1. The bark of the twigs of Metasequoia cracks lengthwise when it is about one year old, while the bark of two to four year old twigs splits in rings. The thick periderm which covers the trunk splits vertically and gradually sloughs away from the surface. 2. The surface of the bark of 2-4 year old twigs which peels off in rings is covered with numerous brown particles. These particles are giant cork cells. They are spherical or ellipsoidal in shape and averaging about 14, 600μ2 in their surface area. Those cells originate from the expanded parenchyma of the bast, taking a spherical or ellipsoidal shape and then separate from the tissue. The phenomenon is characteristic of the bark of Metasequoia. 3. The first cork cambium initiates in the middle of the cortex and the 2nd periderm arises from the pericycle. The periderm of twigs of more than three years old originates in the phloem.
When light-grown plate culture of Chlamydomonas moewusii var. rotunda was flooded with liquid medium and kept in the dark, gamete-cells were obtained. Mating in such dark cells was poor; the activity, however, was increased by illuminating the cells. If the illuminated cells, of any mating type were mixed together in the dark with dark cells of the opposite mating type, the yield of mating pairs was as high as that obtained in a mixture of illuminated cells and the illuminated partners. Furthermore, it was demonstrated that the supernatant of illuminated cultures enhanced non-specifically the mating activity of dark cells. The active principle differed from that for the chemotaxis reported (Tsubo, Y., 1957; 1961) in (1) that it was heatunstable, and (2) that it was detected in cultures of both mating types. Some substances on Krebs cycle seemed to increase the mating activity of dark cells, but illumination definitely gave a higher activity.