PROPAGATION. 



335 



■when insects are rigorously excluded, the flowers are 

 equally fertile. Besides obtaining new varieties by 

 intercrossing the best existing ones, the vigour of 

 the progeny is generally improved. Fertilising the 

 flowers of one individual with the pollen of another 

 ot the same variety, shows no decided advantage in 

 the progeny ; but a marked improvement is ob- 

 servable when two distinct varieties are cross-fer- 

 tilised. New and desirable varieties, when once 

 obtained, are fixed by selection. 



Varieties of th,e Sweet Pea can be grown in 

 mixture without intercrossing naturally, but the dark- 

 coloured varieties are most prolific in seeds, and 

 therefore tend to out-number the others unless they 

 are occasionally selected. 



The Strawberry offers an interesting case iii direct 

 opposition to that of the Pea. The pistil is mattire 

 before the stamens, so that cross-fertilisation must 

 and ddfes constantly ensue. The various species and 

 varieties occasionally become imperfect, and produce 

 either staminate or pistillate flowers. They are 

 more liable to do so in some soils and climates than 

 others. An acre of Keen's Seedling has been re- 

 corded as almost barren, from the absence of stamens. 

 When staminate plants are grown in the immediate 

 vicinity, natural cross-fertilisation of the pistillate 

 flowers is almost a certainty. Chance seedlings of 

 merit may occasionally be obtained from these 

 plants, but the method is too tardy and uncertain 

 for the present generation. 



By selecting varieties possessed of desirable pro- 

 perties, such as size, colom-, or flavour, the hybridist, 

 according to the ends he has in view, can unite 

 them with others of the desired habit, vigorous con- 

 stitution, or productiveness. As already remarked, 

 the varieties of Strawberry in cultivation are the 

 <lescendants of several species, so that the hybridist 

 has abundant material at hand in the way of good 

 and distinct sorts. 



The general subject of hybridisation from a .gar- 

 dener's point of view was well treated of by the 

 late Isaac Anderson Henry, whose observations as 

 well as those of other experimenters are well summa- 

 rised in Burbidge's " Cultivated Plants : their Pro- 

 pagation and Improvement." 



III. Selection.— At first sight the three head- 

 ings of this chapter appear more or less decidedly 

 distinct; but on close and searching inquiry, the 

 secret principle underlying the whole, however 

 much obscured, is to a certain extent the same. For 

 instance, that "like produces like," goes without 

 saying, and this may be true in a measure, but if 

 there never were any variation in nature, how could 

 man improve his favourite races of plants by selec- 

 tior ? The mere fact of selection does not prevent 



the natural intercrossing of varieties when insect or 

 other agencies have access to them. By selection 

 alone several fine varieties of Mignonette have been 

 preserved and increased. The flowers of this plant 

 are great favourites with bees, and the pistil of one 

 flower gives a decided preference — that is to say, is 

 specially acted upon by the pollen from a different 

 flower ; therefore, what is more probable than that 

 the improved variety is the result of natural inter- 

 crossing ? To attain a desired end, this process may 

 be a slow one, but by weeding out the undesirable 

 forms, generally called " rogues," success is none the 

 less certain because tardy. 



Most of the valuable cultivated varieties of cereals 

 have been obtained by selection, a fact which is all 

 the more remarkable seeing that Wheat, Barley, and 

 Oats are, as a rule, self-fertilising, although they do 

 afford opportunities for a cross. Where the process 

 is rigidly adhered to, the mode of operation is to 

 select not only the largest and best-looking heads, 

 but the plumpest and best-looking grains. How- 

 ever, some experts are of opinion that, to preserve the 

 vigour and constitution of the plant, occasional sow- 

 ings of the small grains at the base and apex of the 

 ear of Wheat should he made. 



It is a remarkable fact that hundreds of the best 

 Apples and Pears that stock our gardens, as well as 

 those on the Continent and in America, have origi- 

 nated as chance seedlings, and of course were 

 selected from amongst countless others, devoid of 

 merit. The difference between this kind of selec- 

 tion and that above mentioned is that a meritorious 

 Apple or Pear, once selected, needs only to be pro- 

 pagated by budding and grafting. The various sorts 

 are the descendants of one species in each case, and 

 originated under all sorts of conditions in the gar- 

 dens of the wealthy or the poor, as well as in those of 

 the monks of olden times. Hundreds of unnamed 

 varieties exist in this country, that never advance 

 beyond the locality where they originated, a suffi- 

 cient reason being often found in the fact of their 

 being best adapted to that locality. This is partly 

 accounted for by the parents of such seedlings im- 

 parting to their progeny a constitution best fitted to 

 the climate and soil of that part of the country. 



In the case of Pears especially, the application of 

 this principle would be of the utmost importance, 

 from the fact of its earlier flowering than the Apple, 

 and greater liability to be injured by spring frosts. 

 The tree was cultivated more than 3,000 years ago 

 by the Greeks and Romans, and it is notorious, not- 

 withstanding the hundreds of cultivated sorts, thkt 

 our leading and most valuable varieties are of Con- 

 tinental origin. Despite the many centuries of 

 domestication to which the Pear has been subjected, 

 and its great liability to variation when raised from 



