OF THE HUMAN BODY. 97 



the threads of its cocoon with its saliva, and thus 

 dissolves them. It copulates, lays eggs, and dies. 

 Many of the chrysalides in the cocoons were de- 

 stroyed by white, worm-like, hairless parasites. 



The inhabitants of Westphalia, in Germany, are 

 well acquainted with the important and dangerous 

 diseases and sufferings which are caused by these 

 caterpillars, both in men and animals. It is very 

 doubtful whether the noxious substance which acts 

 like a poison, creating redness, itching, and burn- 

 ing of the external and inflammation of the inter- 

 nal parts, and causing even death, consists of the 

 long hairs of the caterpillar. According to some 

 writers, the nest or cocoon is to be looked upon as 

 the cause of these disorders ; whilst others say 

 that they are caused by an acrid noxious juice 

 which the caterpillar is thought to secrete when it 

 creeps over the surface of the skin. Nicolai con- 

 vinced himself of the impossibility of the latter 

 cause, for he observed itching pustules on his fore- 

 arms, which were covered with clothing, though 

 the caterpillar had never come near them. On one 

 occasion, when attempting to attach to a board a 

 large caterpillar by means of pins, and for this 

 purpose piercing its black back shield, he saw on 



