272 HARMONIES OF VEGETATION. 



fade and drop off, while the germen, on the contrary, 

 proceeds to increase its bulk, and forms the seed-vessel. 



By virtue of this process, so necessary but so diversified, we have 

 the seed at length, in a variety of reservoirs and situations. We 

 have the seeds in the pea tribe regularly disposed in parchment 

 pods, which, though soft and membranous, completely exclude the 

 wet even in the heaviest rains. In some cases, as in the bean, the 

 pod is lined with a fine down; at other times, as in the senna, dis- 

 tended like a blown bladder, or we have the seed enveloped in wool, 

 as in the cotton-plant lodged between the hard and compact scales 

 of a cone, as in the pine, or barricaded, as in the artichoke and this- 

 tle with spikes and prickles. In this way, the continuance of plants 

 is secured by a variety of contrivances, though widely differing in 

 themselves, yet all tending to the same object, the preservation of 

 the seed. 



22. When Nature has perfected her seeds, her next 

 care is to disperse them. The seed cannot answer its 

 purpose, while it remains confined in the capsule. After 

 the seeds are ripened, the seed-vessels open by a cer- 

 tain rule in each plant, to let them out. 



A spontaneous gradual opening of the pericarp, is the usual way 

 by which seeds are set at liberty ; but in some instances, particu- 

 larly in the common furze or goss, the opening of the seed-vessel is 

 instantaneous and accompanied with a noise ; this is also the case 

 with other plants both foreign and native. 



23. The structure and foim of seeds are very differ- 

 ent; but be their form and construction what it may 

 they will always be found to harmonize with the circum- 

 stances to which they have relations. 



Most seeds have defensive coverings or tunics, some hard or pulpy 

 seed-vessels. Most seeds are comparatively smooth, and destined 

 to grow in the Immediate vicinity of the mother plant, while others 



