Notes: Zusammenfassung Es wird eine Technik für die doppelseitige Entfernung der Nierenpapille bei der Ratte beschrieben, nebst Erscheinungen die als Operationsfolge sofort und stationär auftreten.

Notes: Abstract Times to passivation have been measured for zinc electrodes in KOH-KF solutions at room temperature. A linear relationship betweeni andt −1/2 was obtained. The intercept of these lines is interpreted to be a limiting current density. This limiting current density reaches a maximum in solutions 5M in KOH. Beyond this concentration the limiting current density decreases. This phenomenon is explained in terms of the loss of unbound water as the ionic strength of the solution increases.

Notes: Summary With Baker's acid haematein test certain ganglion cells in the brain, their processes and, at some sites, glial cells around blood vessels stain dark blue. This article describes a study of the Baker-positive cells which occur in and around the neurosecretory nuclei. By substituting formol-calcium fixation with glutaraldehyde-formol-calcium fixation shrinkage in brain tissue is completely avoided. If such fixation is used the argument that positive staining of ganglion cells with Baker's method only indicates that these are “shrunken neurons” can no longer be maintained. A comparative histological study, especially of Baker's technique and “controlled chromation” (Elftman) showed that the Baker-positive cells contain a phospholipid, probably bound to a protein, as a labile compound, which is easily lost. We found that to immobilize and localize this labile compound in the ganglion cells the technique of fixation and the pH during chromation (which should be around 3.8) are of fundamental importance. Only under these conditions is the complex sufficiently immobilized to allow of its demonstration with acid haematein. These requirements are now completely met if Baker's acid haematein technique is used. The article stresses that only prefixed and chromated frozen sections can be used for this method, thus avoiding shrinkage and non-specific staining of proteins. The modified Baker method as used by us gives constant and reproducible staining and is described in this article. The functional significance of the Baker-positive reaction in some ganglion cells in the n. s. nuclei or glial cells around blood vessels is not dealt with in this article.

Notes: Summary This paper presents a description of ganglion cells in the neurosecretory nuclei (s.o.n. and p.v.n.), which stain positively by the Baker technique for demonstration of phospholipids. These cells differ from the other cells in these nuclei, which have a more rounded shape and remain completely unstained. Even with iron-haematoxylin these cells are demonstrable. In a study of serial sections these black-staining elements were identified as ganglion cells, not astrocytes. Moreover the Baker-staining cells are possibly identical with the ganglion cells staining homogeneously dark with aldehyde-fuchsin, and often showing a spindle shape and a pyknotic nucleus. In addition to the cells themselves, their processes also stain by the Baker technique. These myelinated processes can often be followed over a considerable distance, passing as they do between the non-staining ganglion cells without forming synaptic junctions. The question is raised whether these Baker-positive cells are ganglion cells which have a separate function in the neurosecretory nuclei, or whether they are lipid-loaded cells which must be regarded as a stage in the cycle of neurosecretion. Apart from the neurosecretory nuclei, it is possible by these staining techniques to demonstrate that throughout the CNS positively staining ganglion cells with their processes occur alongside non-staining ganglion cells. Examples of this were found in the cerebral cortex, the cerebellar cortex, in which the Purkinje cells with their most delicate processes stain, and the cortex of the hippocampus. In slides of the hypothalamus fixed according to Pfuhl, the large neurosecretory ganglion cells frequently contain granules or droplets which stain red with aldehyde-fuchsin, and granules forming the pearl-strings outside the neurosecretory nuclei. These granules, however, cannot be stained with iron-haematoxylin or by the Baker technique. The ganglion cells discussed in this paper stain well with iron-haematoxylin in these Pfuhl-fixed specimens. This indicates a difference between the substance in the granules in the large, round neurosecretion-forming ganglion cells and the pearl-strings, and that in the dark staining cells. Our conclusion is that the neurosecretory nuclei contain two different types of cells. We do not share the view that the Bakerpositive cells are merely shrinking artefacts in the sense used by Scharrer and Cammermeyer.