The twelve crossed plants averaged 11·1 inches in height, whilst the twelve self-fertilised wore less than half of this height, viz., 5 ·45; or as 100 to 49. Bcfor~ the plants had grown to their full height, two of the self-fertilised died, and as I feared that this might happen with others, they were again measured to the tops of their stems, as shown in the preceding table. The twelve crossed plants now averaged 33 · 28, and the ton selffertilised 19 · 9 inches in height, or as 100 to 60 ; so that they differed somewhat less than before. The plants in Pots III. and V. were placed under a net in the greenhouse, two of the crossed plants in the latter pot being pulled up on account of the death of two of the self-fertilised; so that altogether six crossed and six self-fertilised plants were left to fertilise themselves spontaneously. 'l'he pots wore rather small, and the plants did not produce many capsules. The . small size of the self-fertilised plants will largely account for the fewness of the capsules which they produced. The six crossed plants bore 105, and tho six self-fertilised only 30 capsules; or as 100 to 29. The self-fertilised seeds thus obtained from the crossed and self-fertilised plants, after germinating on sand, were planted TABLE LXXIII. Nemophila insignis. Self-fertili sed Plants Self-fertili. ed Plant. No. of Pot. from Crossed Plants. from Self-fertilised Plants. Inches. Inches. I. 27 21a 14 34i -- -- II. 17 ~ 23 24~ 32 III. 16 7 IV. 5 ~ 72 II 5g4 16 Total in inches. 110•13 147 •00 CHAP. v. BORAGO OFFICINALIS. 185 on the opposite sides of four small pots, and treated as before. But many of the plants were unhealthy, and their heights were so unequal-some on both sides being five times as tall as the others -that the averages deduced from the measurements in the preceding table are not in the least trustworthy. Nevertheless I have felt bound to give them, as they are opposed to my general conclusions. The seven self-fertilised plants from the crossed plants here average 15 · 73, and the seven self-fertilised from the self-fertilised 21 inches in height; or as 100 to 133. Strictly analogous experiments with Viola tricolor and Lathyrus odoratus gave a very different result. XXIII. BORAGINAOElE.-BORAGO OFFICINALIS. This plant is frequented by a greater number of bees than almost any other one which I have observed. It is strongly proterandrous (H. Mii.ller, 'Befruchtung,' &c., p. 267), and the flowers can hardly fail to be cross-fertilised; but should this not occur, they are capable of self-fertilisation to a limited extent, as some pollen long remains within the anthers, and is apt to fall on the mature stigma. In the year 1863 I covered up a plant, and examined thirty-five flowers, of which only twelve yielded any seeds; whereas of thirty-five flowers on an exposed plant growing close by, all with the exception of two yielded seeds. The covered-up plant, however, produced altogether twenty-five spontaneously self-fertilised seeds; the exposed plant producing fifty-five seeds, the product, no doubt, of crossfertilisation. In the year 1868 eighteen flowers on a protected plant were crossed with pollen from a distinct plant, but only seven of these produced fruit; and I suspect that I applied pollen to many of the stigmas before they were mature. These fruits contained on an average 2 seeds, with :a maximum in one of three seeds. Twenty-four spontaneously self-fertilised fruits were produced by the same plant, and these contained on an average 1· 2 seeds, with a maximum of two in one fruit. So that the fruits from the artificially crossed flowers yielded seeds compared with those from the spontaneously self-fertilised flowers, in the ratio of 100 to 60. But the self-fertilised seeds, as often occurs when few are produced, were heavier than the crossed seeds in the ratio of 100 to 90. |