CROSSING OR HYBRIDISING. 



317 



cumstance, and left to the simple aid of nature ; 

 but accidental varieties cannot be so perpetuated 

 — if suffered to become wild, they very soon re- 

 vert to the form from which they originally 

 sprung. It is necessary that they should be 

 cultivated with the utmost care ; that seed 

 should be saved from those individuals only in 

 which the marks of the variety are most dis- 

 tinctly traced ; and all plants that indicate any 

 disposition to cast off their peculiar character- 

 istics should be rejected. If this is carefully 

 done, the existence of any variety of annual or 

 perennial plant may be undoubtedly prolonged 

 through many generations." 



The following concise and excellent rules are 

 given in the " Cottage Gardeners' Dictionary," 

 regarding the process and effects of hybridising : 

 " Hybridising, strictly speaking, is obtaining a 

 progeny between two different species, by fer- 

 tilising the stigma of one with the pollen of an- 

 other ; and cross-breeding is obtaining a progeny 

 between varieties of the same species. The pro- 

 geny of hybrids cannot produce seed, but cross- 

 breeds are fertile." The following may act as a 

 guide to the raiser of varieties : " The seed- 

 vessel is not altered in appearance by impreg- 

 nation from another plant ; therefore, no hasty 

 conclusion of failure is justified by that want of 

 change. 



" The colour of the future seed out of that 

 first hybridised seems to be most influenced by 

 the male plant, if its seeds and flowers are darker 

 than those of the female. Captain Thurtell, from 

 his experiments on the pelargonium, found the co- 

 lour and spot of the petals to be more influenced 

 by the male than by the female. Indeed, all expe- 

 rience proves that the progeny usually, though 

 not invariably, most resembles in colour the male 

 parent. Large stature and robustness are trans- 

 mitted to the offspring by either parent, but Mr 

 Knight generally found the most robust female 

 parent producing the finest offspring. Captain 

 Thurtell, from lengthened observation, has as- 

 certained that the form of the petals follows 

 most closely that of the female parent. Mr 

 Knight says that the largest seed, from the finest 

 fruit that has ripened earliest and most per- 

 fectly, should always be selected. In stone fruit, 

 if two kernels are in one stone, these give birth 

 to inferior plants. The most successful mode 

 of obtaining good and very distinct varieties 

 is to employ the pollen from a male flower 

 grown on another plant than that bearing the 

 female parent. To avoid previous and unde- 

 sired impregnation, the anthers of the female 

 parent, if they are produced in the same flower 

 with the pistils, must be removed by a sharp- 

 pointed pair of scissors, and the flower enclosed 

 in a gauze bag to exclude insects, until the de- 

 sired pollen is ripe. Another effectual mode of 

 avoiding undesired impregnation, is bringing 

 the female parent into flower a little earlier 

 than its congeners, and removing the anthers 

 as above described : the stigma will remain a 

 long time vigorous if unimpregnated. "When 

 double flowers are desired, if a double flower 

 should chance to have a fertile anther or two, 

 these should be employed for fertilisation, as 

 their offspring are almost sure to be double." 

 VOL. II. 



Besides the opinions already stated, others be- 

 lieve the sterility of hybrids to arise from a defi- 

 ciency of pollen or fertilising dust ; while the 

 highest authority we can quote (the late Dean of 

 Manchester) was of opinion that it arises from the 

 juices of each individual type being inadequately 

 adapted to yield the exact proportion of what 

 is wanted for the pollen of its kind ; and that, 

 wherever that adaptation is perfect, a perfect 

 offspring is produced. " Where it is not per- 

 fect," he says, "an inadequate or a weak fertili- 

 sation takes place. It is further to be observed 

 that there is frequently an imperfect hybrid 

 fertilisation, which can give life, but not sus- 

 tain it well. There are several crosses which 

 I have frequently obtained, but could not raise 

 the plants to live for any length of time." He 

 states various crosses which he effected, but 

 lost the plants so produced while they were yet 

 young, " on account," as he says, " of his soil 

 being very uncongenial to them" but which, he be- 

 lieved, under more fortunate circumstances, would 

 have been saved. Such crosses sometimes are 

 a hundred times more delicate in their first 

 stage than natural seedlings. " In these cases, 

 I apprehend," says the same authority, " that, 

 although the affinity of the juices is sufficient 

 to enable the pollen to fertilise the ovule, the 

 stimulus is insufficient, the operation languid, 

 and the fertilisation weak, and inadequate to 

 give a healthy constitution. It has been gene- 

 rally observed that hybrid fertilisation is slower 

 than natural fertilisation, and that often a much 

 smaller number of ovules are vivified. The 

 same cause probably operates in that respect ; 

 the affinity not being perfect, the necessary in- 

 gredients are attracted by the pollen less readily 

 and insufficiently, and by many of the grains 

 not at alL" 



Seedlings originated by unknown causes, or 

 sports of nature. — The laws of nature are, upon 

 the whole, uniform, and seldom are they vio- 

 lated. In endeavouring to trace the first origin 

 of our longest established cultivated culinary 

 vegetables and fruits, a degree of obscurity ap- 

 pears to envelop the subject. If all our apples 

 and pears originated from the Pyrus malus and 

 Pyrus communis, and our cabbages and pease 

 from Brassica oleracea and Pisum sativum, as 

 we are taught to believe, when, and by what 

 means, it may be asked, did the first remove 

 from the originals to an improved variety take 

 place ? This is a problem we have never met 

 with any satisfactory solution of. The original 

 plant in either case could not be a hybrid, for 

 there was no other to hybridise it with. High 

 cultivation was very unlikely to be the cause 

 either ; for, at the period of their first appear- 

 ance, we may presume, cultivation was little 

 attended to. Were they accidental sports, as 

 the weeping ash and weeping oak and various 

 others are said to have been ? If so, this pro- 

 cess must have been going on from a very re- 

 mote period, as we are informed that twenty- 

 two sorts of apples, and thirty-six kinds of pears, 

 were known to the Romans in the days of Pliny. 

 The Romans knew nothing of hybridising, nor 

 was it well known to the moderns till about the 

 beginning of the present century. We can readily 



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