84 DIRECT INJURIES CAUSED BY INSECTS. 



is to prevent or revenge an injury which they either 

 fear, or have received from us ; and those which indeed 

 offer us no violencej but yet incommode us extremely 

 in other ways. 



I hope 1 shall not too much offend your delicacy if I 

 begin the first class of our insect assailants with a very 

 disgusting genus, which Providence seems to have 

 created to punish inattention to personal cleanliness. 

 But though this pest of man must not be wholly passad 

 over, yet, since it is unfortunately too well known, it 

 will not be at all necessary for me to enlarge upon its 

 history. I shall only mention one fact which shows the 

 astonishingly rapid increase of these animals, where 

 they have once gotten possession. It is a vulgar no- 

 tion, that a louse in twenty-four hours may see two 

 generations; but this is rather overshooting the mark. 

 Leeuwenhoek, whose love for science overcame the 

 nausea that such creatures are apt to excite, proves 

 that their nits or eggs are not hatched till the eighth 

 day after they are laid, and that they do not themselves 

 commence laying before they are a month old. He as- 

 certained, however, that a single female louse may, in 

 eight weeks, Avitness the birth of five thousand descen- 

 dants'^. You remember how wolves were extirpated 

 from this country, but perhaps never suspected any 

 monarch of imposing a tribute o( lice upon his subjects. 

 Yet we are gravely told that in Mexico and Peru such 

 apoll-taxwas exacted, and that bags full of these trea- 

 sures were found in the palace of Montezuma ^ ! ! ! 



' Lceuw. Epint. 98, 1696. 



•• Biiigley, ylnim, Bhgr. first edition, iii. 437. St. Pierre's Studies, 

 &c. i. 312. 



