CROSSING OR HYBRIDISING. 



313 



tion. Steeping seeds for a few hours in warm 

 water has the "desired effect, more especially 

 when the soil into which they are to be sown is 

 dry, as often occurs during the heat of summer. 

 Hard seeds, such as walnuts, almonds, &c, are 

 often buried for a day or more in matter in a 

 moderate state of fermentation ; and at other 

 times the shell is paired, cut, or filed thin, so as 

 to assist the embryo plant's escape from its hard 

 encasement. The more scientific operations are, 

 watering with chlorine, as first suggested by 

 Baron Humboldt ; the application of iodine and 

 bromine, in conjunction with hydrogen, as pro- 

 posed by Goppert : both these, as well as oxalic 

 and other acids, have no doubt the effect, when 

 frequently applied, of hastening the process of 

 assimilation, and accelerating vegetation. These 

 have, however, the effect of causing the plants 

 thus hastily brought \ into a state of existence 

 to assume a sickly appearance through over- 

 excitement, and not unfrequently many of them 

 die. Dr Hamilton and M. Otto of Berlin made 

 seeds to vegetate, notwithstanding they were 

 from twenty to forty years old. On the use of 

 these, as well as of a diluted solution of chlorine, 

 Dr Lindley, in "Theory of Hort.," remarks, 

 " Theoretically, it would seem that these effects 

 ought to be produced, but general experience 

 does not confirm them ; and it may be conceived 

 that the rapid abstraction of carbon, by the pre- 

 sence of an unnaturally large quantity of oxy- 

 gen, may produce effects as injurious to the 

 health of the seed as the too slow destruction 

 of carbon, in consequence of the languor of the 

 vital principle." 



The natural season for sowing seeds is unques- 

 tionably as soon as they are ripe, but for the 

 purposes of cultivation it is often necessary to 

 defer this process for a few weeks or months. 

 This is pointed out to us by nature ; and, in- 

 deed, some seeds are not capable of retaining 

 their vitality many days after they are removed 

 from the plant. Seeds which naturally fall from 

 the plant, either by their weight or by some 

 other means not easily accounted for, secrete 

 themselves in the ground, or amongst moss or 

 leaves, &c, so as to be ready in spring to start 

 into new life. Many vegetate during autumn, 

 and survive the winter, as it were, in an infant 

 state, and are prepared, upon the approach of the 

 warmth of spring, to perform the offices they 

 are destined for. This is remarkably exempli- 

 fied in the case of most of the plants from North 

 America and California ; and these, according to 

 the most approved mode of culture, should be 

 sown as soon as they are ripe ; while, again, 

 Mexican and Chilian seeds succeed best when 

 sown in spring. According to Mr Gordon of the 

 Chiswick gardens, the seeds of the trees and 

 shrubs of Europe and of India " should be sown 

 in autumn, and annuals or perennials in the 

 spring. All seeds, of whatever kind, should be 

 sown in dry soil, and not wetted till they begin 

 to vegetate. In the case of old or sickly 

 seeds, to water them at the time of sowing is 

 to insure their destruction by rotting. Shad- 

 ing is to be preferred to watering ; and one of 

 the best constructions for the purpose is a pit 

 glazed with double sashes. Finally, all seed- 



lings should be potted or transplanted as soon 

 as possible, except bulbs." 



Experiments in seed-sowing are and have 

 been numerous : that of sowing them in snow, 

 as exemplified by M. Lucas, and detailed in the 

 " Garten Zeitung," is one of the most extraordi- 

 nary, and least in accordance with the laws of 

 vegetable physiology, as snow must be nearly at 

 the temperature of 32°; hence they are placed 

 at the very lowest point of temperature at which 

 germination can take place. For what reason 

 M. Lucas follows this unusual course does not 

 very clearly appear. The majority of seeds ex- 

 perimented upon by him were those of alpine 

 plants, which of necessity in nature vegetate at 

 the lowest temperatures. The idea of sowing 

 seeds in new-fallen snow, or in that which has 

 been frozen in ice-houses, and immediately plac- 

 ing them in a hot-house with a temperature of 

 60° or 65° Fahr., can amount to nothing other 

 than sowing the seeds in the usual way, and 

 drenching them with the coldest water ; and 

 that, with a view to accelerate their vegetation, 

 is contrary, in the fullest extreme, to what has 

 been considered the highest principle of good 

 culture. In the Munich botanic garden, experi- 

 ments were first tried, and frequently since in 

 Britain, of sowing seeds in powdered charcoal, 

 the results being an advance of one day in the 

 process of germination. Minute seeds are often 

 sown on the surface of charcoal blocks, on pieces 

 of sandstone, and woollen cloth kept moist, but 

 with effects of small importance to the general 

 cultivator, although valuable to the botanical 

 gardener, as, by this means, seeds of mosses, 

 ferns, &c. are found to vegetate freely ; while, if 

 sown in soil, they might, from their minuteness, 

 be liable to be too deeply buried. 



According to Mr Limburn, electricity has a 

 powerful influence in accelerating the vegeta- 

 tion of seeds, on account of its connection with 

 all transformations of organic substances, either 

 as cause or effect. Dr Carpenter, entertain- 

 ing the same views, remarks that, " when 

 chemical decomposition takes place, electricity 

 is always developed," but suspects that in some 

 instances it may be absorbed again by the new 

 state of the compound. The influence of dif- 

 ferent coloured glass on the germination of seeds 

 has been successfully experimented upon by Dr 

 Horner of Hull, M. Payen, and others, who 

 arrived at the conclusion that the violet or de- 

 oxidising colour produces similar chemical ef- 

 fects to the negative or alkaline pole, while red 

 produced the acid or opposite effect by the re- 

 tention of the oxygen. Alkalies were success- 

 fully employed by M. Maltuen, who found that 

 seeds vegetated sooner when placed at the nega- 

 tive pole of a galvanic battery than at the posi- 

 tive or acidised pole. Seeds enclosed by him in 

 phials of acids and alkalies were found to ger- 

 minate much quicker in the latter ; while in the 

 former they vegetated much slower, and some- 

 times not at all. 



§ 2. — CROSSING OR HYBRIDISING. 



We have elsewhere stated that most plants 

 originated from seeds resemble their parents in 



