472 POULTRY CULTURE 



correlation, while when fowls of different types and breeding but of 

 like weights are compared, great differences are found in weight 

 of bone and in texture of flesh and skin. In short, while the tend- 

 ency to correlation which constitutes physical symmetry is marked, 

 the fact that it is variable and easily broken up indicates that such 

 characters are not necessarily correlated. 



Correlation of external characters with constitution and function. 

 A distinction must be made between the normal state of a character 

 and transient, abnormal expressions of it. To one observant of the 

 attitudes and actions of animals and birds under a variety of circum- 

 stances, the general attitude and carriage of body and limbs, the 

 movements, the expression of the eye, etc. indicate immediately 

 whether the creature is in normal health or not, and in a healthy 

 creature afford means of estimating its vitality. There is plainly a 

 correlation in such things, but not of the kind under consideration. 

 It is merely the expression of the general condition of the creature. 

 By correlation of external and internal characters is meant such par- 

 ticular relation between a certain external, plainly visible character 

 and a certain functional character, or a certain quality which cannot 

 be determined by ordinary inspection of the creature in life, that the 

 external character serves as an index of the value of the other. 



The most familiar cases of supposed correlation of external and 

 internal characters in poultry relate to the laying capacity in fowls. 

 The size of the comb has long been popularly considered a reliable 

 index of relative laying capacity. To a less extent popularly, but 

 more widely among poultrymen, a certain shape of body is regarded 

 as the egg type, invariably found in great layers. Like all fal- 

 lacies, these have a slight foundation in fact. That the condition 

 of the comb of a hen varies according to the activity or inactivity 

 of the reproductive organs is so evident that no one who has the 

 care of fowls can fail to see it. Normally the comb of a hen is 

 larger when she is laying than when she is not, and brighter in 

 color ; 1 the comb of a pullet does not develop until she is about 

 to lay ; the growth of the comb of a cockerel corresponds with the 



1 The fully developed, bright-red comb is not an infallible sign that the hen 

 is laying. Many hens with diseased ovaries, and some that never lay, have 

 well-developed combs. In a healthy hen, however, there is regularly a difference 

 in the appearance of the comb when she is laying and when she is not. 



