Chap.' XVIII. DOUBLE FLOWERS. 167 



fertile, though sterile when left to themselves, for bees are unable to crawl 

 into the narrow tubular flower. The peloric flowers of Oorydalis solida, 

 according to Godron, 91 are barren ; whilst those of Gloxinia are well known 

 to yield plenty of seed. In our greenhouse Pelargoniums, the central 

 flower of the truss is often peloric, and Mr. Masters informs me that 

 he tried in vain during several years to get seed from these flowers. 

 I likewise made many vain attempts, but sometimes succeeded in fertilising 

 them with pollen from a normal flower of another variety ; and conversely 

 I several times fertilised ordinary flowers with peloric pollen. Only once 

 I succeeded in raising a plant from a peloric flower fertilised by pollen 

 from a peloric flower borne by another variety ; but the plant, it may be 

 added, presented nothing particular in its structure. Hence we may con- 

 clude that no general rule can be laid down ; but any great deviation from 

 the normal structure, even when the reproductive organs themselves are 

 not seriously affected, certainly often leads to sexual impotence. 



Double Flowers. — When the stamens are converted into petals, the plant 

 becomes on the male side sterile; when both stamens and pistils are 

 thus changed, the plant becomes completely barren. Symmetrical flowers 

 having numerous stamens and petals are the most liable to become double, 

 as perhaps follows from all multiple organs being the most subject to 

 variability. But flowers furnished with only a few stamens, and others 

 which are asymmetrical in structure, sometimes become double, as we 

 see with the double gorse or Ulex, Petunia, and Antirrhinum. The 

 Composites bear what are called double flowers by the abnormal develop- 

 ment of the corolla of their central florets. Doubleness is sometimes 

 connected with prolification, 92 or the continued growth of the axis of the 

 flower. Doubleness is strongly inherited. No one has produced, as 

 Lindley remarks, 93 double flowers by promoting the perfect health of the 

 plant. On the contrary, unnatural conditions of life favour their produc- 

 tion. There is some reason to believe that seeds kept during many years, 

 and seeds believed to be imperfectly fertilised, yield double flowers more 

 freely than fresh and perfectly fertilised seed. 94 Long-continued cultiva- 

 tion in rich soil seems to be the commonest exciting cause. A double 

 narcissus and a double Anthemis nobilis, transplanted into very poor soil, 

 have been observed to become single; 95 and I have seen a completely 

 double white primrose rendered permanently single by being divided and 

 transplanted whilst in full flower. It has been observed by Professor 

 Morren that doubleness of the flowers and variegation of the leaves are 

 antagonistic states ; but so many exceptions to the rule have lately been 

 recorded, 96 that, though general, it cannot be looked at as invariable. 



91 'Comptes Eendus,' Dec. 19th, the removal of the anthers, see Mr. 

 1861, p. 103J. Leitner, in Silliman's ' North American 



92 ' Gardener's Chronicle,' 1866, p. Journ. of Science,' vol. xxiii. p. 47 ; and 

 681 • Verlot, ' Des Varietes,' 1865, p. 84. 



w ' Theory of Horticulture,' p. 333. « Lindley's ' Theory of Horticulture,' 



94 Mr. Fairweather, in ' Transact. p. 333. 



Hort. Soc.,' vol. iii. p. 406 ; Bosse, 96 , Gardener's Chronicle,' 1865, p. 



quoted by Bronn, ' Geschichte der 626 ; 1866, pp. 290, 730 ; and Verlot, 



Natur,' B. ii. s. 77. On the effects of « Des Varietes, p. 75. 



