14 SCIENTIFIC ILLUSTRATIONS [App 



annoyances. Men are no more exempt from this law than 

 sheep. Even the most harmless among them has to endure 

 his gad-fly. To one it comes in the form of unaccountable 

 disease, to another in the form of systematic bad fortune, to 

 another in the form of insolent children, to another in the 

 shape of a Zantippe-like wife ; but in some way or other every 

 man has to endure his allotted annoyance. There is not a man 

 who has not his gad-fly. I. 



A Needed Antidote Supplied by Nature. 



The Quinquinas (Genus Cinchona; family Ruliacece) are 

 medical plants, than which none are more precious. They grow 

 along the eastern slope of the Andean Cordilleras in the republics 

 of Venezuela, New Granada, Ecuador, Peru, and Bolivia. The 

 bark is the most effective of all febrifuges, and is endowed with 

 very valuable tonic and depuratory properties. Sir Samuel 

 Baker, in an address to the British Association at Dundee, pro- 

 nounced it the traveller's best friend, the powerful weapon with 

 which he could securely enter the African wilderness, and suc- 

 cessfully contend against its demon-host of fevers and agues. 

 And as if by a kind of compensation, the tropical forests, which 

 contain so many poisonous fruits, produce such trees as these. 



D. 



Appearance at Variance with Character. 



The Medusae are amongst the most beautiful creatures in 

 nature, and appear absolutely harmless. Wonderfully beauti- 

 ful as are their form and colour, the amount of solid matter 

 contained in their tissues is incredibly small. The greater part 

 of their substance appears to consist of a fluid differing little, if 

 at all, from the sea-water in which the animal swims ; and when 

 this is drained away, so extreme is the tenuity of the mem- 

 branes which contained it, that the dried residue of a "jelly 

 fish," weighing two pounds, which was examined by Professor 

 Owen, weighed only thirty grains ! Yet these creatures are 

 capable of executing movements with considerable vivacity; 

 their disc contracts and dilates alternately by the action of a 

 band of what must be regarded as a muscular tissue; their 



