496 APPENDIX. 



eingle blooms, and the desired result is obtained. This is Messrs. 

 Windebank and Kingsbury's modua operandi, the exact process or mode 

 of accomplishment being, however, a professional secret.' 



From what has been said, as well as from other evidence which it is 

 not necessary to detail in this place, it may be seen that the causes 

 assigned by physiologists, and the plans proposed by cultivatoi*8 for the 

 pi-oduction of double flowers, are reducible to three heads, which may 

 be classed under Plethora, Starvation, and Sterility. These three seem 

 inconsistent one with the other, but are not so much so as they at first 

 sight appear to be. 



The advocates of the plethora theory have much in their favour: 

 for instance, the greater frequency of double flowers among cultivated 

 plants than among wild ones. The great preponderance of double 

 flowei-s in plants derived from the northera hemisphere, when con- 

 trasted with those procui-ed from the southern, as alluded to by 

 Dr. Seemann, seems also to point to the effect of cultivation in 

 producing these flowers. Now, although this is, to a large extent, 

 due to the selection that has been for so long a period practised 

 by gardeners, still that process will not account for the appearance 

 of double flowers where no such selection has been exercised ; 

 as in the case of wild plants. Some double peas, observed by Mr. 

 Laxton, appeared suddenly ; they had not been selected or sought for, 

 but they were produced, as it would appear, as a result of high cvdtiva- 

 tion, and during the period when the plant was in gi*eatest vigour ; and 

 as the energies of the plant failed, so the tendency to produce double 

 flowers ceased. Indeed, in reference to this subject, it is always impor- 

 tant to bear in mind the time at which double flowers are produced ; 

 thus, an annual plant subjected to cultivation will, it may be, produce 

 single flowers for the first year or two, then a few partially double 

 flowers are formed, and from these, by careful selection and breeding, a 

 double- flowered race may be secured. Sometimes, as in the peas before 

 alluded to, in the same season the earlier blossoms are single, while 

 later in the year double blossoms are produced. This happens, not only 

 in annuals, but also in perennials, and is not infrequent in the apple ; an 

 illustration of this occurrence in this tree is given in the ' Gardeners' 

 Chronicle' for 1865, p. 554.' Sometimes the flowers on a particular 

 branch are double, while those on the rest of the plant ai-e single.^ 

 On these points, the evidence fm-nished by a double white hawthorn 

 in the Royal Botanic Gardens at Edinburgh is important. Professor 



'Gard. Chron.,' 1867, p. 381. Art. " Chinese primroses." 



* See also p. 79, fig. 36. A similar flower is figured in ' Hort. Eystett. 



Ic. Arb. Vem.,' fol. 5. "Fnictus nondum observatus est fortassis ali- 



mento nberius in flores refuso, nullus sperari possit." 



See De Candolle, ' Plant. Rar. Genev.,' 1829, p. 91 ; and Alph. de 



Candolle. ' Geog. Bot.,' p. 1080. 



