298 MAINE AGRICUI.TURAI, EXPERIMENT STATION. I912. 



cess of rapid enlargement by the deposition of yolk. The next 

 class includes those oocytes in which yolk deposition is started 

 but is proceeding at a slow rate. It is from this class that the 

 first class of rapidly growing yolks is constantly being recruited. 

 Finally the "under imm." class represents the make-up of the 

 bulk of the ovary. It will be understood that these size classes 

 are only roughly delimited, the diameter of each oocyte having 

 been estimated but not carefully measured. 



Columns in the table are devoted to "Total number of eggs 

 laid in life" and "Winter production." The first of these has 

 no particular significance since obviously it depends on when 

 the bird was killed in order to make the oocyte count. Winter 

 production, however, represents a definite entity in fecundity as 

 already pointed out above (p. 292).-^ Winter production records 

 are directly comparable with one another. It is the inheritance 

 of this fecundity unit that is primarily being studied in these 

 investigations. 



From this table a number of points are to be noted. In the 

 first place it is clear that the number of visible oocytes in the 

 ovary of a hen is very large; much larger, I think, than has 

 generally been supposed. While to be sure there are for the 

 most part only vague statements respecting this point in the 

 literature, usually these statements are to the effect that the 

 birds ovary contains 'several hundred' ova. The only direct 

 statement as to the actual number of oocytes in a hen's ovary 

 which I have been able to find is given by Matthews Duncan (8) 

 on the -very dubious authority of Geyelin (11) to the following 

 efi^ect (loc. cit., p. 36) : "It has been ascertained that the ova- 

 rium of a fowl is composed of 600 ovula or eggs ; therefore, a 

 hen during the whole of her life cannot possibly lay more eggs 

 than 600, which in a natural course are distributed over nine 

 years in the following proportion." This statement is followed 

 by an utterly preposterous and presumably entirely imaginary 

 table from Geyelin, supposed to show the laying of hens at 

 different ages. How far from the truth the table is is indicated 



* For general discussion of "winter production" as a unit of fecun- 

 dity, see (28), (30), (34), {37), (38). It comprises the egg production 

 up to March i of the laying year. 



