THE FOOD OF THE SILVER-FISH. 



175 



about a dead individual while I was engaged in placing bait at night. 

 This, of course, suggested an animal bait, and at the same time a 

 suspicion entered my mind that the injury to the binding of books 

 with which they are charged might be the result of eating glue instead 

 of starch. They were then tried with bits of white glue, which they 

 ate readily, alone and also when dusted with Paris green. 



In the light of this observation, statements in some of the earlier 

 accounts of the insect are suggestive of a fondness for animal food. 

 The surface of calendered paper is said sometimes to have been 

 abraded by the jaws of silver-fish. Sizings used on such papers con- 

 tain animal matter (leather), and it seems very probable that it was 



Fig. 10. — Photographic print injured by silver-fish (Lepisma saccharina) . (Original.) 



the sizing alone and not the fiber--which could not furnish nutri- 

 ment anyway — that they were after. Mr. P. R. Uhler, of the Pea- 

 body Library, of Baltimore, is said to have observed that the gnawings 

 of silver-fish cause the white labels on the backs of books to become 

 detached. Here plainly the glue used to stick the labels to the books 

 is the attraction. Again, gilt lettering has been observed to be 

 removed from the backs of books. In this case the insect might be 

 attracted either by sizing used in securing the gold leaf to the books 

 or by that used on the binding. It happens that we have in the 

 Kentucky experiment station library some volumes that were at 



