The Inheritance of Diphtheria Immunity in Ducks

Summary Injection of ducks with diphtheria toxoid resulted in the appearance of antitoxin in their blood serum. The amount of antitoxin present showed wide individual variations. The immunity was found to protect against injections of diphtheria toxin. The serum antitoxin decreased rapidly after injections were discontinued. The decrease coincided with the time when the birds began to lay eggs. The eggs were found to contain antitoxin in the livetin fraction of the egg yolk. The concentration of antitoxin in the yolk was found to vary with the concentration in the serum. The amounts of the proteins vitellin and livetin in unit volume of egg yolk were found to vary independently of each other, and independently of the individual which laid the eggs. No relation was found between yolk livetin concentration and yolk antitoxin concentration. Ducklings newly hatched from eggs laid by immunized birds were found to contain antitoxin in their blood serum. None could be found in the serum of three weeks' old ducklings from the same mothers.