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Notes: Summary 1. Morphological manifestations of the chromosomal metabolism have been found in the first spermatocyte nucleus of Drosophila melanogaster. These “metabolic structures” include several types of well defined components, among which the „tubuli“ and the „reticular elements“ are most conspicuous. The metabolic nature of these elements follows from their phase specifity and from cytochemical data. 2. Masses of tubuli of 300–400 Å diameter are found all over the meiotic prophase chromosomes in the spermatocyte nucleus, but not in the spermatogonial nucleus. The reticular elements appear somewhat later and usually form a single group. Both types of metabolic structures are decomposed during diakinesis when they separate from the chromosomes. 3. The tubuli are mainly composed of a basic protein. In addition they seem to contain RNA. The presence of DNA in small concentration can not yet be excluded. 4. The chromosomal origin of the tubular as well as the reticular elements follows not only from the observed contact with the chromosomes but also from the fact that spermatocyte nuclei of X/O-males of Drosophila melanogaster do not contain these components. This shows that the Y-chromosome is involved. 5. The role of the Y-chromosome in the formation of the metabolic structures has been further elucidated by studying males with partial Y-chromosomes, such as YS, YL, and Y″. Spermatocytes with the long arm of the Y (X/YLc) as a rule contain tubular and reticular elements in nearly normal quantity. X/YS and X/Y″ testes show a highly variable pattern. Some spermatocyte nuclei resemble the X/O-type while the rest represent all intermediate stages between the X/O- and the X/YL-type. 6. The lack of tubuli in X/O or in X/YS and X/YL spermatocyte nuclei is always correlated with the appearance of crystal needles in the nucleus as well as in the cytoplasm. Only very rarely in X/YS spermatocytes is an intranuclear crystal found together with a small amount of tubuli. The X/O crystal needles persist during spermatogenesis and are still found in sperm bundles. The crystal material seems to be a protein which is different from the tubular protein. 7. The possibilities of the involvement of the Y-chromosome in the formation of the metabolic chromosomal structures are discussed. It seems probable that tubuli represent a highly modified state of the Y-chromosome, or parts of this chromosome. The formation of protein crystals in X/O-spermatocytes indicates the presence of a biochemical block. The relation to fertility i.e. sperm motility is unclear. X/YL males do not produce motile sperms although tubuli are regularly present in spermatocyte nuclei.

Notes: Abstract Absolute intensity measurements of the electrons scattered by a polycrystalline Aluminium foil were carried out in the energy range between 25 and 50 keV. The electrons scattered elastically were separated from those scattered inelastically by means of a retarding field. The intensities of the electrons having passed the foil unscattered and of those which were scattered elastically into the Debye-Scherrerrings and into the continuous background can be interpreted by the assumption of reasonable thicknesses of the crystalline Aluminium and the amorphous Aluminium-Oxide. These values agree approximately with the thickness measured by light absorption. Additionally the probability of the inelastic scattering process can be deduced from these measurements. Investigations of the angular distribution were carried out in order to study the influence of the inelastic scattering on the shape of the primary beam, the rings and the continuous background. The results are discussed in detail. Some results are given in particular, concerning the increase of the half width of the rings due to inelastic scattering processes.