however, various points require
investigation. We ought to be able to answer such questions as the
following:--

1. What differences exist between the characters of starch produced by
different plants?

2. What are the qualities or properties that lead
manufacturers--calico printers for example--to prefer one variety to
another?

3. For culinary purposes, and as an article of diet, what qualities
or characters obtain a preference?

4. Can the starches from different plants be distinguished from one
another by distinct and well marked characters, so that the
substitution of a less esteemed variety for a more esteemed one, or
the adulteration of a high priced variety with a cheaper one, could be
readily detected?

5. What plants produce the most esteemed varieties?

6. What plants produce it in the largest quantity?

7. What plants produce the largest yield per acre?

8. From what plants is it most easily manufactured?

9. Is the process attended with any particular difficulties that ought
to deter the East and West India planters from engaging in it?

In the following observations (continues Dr. Shier) I shall be able to
reply to several of these questions, especially those capable of being
settled in the laboratory. On other points, particularly those
relating to the returns per acre, I am at present but imperfectly
informed, in consequence of the limited extent to which these plants
have hitherto been cultivated in this colony (Demerara), and from the
total absence of authentic data regarding the amount of yield.

_Characters of starch produced from different plants_.--Starches from
different plants are best distinguished from one another by
examination under a good miscroscope. The grains or globules may be
examined either as transparent or opaque objects; and although in the
same species there are considerable differences in size and form, the
different kinds are, on the whole, quite distinguishable. One of the
best ways of examining the form of the globules, under the microscope,
is to lay them on a plate of glass and cover them with a drop of
aqueous solution of iodine, which renders them gradually blue and
opaque. When the difference in size and form between the globules of
different species is considerable, as between the _Tous les mois_
starch and cassava starch, or even between the arrowroot starch and
cassava starch frequently used to adulterate it, it is not difficult,
with a little practice,