Standardized extracts of ant. pituitary-like hormone derived from pregnancy urine when injected into the [female] Xenopus laevis were capable of inducing ovulation and extrusion of hundreds of ova within 18 hrs. The APL hormone of pregnancy urine was the responsible factor in the Xenopus test for the early diagnosis of pregnancy. Since amts. of the hormone in excess of 50 R.U. were required to produce the reaction, it was believed that normal urines could in no manner produce this biological phenomenon in the quantities injected into Xenopus.