566 
certain diseases, as in the case of the 
Negro in relation to malarial diseases. 
In certain physical conditions, persons 
and plants are more susceptible than 
others, as in the case of fatigue, starva- 
tion, exposure to cold and whatever would 
tend to lower the vitality. This has been 
observed to be true in plants as well as 
in animals. A tree that is not proper- 
ly nourished, is susceptible to many forms 
of disease, to which the healthy tree is 
immune. On this general subject, Pro- 
fessor Muir, of the University of Glas- 
gow, says: 
“In this way conditions formerly be- 
lieved to be the causes of disease, are 
now recognized as playing their part in 
predisposing to the action of the true 
causal agent, viz.: the bacterium. In 
health the blood and internal tissues, are 
bacterium free; after death, they offer 
a most suitable pabulum for various bac- 
teria; but between these two extreme 
states are conditions of varying liability 
to infection. It is also probable that in 
a state of health, organisms do gain en- 
trance to the blood from time to time 
and are rapidly killed off. Immunity is 
generally spoken of under three distinct 
heads: 
“First. Natural immunity. 
“Second. Active immunity. 
“Third. Passive immunity. 
“Natural immunity may depend upon 
lack of sensitiveness to the bacteria or 
its toxins; as in the case of pear blight, 
which might enter the tips of the 
branches or the flowers, but could not 
enter where the bark is thick, unless in- 
jected by some insect or instrument. 
“Active immunity is illustrated in the 
case of persons who after recovering 
from an attack of certain infective dis- 
ease, such as smallpox, are not suscept- 
ible to subsequent attacks. Or, it may be 
illustrated again, by persons who have 
been inoculated with bacteria, that pro- 
duce a modified attack of the disease as 
a prevention from attack in its more 
virulent form. Sometimes the injections 
are small at first, and are increased from 
time to time, and in this manner per- 
sons have been rendered free from snakes, 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
scorpions and certain vegetable toxins. 
It is noted that the stings of bees, which 
to some persons are very poisonous, are 
not so to the same persons, after having 
been stung a number of times, 
“Passive immunity is secured by giving 
anti-toxins or anti-sera.”’ 
GRANVILLE LOWTHER 
BALANCED Sorts. See Soil. 
Banana 
The fruit of the banana plant Musa 
sapientum grows in clusters of large 
finger-like forms, upon a very large spike 
or stem, containing. within a red or 
yellow rind, a nutritious pulp. This 
pulp is usually seedless and constitutes 
an important article of food. In some 
of the islands of the Pacific, it is a staple 
article of diet for the natives. 
Scientists have recognized and classi- 
fied as many as 40 different species, rang- 
ing from the ornamental groups that do 
not develop fruit, to the giant bananas, 
the Platano of the Spaniards. 
The red banana is not common in the 
American markets. ‘‘There is a reason.” 
In the United States it is used only to 
“dress” fancy baskets of fruit, but in the 
tropical countries it is quite a favorite. 
The individual banana is large, but the 
stalk does not carry as many “hands” as 
the yellow varieties, so as it does not 
bring as large a price to the grower and 
wholesaler, its extensive cultivation is 
not encouraged. 
Banana culture is one of the oldest of 
industries. It has been known since the 
origin of the human race. Long before 
the dawn of history in the Old World, 
perhaps long before the Old World rose 
from the waters, man lived on the fruit 
of the Musas. The banana was generally 
considered a native of Southern Asia and 
to have been carried into America by 
Europeans, until Humboldt threw doubt 
upon its purely Asiatic origin, quoting 
early authors who asserted that the 
banana was cultivated in America long 
before the Conquest. It is claimed that 
at the time of the Incas in Peru, bana- 
nas formed one of the staple foods of the 
natives of the warm and temperate reg- 
