BOOK-LOUSE AND SILVER-FISH INSECT 315 



silvery appearance is due to vast numbers of minute 

 scales with which the body is covered, and which are 

 well known to micro- 

 scopists as test objects, 

 closely allied to the 

 celebrated Podura 

 scales. The insect is 

 about one-third of an 

 inch long, and is not 

 unfrequently found in 

 houses, though appa- 

 rently less commonly 

 now than formerly. 



The earliest notice 

 of this little creature 

 is to be found in a 

 curious book, entitled 

 " Micrographia," pub- 

 lished by R. Hooke in 

 1665, at the instance 

 of the Royal Society, 

 to detail some of the 

 first observations made 

 in this country by 

 means of the micro- 

 scope. In this book, 

 which represents a 

 good deal of careful 



work, the insect is Fia Io6 ._The Silver-fish Insect (Lepisma 



called the "Small 



Silver-coloured Book-worm," and, after the manner of the 

 times, an enormously magnified figure is given, executed 

 with great care, and sufficiently accurate to be easily 

 recognisable. Hooke's notice of the insect is introduced 



