ARDEIDAE. 



and Forestry School at Wageningen, very kindly undertook to che- 

 mically analyze them, for which 1 hereby once more express my 

 cordial thanks to him. 



The results of this analysis showed that the said spots on cinerea- 

 and purpiirea-cggs are composed of a very small quantity of cal- 

 cium carbonate, mainly however of uric acid mingled with sodium 

 urate and probably also with ammonium urate; that, therefore, they 

 are analogous in composition to the white constituents of bird- 

 excrements. 



If, on the egg leaving the uterus, uratic compounds are passed 

 in consequence of pressure on the rectum, or if in the somewhat 

 bellmouthed rim of the cloaco and perhaps also on the feathers 

 round the anal opening faeces or rests thereof remain, the surface 

 of the shell is more or less besmeared with it. 



About the possible occurrence of pigment spots in Ardea-species, 

 among others. Dr. E. Rey wrote to me as follows (in a letter of April 

 22, 1908): — 



„Bei den Ardea-Arten ist mir bisher eine wirkliche Pigmentierung 

 „noch nicht vorgekommen, obgleich mir viele Tausende durch die 

 „Hande gegangen sind. Unmoglich ist es aber natiirlich nicht, dass 

 „auch einmal bei Ardea (oder Botaurus) gefleckte Eier vorkommen 

 ,konnen, da ja doch Plataleo gefleckte Eier legt. Was ich von 

 ,Flecken bei Reihereiern bisher sah waren Blutflecken, die wie 

 „Rostflecke aussahen und nie gleichmassig vertheilt auftraten, son- 

 „dern an irgend einer Stelle eine kleinere oder grossere Gruppe 

 ,bildeten". 



ARDEA CINEREA L. 



NozEMAN, who describes these eggs as being marked with a few 



