HYBRIDISING AND CROSS-BREEDING. 99 



theless facts often very beautiful facts and not unfrequently 

 the florist welcomes them, and increases them by grafting or 

 budding, well knowing that if distinct, as is frequently the 

 case, they are facts worth gold. Many varieties of Roses, 

 Camellias, Chrysanthemums, bronze and tricolor Pelargoniums, 

 Bouvardias, Azaleas, &c., have originated in this manner, and 

 have been at once seized and turned to good account by the 

 intelligent cultivator. In the case of cultural or cross-bred 

 varieties, this variability may be partly owing to culture or 

 nutrition, but whole or partial reversion to pre-existing types 

 offers another source of explanation. The theory of pangenesis 

 as advanced by Darwin shows pretty plainly how this may take 

 place : a trace of colour or hereditary taint may linger from 

 generation to generation without showing itself, and then, owing to 

 some cause of which we know nothing, some interruption to the 

 smoothness and sameness of plant-life takes place, and the result 

 is variation in habit, form, colour, or precocity. The theory of 

 reversion is feasible enough wherever varieties are concerned ; 

 but when we remember cases of species which sport take for 

 example the Chestnut near Geneva, cited by Decandolle, one 

 branch only of which bears double flowers no theory of rever- 

 sion to pre-existing types, or pangenesis, will go far towards 

 explaining this singular phenomenon. Mr Henderson, a 

 distinguished American horticulturist, remarks that in a bed 

 of about one hundred cuttings of the new Tea Rose,. " La 

 Nankin," all made from one parent plant, he found four 

 distinct varieties, some with clear nankeen flowers, others pure 

 white, others light pink or blush, and the remainder in the 

 normal state, white above and nankeen below. 1 Mr T. A. 

 Knight mentions a case where a tree of the yellow Magnum 

 Bonum Plum, 40 years old, suddenly produced red fruit on 

 one branch ; and he had a Mayduke Cherry in his garden, one 

 branch of which annually bore oblong, heavier, and later fruit 

 than the rest of the tree, but of inferior flavour. (See Trans. 

 Hort. Soc., vol. ii. p. 160.) There is no practical and very 

 slight theoretical difference between a bud variation, i.e., sport, 

 and a seedling variety, since both may be perpetuated, if de- 

 sirable, either by cuttings, layers, or by grafting ; and in this 

 way many weeping, fastigiate, cut-leaved, and other ornamental 

 trees have been obtained, to say nothing of all the many varie- 

 gated plants which add so much variety to our own gardens as 

 well as to those of China and Japan.* 



* Those who wish to pursue this subject further should read Dr M. T. 

 Masters's valuable paper on "Bud Variation" in ' Gard. Chron.,' 1872, 

 p. 1388, 1453, and 1523. The papers of Naudin, Braun (" Rejuvenes- 



