1. In tile present study, the concentration of antisecretory factor (A
SF), a lectin with hormone-like properties, and with the capacity to r
egulate water and electrolyte transport in the small intestine, was hi
gher in hen's egg yolk than in egg white (1.20 v. 0.46 units/ml). 2. T
he blood plasma concentrations of ASF activity were higher in d-old ch
icks (1.03 units/ml) than in 7-d-old (0.42 units/ml) or 21-d-old birds
(0.18 units/ml); the contents were found to be high again in 35-d-old
chickens, but to have decreased by 60 to 90% after transport to slaug
hter 1 day later. 3. The amount of ASF activity was lower in two group
s of chickens manifesting patent loose droppings at slaughter (0.15 un
its/ml in one group, and 0.08 units/ml in the other), than in two grou
ps with normal faecal consistency (0.65 units/ml in one group, and 0.7
2 units/ml in the other). 4. The results demonstrate the presence of A
SF in eggs, and a variation of ASF activity in chickens blood plasma i
n relation to age, stress and faecal consistency. The interpretation o
f these data suggests a regulatory influence of ASF on chicken intesti
nal transport of water.