BY ALEX. G. HAMILTON, 21 



the same jjlaut. I then captured the insect, and found it covered 

 with pollen of CandoUea, and I could not afterwards detect that 

 of any other plant under the \ inch power of the microscope. I 

 might remark that, as Sir John Lubbock states, bees almost always 

 keep to one species during a trip, but I am able to say that this is 

 not invariable. I have several times seen a bee visit a number 

 of different species of plants, and belonging to totally different 

 natural orders, one after another. 



In many flowers, the column had been sprung previous to the 

 bee's visit, and in getting into position to search the tube the 

 insect always rubbed its back against the gynsecium. If in any 

 of these the stigma was mature, it would result in fertilisation 

 just as certainly as if the column had struck the bee. Some 

 columns with the stigma mature I noted standing for a long time 

 without returning, and if an insect seeking nectar brushed against 

 them, fertilisation would ensue if there was pollen on its bank. 

 I should not be surprised to learn that an unfertilised column at 

 last lost its sensibility and stood in the sprung position to give 

 the flower a last chance of receiving pollen. But I was not able 

 to make any certain observation of the fact. 



It seems important that the insect should be of such a size that 

 the gynsecium should strike the upper surface of the abdomen or 

 the thorax, and this requirement is fulfilled by many native bees 

 and pollen-feeding flies. 



Observations and experiments revealed the following facts : — 

 The action is most vigorous on a warm diy day. On a cold day 

 many columns will not respond to a stimulus, and others do so 

 very slowly. Dr. Woolls remarks : — " This [the action of the 

 column] does not take place in moist weather."* I found, how- 

 ever, that most columns would respond to a stimulus on a warm 

 moist day, but on a cold day whether wet or dry, they remained 

 inactive. The column below the hinge, the anthers and the 

 stigma are not sensitive or do not transmit a stimulus, if gentle. 



* Lectures on the Vegetable Kingdom, p. 100. 



