The standing crop and productive structure of phytoplankton communities in some lakes of central Japan have mainly been investigated by chlorophyll extraction method. 1.Remarkable difference of chlorophyll content with lake type was ascertained. In summer, average values of the chlorophyll content in epilimnion are in maximum ca. 50mg/m3 in eutrophic lakes, and less than 1mg/m3 in oligotrophic and dystrophic ones. 2. The chlorophyll content in lakes varied not only in quantity but also in the vertical distribution, -the productive structure of phytoplankton community-, of which two main types, i.e., homogeneous distribution and stratum one (Fig. 3), were recognized and both the types appeared alter nately in the course of year, The process of the transformation of the two types was analysed on the basis of metabolism of phytoplankton. 3.The standing crop of phytoplankton was investigated with the amount of chlorophyll. It showed that in summer the seston was mainly composed of phytoplankton but in winter mainly inorganic matter and non-chlorophyllic organisms.
The fresh weight of sectioned pieces of Avena coleoptile did not increase in an auxin solution if this contained lactose or mannitol to cause incipient plasmolysis of the cells. When transferred from the sugar solutions to water, the pieces treated by auxin absorbed more water than those without auxin action. The results suggest that auxin acts to decrease the wall pressure, rather than to increase the absorbing power of cell contents. O2 uptake, as well as its stimulation by auxin, was not much inhibited in the state of incipient plasmolysis. This partly answers the objection that metabolic activities which support active water absorption might be inhibited under the abnomal osmotic condition.
The transmission rate of the photoperiodic stimulus across the graft union in Pharbitis Nil was found to be 2.8 and 2.4mm per hour. The stimulus travels in the grafted plants approximately with the same velocity as in the two-branched plants; the graft union has no significantly hindering effect upon the transmission of the stimulus.