OP THE HUMAN BODY. 99 



similar effects. The microscope shows the dust 

 to consist of very fine, straight, spiry, minute hairs, 

 beset with barbs. They are exceedingly light, 

 swim on water, and are sometimes carried away 

 by the wind, flying about for some time in the 

 forest. The dust is carried on to objects and into 

 the air by the creeping of the caterpillar on a damp 

 place, by touching it, by moving through the air, 

 and by the falling of drops of rain on the bark. 

 This dust seems , however, only to be formed after the 

 second and last casting of the skin of the caterpillar. 

 In places where the caterpillar is of frequent 

 occurrence, the animals which come into the 

 forests are attacked by various diseases : sheep, 

 by inflammation of the eyes and violent coughing ; 

 cows and goats, by the same symptoms, with in- 

 ternal inflammations and ulcers all over the skin, 

 the violent itching of which, makes the animals 

 restless, and drives them almost to madness ; 

 horses more especially suffer from it. The dis- 

 eases of the eye caused by it are : Blenorrhoea of 

 the conjunctiva, dimness of vision, and perforation 

 of the eye. People become exposed to this poison 

 by staying in a forest, by sleeping, working, or 

 taking a ride, playing, cutting down wood even in 



