50 



feet organisms may be produced in any. number in the short 

 space of twenty^-one days, the parent fowls may be kept under 

 such conditions as th; investigator may wish and that these 

 conditions may be varied at will, that the embryo may be 

 followed through all the stages of its development, you realize 

 at once what a field the poultry business presents for a study 

 of the problem of sex, and the business takes on a new dignity 

 and interest. 



Some very important facts bearing on sex have been gath- 

 ered. The point on which investigators are more fully agreed 

 is that nutrition has a profound influence upon sex. Begin- 

 ning with insects it has been found that if caterpillars are 

 starved before entering the chrysalis state the resultant but- 

 terflies or moths are males, while others of the same brood 

 highly nourished are females. With bees, too, the relation 

 between nutrition and sex seems equally well established. 

 Experiments with tadpoles, which were supplied with a diet 

 steadily increasing in sumptuousness, showed a steady and 

 corresponding increase in the number of females produced. 

 The proportion of females to males, which was originally 

 fifty-seven to forty-three, rose steadily as the diet became 

 more and more highly nutritious, until out of 100 tadpoles 

 ninety-two were females and eight males. Coming up in the 

 scale of life it has been found that among mammals the same 

 principle holds, although of course other influences come in 

 more than among the lower orders. 



Another feature that is believed to have an influence upon 

 sex is the time of impregnation. The fresher the ovum when 

 fertilized the greater the likelihood that the offspring will be 

 a female. If this conclusion is correct eggs laid at the be- 

 ginning of a litter should hatch a larger proportion of pullets 

 than eggs laid later. 



The relative age of the parents is believed to affect the 

 sex. Where the male parent is the older the offspring are 

 preponderatingly male, and where the ages are even, or where 

 the mother is the superior in age, the preponderance is the 

 other way. I find that this is a theory quite generally held. 

 I sometimes receive letters from would-be purchasers asking 

 for eggs from hens mated with cockerels. It is a theory very 

 easy to test, and the reader should give it a trial in his yards. 



Temperature is also a feature to be reckoned with. I have 

 noticed in my own yards that in the cold months the pro- 

 portion of pullets hatched is smaller than it is later in. the 



