Humboldt's observations 11 



near his church, upon a scaffolding of palm trunks, a little room in which he can 

 breathe more freely. We mounted there in the evening by the help of a ladder, 

 to dry our plants and to write up our journey. The missionary had noticed with 

 exactness that the insects abound most in the lower layer of the atmosphere, that 

 which is near the soil, up to 12 to 15 feet in height. At Maypures the indians 

 leave their village in the night in order to go to sleep on the little islands in the 

 middle of the cataract. They get some sleep there; the mosquitoes appear to 

 avoid the air surcharged with vapors. Everywhere we found them less abundant 

 in the middle of the river than on the banks; in descending the Orinoco one 

 suffers only when getting into the boat. 



" Persons who have not sailed upon the great rivers of equinoctial America, 

 the Orinoco for example, or the Magdalena, can not conceive that at every mo- 

 ment, without interruption, one can be tormented by the insects swarming in the 

 air, and how the number of these little animals can render vast regions almost 

 uninhabitable. One can never become accustomed there to stand the bites with- 

 out complaint. However lively may be one's interest in the objects of his search, 

 it is impossible that one should not be constantly distracted by the mosquitos, 

 the zancudos, the jejen, and tempraneros, which cover the hands and face, which 

 pierce the clothing with their spear-like suckers, and which, getting into the 

 nostrils and into the mouth, make you cough and sneeze. Thus ... in the 

 missions of the Orinoco, in these villages placed on the banks of the river, sur- 

 rounded by immense forests, the plague of flies affords a constant topic for con- 

 versation. When two persons meet in the morning the first question asked is, 

 ' How have you found the zancudos during the night ? ' 



" This is the place to mention the geographic distribution of these insects 



which shows quite remarkable phenomena. It does not appear to depend solely 



upon the heat of the climate, upon the excess of humidity, or the thickness of 



the forests, but upon the local conditions difficult to characterize. It can be said, 



for example, that the torment of mosquitos and zancudos, is not as general in 



the torrid zone as is commonly believed. Upon plateaux more than 400 fathoms 



higher than the ocean level, on very dry plains distant from the banks of great 



rivers, for example at Cumana and at Calabozo, there are not obviously more 



mosquitos than in the most civilized part of Europe. Their number becomes 



enormously increased in Neuva Barcelona, and, more to the west, upon the coast 



which extends towards Cape Codera. Between the little port of Higuerote and 



to the mouth of the Eiver Unare the unfortunate inhabitants have the custom 



of stretching themselves upon the ground and passing the night covered with 



earth 3 or 4 inches thick, leaving out only the head, which they cover with a 



handkerchief. One still suffers from the bite of the insects, but in so much less 



degree that it can be easily borne, in descending the Orinoco from Cabruta 



towards Angostura, and in going up from Cabruta towards Uruana, between the 



7th and 8th degree of latitude. But beyond the mouth of the Arauca Eiver, 



after the Straight of Baraguan is passed, the scene changes constantly. Beyond 



this point there is no longer any repose for the traveller. If one remembers his 



Dante he believes that he has entered the cittd dolente, and he will believe he can 



read upon the granite rocks of Baraguan the memorable lines of the third canto : 



Noi sera venuti al luogo, ov'i' t'ho detto 

 Che tu vedrai le genti dolorose. 



" The lower layers of the air, from the earth up to 15 to 20 feet in height, are 

 filled with venomous insects like a condensed vapor. If one places himself in 

 an obscure place, as, for example, in the grottos of the cataracts formed by 

 blocks of granite, and directs his eyes towards the opening, one sees clouds of 

 mosquitos which are thicker or thinner according as these little animals in 

 their movements come together or disperse. At the mission of San Borja they 



