No. 5.] STRUCTURE IN AN ABNORMAL PIGEON. 223. 



means implausible. The subject is at least deserving of very 

 careful consideration. 



The principal facts adduced in this paper are briefly as 

 follows : 



(1) A dove, the offspring of a Vienna white {Cohnnba alba) 

 and a common ringdove {Titrtiir risorius), remarkable for her 

 unusual appearance and manner, was found, upon dissection, to 

 have an abnormal ovary ; 



(2) The ovary contained many double eggs, that is, two or 

 more eggs lay within one follicle; they might or might not be 

 separated by a distinct membrane ; 



(3) Nearly all of the larger eggs were vacuolated ; 



(4) The vacuoles always appeared in connection with the 

 substance of the attraction sphere ; 



(5) The membrane separating double eggs also seemed to 

 be related in some way to the sphere ; 



(6) The nuclei, especially of the larger eggs, were generally 

 shrunken and seemed to be degenerating ; 



(7) Nucleoli were frequently present, but in many cases 

 were indistinct and irregular in outline; 



(8) Centrosomes were frequently present, but mitotic divi- 

 sion of the eggs was never observed ; 



(9) Many of the eggs, especially the larger ones, were under- 

 going resorption by means of phagocytes, which in the vast 

 majority of cases, if not all, were transformed follicle cells ; 



(10) Instances were found where the follicle cells had dis- 

 appeared along part of the periphery of the egg, leaving behind 

 a deposit of pigment. In such cases one side of the ^gg was 

 usually undergoing dissolution through the activity of the 

 phagocytes ; 



(11) The doubling of eggs seemed to be due in most of the 

 smaller eggs to {a) a division of the primordial cell, and in the 

 larger ones to {b) a fusion of contiguous cells ; 



(12) The cause of such abnormalities is not known. Possibly 

 some connection with hybridization may be shown later. 



Hull Zoological Laboratory, 

 March 10, 1899. 



