26 
Botanical Reminiscences. 
disturbed by us, would rise with their peculiar rattling voice. 
Very seldom did I observe this ibis on the borders of the 
swamps, but generally on the dry savanna, where they are 
principally found in flocks of from six to eight. The giant 
stork, Mycteria americana, Lin., and Cieonia Maguari, Temm., 
and cranes were seen only on such places where a little water 
still remained. 
About mid-day the heat had reached to 125"^ Fahrenheit, 
accompanied by those effects of the reflecting rays of the sun, 
which make all objects appear in a dancing, dazzling motion. 
A peculiar, and at the same time, a new meteorological 
phenomenon were the whirlwinds and the columns of dust 
produced by them, which were not observed by me in such 
numbers over the savannas. Suddenly, the dust and dry 
leaves of the shrubs, rising from a certain point very nearly 
horizontal, gradually take the true form of a spiral column, 
which remains in the air for a short time motionless, and 
afterwards being driven with great velocity across the 
savanna, and getting more transparent at its extremity towards 
the ground, breaks in the middle, and then disappears in 
the air. The appearance of so many dust columns, no doubt, 
arises from the reflected heat of the sun, and the consequent 
inequality of the temperature, and also from the currents of 
air, which, although parallel, move in opposite directions. 
Since we left the Lake Venturu, the water of which was 
hardly drinkable, we had travelled again from eight to ten 
miles without being able to quench our thirst, the heat 
reaching, at about three o’clock, 130° Fahr. in the sun. 
The long Indian file was broken long before, and when 
looking back we could see the weary rear guard in the dis- 
tance, and some of them were lost sight of altogether. 
We left Pirara with all the signs of joking and rejoicing, 
but in the same measure as the heat increased the joyous 
voices became silent. Wherever a crippled tree gave a little 
shade, we would see the Europeans and negroes hasten to it 
to take a rest. The Indians, on the contrary, would not 
permit themselves to show such weakness, and carried their 
heavy burdens without a complaint regarding the heat. ' 
Most vigorously they proceeded on the narrow paths, and 
when pressing questions were put to them how -far was it to 
the mouth of the Pirara Eiver, the aim of our day’s travel, 
they would reply, ^Wery far, very far,” certainly a poor 
consolation for anybody who was tired and parched with 
