MICROSCOPIC DRAWING AND ENGRAVING. 



63. That the itch is occasioned by such an insect is by no 

 means a modern doctrine. Kirby mentions a Moorish physician, 

 who, in the twelfth century, affirmed that the malady was pro- 

 duced by little mites or lice that creep under the skin of the 

 hands, legs, and feet, producing pustules full of matter ; he 

 quotes also " Joubert," another ancient physician, who describes 



Fig. 42. VILW Of THE ITCH INSECT, DRAWN WITH A CAMERA 

 BY DR. MANDL, MAGNIFIED 120 TIMES IN ITS LINEAR, AND 

 THEREFORE 14400 TIMES IN ITS SUPERFICIAL DIMENSIONS. 



the itch insects under the name of " sirones," and says they are 

 always concealed beneath the epidermis, under which they creep 

 like moles, gnawing it, and producing a most troublesome itching. 

 It was supposed by some that they were identical with lice ; but 

 Dr. Adams showed that this could not be the case, since they live 

 under the cuticle ; he speaks of them as living in burrows which 

 they have excavated in the skin, near a lake of water, from which 

 if they be extracted with a needle, and put upon the nail, they 

 show in the sun their red heads and the feet with which they 

 walk ; they have been extracted and delineated with the aid of 

 the microscope by many modern observers. The individual 

 delineated in fig. 42, was drawn by my friend Dr. Mandl, well 

 known for his great work on microscopic anatomy. 



