THE FEETILIZATION AND EAKLY DEVELOPMENT OP THE 



PIGEON'S EGG. 



BY 



EUGENE HOWARD HARPER, Ph. D. 

 With 4 Double Piates and 6 Diaqeams in the Text. 



TABLE OF CONTENTS. 

 Introduction. 

 Methods. 



Some observations on the breeding habits of the common pigeon. 

 The fertilization of the egg and its passage through the oviduct. 

 Some late stages of the ovarian egg. 



Nucleoli in the ovarian egg. 

 The fertilized egg: 



Maturation divisions. 



Fertilization stages. 



Early cleavage stages. 

 Development of the accessory nuclei (diagrams 1-6). 

 The yolk nuclei of later cleavage stages. 

 Polyspermy in other eggs. 

 Some features of mitosis in the pigeon's egg. 

 Conclusions. 

 Bibliography. 

 Description of plates. 

 Plates. 



The investigation, the results of which are here described, was pro- 

 posed to me by Dr. C. 0. Whitman, and the work has been carried on 

 tinder his direction, being designed as part of a more general work 

 upon the Natural History of Pigeons. My thanks are due to Prof. 

 Whitman for his encouragement and suggestions and his assistance in 

 obtaining the material. 



In this paper the aim has been to get a view of that period of develop- 

 ment of the bird's egg which has hitherto been scarcely touched upon, 

 including the maturation, fertilization and early cleavage. Material was 

 obtained from only one species, the common pigeon, Columba livia 

 domestica. On account of the prolonged breeding season of pigeons 

 and the ease with which they may be kept in confinement, they are 



