All 54 females produced both sexes, but because of the small 
numbers used, he still did not rule out this possibility. In 
1960, Beilhary showed, at least to his own satisfaction, that 
sex reversal was not involved. He used for his cross, two breeds 
in which the sex-link gene for inhibition of dermal melanin was 
present in one breed but not in the other. Thus, all chicks 
hatched could be genetically sexed with males having white. 
shanks and females having black shanks. The hens were treated 
with 15 mg. stilbestrol tablets and eggs were hatched before 
and during the period of maximum effect (4-5 months production). 
At the time of hatching, chicks were vent sexed and all cock-= 
erels and doubtfuls were discarded. No sex-ratio at hatching 
appeared in the data. One-hundred and ten females were produced 
during the 4-5 month period and shank color was not elassified 
until maturity. He states that some of the 110 pullets did not 
develop marked shank color, but that they did not have the white 
shanks of the males. From this imperfect data he believed that 
sex reversal was not involved. 
Lerner, et al. (Gaunt et al., 1961) reported the anti- 
estrogenic action of Mer=25 in blocking effectively both endo- 
genous and exogenous estrogens in chicks. 
The thyroid and its secretion level of thyroxine has 
an effect on egg production. Winchester and Scarborough (1953) 
radio«-thyroid-ecrecticized some New Hampshire twoeday-old 
female chicks with radioactive iodine. At six weeks of age, 
thyroid replacement therapy was started with various dosages of 
thyroxine. Normal or nearly normal production was achieved by 
the groups given 4 through 32 gamma thyroxine per unit of body 
size daily or 200 to 1600 per cent of normal output for growing 
birds. Those receiving .25 to 4.0 gamma and 32 to 64 gamma had 
reduced production and those receiving less than .25 gamma or 
more than 128 gamma did not lay at all. Other investigators 
feeding 0.3 per cent thiouracil (McCartney et ale, 1950), or 
10 grams of thyroprotein per 100 pounds of feed (Oloufa, 1953) 
have shown significantly reduced egg production also, thus over- 
and under-production of thyroxine seems to reduce egg production. 
The hormones of the adrenal gland also affect egg pro- 
duction. An injection of 3 mg./lb. body weight of cortisone 
acetate stopped egg production within four days for a period of 
17 days (Kudzia, 1953), whereas massive dosages (50 to 300 mg./ 
week) resulted in adrenal and gonadal atrophy in about four weeks 
(Urist et al., 1960). Desoxycorticosterone acetate in exceés 
of 10 mg. /week was equal to progesterone in depressing productin 
(Herrick et al., 1957). Sykes T1955) using adrenaline, lowered 
production by 20.6 per cent with as small a dose as 0.25 mg. 
Dosages of 5 mg., or more, completely inhibited egg production. 
These adrenal hormones seem to influence the pituitary in its 
output of A.C.T.H. and gonadotropic hormones, particularly in- 
hibiting the secretion of L.H. 
57 
