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Cyclopropanation of allylic tertiary amines using the Simmons−Smith reagent has been achieved by employing chelating groups in close proximity to the amine. The chelating groups promote cyclopropanation at the expense of N-ylide formation. Using pseudoephedrine as the chelating group, high diastereoselectivity is observed.

Zinc-complexed methylene ammonium ylides are formed from tertiary amines and the Simmons−Smith reagent. These stable entities can be activated with n-BuLi to allow reactions typical of ammonium ylides such as [2,3] rearrangements. In the case of oxazolidine 12, ylide formation, activation, and subsequent [2,3] rearrangement was highly efficient and occurred with very high diastereoselectivity.

The practicalities of the asymmetric hydrogenation of acetophenone derivatives are addressed. The catalysts used, derived from the precatalysts [(xylylPhanePhos)RuCl2(DPEN)] (S)-(R,R)-1 and (R)-(S,S)-1, were shown to possess very high reactivity. 4‘-Fluoroacetophenone was hydrogenated at a molar substrate-to-catalyst ratio (S/C) of 100,000 with complete conversion effected in as little as 80 min (average turnover ~1200 min^-1, peak turnover ~2500 min^-1). The catalysts are tolerant of a range of commercial grade substrates, in most cases a S/C of 5000−10000 was achieved without the need to purify the ketone. Using precatalyst 1 enantioselectivities of 95 → 99% ee were achieved. The high selectivity and catalyst activity, plus the simplicity of the process, offers significant advantages over other enantioselective ketone reductions.

The acroblast of Helix spermatids is a duplex structure: it consists of an ‘externum’ (which appears dark by positive phase-contrast microscopy and becomes impregnated with osmium) enclosing a region called the ‘internum’. Histochemical studies show the externum to be composed principally of phospholipid and to contain glycolipid, alkaline phosphatase, and an enzyme which splits thiamine pyrophosphate. The internum contains neutral mucopolysaccharide. Ribonucleic acid and acid phosphatase are not present in the acroblast. These histochemical results suggest a homology between the invertebrate acroblast and the Golgi apparatus in vertebrate cells.

The three kinds of lipid globules recognizable in the living neurones of Helix aspersa have been examined under the electron microscope. The globules of the kind that can be stained blue with methylene blue during life are seen in electron micrographs as spheres or spheroids, with concentric lamination, after calcium-osmium fixation. After fixation with sucrose-osmium laminated crescentic bodies are seen instead; these appear to be formed by distortion of the ‘blue’ globules. The yellow globules contain electrondense material, and sometimes appear reticular. It is possible that the yellow globules may originate by transformation of some of the ‘blue’ globules. The colourless globules generally appear as crenated objects; this appearance may be a shrinkage artifact. Apart from the mitochondria and the three kinds of lipid globules described, no other object large enough to be identified with the light microscope has been seen in the cytoplasm.

The fibrocytes and the fibres of Hirudo medicinalis have been studied with the electron microscope. The fibrocyte can be shown by other methods to contain triglyceride droplets, phospholipid droplets, and mitochondria, all of which can be recognized in the electron micrographs. In addition, a ‘vesicular’ component has been observed just below the cell surface. The collagenous ‘cortex’ of the fibre is tubular, and can be shown to contain a long process of the cell which secretes it. There are many small fibrils about 250 Å in diameter comprising the cortex of the fibre; they lie along the fibre axis, and often are associated in pairs or groups of three or four. These fibrils sometimes show a poorly defined periodicity of 300 Å. It seems that the fibrils ‘shred off’ from the surface of the fibrocyte. The process shows some resemblance to that described in the chick by other authors.

The classical site of the ‘Golgi apparatus’, the Purkinje cells of the cerebellum of owls, has been examined by electron microscopy. The greater part of the cytoplasm consists of aggregates of closely packed granular membranes ofendoplasmic reticulum. The objects described by Dalton and Felix in electron micrographs and called by them the Golgi apparatus are rarely seen in these preparations. It seems likely that the ‘Golgi apparatus’ of this cell as seen in the optical microscope is formed by the deposition of silver or osmium on the membranes of the endoplasmic reticulum, which form a network throughout the cytoplasm of this cell.

The action of buffered potassium permanganate as a fixative for electron microscopy has been investigated. Electron contrast has been shown to be produced by the deposition of granular material in the tissue. The particles are about 50 Å in diameter. Actual fixation of the tissue is performed by the dehydrating alcohol. Histochemical studies have shown that RNA and histones are removed, whereas phospholipid-protein complexes are ‘unmasked’. The reaction of the permanganate with unmasked protein gives rise to high membrane contrast in electron micrographs.