820 



" Guano is formed of the excrements of different kinds of marine 

 birds, as mews, divers, slieerbeaks, &c. ; but the species which I can 

 name with more precision are the following: Larus modest us, Tsch. ; 

 Rhinchops nigra, Linn. ; Plotus anhinga, Linn. ; Pelecamis tliayus, 

 Mol. ; Phalacrocorax Gaimardii and albigula, Tsch. {Pelecamis 

 Gaiviardii, Less., Carbo albigula, Brandt), and chiefly the Sula va- 

 riegata, Tsch. 



" The immense flocks of these birds as they fly along the coast 

 appear like clouds. When their vast numbers, their extraordinary 

 voracity, and the facility with which they procure their food, are con- 

 sidered, one cannot be surprised at the magnitude of the beds of 

 guano, which have resulted from uninterrupted accumulations during 

 many thousands of years. I kept for some days a living Sula varie- 

 gata, which I fed abundantly with fish. The average weight of the 

 excrements daily was from three-and-a-half to five ounces. I have 

 no doubt that when the bird is in a state of freedom the weight must 

 be much greater, for these birds are constantly plunging into the sea, 

 in order to devour the fishes which they find in extraordinary masses 

 around all the islands. When an island is inhabited by millions of 

 sea-birds, though two-thirds of the guano should be lost while flying, 

 still a very considerable stratum would be accumulated in the course 

 of a year. 



" The marine birds nestle on the uninhabited islands, or on rocks 

 near the shore ; but they never settle on the flat beach, or any place 

 distant from it inland. On this fact I ground my conjecture that 

 those beds of guano in the interior, which may have been removed 

 from the shore by important elevations of the coast, are to be found 

 only on hills. 



" During the first year of the deposit the strata are white, and the 

 guano is then called guano bianco. In the opinion of the Peruvian 

 cultivators, this is the most efficacious kind. It is found in the 

 Punta de Hormillos, on the islands of Islay, Jesus, Margarita, &c. 



" 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 they have withdrawn from the islands in the neighbourhood of the 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. 



"Much has recently been written on the employment and utility 

 of guano ; but the manner in which it is applied as manure in Peru 

 seems to be but little known. The Peruvians use it chiefly in the 

 cultivation of maize and potatoes. A few weeks after the seeds be- 



