270 GEORGE W. BARTELMEZ 



I. INTRODUCTION 



Whitman in his paper on the development of Clepsine (78), 

 gave the first .full and connected account of egg organization ; 

 since then much evidence has accumulated to show that many 

 eggs are highly organized before cleavage begins and there are 

 cases in which the origin of this organization has been traced 

 back into the ovarian history of the egg. Thus it is well known 

 that the axis of bilaterality, one of the most fundamental mani- 

 festations of organization, appears, in the insect, while the egg is 

 still in the ovary and there is some evidence that the ovarian egg 

 in at least two primitive vertebrates has a bilateral structure. 

 These facts make the relations between the egg and the embryonic 

 axis of certain reptiles and birds verj^ suggestive. The work of 

 Kolliker ('76), Duval ('84) and others established the existence, 

 in the hen's egg, of a fairly definite relation between the embry- 

 onic and chalazal axes and similar conditions were found in the 

 pigeon's egg by Patterson ('09). This relation cannot have 

 arisen after the chalazae have been laid down in the oviduct; 

 I have met with only two considerations of the significance of 

 this fact, one in a paper written in 1893 which was found among 

 Professor Whitman's unpublished manuscripts, the other is in 

 Lillie's book on the chick ('08). It has been found that in the 

 pigeon the position of the chalazae is determined before cleavage 

 begins and it follow\s accordingly that the pigeon egg is bilaterally 

 organized shortl}^ after fertilization. Evidence will here be pre- 

 sented to show that the antero-posterior axis of the pigeon not 

 only appears clearly at the time of fertilization but may also be 

 traced back into the ovarian history at least as far as the youngest 

 oocytes found in the adult ovary. 



I am indebted to Professor Whitman for the opportunity of 

 working on this material and for many of the birds that were used. 

 It is difficult for a student of his to express the appreciation he 

 feels of the piivilege of working under Professor Whitman. His 

 clear insight into fundamentals, his keen criticism and high ideals, 

 his whole personality made every conference with him an inspir- 

 ation. It is a pleasure also, to express my obligations to Prof. F. 



