"GALVANOTROPISM" OF ROOTS

1. New experiments, made in such a way to eliminate as completely as possible products of polarization and the migration of such products when formed, have shown that the exhibition of galvanotropic curvature in roots is mainly dependent upon such products, since no curvature appears when they are excluded. 2. The polarization products injure the external layer of cells of the root; this allows these cells to act as electrodes directly applied on the internal tissues. The inner electrolysis produces such changes in the interior cells that they may be considered as becoming ionically different. This differential state is responsible for curvature. 3. "Galvanotropism" of roots, therefore, cannot be regarded as exactly comparable to the galvanotropic orientations of certain animals, but is essentially dependent upon injury.     

METABOLISM OF GLUCOSE IN THE PROCESS OF "GLUCOSE-BLEACHING" OF CHLORELLA PROTOTHECOIDES

1. As previously demonstrated, normal cells of Chlorella protothecoidesare bleached with degeneration of chloroplasts when they areincubated, under aerobic conditions—either in the lightor in darkness—, in a glucose-containing medium withoutadded nitrogen source ("glucose-bleaching"). It was found inthe present study that under the atmosphere of N₂, neither bleachingnor growth of algal cells occurs in the dark, while in the lighta significant growth of cells takes place with formation ofa certain amount of chlorophyll.
2. Studies on the effects ofvarious inhibitors (ammonium ion,DNP, CMU, -hydroxysulphonates,arsenate, cyanide, azide, andantimycin A) under different conditionsshowed that oxidativephosphorylation is a necessary processfor the occurrence ofthe glucosebleaching as well as the assimilationof glucose(cellular growth). Under light-anaerobic conditionsin the presenceof glucose, assimilation of glucose (cellulargrowth) takesplace being supported by photophosphorylation,but no bleachingoccurs.
3. When the algal cells in the courseof bleaching were transferredto the glucose-free mineral medium,the cell growth ceased immediatelybut the cell bleaching proceededfor several hours before itscessation. The respiratory activity,which was high in the glucose-containingmedium, became loweron transferring the algal cells into theglucose-free medium.The lowered level of respiration was maintained,for more than8 hr after the transfer of cells to the glucose-freemedium.
4. When the cells in the course of bleaching were placed underthe atmosphere of N₂, the cell bleaching ceased almost instantaneously.
5. Based on these observations and other inhibition experiments,it was inferred that a certain intermediate(s) produced by theaerobic respiration of glucose is closely associated with theoccurrence of cell bleaching, and that an O₂-requiring stepmay be involved in the process of chlorophyll degradation.

(Received September 9, 1965; )     

"GIGANTISM" OF CHLORELLA VULGARIS I. MECHANISM OF INDUCTION OF CIGANTISM

1. Based on the microscopic observations, two stages, "giant cellstage" and the subsequent "palmelloid body stage", were distinguishedin the process of formation of giant Chlorella induced by theaddition of sugars. The "giant cell" is much larger in sizethan the control cell, but the other morphological featuresare the same as those of the latter. The "palmelloid body" isa form composed of many conjoined autospores.
2. When a highconcentration of glucose was maintained in the medium,gigantismwas also maintained. Under this condition, the algashows acyclic transformation between "giant cell" and "palmelloidbody"without returning to the small single cells.
3. Large amountsof carbohydrate composed of hexose were foundto be accumulatedin the giant algal cells, and it was inferredthat this carbohydrateaccumulation causes greater enlargementof cell volume as comparedwith control cells.
4. Uronic acids, which were found to be absentin the control cells,were formed and lost in the cells culturedin the glucose mediumin parallel with the appearance and disappearanceof gigantism.
5. Pectic substances, from which uronic acids areconsidered tobe derived during the extraction procedure, werefound to bepresent only in giant Chlorella.
6. The conjoinedautospores in giant Chlorella (at the palmelloidbody stage)were separated to some extent by the addition ofEDTA, and theresulting cells were similar to control Chlorellacells.
7. Basedon these results it was inferred that inductive formationofthe pectic substances is causally related with the appearanceof "palmelloid body".

¹ Present address: Department of Chemistry, College of GeneralEducation, Osaka University, Toyonaka, Osaka.