456 THE MICROSCOPE. 



fied 350 diameters). Dr. Bononio made out the true 

 character of the very troublesome disease known as the 

 itch. Upon examining one of the pustules, or little 

 bladders, from between the fingers, with the points of very 

 fine needles, under the microscope, he discovered a most 

 minute animal, very nimble in its motion, covered with 

 short hairs, having a formidable head with a pair of strong 

 mandibles or cutting jaws, and eight legs, from the ex- 

 tremities of which are appended remarkable feet, each 

 provided with a sucker ; by means of which it no doubt 

 sucks or draws its way beneath the skin, having first cut 

 out a small section with its mandibles; here the pest 

 forms a nest, lays its eggs, multiplying rapidly, and is 

 most difficult to dislodge. 



To find the itch-insect, the operator must examine care- 

 fully the parts surrounding each pustule, he will then see 

 a red line or spot communicating with it ; this part, and 

 not tjhe pustule, must be probed with a fine-pointed instru- 

 ment ; the operator must not be disappointed by repeated 

 failures. As it is most difficult to detect the haunts of the 

 insect, an eye-magnifier should be made use of to assist. 



Dr. Bourguignon bestowed much time in studying 

 the habits of this troublesome parasite. To arrive at 

 a knowledge of its habits the Doctor had recourse to a 

 peculiar kind of moveable microscope, which enabled him 

 to observe it under the skin of the diseased person. The 

 microscope is composed of the frame of an ordinary in- 

 strument, the optical and essential parts of which have 

 been raised from the socket that supported it, and articu- 

 lated to a moveable knee at the extremity of a lever. The 

 rays of light from a lamp or candle are brought to a 

 brilliant focus by means of the condensing or bull's-eye 

 lens ; which focus is directed upon the chosen point of 

 observation. Warington's microscope answers the pur- 

 pose equally well. 



He then saw that the feet are armed with suckers, 

 which enable it to fasten itself in the furrows under the 

 skin, aided by its small bristles ; being likewise covered 

 by these bristles in various parts of the body, it more 

 firmly fixes itself there, and with its terrible mandibles 

 accomplishes its destructive mission. It has no eyes; but 



