PROPAGATION. 



67 



them, under atmos]ph.eric conditions such as would 

 iuliil the same purpose. So soon as absorption takes 

 place, germination will or ought to commence. Old 

 seeds or immature ones will often fail to grow if 

 kept very moist, but may be induced to push into 

 activity by keeping them comparatively dry till 

 germination has commenced, increasing the amount 

 of moisture as growth continues. " When the vital 

 energies of a seed are diminished, it does not lose its 

 power of absorbing water, but is less capable of 

 decomposing it. The consequence of this is that the 

 free water introduced into the system collects in the 

 cavities of the seed and produces putrefaction ; the 

 sign of which is the rotting of seeds in the ground." 



At Kew, where all kinds of seeds are received in 

 large quantities annually, it is the custom to treat 

 old or sickly-looking seeds as follows : — The seeds 

 are first thoroughly dried, so as to destroy any germs 

 of decay or disease of any kind which may have 

 attacked the seeds before their arrival. They are 

 then spread out tliinly upon slates, placed in a warm 

 and moist atmosphere, and covered with a sheet of 

 paper. If vitality has not been destroyed, this 

 treatment generally brings about germination, on 

 the first sign of which the seeds are placed in soil. 

 Any healthy seed will germinate if immersed in 

 water of the required temperature, but unless the 

 plant be an aquatic the excess of water soon proves 

 fatal. For all seeds of terrestrial plants, therefore, 

 no more moisture should be allowed than is sufficient 

 to keep the medium on which the seeds are sown in 

 a moist condition. An excellent guide to follow is 

 that of the plants to which the seeds belong, giving 

 their seeds the same amount of moisture as would be 

 enjoyed by the plants themselves. 



In the case of very fine seeds which are sown on 

 the top of the soil, it is wise either to stand the pots 

 containing the seeds in shallow pans of water, so 

 that the soil may be "kept moist by capillary attrac- 

 tion, or to effect the same purpose by dipping the 

 pots almost up to the rim in water, and holding them 

 there for a few moments till the soil has become 

 thoroughly moistened. The length of time seeds 

 may be allowed to remain in water without injury 

 depends on the nature of their outer covei-ings. 



j Mr. Darwin made numerous experiments for the 

 purpose of discovering how long the seeds of land 

 plants might be immersed in sea- water without 



I losing the power to germinate. He, found in many 

 instances the time was unusually long, some of the 

 seeds thras tested germinating after an immersion 

 of 137 days. In like manner many seeds may be 

 kept in fresh water for a long time, if the tempe- 

 I rature is not high enough to excite germination 

 ; It is quite a common practice with gardeners to 



*: steep hard-coated seeds in warm water for a few 



hours before sowing, the effect of which is the 

 softening of the seed-coats and the excitement of 

 the vital principle, so that germination is much 

 quickened. Peas, Beans, Erythrinas, Acacias, in 

 fact all those seeds belonging to Leguminosce may be 

 thus treated before sowing. The effects of soaking 

 in warm water are sometimes of a startling character. 

 At Kew, some time ago, a number of large seeds of 

 various kinds were examined after having been 

 sown in a warm house for over a year, and were 

 found to be quite intact, but showed no signs of 

 germination. They were then placed in water 

 heated to 160°, and allowed to remain in soak for 

 twenty-four hours, after which they were re-sown. 

 In less than a fortnight after this most of the seeds 

 had begun to germinate, and nearly every seed 

 eventually grew and formed a strong plant. In 

 the same establishment large numbers of Brazil- 

 nuts, Sapucayo-nuts, and other large hard-coated 

 seeds are annually sown, and it is found that by 

 carefully removing the shells before sowing, germi- 

 nation takes place much more speedily than when 

 they are allowed to remain. The same plan is often 

 had recourse to in the treatment of seeds of Olives, 

 Coniferce, &c. 



Aquatic plants, such as Nymphseas, Yictoria, 

 Euryale, the Buckbean, &c., naturally shed their 

 seeds in water, where they remain dormant as long- 

 as the temperature of the water is low, germinating 

 freely and developing into plants on the retiirn of a 

 higher temperature. Although it appears to be 

 nature's plan to preserve these seeds in water, yet 

 they may be kept for a long time in a perfectly dry 

 condition without losing their vitality. Seeds of 

 Nelumbium have been known to germinate after 

 having been kept dry for over one hundred years. 



These seeds may be kept equally well in water if 

 the temperature is not allowed to approach that 

 which induces germination. There are instances 

 recorded of seeds which had commenced to grow 

 having been dried again, and which, on being- 

 replaced in a moist situation, grew freely without 

 suffering materially from the check. But these are 

 exceptional cases, and by no means such as need be 

 regarded as of horticultural importance. There can 

 be no doubt that when once germination has begun, 

 any check to its progress is as likely to prove fatal 

 as it would be in the case of eggs after incubation 

 had commenced. All seeds, therefore, should be kept 

 dry and in a low temperature till required for 

 sowing, and when once wetted, no check in the 

 shape of drought or low temperature should bo 

 permitted, for even if such check do not prove fatal, 

 it cannot but prove highly injurious to an organism 

 of such extreme delicacy as a germinating seed or 

 seedling. 



