wal Proceedings of Learned Socteties, 
tinues the reporter, has shewn that this 
mode ‘of growth is common to most of 
the monocotyledonous plants, and..that 
riven ts by this circumstance they are i 
general distinguished from the dicotyle- 
donous. 
But M, du Petit-Thouars, having re- 
marked that the dracena, a tree really 
monocotyledonous, ramifies, so to speak, 
like common trees, and anxious to ex- 
plain this phenomenon, he convinced 
himself by dissection, that the axis of a 
twig, or branch, has no communication 
with that of the tree, but that its fibres, 
on reaching the place of their junction 
with the tra: rk, extend themselves on the 
latter, like radu; while the lower fibres 
descend directly ; the superior, after de- 
scending a little way, bend backward, 
and descend aiso. Hence it is evident, 
that these trees augment in growth by 
coneeitric layers, and, in fact, their di- 
mensions increase in proportion as they 
ramify.. Such are the facts on which 
the following system is founded. 
M. du Petit-Thouars, applying these 
observations to trees in gene) ral, having 
concentric layers, inferred, that tie new 
Jayers are not produced by the bark, but 
by the buds; that the fibres are desten- 
ding, as the shoots are ascending prolon- 
gations of these buds. He thinks that 
the sap or juice contained in the pith, or 
medulla, furnishes the buds with their 
first nourishment, in the saine manner 
as the cotyledons furnish it to the young 
plant; he is compelled to add that these 
fibres are developed from the buds, 
whence they proceed to the roots, with 
a rapidity which he compares to that of 
light, or electricity, smce the woody, or 
ligneous layer is formed upon the whole 
extent of the tree, in the space of a few 
days. The necessity of admitting such 
a rapid growth affords, as has already 
been observed, a strong objection against 
this hypothesis ; besides another obyec- 
tion, which should seem to be still more 
forcible: when.one kind of tree is en- 
grafted on another, a pear-tree, for in- 
stance, on an apple-stock, each species 
produces its own wood, the stock below 
the insertion is wholly composed of ap- 
ple-tree wood, while all above this point 
45, on the contvary, pear-tree wood. We 
377 
can distinctly mark the place, at which 
the two woods are separated; and as 
great care is taken to strip the stock of 
its buds, it must necessarily follow that 
its wood was furnished by the bark 
alone; for how, the adherents of the an= 
cient doctrine may ask, can pear-treé 
buds produce appile-tree wood? It is, 
answers M, du Petit-Thouars, because 
the fibres which descend from these 
buds, cannot be nourished in their pas- 
sage along the trunk of the apple-stock, 
except by the juiges furnished to them 
by the latter. 
While a noble emulation, says M, 
Cuvier, thus animated the candidates, 
the botanical members of the class have, 
by a perseverance in thew labours, 
evinced themselves worthy of beimg the 
judges of the merits of the various come 
petitors, 
M. Ventenat, we are informed, con 
tinues to prosecute his interesting re- 
searches in the Garden at Malmaison. 
Another sheet, the twentieth, has ap- 
peared during the last half year. 
The first species which he describes, is 
a superb leguminous plant, a native of 
New Holland, and which displays cha+ 
racters in the organs of fructification, 
that have not hitherto been observed iw 
any of the plants belonging to this fae 
mily. M. Ventenat considers it as con 
stituting a new genus, under which he 
ranks a second species, cultivated alse 
at Malmaison, though it has not yet 
flowered; butit so much resembles the 
former in its aspect and manner of 
growth, as to render it almost certain 
that 1t must agree with it in the organs 
of fructification. 
The last is a malvaceous plant, indi 
genous in the Canary Islands; its flowers, 
equally large as those of the ketmia 
cultivated in gardens, are of a brilliant 
red, a colour which is extremely uncome 
mon in plants of this family. This part, 
as well as those formerly published, ren- 
ders it a matter of regret to those whe 
take an interest in the science, that the 
author’s want of health should, for the 
present, have compelled him to discon- 
tinue it. 
( To be continued. ) 
