INTEODUCTION. t 



The foregoing remarks, it is feared, will be criticised 

 as having too much of a desultory character, and the 

 author perchance has, through misapprehension, laid 

 himself open to censure in the words of our illustrious 

 countryman, "William Harvey, so happily quoted the 

 other day by Professor Clark Maxwell : — " Whoever 

 they be that read authors and do not by the aid of 

 their own senses abstract true representations of the 

 things themselves, they do not represent true ideas, 

 but deceitful idols and phantasms by which means they 

 frame to themselves certain shadows and chimeras, 

 and all their theory and contemplation (which they 

 call science) represent nothing but waking men's 

 dreams and sick men's phrenzies." 



Now-a-days, when the multiplication of books is one 

 of the marvels of the age, we run some risk of an 

 intellectual indigestion and repletion, through the 

 neglect of such mental athletics as are afforded by 

 healthy experimental exercises, and appeals to, and 

 wrestles with nature for her momentous secrets. 



In conclusion, I wish to express my obligations to 

 those friends who have given me their aid by procuring 

 living specimens for my examination. Particularly I 

 would name Sir Sidney S. Saunders, who not only lent 

 me specimens from his own cabinet, but kindly perused 

 my manuscript notes on the predacious Hymenoptera. 

 I also thank cordially M. Jules Lichtenstein, of Mont- 

 pellier, for providing me with several hitherto unde- 

 scribed sexual forms of Aphides common to both Great 

 Britain and the South of France, and also I thank him 

 for much interesting matter conveyed to me in his 

 correspondence. 



