GUANO. 169 
over numerous localities in the intertropical regions. It abounds 
on many of the rocky islets of the Red Sea, where the life-teeming 
waters afford sustenance to innumerable sea-gulls, cormorants, 
and pelicans; but its most widely velebrated stores cover the small 
Chincha Islands, not far from Pisco, about a hundred miles to the 
south of Callao, where they form enormous layers 50 or 60 feet deep. 
The upper strata are of a greyish-brown colour, which lower 
down becomes darker ; and in the inferior strata the colour is a 
rusty red, as if tinged by oxide of iron. The guano becomes 
progressively more and more compact from the surface down- 
wards, a circumstance naturally accounted for by the gradual 
deposit of the strata and the increasing superincumbent weight. 
As is universally known, guano is formed of the excrements of 
different kinds of marine birds; but the species which Tschudi, 
the celebrated Peruvian traveller, more particularly enumerates 
are—Larus modestus (Tschudi), Rhynchops nigra (Linn.), 
Plotus anhinga (Linn.), Pelecanus thayus (Mol.), Phalacro- 
corax Gaimardit and albigula (Tsch.), and chiefly the Sula 
variegata (Tsch.). 
The immense flocks of these birds, as they fly along the coast, 
appear like aérial islands; and when their vast numbers, their 
extraordinary voracity, and the facility with which they procure 
their food are considered, we cannot be surprised at the magni- 
tude of the beds of guano which have resulted from the uninter- 
rupted accumulations of countless ages. During the first year 
of the deposit the strata are white, and the guano is then called 
Guano blanco. In the opinion of the Peruvian cultivators, this 
is the most efficacious kind. As soon as the dealers in guano 
begin to work one of the beds, the island on which it is formed 
is abandoned by the birds. It has also been remarked that, since 
the increase of trade and navigation, they have withdrawn from 
the islands in the neighbourhood of the ports. Under the em- 
pire of the Incas, the guano was regarded as an important branch 
of state economy. It was forbidden, on pain of death, to kill 
the young birds. Each island had its own inspector, and was 
assigned to a certain province. The whole distance between 
Arica and Chaucay, a length of two hundred nautical miles, was 
exclusively manured with guano. These wise provisions have 
been entirely forgotten by the Spaniards, but the Peruvians now 
begin to discover the error of their former masters, and look 
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