210 THE VEGETABLE WORLD. 
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they were not all of equal value. The results of his calculations 
were frequently found to be false, as would inevitably happen with 
any sum where no regard was paid to the quality of the metal, 
but only to the shape and volume of the coin. oe 
The year 1789 was the date of the true creation of natural 
families among vegetables. It was about this time that Laurent — 
de Jussieu published his celebrated “Genera Plantarum,” which — 
raised the science of botany, and marked a new era, not only in 
vegetable science, but in the classification of animals. 
The catalogues of the Gardens of the Trianon, prepared by Ber- 
nard de Jussieu, and the conversations of the latter with his nephew, 
were the primitive spark whence the latter drew his inspiration. — 
We shall, however, leave his grandson, Adrien de Jussieu, to state 
the true basis of the Natural System, and the considerations which 
guided his relation. “Like Adanson,’’ says Adrien, “ Antoine- 
Laurent de Jussieu admits that the examination of all parts of a 
plant is necessary in order to its classification ; but in pursuing this... 2 
examination it is not sought to deduce theoretically the combina- 
tion of the genera; thus in grouping them into families, he imitated 
the proceedings followed in the formation of the genera themselves. 
The botanist, struck by the complete and constant resemblance of 
certain individual plants, formed them into species; then, observing 
a resemblance equally constant, but much less perfect, he formed — 
them into genera. The characters, which might vary evenin the = 
same species, ought to depend on causes exterior to the plant, amd 
not on the plant itself: for example, its size, consistence, certain 
modifications of form and colour, which we see change with the = 
sun, the climate, and under other influences purely circumstantial. 
The specific characters, on the contrary, those especially which | 
every, individual should possess, as belonging to certain species; 
whatever be the circumstances in which they are found, ought to 
hold to the nature of the plant. Among these characters some are oe: 
more important than others, and less subject to variation. Finding 
these characters in a certain number of species marks what consti- 
tutes a genus. These would, from their general nature, have. 
more value than the specific, as the specific is of more value than 
the individual characteristics, — 
“ But how are we to discover and estimate these different values? _ 
