CELLS. STARCH. 
31 
little of this water be examined under the micro- 
scope, the colour will he seen only in the remains of 
the granule- membrane ; and if the water be allowed 
to stand, all the colouring matter will fall to the bottom 
of the vessel as a precipitate, showing that all parts 
of the starch grain are of greater specific gravity than 
water. 
I have stated that the starch grains have definite and 
peculiar characters in different plants; and as starch, 
under certain names, such as Tons les mois , tapioca, 
sago, arrow-root, &c., is largely used by invalids and 
children, it becomes of importance for us, as medical 
men, to be able to detect frauds which are frequently 
practised in these articles. In Fig. 19 , a, b , c, d, e, &c., 
you have representations of the principal varieties of starch, 
all of which are drawn to a fixed scale ; they, therefore, 
exhibit their peculiar form and proportionate size ; and 
it will be readily seen that by means of the micro- 
scope, any mixture of two or more of them, or of 
other varieties with them could he easily detected, as 
was strikingly exemplified, some years since, in a case 
which our distinguished chemist, Dr. Ure, was em- 
ployed to investigate. This was an attempt to im- 
port the starch of the Cassava, which bears a duty, as 
arrow-root, upon which there is no duty ; thereby an 
attempt was made to defraud the revenue to a con- 
siderable amount. The difference between the two 
starches was not sufficiently obvious to the naked 
eye ; but by means of the microscope, and a knowledge 
