SUMMARY1. In pentobarbitone-anaesthetized cats, responses were recorded in peripheral nerves or cervical dorsal columns from sensory fibres associated with Pacinian corpuscle (P.c.) receptors in the forelimb footpads. Factors affecting the phase of response to cutaneous vibration in individual P.c. fibres, and the extent of phase coherence in the responses of different P.c. fibres were examined when sinusoidal vibratory stimuli at 100-400 Hz were delivered using a 1 mm diameter probe.2. Increases in vibration amplitude from the absolute to the 1 : 1 threshold for the P.c. fibre led to phase advances in the response, often of about 60 deg, in over 850 of fibres tested at 200 and 300 Hz, but further increases had little effect.3. Variations in stimulus position within the receptive field led to unpredictable changes in the response phase that ranged from minimal change to shifts of 180 deg. As the response phase was unrelated to the distance from the point of peak sensitivity it is likely that at high vibration frequencies ( > 100 Hz) the recruited population of P.c. fibres will respond over the whole range of phase angles.4. The calculated phase of spike initiation in different pairs of P.c. fibres that shared coincident points of best sensitivity on the skin ranged from near synchrony to maximum asynchrony indicating that there is little phase coherence even in the subpopulation of somatotopically related P.c. fibres recruited by high-frequency cutaneous vibration.5. Paired recordings from P.c. fibres within the cervical dorsal columns revealed a broad range of phase discrepancies in the responses of P.c. fibres to vibration at 200 and 300 Hz.6. Several hypotheses are considered to explain the known presence of phaselocked responses to high-frequency ( > 100 Hz) vibration in the central neurones of dorsal column nuclei.

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Lead(iv) acetate was found to be a suitable dehydrogenating agent for the preparation of 6H-benzofut.o[3,2-c] benzopyran from its 6a,ll a-dihydro-derivative. The product was also synthesised independently. A scheme for the chemical interconversion of the 6H-benzofuro[3,2-c] benzopyrans and the related isoflavonoids is suggested. 10 Brink and his associates used DDQ to cyclise (+)homoedudiol to neorautenol and to dehydrogenate 2',3'-dihydroneoduleen to neoduleen. The low yields

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