y small amounts of fertilising constituents." In connection with this
he further says "that even when the seed is taken away along with the
lint, cotton still removes smaller amounts of fertilising materials from
the soil than either oats or corn." It should be borne in mind that the
soil upon which cotton is cultivated lies fallow for a greater part of
the year, and the fact of absence of cultivation, with consequent
non-fertilising and non-enriching of land, must tend in the direction of
soil exhaustion by the Cotton plant.

Another useful and important fact in connection with the Cotton plant is
the medicinal use to which the roots are put. According to the _American
Journal of Pharmacy_, the bark from the roots of the Cotton plant
contain an active ingredient which in its effects is very much like
ergot.

Chemical investigations have conclusively proved that the ripe fibre of
the Cotton plant is composed of the following substances:--

Carbon, Hydrogen, Oxygen, and they tell us that when cotton is fully
ripe it is almost pure cellulose.

Dr. Bowman has pointed out that the percentage of water in cotton fibre
"varies with different seasons from 1 to 4 per cent. in the new crop,
and rather less as the season advances. Above 2 per cent. of moisture,
however, seems to be an excessive quantity even in a new crop cotton,
and when more than this is present it is either the result of a wet
season and the cotton has been packed before drying, or else it has been
artificially added."

About one fifth of the whole plant by weight consists of the seed, and
an analysis of this shows them to be composed of water, ash, nitrogen,
phosphoric acid, potash, soda, lime, magnesia, sulphuric acid, ferric
oxide, chlorine, and insoluble matter.

As a commercial product seeds are exceedingly valuable, and yield the
following substances:--oil, meal, hulls, and linters. When the hulls are
ground they receive the name of cotton seed bran. The inside of the
seed, when the hull has been removed, is often called the kernel and is
sometimes also designated peeled seed, hulled seed, and meats. It is
this kernel seed which, when properly treated, yields large supplies of
oil and meal.

CHAPTER II.

COTTON-PLANT DISEASES AND PESTS.

There are several classes of agents all of which act injuriously more or
less on the Cotton plant.

1. Climatic changes, including hygrometric variations of the
atmosphere, and extremes o