112 ESSAYS OF A BIOLOGIST 



and after a short excited space they settle down close 

 together. This type of greeting is repeated every day 

 until the young leave the nest ; for after the eggs are 

 laid both sexes brood, and there is a nest-relief four 

 times in every twenty-four hours. Each time the 

 same attitudes, the same cries, the same excitement ; 

 only now at the end of it all, one steps off the nest, 

 the other on. One might suppose that this closed 

 the performance. But no : the bird that has been 

 relieved is still apparently animated by stores of un- 

 expended emotion ; it searches about for a twig, 

 breaks it off or picks it up, and returns with it in beak 

 to present to the other. During the presentation the 

 greeting ceremony is again gone through ; after each 

 relief the whole business of presentation and greeting 

 may be repeated two, or four, or up even to ten or 

 eleven times before the free bird flies away. 



When there are numerous repetitions of the cere- 

 mony, it is extremely interesting to watch the pro- 

 gressive extinction of excitement. During the last 

 one or two presentations the twig-bringing bird may 

 scarcely raise his wings or plumes, and will often 

 betray an absent air, turning his head in the direction 

 in which he is proposing to fly off. 



No one who had seen a pair of Egrets thus change 

 places on the nest, bodies bowed forward, plumes a 

 cloudy fan of lace, absolute whiteness of plumage 

 relieved by gold of eye and lore and black of bill, and 

 the whole scene animated by the repeated, excited cry. 



