INHERITANCE OF FECUNDITY 169 



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 pre- 

 sumably 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 by the fact that according to it 

 the pullet year is the least productive of any of a hen's life, save 

 only for the ninth year when the last remnants of the original 600 

 eggs are being tardily and, one must suppose, sorrowfully ejacu- 

 lated!^ As a matter of fact repeated trap-nest and other tests in 

 all parts of the world have shown again and again that, on the 

 average, the pullet year is the most productive of a hen's life. 

 From the figures given in table 4 it is furthermore apparent that 

 the absolute number of oocytes in the hen's ovary is very much 

 larger than the number of eggs which any hen ever lays. A 

 record of 200 eggs in the year is a high record of fecundity for the 

 domestic fowl, though in exceptional cases it may go even a hun- 

 dred eggs higher than this (cf . 29) . But even a 200-egg record is 

 only a little more than a tenth of the average total number of 

 visible oocytes in a bird's ovary, to say nothing of the probably 

 much larger number of oocytes invisible to the ung,ided eye, but 

 capable of growth and development. In other words it is quite 

 evident from these figures that the potential ' anatomical' fecund- 

 ity is ver}'' much higher than the actually realized fecundity 

 This is true even if we suppose the bird to be allowed to live until 

 it dies a natural death. Experience shows that birds which make 

 a high fecundity record in the first year of their life, generally 

 speaking, never do so thereafter. In general an examination of 

 what long period records are available in the statistics of this 

 Station, and also in the literature, indicates that probably only 

 relatively few birds of the American or Asiatic breeds at least, 

 would lay many more than 400 to 500 eggs in their natural life 

 time, if they were allowed to live it out. Records of '1000-egg' 

 birds are in existence, but such birds are rare. 



" It is difficult to understand how so aoute an investigator as F. H. A. Marshall 

 could have been so imposed upon by this wonderful table of Geyelin's as to repub- 

 lish it in his valuable and interesting book on the "Physiology of Reproduction." 



THE JOURNAL OF EXPERIMENTAL ZOSLOGY, VOL. 13, NO. 2 



