GERMINATION. 131 



having been duly fecundated by the pollen, then per- 

 fectly ripened, and afterwards not exposed to destruc- 

 tive degrees of cold or of heat, to freeze its juices in 

 the one case, or parch them up in the other. Some 

 seeds, as those of the coffee plant, require to be sown 

 almost immediately on being gathered; others, if kept 

 from air, light, and moisture, may be kept long good, 

 such as those of the sensitive plant 



The external circumstances necessary to germination 

 depend on water, heat, and air, and, as connected with 

 these, on soil and situation ; though soil is not indis- 

 pensable, for seeds, such as those of mustard, will 

 germinate on a sponge or a moist piece of flannel. 



Water is indispensable, from its being the common 

 vehicle in which the food of plants is taken up by the 

 spongelets. In germination, water enters into the 

 substance of the seed, swells the kernel, and causes 

 the enveloping shell to burst, and, by carrying food 

 into the seed-pulp and the seed-lobes, it supplies them 

 with materials for increasing in bulk, its decomposi- 

 tion and the new combinations of the elementary 

 matters, producing starch, sugar, acids, oils, resins, 

 woody fibre, and whatever else may be found in the 

 germinating seed. Water, however, should not be too 

 abundantly supplied, as in that case it will macerate 

 the seeds, and cause them to rot; and hence a wet 

 spring is unfavourable to corn, French beans, &c. and 

 hence, also, the advantage of sowing in dry, rather 

 than moist, weather. 



Heat is no less indispensable than water ; for the 

 expansion of the parts is prevented by a temperature 



