580 F. C. F. Jourdain 



OX COLOUE VARIATION IN THE EGGS OF 

 PAL.EARCTIC BIRDS. 



BY THE 



Rev. F. C. R. Jourdain, M.A., M.B.O.U. 



Until some thirty years ago very little attention was paid to 

 the nature and composition of the pigments from which 

 birds' eggs derive their varied and beautiful hues. Various 

 suggestions, more or less probable, were made by Leuckart, 

 Wilke, Leconte, Blasius, and others, some ascribing the red 

 colour to secretions of the blood, while others held that both 

 red and green were due to bile pigments. 1 In 1875 Mr. 

 H. C. Sorby published the results of his investigations by 

 means of spectrum analysis in the " Proceedings of the 

 Zoological Society," 1875, p. 351. Here, for the first time, 

 the matter was placed upon a scientific basis, and though 

 some of Mr. Sorby' s conclusions have not been borne out by 

 subsequent observations, he deserves all credit for being the 

 first to open out a new field of research. Roughly speaking*, 

 his method of study was as follows : The earthy carbonates 

 were first dissolved out by weak hydrochloric acid, the 

 membranous matter was then removed by nitration, and the 

 residue dissolved in absolute alcohol, or alcohol containing 

 free acetic or hydrochloric acid. From the study of the 

 spectra of these solutions, Sorby inferred that seven well- 

 marked substances were present in the colouring matter of 

 eggs. These he called Oorhodeine, Oocyan, Banded Oocyan, 

 Yellow Ooxanthhie, Rufous Ooxanthhie — a sixth substance 

 imperfectly distinguished — and Lichnoxanthhie. 



The later investigations of Liebermann and C. F. W. 

 Krukenberg have, however, somewhat modified this list, 2 

 Oocyan and Banded Oocyan have been identified with 

 Biliverdin (C l6 H l8 N 2 ) : Yellow Ooxanthine of Sorby is 



1 Cf. Leuckart, " Handwörterbuch cl. Physiologie," Vol. IV., p. 894; Wilke, 

 " Xaumannia," 1858, p. 393 ; C. Leconte, " Rev. et Mag. de Zoologie," 1860, 

 p. 199 ; Blasius, " Zeitsckr. für wiss. Zoologie," XVII., p. 480, etc. 



" " Die Farbstoffe der Vogeleiersclialen," Verliandl. d. pliys. — med. Gresellsch. 

 zu Wurzburg, XF., XVII., Bd., Nr. S. 



