A COMPARISON OF THE OFFICIAL AND THE CHICKEN METHODS FOR THE OXYTOCIC BIOASSAY OF POSTERIOR PITUITARY ABA2

The purpose of this investigation was to compare the chicken blood pressure and the official uterine methods for the oxytocic bioassay of posterior pituitary preparations. The present official method (1) is essentially that described by Dale and Laid-law (2) in 1912. It has not been uniformly successful in the hands of all bio-assayists and has been criticized by many workers from Hamilton and Rowe (3) in 1916 to Morrell, Ailmark, and Bachinski (4) in 1940. The chicken blood pressure depressor method was introduced in 1939 by Coon (5), who claimed many advantages for it. This method is based on the fact, first described by Paton and Watson (6) in 1912, that the intravenous injection of posterior pituitary solution elicits a precipitous and fleeting fall of blood pres-sure in the bird. This response was shown by the same workers to be accom-panied by a splanchriic vasodilatation. Hogben and Schlapp (7) showed that this effect was not due to histamine or histamine-like substances, and Hogben (8) proved the ability to elicit the avian depressor response to be a specifi