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Two new preparation techniques for total-reflection X-ray fluorescence (TXRF) element determination of single freshwater crustacean specimens (dry weight: 3–40 μg ind−1) have been developed and tested using Daphnia pulex from a deep, oligotrophic freshwater lake located in southern Chile. Dry method: Specimens were washed with 0.2 μm filtered lake water and frozen in liquid nitrogen. The freeze-dried Daphnia specimens were weighed using an ultra-fine microbalance and placed on quartz glass carriers for TXRF analysis. Wet method: Specimens were washed with 0.2 μm filtered lake water and placed on quartz glass carriers for TXRF analysis and dried in air. The dry weight was determined using the previously established body length–dry weight relationship. Method validation for both the dry and the wet preparation method in combination with TXRF spectrometry for the element determination in small single freshwater crustaceans showed that both methods can be used for routine investigations. There were no significant differences between the dry and the wet methods concerning the elements Ca, K, Fe, Zn, Br, P, Cu, but the determination of Mn, S and Sr revealed significant differences between the two methods. It seems that the dry method yields more precise results, but the wet method is easier to handle in the field when samples cannot be fixed with liquid nitrogen.

Es wird erstmalig der Versuch gemacht, die Vitamin A-Versorgung der deutschen Bevolkernng zahlenmasig zu erfassen. Die durchschnittliche Tagesaufnahme an Vitamin A betragt mindestens: bei der Stadtbevolkerung 2–3, Landbevolkerung 3–5, bei der Wehrmacht 3–5, Klinikkost 3. Klasse 4–5 mg β-Carotin. Es wird erortert, wieweit die Versorgung als ausreichend anzusehen ist.

Die durch UV.-Bestrahlung am Menschen erzielte Pigmentierung wird durch Vitamin C nicht beeinflust.

Der Vitamin A-Bedarf des Menschen wurde im Vitamin A-Mangelversuch am Gesunden (Selbstversuch) auf optimal etwa 5,9 mgβ-Carotin=9800 IE. taglich festgestellt. Die Zone des A-Mangels von der leichten Hypo- bis zur schweren Avitaminose ist am Menschen dank dem grosen Speicherungsvermogen fur A sehr gros. Die A-Vorrate des Menschen reichen fur mehrere Monate aus; die leichte Hypovitaminose beginnt jedoch sehr fruh. Die Konsequenzen der Ergebnisse und Berechnungen werden besprochen.

Recently, a number of soil samples isolated from geographically distinct regions in the Asgard Range-Vanda Lake area of the Antarctic, were shown to contain living microorganisms which displayed bacterial-like morphologies. The microorganisms isolated from these samples were observed to have heterogeneous structural characteristics ranging from those with “typical” Gram - or Gram + morphologies, to those with “unique” morphologies which may be intermediate to the eubacteria and lower algae.Cell pellets prepared from the various soil samples were rinsed in phosphate buffered saline and fixed in Dalton's Chrome Osmium. These were then post-fixed in aqueous Uranyl Acetate, dehydrated in a graded alcohol series, and then embedded in Epon for electron microscopy. Examination of these preparations revealed the existence of several distinct morphologic types of bacterial-like microorganisms.