AT THE PERIOD OF PUBERTY. 155 



calls forth more speedily the reproductive energies, and 

 brings the life of the plant to an early close. If the plant 

 is an annual, the whole organism perishes the first year; 

 but if it be a perennial, the part of the organism developed 

 into the atmosphere alone dies : for, as we have seen, it is 

 without the means of protecting itself against the incle- 

 mency of the weather ; but the part of the organism still 

 below the soil is protected, and lives securely sheltered by 

 its friendly covering till warm weather comes again, and 

 then from that still living underground rhizome, or sub- 

 terranean stem, the same plant springs forth in the renewed 

 beauty and freshness of youth, to go through the same 

 brief but interesting life-changes. 



It is otherwise with ligneous plants, such as shrubs and 

 forest trees ; in them we see the working of the same 

 natural laws, but in a somewhat modified manner, and on 

 a far grander scale. It is the intention of Nature, in the 

 case of trees, that her work should be preserved, and 

 therefore she seeks to consolidate their fabric, by the pre- 

 servation, through the winter months, of the amount of 

 work done by the leaves of each season. In trees, under 

 ordinary circumstances, only one generation of shoots is 

 produced in a year, and these shoots do not branch any 

 further than the formation of buds in the axilla of their 

 leaves. These buds, or vegetative points, are always more 

 or less perfectly formed by the leaves before the tree 

 becomes defoliated. Like the original seed out of which 

 the whole tree has been gradually developed, they indi- 

 vidually contain, in an embryonic condition, a shoot and 

 leaves precisely like the first year's growth from the seed. 



An additional set of organs, usually called bud-scales, 

 is therefore furnished to trees, in order to protect their 

 young rudimentary branches. These I have ventured to 

 call, in this work, folia tegmentia, covering leaves. These 

 leaves are assisted in their protective function, in some 

 instances, by a covering of hard, dry varnish ; and, in not 

 a few cases, they have, internally, a warm, woolly lining. 

 Every pore is thus sealed up, and the atmosphere of winter 



