198 INSECTS. 



various architectural contrivances ; such as the use in one 

 case of beams in the construction of a ceiling, while in 

 another a large chamber will be strongly roofed without 

 beams or central support, by the application of the arch. 



The nests here spoken of are constructed in the earth, 

 those of some species are excavated in the trunks of old 

 trees. Their internal temperature is high, the Ants, like 

 the Bees, having the power of generating a considerable 

 degree of heat. They are strongly redolent of a secretion 

 peculiar to the Ants, formerly called " formic acid," and 

 which is nearly powerful enough to take away the breath 

 if the head be held over a large and disturbed nest. This 

 acid the Ants have the power of squirting to a consider- 

 able distance, and it forms a considerable weapon in their 

 warfare. The whole of the inside of nests hollowed out 

 in the trunks of trees is stained black by this acid, while 

 Ray records that blue flowers placed in an ant-hill turn 

 red, and that a similar effect is produced in a Bluebottle 

 by the sting of an Ant. 



It is probably for the sake of this acid that the insect 

 is used by the New Zealanders in the composition of the 

 wourali poison. 



In Switzerland Ants are used crushed into a plaster 

 or poultice to be applied to the head to cure the head- 

 ache, while their stimulating property is well known to 

 Swiss schoolgirls, who rub their foreheads with the 

 insects " pour se fortifier la memoire." Ants give out 

 the acid so freely that in the same country the children 

 lay a wet branch across the nest of the large Wood Ant, 

 and when it is well covered with the insects, brush them 

 off and suck from it the "hot vinegar." 



The principal use, however, made of these insects, 

 both in Switzerland and Germany, is in the composition 



