ON THE STRUCTURE OF THE BEET-ROOT. ~ 279 
opaque cells, rounded, dilated, distributed without order, red, pink, 
r white according to the varieties, 
The cortical zone, in which the vascular circles develope 
successively, is homogeneous, rather dense, succulent, becoming pale in 
the interior in the coloured varieties, opaque in the white variety. 
It is composed of elongated cells, often with four angles, with rounded 
extremities united end to end; their walls are thick, obscure at the 
ines of union, covered with a granular matter exhibiting a nucleus 
in a transverse section. 
The transparent traces which occur in the cortical zone not fur 
from its inner border, and in which the vessels would be developed, 
are formed of elongated cells a little rounded at the extremities, with 
which in the transverse section represents a scarcely visible nucleus ; 
in a word, the cells are similar to those of the fibrous tissue of the 
woody bundles, and of those of the cortical bundle of which it is the 
origin. The zone of coloured or opaque tissue, which is separated 
- from the cortical zone by the transparent tissue which occurs in this 
last, has the same organisation as the cortical zone itself: but its 
cells enlarge (se dilatent) by the development of the medullary zone 
of which it is the commencement. ‘The external zone of cortical 
parenchyma, which is quite transitory, is formed of large cells, dilated, 
sometimes provided with a granular nucleus confusedly distributed, 
red or uncoloured, separated by lacunw. The epidermis is formed of 
lan ou r : 
bundles in the cortical parenchyma outside the dnterstice d’ac- 
croissement ; the external zone is uniformly cellular and does not 
contain the elements of a complete cortex. The new bundles 
ey are more 
doubt due to 
t contains so large a proportion 
of sugar and is difficult to preserve. l 
have described are those which distinguish the “heterogens” ; one 
difference only exists between the Beet and the heterogens best 
known—it is that they are woody and have a prolonged existence, 
while the Beet is biennial. 4 
The Beet is distinguished at first sight from fleshy roots which, 
like the Carrot, have a bark separated trom the central system by a 
cumbium, and formed of large parenchyma, of very distinct sca 
lary prolongations, and of transparent bundles of large diametra 
s greater as th 
