الفهرس 
REVIEW OF LITERATlJREOnly 14 pages are availabe for public view
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Abstract
The present work was conducted to study the effect of
X-ray on the biotic potential, and cercaria! production of
laboratory and field fresh water snails, B.alexandrina and
B.truncatus.
The effect of different sublethal concentrations of cobalt
(Co++) and chrome (Cr+++) on the survival rate, the egg
production and the growth rate of both laboratory and field
snails was also considered. Also the accmnulation of cobalt and
chrome in the shells and soft parts of snails was studied.
Considering the effectiveness of X-ray on the survival
rate, the higher the dose of X-ray, the higher was the rate of
mortality and vice versa. As a general trend B.alexandrina
proved to be more tolerant to X-ray when compared with
B.truncatus. The low doses of X-ray 0.2, 3 and 5 rad had no
effect on the egg laying capacity of the field strain of
Biompholaria and Bulinus, while the dose of 20 rad decreased
the egg production. The hatchability percentage of
B.alexandrina and B.truncatus in early stages of development
was higher when exposed to 0.2 rad