摘要:

SUMMARYA study has been made of the bordered pit structure in the tracheids ofPiceaspecies,Pinus sylvestrisandPinus radiatawith the aid of the scanning reflection electron microscope. Cellulase treatment was applied to gain more detailed information on the pit morphology.It was found that the pit membrane on both sides was covered with a thin membranous layer. The margo fibrils were digested in the cellulase preparation in nearly all samples.The central part of thePinustorus was often found weakened and very flexible: in many pits it had entirely disappeared, as was found by Stemsrud (1956). After enzyme treatment the amount of this type of torus increased. In the branch wood ofPinus sylvestrismany pits with aberrant membrane structures were found.As a whole the overall structure of the pit dome as described by Jutte&Spit (1963) and Murmanis&Sachs (1969) was confirmed.The pit porus inPiceaspecies often seemed to be strengthened by the presence of a thick fibrillar strand, possibly representing the S3layer.In the cellulase preparation the lignified cell walls looked smoother, proving that some changes had occurred in their chemical components. After cellulase treatment the inside of the pit domes in bothPinusspecies were readily lifted or peeled off in a flat helix, but not inPiceasp. The tori in the aspirated pits were very tightly attached to the porus whose edge seemed to be pushed into the torus. The torus was not removed during cellulase treatment.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00730.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe seedling ofStruthanthus quercicolahas a well‐marked hypocotyl bearing raised stomata interpreted as hydathodes. The haustorial disk is already present in the seed and enlarges greatly. The development and architecture of the young haustorium corresponds closely to those of most other Santalalean haustoria, and includes a large gland, and at least two separate collapsed zone

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00731.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYA reconstruction of the vascular organization of the stem ofSewardioxylon sahniiis given along with the description of the manner of origin of leaf traces and the formation of the inner inverted ring of bundles in the main stele.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00732.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYRoots of decapitated barley plants were allowed to equlibrate with Na+solutions of different concentration. The kinetic characteristics of this process were examined.Attainment of the saturation level appeared to involve not only strong reduction of the net flux but also of the influx as measured with22Na+.The final Na+content of the tissue depended on the external Na+concentration. Reckoned from a certain level of internal Na+the relationship was the same as for the initial rate of Na+uptake.Transfer of roots saturated at a low Na+concentration to a more concentrated Na+solution brought about a resumption of Na+absorption until a level characteristic of the new concentration had been attained. On the other hand transfer of the material from a higher to a lower concentration after saturation did not involve appreciable loss of Na+from the tissue.A kinetic model is proposed to explain these phenomena.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00733.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe influence of G.A. and I.A.A. on the hydroxyproline content of cell walls was examined with reference to the concept of wall‐bound protein as a cross‐linking agent regulating wall extensibility. It appeared that the hydroxyproline‐rich protein content of cell walls pf elongating cells from the stems of two pea varieties, Alaska and Rondo, differed remarkably. In accordance with Lamport's hypothesis, the dwarf variety (Rondo) had a much higher hydroxyproline content than the standard variety (Alaska). When G.A. was applied to the top of the slow growing dwarf variety, the growth rate increased until comparable to the standard variety and the hydroxyproline content of the cell walls decreased somewhat. However, no linear relationship between growth stimulation and decreased hydroxyproline content existed.Experiments performed with excised elongating pea stem segments, grown in a culture solution containing phosphate buffer, showed that the hydroxyproline content of the cell walls increased considerably during an incubation time of 24 hours. IAA strongly inhibited this increase while stimulating elongation. However, a solution containing IAA and sugar caused the greatest elongation but also the greatest formation of hydroxyproline. It was concluded that cell extension and the hydroxyproline content of cell walls are not necessarily inversely corre

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00734.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYA description and discussion are given of the morphological changes of the cell organelles during the middle and late tetrad stage and the young microspore ofPinus sylvestriswith special reference to the pollen wall formation.In the middle tetrad stage the template of the pollen wall pattern appears to be the result of Golgi material excretion and callose wall formation. The fine fibrillar material from the content of the Golgi vesicles, consisting partly of a polysaccharide, forms the primesexine. During the late tetrad stage the sporopollenin originates from the microspore and is deposited on membranes mainly outside the cell. It penetrates into the primesexine. The starch in the plastids disappears and the lipid granules become voluminous; both elements are related to the pollen wall formation. The swelling of the sacci may be an osmotic process.From the quantitative approach it appears, that the young microspore contains approximately one fourth of the number of cell organelles present in the cell during zygotene. The cell organelle population probably does not change in number during the meiotic stages.A general survey summarizes the whole process of microsporogenesis till the young microspore stage. The control of pollen wall formation is also discussed.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00735.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYFor the early Neolithic site of Nea Nikomedeia in northern Greece (ca. 5470 B.C.) the following plant species could be established:Triticum monococcum, Triticum dicoccum, Hordeum vulgarevar.nudum, Lens culinaris, Pisum sativum, Vicia ervilia, Quercussp.,Cornus mas, andPrunuscf.spinosa.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00736.x

年代:1971

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00737.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYChromosome numbers ofT. verticillataForman have been preliminarily found to be n =c. 21 and 2n = 40, 42, 44. They require future verification based on the study of more collections from its geographical range of distribution.The haploid chromosome numbers inFagaceaeso far known are 12 in most of the genera and 13 inNothofagus.The number ofc.21 forTrigonobalanusis unique and new in this family.Irregularities of chromosome behaviour during meiosis, such as secondary association, lagging, precocious separation of chromosomes, etc. have been observed.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00738.x

年代:1971

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00739.x

年代:1971

数据来源: WILEY