86 SCIENTIFIC ILLUSTRATIONS [Dev 



lighted match flung carelessly away, or the ashes dropped from 

 a hunter's pipe, will kindle the most awful conflagrations, and 

 the flames will spread devouringly over leagues of open ground, 

 consuming trees and shrubs, and burning to death the cattle or 

 wild animals which haply fall within their range. With the 

 crackling, hissing, seething noises of the fire mingle the groans 

 of the perishing beasts, while huge clouds of smoke roll before 

 the wind like the billows of a wind-swept ocean, and live 

 tongues of flame ever and anon light up the terrible scene with 

 lurid splendour. These " prairie fires " are sometimes kindled 

 in revenge by the Indians, and occasionally the settlers resort to 

 this dangerous but summary method of clearing the encumbered 

 ground. D. 



Proper Development Dependent on Proper 

 Conditions. 



Plants as well as animals, nurtured and grown in perfect 

 darkness, never acquire their natural colour. The former become 

 white instead of green. This fact is observed in the etiolation 

 or blanching, as it is termed, of certain kinds of vegetables, such 

 as celery, seakale, endive, etc. Their leaves, deprived of the 

 sun's rays, do not attain their normal growth or form, neither is 

 the natural odour of such plants fully developed. Professor 

 Robinson, descending into a coal mine, accidentally met with a 

 plant growing luxuriantly. Its form and qualities were new to 

 him. The sod on which it grew was removed, potted, and care- 

 fully attended to in his garden. The etiolated plant languished 

 and died, but the roots speedily threw out vigorous shoots which, 

 from the form of the leaves and their peculiar odour, he readily 

 recognised as tansey. He repeated similar experiments upon 

 other plants, viz., lovage, carvi, and mint, with analogous results. 

 The biography of mankind affords innumerable examples illus- 

 trative of this same principle, that the proper development of 

 every kind of life is dependent on proper conditions. It is not 

 thereby necessarily implied that man is the slave of his circum- 

 stances, because, unlike the lower creation, he possesses within 

 certain limits power to bring himself under the influence of the 

 conditions favourable to the proper development of his intellect 



