OBSERVATIONS ON INSECT LIFE 171 



I made a few experiments to test the special senses 

 of the Notonectidce. I think that they appreciate the 

 events in their own little world almost solely through 

 the organs of sight and touch. It is obvious that they 

 possess the power of vision. One has only to look 

 at their large eyes and observe the manner in which 

 they dart under the water at one's approach to a pool 

 to be satisfied that their sense of sight is acute. They 

 do not appear to be fastidious in their taste. I drop 

 some evil-smelling Heteroptera and other nauseous 

 insects into the pool ; the boatmen dart out and 

 eagerly devour them. I throw some bitter alkaloids 

 into the water, but the boatmen take no notice. I 

 place some boatmen in a basin of water and let fall 

 close to them a few drops of a solution of quinine ; 

 the boatmen remain unaffected ; the quinine no more 

 disturbs them than the fall of drops of water. I throw 

 them some insects injected with quinine ; the bitter 

 morsels are eagerly devoured. I give to one a frag- 

 ment of a strychnine tablet ; it is seized and carried 

 down beneath the water as though it was an 

 appetizing prey. I cannot, therefore, think that the 

 Notonectidce possess much sense of taste. I doubt if 

 their power of smell is any more acute. They 

 certainly did not behave like ants and spiders and 

 recoil from the presence of camphor, but, rather, 

 dealt with it in the same way as they treated the 

 strychnine. Nor does their sense of hearing enlarge 

 much further their prospect on life, for, if care be 

 taken that the experimenter is not seen by them, he 

 may shout, clap hands or blow shrill whistles without 

 alarming them in the slightest. It is, I believe, 

 through the sense of touch that they "live and move 



