182 
POPULAR SCIENCE REVIEW. 
which yields the Upland cotton of the Americans. It has 
the short staple and green seeds of the Upland Georgia 
cotton, and which there is reason to believe originated in the 
culture of the Gossypium barbadense. The principal distinction 
upon which the botanist relies for a specific difference, is the 
green colour of the seeds, which is found to depend upon the 
presence on the surface of the seed, of the pubescence or short 
hairs which have been before alluded to. In the typical Gossy- 
pium barbadense there is no pubescence, nothing but the long 
cotton-hair, imderneath which the seed is black. 
4. Gossypium Peruvianum . — The Peruvian Cotton-plant, also 
described as Gossypium acuminatum, is recognized by most 
botanists as a distinct species. Like the Bourbon cotton, it 
has black seeds and yellow flowers. The seeds adhere together, 
however, in a peculiar way in a kidney-shaped mass ; and 
although in other respects it resembles the last species, it has 
a peculiar appearance, and cannot in any way be traced to the 
species of the Old World for its introduction. On the conquest 
of Peru and Mexico by Pizarro and Cortes, it is worthy of note 
that in both countries the inhabitants were found to have 
acquired the art of weaving cotton. The species of plant 
from which this cotton was obtained was the present one, 
which is undoubtedly the only species truly indigenous in 
America. It is this which yields the Pernambuco and Maran- 
liam cottons of the markets. After the Sea-Island and 
Egyptian, these South- American cottons obtain the highest 
price in the market. 
It becomes an important matter to ascertain what are the con- 
ditions under which the various species of cotton-plant thrive, as 
we can only hope to extend its culture successfully by ascer- 
taining the external circumstances under which it has prospered, 
and securing them for future experiments. In the first place, 
with regard to heat. We find that the cotton flourishes best 
in the tropics ; but its culture has been successfully extended in 
warm districts, in both south and north subtropical climates. 
It has been produced in great perfection in Egypt (fig. 9), 
and the islands of the Grecian Archipelago ; and cotton equal 
to the finest Sea-Island has been produced at Algoa Bay and 
in Australia (fig. 13). 
A second element which seems to exercise an important 
influence on the growth of cotton, is moisture. The humid 
atmosphere that prevails along the coasts of Georgia seems to be 
the circumstance, above all others, that has led to the great 
superiority of the Sea-Island cotton. That this is the case we may 
observe from the fact of the same plant, when taken to the dry up- 
lands, producing a very different and inferior kind of cotton. It has 
been stated that the atmosphere of the coasts of America con- 
tains in it a considerable quantity of salt, or chloride of sodium, 
