Altitudinal variation of resin ducts in Pinus taiwanensis Hayata (Pinaceae) needles
The variation of resin ducts in needles of Pinus taiwanensis along an altitude gradient (700 m- 3,100 m) in central Taiwan is revealed for the first time in this study, including position type, number, size, arrangement pattern and anatomical structural variation. Three types of resin ducts-medial, external and septal-were found according to their relative positions in the mesophyll. All needles sampled showed combinations of these three resin duct types. Mostly, 3-7 resin ducts were found in the mesophyll per needle, and the number of resin ducts was significantly greater at mid altitudes than at high and low altitudes. Septal ducts decreased in number with an increase in altitude; however, needles from mid altitudes had more external ducts. Eight patterns (basic and patterns I-VII) of resin ducts in the mesophyll of needles were delineated to present the arrangement variations. In addition to the primary ducts found in the mesophyll, we found the rare bundle sheath ducts in some needles, and their frequencies decreased obviously with an increase in altitude. The consistent combination feature of medial, external, and septal ducts in needles of P. taiwanensis from Taiwan could be easily distinguished from those with medial ducts from mainland China. However, this difference has unrecognized before, and it should be considered in future taxonomic work.
Resin canals in Pinus taeda. Longitudinal canal lengths and interconnections between longitudinal and radial canals.
Lengths of longitudinal resin canals in Pinus taeda (loblolly pine) wood were determined by 1) peeling offthe bark and measuring the canals, visible as white lines along the surface, to the nearest mm, and 2) photographing aseries ofcross sections (4000) ofknown thickness with a movie camera, and sub sequently using a film editor and frame counter to ca1culate lengths. The values yielded by the. two methods were not significantly different and indicate that the less time-consuming method of peeling and measuring lengths is as reliable as the cinematographic technique.
A Rapid Method for the Extraction of Radioiodide from Urine
THE extraction of radioiodide from urine is important in radioiodide therapy, since without it the large quantities of highly radioactive urine which accumulate must be stored until the activity decays sufficiently to allow disposal.