“…However, in counteracting the toxic manifestation of the folic‐acid antagonists used in the chemotherapy of neoplastic disease, folvinic acid may be advantageous (12). The reactions in which folic acid participates are of great importance—the synthesis of deoxyribonucleic acid (13) and of ribonucleic acid (14, 15), and essential roles in the maintenance of nerve cells, myelin sheaths and the long cortico‐spinal axons (16). Interrelationship with vitamin B 12 is manifested not only in erythropoiesis, but also in its major neurotrophic effects on the myelinated nerve elements (17).…”