26 



HYBRIDIZING. 



follows that of the female parent (this at 

 least has been observed in the Pelargo- 

 nium.) 



Size and robustness are communicated 

 by either parent. 



In seeds the colour of those of the male 

 parent predominates. 



In some cases the intended female flowers 

 should be much less advanced than the 

 other; the Calceolaria is an instance. Other 

 plants, as the Pelargonium, require to be 

 more advanced. The moment is to be 

 seized when the stigma of one flower, 

 and the pollen of the other, are in perfec- 

 tion. 



Flowers intended to be crossed should be 

 secured against the intrusion of insects he- 

 fore they become developed, and this pro- 

 tection must be continued till after there is 

 evidence of impregnation being effected. 



It is not requisite, as often stated, that 

 the flowers on both parent plants should be 

 as nearly as possible in the same stage of 

 advancement ; it has been ascertained that 

 pollen may be kept for any reasonable pe- 

 riod, and when there is a store of pollen it 

 is only necessary that the stigma should be 

 properly developed — that is, fresh, and 

 covered with its mucous secretion. 



The anthers from the intended fem.ale 

 flower should be removed before they are 

 enough advanced to have burst their pollen 

 cells, so that the pollen may not escape on 

 to the stigma ; a very small portion indeed 

 of the natural pollen being sufficient to set 

 aside any experiment. 



A considerable quantity of the applied 

 pollen should be used, it being less active 

 than the natural pollen of the plant. 



There must be a near resemblance, an 

 accordance in general structure and affinity, 

 between the plants to be crossed. Some 

 are more difficult to cross than others, pro- 

 bably from the tubes of the pollen grains 

 being too large to pass down to the ovary 

 through the pistils. 



It is not to be expected that every instance 

 of attempting to impregnate flowers will be 

 successful. 



The number of fertile seeds is usually 

 smaller in cases of crossing, than is natural 

 to the particular kinds of plants. 



Crossed plants being often less fertile, 

 sometimes even sterile, are in the same pro- 



portion more luxuriant, and produce larger 

 flowers. 



Mule plants — that is, crosses between 

 different species of the same genus, are 

 usually either sterile, or become so in tlie- 

 second, third, or very rarely in the fourth 

 generation. They may be fertilized by 

 applying the pollen of either parent, and 

 in that case assume the character of 

 tiie parent by which the pollen- was sup- 

 plied. 



The fertility of a h)^brid seems to depend 

 more upon the constitutional, than the bo- 

 tanical affinities of the parents ; thus, Mr. 

 Herbert found that Crinum capense, aiii 

 aquatic, or swamp plant, impregnated either 

 by C. zeyLanicum, or C. scabrum, which 

 affect drier habitats, produced offspring 

 which during sixteen years proved sterile, 

 while the same species impregnated by C. 

 pedunculatum, C. canaliculatum, or C. de- 

 fixum — all swamp plants, produced a fer- 

 tile cross. 



There is usually a greater probability of 

 success with plants that have been accele- 

 rated by slight forcing, because there is less 

 risk of the plants being fertilized by the 

 accidental escape of the natural pollen. 



Mr. Herbert found that in crossing some- 

 brilliant coloured flowers with others less 

 showy, the seedlings produced flowers 

 nearer the duller colour. This he attri- 

 butes to (as he supposes) the climate being 

 more congenial to the duller coloured pa- 

 rent ; and he suggests that it would pro- 

 bably not take place in a climate more per- 

 fectly congenial to the more brilliant co- 

 loured parent. 



Some of the best double-flowered hybrids- 

 — as of Camellia for example — have been 

 obtained from single varieties impregnated 

 by pollen from partly double flowers; that 

 which is borne on a petal, or, in other 

 words, on a petaloid filament, is to be pre- 

 ferred. Probably Indian Azaleas, in which 

 they usually abouad, might be obtained 

 double in this manner. It is, no doubt,, 

 also important that the parent plants should 

 be in a floriferous rather than a vigorous 

 growing condition, if fine double flowers 

 are desired. Pollen cannot always, though 

 it may sometimes, be obtained from double 

 flowers. Dr. Herbert observed a very cu- 

 rious morphological fact in the case of thst 



