Researches into the Anatomy of Plants. 2717 
pith of plants untouched. The celebrated Bonnet repeated 
these éxperiments with success; and finally Reichel, pro- 
fessor at Leipsic, observed in 1758*, that the trachece 
alone assumed the colour, and that it neither touched the 
fibres nor the cellular texture. The above were the most 
important discussions on the anatomy of plants in the 
eighteenth century. 
Towards the end of that century, Hedwig, celebrated by 
his work upon Mosses, announced a discovery which has 
not been confirmed by any subsequent observer. He main- 
tained that the trachez are composed of two vessels, one 
straight, filled with air, the other twisted around the former, 
filled with sap, and destined to draw up the nutritive sap 
from plants. 
Two naturalists, the one French, the other German, have 
renewed and systematized the anatomy of plants, towards 
the commencement of the nineteenth century. Messrs. 
Mirbel and Sprengel published the first works, for many 
years, which contained a great number of real discoveries, 
and which elucidated several points of vegetable organiza- 
tion. But there were still so many difficulties to resolve, 
that the Royal Society of Gottingen proposed a prize for 
1805, on the subject of the vessels of plants. This prize 
was divided between M. Rudolphi and myself, and the ac- 
cepit granted to M. Treviranus. From this time the Eluci- 
dation of the Theory of vegetable Organization, by M. Mir- 
bel, and the Essays on the Organization of Plants, by M. 
Albert du Petit Thouars, have increased our stock of 
knowledge upon this subject. All these authors, far from 
being agreed, differ almost always as toihe most essential 
facts of vegetable organization. In this embarrassment 
there is scarcely an observation which may not be useful in 
some respect, and it is this which led me to present these 
additional inquiries to the judgement of enlightened na- 
turalists. 
I shall first speak of the cellular texture, because it exists 
in almost all plants, and because it constitutes the greater 
part of them. 
I. Cellular Texture. 
The cellular texture consists of small membranous vee 
sicles, the figure of which varies much. Nothing fibrous 
is visible in it, and it is with good reason that M. Mirbel 
and M. Sprengel have rejected the common opinion, which 
makes all be developed from the fibres, and which finds 
* Vide Diss, de Vasis Plant, spiralitus, Lips. 4, 
: $3 them 
