THE BREEDING OF CHICKENS 141 



Selection for this point depends upon trap-nesting. The 

 time involved in \isiting the nests several times a day and 

 recording the numl)er of the hen laying each individual egg 

 is out of proportion to the price received for tlie products 

 and would fail to find a phxce in most schemes of manage- 

 ment of the general farm. For improvement in this quality, 

 great as is its importance, tJie ordinary producer must depend 

 upon the breeder, seeking it through the medium of impro\ed 

 breeding males. 



Constitutional Vigor and Hatching Power. — Williams' 

 found that in choosing four Black Langshan hens for their 

 strong vitality, and comparing them with four others of 

 the same breed that were lacking in vitality, 62.95 per 

 cent of all eggs laid by the vigorous birds that were 

 incubated hatched. On the other hand, only 29.27 per 

 cent of the eggs incubated from those laid by the hens that 

 were noticeably weak hatched. 



In tests involving over three thousand eggs from White 

 Leghorns and over one thousand from Barred Plymouth 

 Rocks, Rice and Rogers^ found that the average fertility 

 of the eggs from flocks selected for their good \-itality was 

 7.5 per cent greater and the actual hatching power was 7.G 

 per cent greater than in the case of eggs from flocks of birds 

 that at some time had exhibited signs of weakness. 



Hcai'u Production and Hatching Poiccr. ^Thc fpiestion of 

 whether high fecundity tends to lessen hatching power, 

 is one upon which ojHnion varies and ui)on which there 

 is comparatively little evidence. Rogers' reports on work 

 with eightj'-two hens in which all the eggs incubated during 

 the second season were used. He found that taking the 

 two years' production as a basis of comparison the hatching 

 power was higher with average producers than with those 

 individuals whose production was exceptionally high or 

 exceptionally low. 



The hen that lays large numbers of eggs appears to slight 

 them somewhat from the physiologic stand-point. Beyond 



' Bachelor's Thesis, Oklahoma Agricultural College, 1913. 



2 Cornell Bulletin No. 318. 



3 Cornell Countryman, vol. ix. No. 3. 



