ORDER THYSANURA 255 



ing as detrimental to health, and with certain related orders 

 that may be classed as inert ; but we have still to notice 

 several orders that include species, outside any of the foregoing 

 orders, which, in any or every active stage of their existence, 

 are predaceous upon other kinds of insects. 



No doubt predaceous insects deal impartial damage to 

 friend and foe, and the view, sometimes strongly advocated, 

 that they are all tried friends, to be grappled to the medical 

 officer's soul with hooks of steel, is somewhat optimistic. 



