20 SCIENTIFIC ILLUSTRATIONS [Aud 



and the two faces are pressed and turned against each other 

 until they are in the closest contact, they adhere so strongly as 

 to require a force of more that 100 grammes to separate them. 

 The same experiment may be made with two equal pieces of 

 glass, which are polished and made perfectly plane. When 

 they are pressed one against the other, the adhesion is so 

 powerful that they cannot be separated without breaking. As 

 the experiment succeeds in vacuo it cannot be due to atmo- 

 spheric pressure, but must be attributed to a reciprocal attraction 

 between the two surfaces. The attraction also increases as the 

 contact is prolonged, and is greater in proportion as the contact 

 is close. So with true friendship. EL. 



The Attractive may be Perilous. 



Of the poisonous plants of South America, an interesting one 

 is the manchineal (Hippomam mancenilla). This tree thrives 

 best, it is said, on the sea-shore. It bears a profusion of very pretty 

 fruit, resembling in form and colour the red apple (the Spanish 

 Manzanilla), and exhaling an agreeable lemon-like odour. They 

 are, therefore, scarcely less beguiling than Dead-Sea fruits ; but 

 they are also very poisonous, yet less deadly than the milky 

 juice which flows from the slightest incision made in the tree's 

 thick and greyish bark. This juice, received into the stomach, 

 or introduced into the blood through a wound, slays the victim 

 with awful quickness. If it do but touch the skin, it excites 

 a violent irritation, and raises swellings or boils of the worst 

 description. The very vapour which it emits causes a painful 

 itching in the eyes, the lips, and the nostrils. It was formerly 

 asserted that to sleep under the shade of a manchineal tree was 

 certain death, but the naturalist Jacquin, in the interests of 

 science, courageously made the experiment and proved the 

 falsity of the story. D. 



Audacity and Ingratitude as Natural Characteristics. 



The cuckoo is a perfect type of a creature endowed by 

 nature with audacity and ingratitude as its prominent character- 



