
birds from 5 to 8 months was more than twice as high as in 
others. The high frequency of ovarian retrogression was tenta- 
tively attributed te artificial lighting of immature pullets, 
with resultant refractoriness to light and disturbed endocrine 
balance at maturity. 
Mason (1952) observed that adequate doses of pro- 
gestrone in combination with low doses of estrogens caused hy-= 
pertrophy of the oviduct, but that progesterone in combination 
with large doses of estrogens caused a decrease in oviduct 
welght. Decreased oviduct weight was observed when progesterone 
at hi ug. was used with 200 ug. of estradiol or stilbestrol 
per aaye | 
3. Factors affecting albumen secretion and/or albumen quality. 
Blological processes are generally inhibited by ione 
izing radiation, except at low levels, and the biological ree 
sponse to the irradiations is proportional to the quantity of 
radiant energy absorbed by the tissue or organism. The mechan- 
ism of action of lonizing radiation is not yet well understood. 
Smith et al. (1956) irradiated laying White Leghorn 
chickens by exposing the oviducts and surrounding them by lead 
plates so as to shield the rest of the organs from radiation. 
The birds were between 9 and 18 months of age. The radiation 
doses varied from 50 to 5,000 r. with a dosage rate of 425 r, 
per minute. The mean laying rate of all hens prior to ir- 
radiation was 69 per cent, the mean egg weight about 57 grams. 
Egg weight was significantly decreased at dosages of 3,000 r. 
or greater. Most of the decrease in egg weight resulted from 
a diminished albumen. The inhibition of albumen formation was 
found to increase by a factor of 2/3 with aach 1000 r. increase 
in irradiation. <A decrease in shell weight was noted in birds 
receiving 3,500 r. when the whole oviduct was irradiated. The 
irradiation of the oviduct did not seem to affect yolk weight, 
which was to be expected, since the ovary was well protected. 
This independence in yolk and albumen weight indicates that the 
weight of the albumen is largely determined by the oviduat char- 
acteristics, rather than by merely the degree of stimulation by 
yolk size. At levels above 4,000 r. very little thick albumen 
was evident. An abnormal appearance of the albumen was observed, 
resulting from opaque material occurring in large bodies or in 
dispersed form presenting a milky appearance. There was a large 
number of abnormalities in egg shape in all treatment groups. 
The recovery time following treatment was between 2 and 3 weeks. 
4, Factors affecting the deposition of egg shell. 
a) Sulfonamides. 
A large amount of work has been carried out on the | 
affect of sulfonilamide and related compounds on egg production. 
26 
