28 PHENOMENA OP VEGETATION. 



in proportion to their size, much more abundantly. The question, 

 Whence is this obtained 1 has been raised oftener than once. 



Dr Livingstone, in describing a severe and long-continued drough:| 

 at Kolobeng (the mission station occupied by him before he entered 

 on his journeyings in the interior), a drought during which " needles 

 lying out of doors for months did not rust, and a mixture of sulphuric 

 acid and water, used in a galvanic battery, parted with all its water to 

 the air instead of imbibing more from it, as it would have done in 

 England," says, — " The leaves of indigenous trees were all drooping, 

 soft and shrivelled, though not dead; and those of the Mimosse were 

 closed at mid-day, the same as they are at night. In the midst of 

 this dreary drought, it was wonderful to see those tiny creatures the 

 ants running about with their accustomed vivacity. I put the bulb 

 of a thermometer 3 inches under the soil in the sun at mid-day, and 

 found the mercury to stand at 132'^ and 134°; and if certain kinds 

 of beetles were placed on the surface they ran about a few seconds 

 and then expired ; but this boiling heat only augmented the activity 

 of the long-legged black ants." And having raised the question, 

 "Where do these ants get their moisture?" he proceeds, — "Our house 

 was built on a hard ferruginous conglomerate, in order to be out of 

 the way of the white ant, but they came in despite the precaution ; 

 and not only were they, in this sultry weather, able individually to 

 moisten soil to the consistency of matter for the formation of galleries, 

 which in their way of working is done by night (so that they are 

 screened from the observation of birds by day in passing and repassing 

 towards any vegetable matter they may wish to devour), but when 

 their inner chambers were laid open these were also surprisingly 

 humid ; yet there was no dew, and the house being placed on a rock 

 they could have no subterranean passage to the bed of the river, 

 which ran about 300 yards below the brow of the hill. Can it be 

 that they have the power of combining the oxygen and hydrogen of 

 their vegetable food by vital force so as to form water f 



A still more remarkable case is mentioned by Dr Livingstone. 

 Writing from Golungo Alto Angola, on the west coast, lat. 91° S., he 

 says, — " Before leaving I had an opportunity of observing a curious 

 insect which inhabits trees of the fig family (Ficusj, upwards of 

 twenty species of which are found here. Seven or eight of them 

 cluster round a spot on one of the smaller branches and there keep 

 up a constant distillation of a clear fluid, which, dropping to the 

 ground, forms a little puddle below. If a vessel is placed under 

 them in the evening it contains three or four pints of fluid in the 



