The vegetative shoot apex ofClethra barbinervisSieb. et Zucc. was analyzed in longisectional view and discussed from the viewpoint of the three-dimensional aspect. The width of the central zone fluctuates during a plastochron but the depth scarcely changes. The beginning of leaf initiation is recognized in a very early stage of growth even in longisectional view, if sector development is carefully examined. When two reconstructed and overlapped figures for the first cell layer of the apex are depicted, changes occurring at the apex in the superficial view come to be easily understood. Moreover, if the shoot apex is analyzed for T divisions, a type of analysis recommended for the root apex by Schüepp (1917), anatomical changes of the apex are fairly well understood even from the viewpoint of the three-dimensional aspect.
The North American populations ofMaianthemum dilatatum sensu lato (=M. kamtschaticumauct.) were studied from morphological, karyological, and ecological standpoints, and were compared with those from Northeastern Asia. It became apparent that the variability of North American populations ofM. dilatatumis quite broad, but differs significantly in several important morphological characters from that of Northeastern Asiatic populations, and thus forms another additional discrete geographical population group withinM. dilatatum. In comparison with the Asiatic plants, those from North America have much more robust and taller flowering scapes with longer racemes, ranging from 3 to 6 cm in length, and more robust rhizomes. The cauline leaves are much larger, often markedly thick, lucid, and ovate which are clearly attenuate toward the tip. Ecologically, the habitats of North AmericanM. dilatatum extend primarily in the underlayer of evergreen coniferous forests represented byPicea sitchensis, the underlying ecophysiologic conditions markedly distinct from those in Eastern Asia. Karyologically, however, the North American plants proved to be diploid with 2n=36 chromosomes, with karyotype composition quite identical to those observed in Asiatic materials, namely, 2n=36=4V (2V1+2V2)+16J+8j+8v.
Detailed morphological studies were carried out on the vegetative thallus and female, and tetrasporangiate systems of the red alga, Hyalosiphonia caespitosa Okamura (family Dumontiaceae). As a result, the following data were obtained : 1) each segment cell produces four vegetative laterals, of which the distal ends form a tight cortex, 2) basal cells of the cortex bear a carpogonial branch and an auxiliary cell branch separately, 3) both carpogonial branch and auxiliary cell branch are strongly curved and 4) after fertilization, the carpogonium fuses with a cell of a carpogonial branch and they form a fused area from which develops a connecting filament which ultimately fuses with the auxiliary cell. These features support well the systematic position of the genus Hyalosiphonia as a taxon of the Dumontiaceae.
The results of a cytotaxonomical research for Nitella flexilis (n=12, from four habitats), Nitella inokasiraensis (n=6) and Nitella opaca (n=6) are reported. Special relations between the centromere positions of the chromosomes of N. flexilis complex were found, and the basic number (x=3) for the section Nitella is suggested. The patterns of the karyotypes of the 3 species and 1 form were analysed.
Morphological and cytological characters of Indian tetraploid S. nigrum (n=24) and S. nodiflorum (n=12) have been studied. The lack of close genetic relationship between the two species is shown by cytological studies of their triploid hybrids (n=18) which are sterile. It has been concluded that chromosomal sterility and cryptic structural hybridity play an important role in intersterility and the genetic distinctiveness of Indian tetraploid S. nigrum and S. nodiflorum.
In a sordariaceous fungus, Gelasinospora reticulispora, ascocarps induced by white light irradiation after a period of dark incubation or by aging of the culture were typically ostiolate perithecia. But those triggered by the arrival of the hyphal tip at the distal end of the growth tube were nearly always devoid of an ostiole, so that spores were discharged in a cleistothecial manner. The asci developed at a similar rate irrespective of the methods of induction. In all the cases ascocarps were formed at various depths of the agar medium, and the orientation of asci was totally at random although it always coincided with the orientation of the ostiole if present.