SPECIES OF FECULA EMPLOYED IN PHARMACY. 
23 
congratulating Berzelius upon his new regard for microscopic 
observations, we cannot avoid deploring the species of com- 
plaisance which has led him to record, in the catalogues which 
he has invested with the authority of his name, observations at 
least as superficial as those he has borrowed from Guibourt. 
According to the characters assigned by the latter to the 
fecula of arrow root, there are in France perhaps an hundred 
vegetables, the fecula of which may be confounded with this 
Brazilian substance. What fecula is not translucent? And what 
fecula is more translucent than that, of Solanum? Finally, 
what fecula, with the exception of that of the seeds of Chara, 
has not the grain smaller and the size as variable as that 
of the fecula of the potato? As to forms, how many are 
there whose forms vary to infinity? But as it unluckily 
happens, so far from being translucent, the grains of arrow 
root are more clouded than any that have been observed by 
us, and present characters that we have not met with in others. 
They are the following: 
The fecula of arrow root examined in mass has a crystalline 
aspect, but dull; it is harsher to the feel than that of potato, 
and almost as harsh as wheat starch; it contains lumps which 
resist compression and crackle between the fingers. Exa- 
mined in water by the aid of the microscope, it presents groups 
of five, six, and even ten or a dozen grains, which the most 
rapid motion and prolonged agitation do not separate, and 
which float together in the liquid. 
But what is most distinct in the physical characters of this 
fecula, is the circumstance that each of these grains represents 
a half, a fourth, or a third, &c, of a solid sphere, some of them 
being small cylinders, with one extremity rounded like a cap, 
and the other flattened; while others exactly resemble a paint 
mullar; hence, each of these grains has always one or more 
angular surfaces, the refraction of which produces shadows 
so strong and so various, observed upon the contour of 
the microscopic image, that it would be supposed there were 
crystals presented to the eye. This structure is of such a 
nature, that a written description is better adapted to give an 
idea of it than the most exact figure. In addition, there are 
