422 



is deposited, b) Normal eggs with one yolk, c) Double-yolked eggs. 

 d) Triple-yolked eggs. 



The average weights of* these different classes of eggs for Plymouth 

 Rock hens are given in Table I, and are shown graphically in Fig. 2. 

 The second column in the table and the zigzag line of the diagram give 

 the observed weights. The third column and the smooth curve are the 

 parabola, 



ir= 16,242 + 43,762 Y— 4,450 1'-^ 

 where TF denotes the mean weigth of the egg and 1' denotes the number 

 of yolks contained. 



Table I. 

 Weight of Hens' Eggs and Number of Contained Yolks. 



It is clear from both diagram and table that the parabola gives an 

 extremely close fit to the observations. 



The facts just noted indicate that there probably exists a definite 

 relation between the amount of albumen secreted by the oviduct in any 

 given case and the amount of yolk present in the oviduct at the time. 

 Such a relation would be expected in view of the fact that the immediate 

 stimulus to secretory activity of certain (and probably of all) parts of 

 the oviduct is primarily mechanical in character 9. What the precise 

 quantitative character of this relation between amount of yolk and 

 amount of albumen is must be determined by further study. 



Internal Characteristics of the Egg. 



The disposition of the three yolks in this egg is clearly shown in 

 Fig. 1. Each yolk was enclosed in a separate yolk membrane. While 

 the three yolks were in contact with each other, they were in no way 

 fastened together. All of the yolks were of normal size, and of approxi- 

 mately the same size. Unfortunately no measurements of the yolks are 

 available. Each yolk possessed a germ disc. These were normal so far 



7 This is the mean of these dwarf eggs wliich have been studied in this labora- 

 tory. The complete data regarding them will be publislied later. 



s This is the mean of Aker's case and the egg described in the present paper. 



'J Cf. Pearl, R. and F. M. Surface, The Nature of the Stimulus which cau- 

 ses a Shell to be Formed on a Birds Egg. Science, N. S. Vol. 29. p. 428 and 429. 

 1909. 



