
New (1957) demonstrated the necessity of turning eggs 
during artificial incubation. The critical period was found to 
be 4 to 7 days. 
Irradiation by x-ray or gamma nuclear radiation affects 
hatchability and fertility. Glasser et al. (1955) noted that 
total dose and percentage survival showed an inverse relationship 
for both 6=< and 12eday-old embryos irradiated. At 20 r. per 
minute, 400 r. produced 96.9 per cent survival, while 800 r. 
produced 0.7 per cent survival. Goldman found that 800 r. 
at 17re per minute killed 62 per cent of irradiated eggs within 
21 hours and 100 per cent at 48 hours. In the wild, Norris 
(1958) irradiated nine eggs of the Bastern Bluebird. The mean 
dose was 420 r. The results were 3 embryos dead, 3 hatchlings 
dead and 3 fledged. When adults were treated with radiation and 
their fledgling success compared with untreated adults, no 
Significant difference was noted at doses of 200 r. and 600 r. 
Irradiation dosimetry and numbers of experimental 
subjects constitute the greatest weakness of work done in this 
area. Currently, Wetherbee and Landy are conducting experinents 
in irradiation at the University of Massachusetts. 
46 
