Researches into the Anatomy of Plants. 391 
who originally took up the subject. I am now of opinion 
that the fibres of the plants are vessels in which the sap 
ascends; that they are entirely different from the cellular 
texture, and that they constitute a class of particular or- 
gans. 
Malpighi gives some very accurate ficures of the fibres of 
plants: he supposes that these fibres are the vessels de- 
signed to transfer the sap. Grew entertained the same 
opinion*before Malpighi. Naturalists adopted the theory 
of these great men until the discoveries of Sarrabat, Bonnet, 
and Reichel rendered it very doubtful. Hedwig said that 
the fibre of the plant is formed by the sap-vessels which 
twist themselves round the air-tube. Sprengel asserts that 
the fibres consist only of the cellular tissue; and Mirbel 
appears to be of the same opinion. The opinions of these 
philosophers made MM. Radolphi, Treviranus, and me un- 
willing to admit that the fibres are distinct organs, differing 
from the cellular tissue. Only two modern naturalists, 
MM. Petit Thouars and Medicus, retain the ancient opi- 
ion, and support the existence of fibres. 
The fibres of flax, hemp, and other plants, carefully ex- 
amined with a good microscope, did not exhibit the least 
vestige of any partitions or intertexture. I took the longest 
fibres which [ could procure, and examined them from one 
end to the other without finding an intertexture in their 
whole length. They appeared to be straight and continuous 
tubes. I have seen the same thing in the ramifications of 
the leaves of Bromelia ananas, from which we may draw 
the threads by tearing the leaves. The same thing happens 
when we tear the leaves of Planiago mujor, in which the 
fibres are joined to the trachez in a small fasciculus, which 
is easily detached from the parenchyma. Finally, the in- 
terior bark and’the wood of the trecs have afforded me the 
same result: having once seen the fibres distinctly, I was 
able to recognise them every where, and to distinguish them 
easily from the cellular texture. See Pl. I. fig. 12, (Plate IV.) 
these fibres taken from the inner bark of the Liburnum lan- 
tana. The texinre of the hazel-tree resembles considerably 
these fibres, particularly if they are not parallel, and if they 
cross each other under a very acute angle; but maceration 
destroys the texture, and leaves the fibres entirely. In ge- 
neral these fibres accompany the trachez, and constitute 
with them the wood of the plants, Nevertheless we find in 
some plaats fasciculi of fibres under the epidermis separated 
from the wood, and the tracheze, e. g.in the Labiate, the 
Bb4 Umlelliferee, 
