22 
SELECTED ARTICLES. 
of their faces by a black cross, or three black rays united in 
the centre of the grain. Yet we have examined several spe- 
cimens of rye, which were furnished in 1834, by M. Bosson, 
a pharmacien of Mantes, of which the grains of fecula had not 
this cross in their interior. 
Oat Fecula. 
(Jivena sativa, L.) PI. fig. 6. The farina of this grain has, to 
the naked eye, a cottony or downy appearance, in consequence 
of the presence of an innumerable quantity of hairs covering 
the grains. When this farina is observed magnified to 100 
diameters, by Sellique's microscope, it appears as if there were 
presented to the vision an unequal mixture, consisting of 
large grains of fecula deeply shaded and opaque, oblong or 
ovoid, from the ^ to the of a millimetre, and from T ^ to ^ 
and by the side of, and sometimes adherent to, the surface 
of these first, small grains about ^i^- of a millimetre. In the 
first edition of my work, from not having examined this mix- 
ture by a superior power, I in fact took the large opaque 
grains for grains of fecula, but I have rectified this error by 
using a power of 350 times. They are, however, glutinous 
cellules, as large as grains of fecula, and which are so clearly 
isolated, and appear under such rounded forms, as to resemble 
isolated grains of fecula. These glutinous cellules allow the 
fecula that they contain to be colored by iodine, and the trans- 
parency of their parieties is such as not to present an obstacle 
to the display of the blue coloring. 
Arrow Root Fecula. 
(Maranta arundinacea, L.) PI. fig. 8. "Arrow root," says 
Berzelius, " being esteemed by some physicians as possessed of 
strengthening properties, is sold at a high rate, and it be- 
comes of importance to distinguish it with certainty from 
other species of amidon. According to Guibourt, it is re- 
cognised under the microscope, for the grains of arrow root 
are translucent, and smaller than those of the amidon of the 
potato, although their form and size are as variable." Fully 
