Physiology of Reproduction in Domestic Fowl 347 



in Ceratophyllum." It was expressed in this way (p. 125): "If 

 we let y stand for number of leaves in the whorl and x denote 

 the position in the series of successively formed whorls, then we 

 find that y'\s 2. simple logarithmic function of ^ as follows: 



y = A + C log {x — a) 



where y^, C, and a are constants. " 



In connection with this work on Ceratophyllum it was pointed 

 out that a logarithmic change in growth and development was 

 probably very general for different organisms and different char- 

 acters. Subsequent studies have served to strengthen this con- 

 viction. It is the purpose of this paper to present the results 

 of an investigation of a case of "physiological morphogenesis" 

 which shows in the successive production of a series of "like" 

 structures (eggs) a progressive change from a very abnormal prod- 

 uct to a normal one (i.e., a regulatory change sensu strictu)^ this 

 change following a logarithmic law. 



DESCRIPTION OF CASE 



On January 30, 1908, a barred plymouth rock pullet in the 

 poultry house at the Maine Experiment Station laid her first egg. 

 This egg, because of its strikingly abnormal shape, attracted the 

 attention of the poultryman who brought it to the notice of the 

 writer. The specimen was so remarkable, especially when the 

 fact that it was the first egg ever laid by this bird was taken into 

 consideration, that arrangements were made to have every egg 

 which she laid saved and dated as they were laid. The character 

 of this first egg is indicated in Fig. I of Plate I. It will be seen that 

 the egg was strikingly long and narrow and furthermore misshapen 

 in respect to being concave along the sides which are usually 

 convex. This gave the egg an elongated ovate pyriform shape 

 as a whole. When this egg was examined the question at once 

 arose as to whether the succeeding eggs laid by this hen No. 183 

 would be on the whole like this first egg, or whether they would 

 approach the normal form of eggs in general. If the latter should 

 be found to be the case, how would this change occur ? Would 



