Histidine Decarboxylase Activity in the Walker Carcinosarcoma 256 ∗

Conclusions

1. Histidine decarboxylase activity in the Walker carcinosarcoma 256, although measurable, is very low. 2. No consistent change occurred in excretion of histamine in the urine of female rats when the tumors were implanted or growing rapidly, or after their removal and subsequent recurrence.