Studies on the Relation Between the Ultrastructure of Secretory Cells and Their Synthesis and Secretion of Lacquer in Laticiferous Canals of Rhus verniciflus Structure and Development of Phloem in Toxicodendron vernicifluum Variation of Urushiol Content in Raw Lacquer and the Bark Structure of Toxicodendron vernicifluum in Different Seasons and Their Correlation STUDIES ON THE RELATION BETWEEN SYNTHESIS OF LACQUER AND SUBMICROSTRUCTURE OF THE TISSUE WHERE LATICIFEROUS CANAL LIES IN TOXICODENDRON VERNICIFLUM Distributed Regularity and Anatomic Feature of Laticiferous Canals of Toxicodendron vernicifluum (Stokes) F. A. Barkley