114 ESSAYS OF A BIOLOGIST 



and betake themselves to their fishing or resting or 

 preening again. This is the commonest bit of love- 

 making J but now and then the excitement evident 

 even in these somewhat casual ceremonies is raised 

 to greater heights and seems to reinforce itself. The 

 little bouts of shaking are repeated again and again. 

 I have seen over eighty succeed each other uninterrupt- 

 edly. And at the close the birds do not relapse into 

 ordinary life. Instead, they raise their ruffs still 

 further, making them almost Elizabethan in shape. 

 Then one bird dives ; then the other : the seconds 

 pass. At last, after perhaps half or three-quarters of 

 a minute (half a minute is a long time when one is 

 thus waiting for a bird's reappearance !) one after 

 the other they emerge. Both hold masses of dark 

 brownish-green weed, torn from the bottom of the 

 pond, in their beaks, and carry their heads down and 

 back on their shoulders, so that either can scarcely 

 see anything of the other confronting it save the 

 concentric colours of the raised ruff. In this position 

 they swim together. It is interesting to see the eager 

 looks of the first-emerged, and its immediate start 

 towards the second when it too reappears. They 

 approach, rapidly, until the watcher wonders what 

 will be done to avert a collision. The answer is 

 simple : there is no averting of a collision ! But 

 the collision is executed in a remarkable way : the 

 two birds, when close to each other, leap up from the 

 water and meet breast to breast,almost vertical, suddenly 



