150 On the Caterpillar which 



Caterpillar. The hair attaches itself to the hands, face, 

 and eye- lids, and causes an itching very troublesome and 

 burning, continuing sometimes during four or five days, 

 particularly on the part pained being rubbed. Often 

 the skin rises into blisters," &c. 



So far as relates to the fact, it is wholly unimportant 

 whether the injurious properties of the reptile operate 

 mechanically, disorganizing the body, or by way of an 

 inscrutable subtil venom. The difference of the philo- 

 sophy of the fact cannot effect its reality. How do the 

 properties of the Spanish fly act ; mechanically or che- 

 mically ? From what, upon the sting of a bee or wasp, 

 do the pain and tumefaction arise ? To these we may- 

 add mustard, &x. Do these produce their separate in- 

 juries mechanically ? Their properties are explained 

 best by their effects. They are hostile and poisonous 

 to the living principle. Nor would I take upon myself 

 to decide whether, by a peculiar power of stimulation, 

 they change the healthy excitability of the animal sys- 

 tem, or by inscrutable chemical affinities mix with the 

 fluids, and thus indirectly break up the structure thereof. 

 I leave this to those gentlemen who are fond of unravel- 

 ling clues of hypotheses, loose at both ends. It is of no 

 moment, in the present business, what path we take, so 

 we arrive in safety at our journey's end. We are in 

 search of facts, not their peculiar philosophy. 



Dr. Hawkesu'orth tells us, that, in the voyages in the 

 tropical latitudes, they discovered a species of Caterpillar, 

 which, " when the men touched them, they found that 



