342 Raymond Pearl 



relation of each to the general problem. Statements and discus- 

 sions of the subsidiary problems connected with each of the topics 

 in the outline will be given in connection with the detailed treat- 

 ment of those topics. 



In attacking this problem we are bound to no exclusive method 

 of investigation. The observational, experimental and statistical 

 methods will be used as they appear to be demanded by the exi- 

 gencies of the case. The writer's standpoint is that the problem 

 is one in general physiology, involving questions having to do both 

 with individual and with racial physiology. On a certain 

 number of the points covered in the outline work has been com- 

 pleted and will be published as soon as possible. On other 

 phases of the problem the work is well advanced though not ready 

 for publication. 



The present paper deals with a definite and circumscribed 

 topic falling under IB4 and IC of the outline. It is well known by 

 poultrymen that the first eggs laid by a pullet often differ from 

 the normal eggs and from eggs laid later by the same bird in regard 

 to both size and shape. This implies a process of regulation in 

 the continued activity of the oviduct in shaping successively laid 

 eggs. The present paper deals with the detailed analysis of a 

 clear-cut and unusually pronounced case of such regulatory ac- 

 tivity of the oviduct. 



THE MORPHOGENETIC ACTIVITY OF THE OVIDUCT 



A bird's egg is an object of very characteristic shape. While 

 the form of the egg varies in different species, and also within the 

 single species, all such variation is comprised between relatively 

 narrow limits. The conformation to type in the case of eggs from 

 birds of a single species is in most cases quite close. It is usually 

 still closer in a series of eggs laid by the same bird, as in the case 

 of any of the domesticated fowls. The production of a series of 

 definitely and characteristically formed bodies all conforming closely 

 to a type by an organism implies that the organs concerned in this 

 production have a morphogenetic function along with others. 



It is a well established fact that the shape of the egg of any 



