374 POLLEN. 



pollen ; and that whatever flowers they first alighted 

 upon decided their choice for that excursion, all 

 other species being passed over unregarded : 

 BUTLER had previously asserted the same thing. 

 Here we see the operation of a discriminating in- 

 stinct, which in the first place leads the insect to 

 make an aggregation of homogeneous particles, 

 which of course form the closest cohesion ; and in 

 the next place prevents the multiplication of 

 hybrid plants. This remark was made by SPREN- 

 GEL, who has confirmed the observations of Dobbs, 

 Butler, and others. The bees, which Reaumur 

 observed to visit flowers of different species, 

 might have been in quest of honey as well as of 

 pollen. 



