4, Inhibition of germinal viability resulting in infertile eggs. 
Germinal viability or egg fertility, is influenced by 
only a very small number of drugs. The following drugs affect 
the female's fertility: NF-180 (Smyth et ale, 1959, and McCartney 
et al., 1960); reserpine in turkeys at 2 ppm. ee et ala, 
961); and prdgesterone at 10-40 mg. per week (Herrick et al., 
1955). 
In oogenesis there are ample means and opportunity for 
one to manipulate reproductive rate. The one important limiting 
factor is that most of the methods mentioned require close 
control of the birds under treatment. 
64 
