Untersuchungen über den chemischen Sinn beim schwarzen Kolbenwasserkäfer Hydrous piceus

Ohne ZusammenfassungDissertation der Philosophischen Fakultät II. Sektion der Ludwig-Maximilians-Universität München.     

Action dichroism in perception of vectorial photo-excitation in the solar-tracking leaf ofLavatera cretica L.

The leaf lamina ofLavatera cretica L. exhibits a diaphototropic response that discriminates between two opposite, constant vectorial excitations by white light beams whose fluence rates differ by as little as 10% (50 versus 45 μmol·m⁻²·S⁻¹). The relationship between the response (angular velocity of laminar reorientation) and the fluence-rate ratio is linear. The lamina similarly discriminates between two such excitations by polarized light, one with the electrical vector transverse to the plane of the two beams (θ) and the opposite one with the vector parallel to that plane (⪙). When two such beams were of equal fluence rate, the lamina reoriented towards the ⪙ beam. When the fluence rate of the θ beam was maintained at 50 μmol·m⁻²·s⁻¹ and that of the ⪙ beam was reduced, the response to the latter (angular velocity of laminar reorientation) was reduced progressively. Further reduction in the fluence rate of the ⪙ polarized beam eventually resulted in reorientation in the opposite direction (towards the θ beam) and the response to the latter increased progressively with the reduction in fluence rate. The equilibrium was at a ⪙/θ ratio of 0.62. Measurements of reflectance of oblique beams of ⪙ and θ polarized light from the upper laminar surface, and of transmittance of such light ghrough the lamina, eliminated the possibility that optical dichroism of the lamina contributed significantly to these results. The implications of this action dichroism to the postulated mechanism of perception of vectorial excitation by these leaves is discussed. Dedicated to the 60thbirth day of Professor Hans Mohr     

Effect of pteridines on normal and neoplastic cell lines of Xiphophorus

The effect of three pteridines namely biopterin, isoxanthopterin and xanthopterin on cell growth, viability and morphology of three embryo and one melanoma derived cell lines was studied. Pteridines were assayed in the range of 10(-6) M to 10(-4) M. Biopterin exerted no influence on all cell lines tested, whereas isoxanthopterin and xanthopterin caused a decrease in growth rate with increasing concentrations. The strongest decrease of cell growth was exerted by 10(-4) M xanthopterin. Furthermore at this concentration xanthopterin reduced the viability of normal cells and influenced the morphology of both normal and neoplastic cells. In general, normal cells were more sensitive to pteridines than neoplastic cells.     

Ueber das Vorkommen derZahlbrucknera paradoxa Rchb.

Ohne Zusammenfassung     

Ueber den Geruch der Pflanzen

Ohne Zusammenfassung     

Besteigung des Hochgolling's

Ohne Zusammenfassung     

Ueber die Umgrenzung der Pflanzenformationen

Ohne Zusammenfassung