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Rescatches into the Anatomy of Plants. 467 ~ 
very little cellular texture dispérsed in the wood and in a 
compressed state. ie 
5. The sap cannot ascend in the interval between the 
bark and the wood. I have seen branches issue where this 
interval did not as yet exist, and where the bark was strongly 
adherent to the wood. We may strip off a ring of bark all 
round a branch so as completely to interrupt this interval, 
and the branch continues to vegetate and to push out other 
branches. Neither can the sap ascend in the intervals be- 
tween the fibres, for these intervals are extremely small 5 
smaller than the diameter of the fibres; or rather these in- 
tervals do not exist, because these fibres are pressed against 
each other. 
It is true that coloured liquids, such as tincture of turn- 
sole, fernambouc, &c. are attracted by the trachez, and 
cannot penetrate into the fibres. But the experiment never 
succeeds if the branches are not cut, in which case the liquor 
may ascend into the trachee, as in capillary tubes. I 
never saw the trachez tinged when I allowed seeds to ger- 
minate in these liquors, or when [infused plants, the roots 
of which were not at all injured. It is known besides that 
the colour of all these tinctures is only visible when we look 
at an extended surface: this is the reason why we do not 
observe the tincture in the narrow fibres, although it enters 
into, them, and we see it very well in trachez, whose dia- 
meter is greater. 
The fibres, therefore, which I shall call fibrous vessels, 
carry the sap wherever it is wanted throughout the plant. 
We may prove this theory by a multiplicity of experiments 
and observations. When we insert the end of a cut branch 
in water, it pushes out other branches under the same spot. 
Succulent plants continue to vegetate when we have cut 
their roots; they flourish frequently in this state, but as 
soon as they produce fresh leaves and flowers the old ones 
wither and fall off. It is therefore clear that the sap from 
one part is re-absorbed to furnish some to others: one part 
serves to nourish the others. The same thing happens with 
bulbs when suspended from the cieling; the plant is de- 
velopped and flourishes; but at the same time the bulb 
disappears, because it has given up the sap which it con- 
tained to the stalk to develop and nourish it. This is the 
reason why the stipul# are formed before the leaves, and 
the leaves before the branches, which are generally found in 
the axilla of the leaves: itis for the same reason that so 
many foliaceous parts issue before the parts of generation 
and of fructification, and that the latter do not attain per- 
Gg2 fection 
