THE FARMERS' REGISTER. 



581 



sterility. Pollen will not produce its impregiiat- 1 

 ing tubes in too low a temperature, or when the 

 ains cliarjied with moisture ; neiiher, in the ab- I 

 Bence of wiml or insects, have some plants die j 

 power of conveying the pollen to the stigma, i 

 their anthers having no special irritability, and j 

 only opening for the discharge of the pollen, not | 

 ejecting it with Ibrce. If we watch the hazel, j 

 or any of the coniferous order, in which the enor- j 

 nious quantity of pollen eni[iloyed to secure the ' 

 impregnation of the seed renders it easy to see I 

 what happens, it will be lound that no pollen is , 

 scattered in damp cold weather ; but, in a sunny, 

 warm, dry morning, the atmosphere surrounding ' 

 such plants is, in the impregnating season, filled ! 

 with grains o!" pollen discharged by the anthers, j 

 In wet springs the crops oC fruit fail, because [ 

 the anthers are notsufficienlly dried to shrivel and 

 discharge their contents, which remain locked up 

 in the anther cells till the power of impregnation 

 is lost. In vineries and Ibrcing-houses generally, 

 into which no air is admitted to disturb the foliage, 

 nor any artificial means employed for the same 

 end, and when the season is too early for the pre- 

 sence of bees, flies, and other insects, the grapes 

 will not set: and in the Irames of melons and 

 cucumbers, from which insects are excluded, no 

 seed is formed unless the pollen is conveyed by 

 hand, from those flowers in which it is formed, to 

 others in which the young fruit alone is generated. 

 In all cases of this kind, the remedy for sterility 

 is obvious enough where plants exist in an artifi- 

 cial condition ; but, when they occur in the 

 orchard or the flower-garden, in the open air, 

 science suggests no assistance. 



It sometimes happens that particular parts of 

 plants, distant from the fruit, are so constructed as 

 to attract to themselves the food intended lor the 

 fruit, and thus to prevent the formation of seed. 

 For example: — The early varieties of potato do 

 not readily produce seed, owing to the abstrac- 

 tion by their tubers of the nutritive matter requir- 

 ed for the support of the seed. Mr. Knight lound 

 that by destroying the tubers in part, as they 

 formed, seeds were readily procured from such 

 varieties.* 



But perhaps the most frequent cause of sterility 

 is the monstrous condition of the flowers of many 

 cultivated plants. It has been fully explained 

 that the floral organs of plants are nothing more 

 than leaves, so modified as to be capable of per- 

 forming special acts, for particular purposes; but 

 they are not capable of performing those acts any 

 longer than they retain their modified condition : 

 and therefore the stamens cannot secrete pollen, 

 when, by accidental circumstances, they are 

 changed into leaves, as happens in double flowers ; 

 then, there is nothing to lertilize the stigma, and, 

 of course, no seed is produced. Or the carpels 

 themselves may be converted into leaves, and 

 have lost their seed-bearing property. Double 

 flowers in the latter case cannot possibly bear 



* [ Vice versa, the produce of the potatoes may be 

 much increased by plucking off the blossoms, in which 

 case the nutritive matter which would have been ex- 

 pended upon them and the berries, or fruit, serves to 

 increase the size of the tubers, for which ^alone the 

 plant is cultivated. This fact, so perfectly consistent 

 with theory, has been completely confirmed by expe- 

 riment. See Liebig's Organic Chemistry, p. 125. 

 A. G.] 



seed ; but in the condition first mentioned they 

 may, and often do. To bring this about, the 

 cultivator plants in the vicinity of his sterile 

 flowers others of the same species in which a part 

 ai least of" the stamens are perfect, and they I'ur- 

 nish a siifliciency of pollen lor the imprejznation 

 of the other flowers in which there are no sta- 

 mens. 



In some cases, principally in those of compo- 

 site flowers, the seed is formed and advanced 

 towards perfection, and then decays ; this is owing 

 to the flower heads of such plants being compos"^ 

 ed, in a great measure, of soft scales, absorbent 

 and retentive of moisture, to which, in their own 

 country, they are not exposed in the fruiting 

 season, but by which they are affected unde7 

 the hands of the cultivator. When the heads 

 of such flowers are soaked with moisture, which 

 they cannot get rid of, the scales rot, and decay 

 spreads to all the other parts, and thus the pro- 

 duction of seed is prevented. The Chinese 

 chrysanthemum is a familiar instance of this. 

 Such plants seed readily if the flower heads are 

 kept warm and dry ; and it is thus that the sterile 

 chrysanthemum has been made seedful ; that is 

 to say, by growing it in a dry warm vvinter border, 

 protected li'om showers by a roof of glass, or 

 by using some such means of guarding it ; or by 

 rearing it in a warm dry climate. 



When seeds are freely produced, it is not alto- 

 gether a subject of indiflierence in what way they 

 are saved, if it is desired that their progeny should 

 be the most perfect that can be obtained. Weak 

 seeds produce weak plants, and therefore recourse 

 should be had, in all delicate cases, to ariifictal 

 means (or giving vigor to the seed. In general, 

 thecullivator trusts to his eye for separating the 

 plumpest and most completely formed seeds ; or 

 to floating them in water, selecting only the heavy 

 grains that sink, and rejecting all those which 

 are buoyant enough to float. 



-But the energy of the vital principle in a seed 

 may be, undoubiedly, increased by abstracting 

 neighboring fruits, by improving the general 

 health of the parent plant, by a full exposure of it 

 to light, and by prolonging the period of matura- 

 tion as much as is consistent with the health of 

 ihelruit. It is a constant rule that seedlings take 

 after their parents, an unhealthy mother pro- 

 ducing a diseased offspring and a vigorous parent 

 yielding a healthy progeny, in all their minute 

 gradation? and modifications ; and this is so true, 

 that, as florists very well know, semi-double 

 ranunculi, anemones, and similar flowers, will 

 rarely yield double varieties, while the seed of the 

 latter as unfiequently give birth to semi-double 

 degenerations. Independently of these things, it 

 is indispensable that the seed of a plant, when 

 saved, should be perliicily ripe, if it is intended 

 to be laid by lor lijture sowini;. The effect of 

 ripening is to load the seed with carbon in the 

 Ibrm of starch, or some such substance and to 

 deprive it of water, conditions necessary for its 

 preservation : but, if a seed is gathered before 

 being ripe, these conditions are not secured ; and, 

 in proportion to the deficiency ofcarbon and super- 

 abundance of water is the seed liable to perish. 



The complete matur:ition of the seed is, howe- 

 ver, a disadvantage, vvhen it has to be sown im- 

 mediately after being gathered ; lor the embryo 

 is Ibrmed, and capable of germinating, long belbre 



