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Table XV.-Mean Length of Telson for observed Values of Total Carapace Length. (Plymouth: 1000 individuals.)

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Table XVI.-Value of Total Carapace Length for observed Length of Telson. (Plymouth: 1000 individuals.)

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Table XVII.-Mean Length of Telson for observed Values of Total Carapace Length. (Southport: 800 individuals.)

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Table XVIII.-Mean Value of Total Carapace Length for observed Lengths of Telson. (Southport: 800 individuals.)

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Table XIX.-Mean Length of Sixth Abdominal Tergum for observed Lengths of Telson. (Plymouth: 1000 individuals.)

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Table XX.-Mean Length of Telson for observed Lengths of Sixth Abdominal Tergum. (Plymouth: 1000 individuals.)

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Table XXI.-Mean Length of Sixth Abdominal Tergum for observed Lengths of Telson. (Southport: 800 individuals.)

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Table XXII.-Mean Length of Telson for observed Lengths of Sixth Abdominal Tergum. (Southport: 800 individuals.)

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II. "An Experimental Investigation of the Nerve Roots which enter into the formation of the Brachial Plexus of the Dog." By J. S. RISIEN RUSSELL, M.B., M.R.C.P. Communicated by Professor VICTOR HORSLEY, F.R.S. Received February 18, 1892.

(From the Physiological Institute of Berlin and the Pathological Laboratory of University College, London).

(Abstract.)

The subject is introduced by an allusion to the attempts that have been made by anatomists to determine the functional relationships between the nerve roots and groups of muscles they supply, in which connexion the work of Krause, Schwalbe, Herringham, and Paterson are cited. A brief reference is made to the observations of Erb, Duchenne, Knie, and Thorburn, after which the author refers to the experimental work that has been done in this field by Müller and Van Deen, Kronenberg, Panizza, Peyer, Krause, Ferrier and Yec, Bert, Marcacci, and Forgue. The anatomical accounts of the brachial plexus of the dog as given by Ellenberger and Baum, Chauveau and Arloing, and Forgue are quoted, the discrepancies which exist between these different accounts pointed out, and the author's own experiences in this connexion, differing in some points, while agreeing in others, with the descriptions given by these observers, are detailed.

He then proceeds to explain his methods of experimentation, which consisted in:

1. Observation of the compound movements in the fore limb of the dog by electrical excitation of the peripheral end of the whole of a cervico-brachial nerve root which had been previously exposed and divided.

2. Minute differentiation obtained by electrical excitation of the individual bundles composing such a nerve root.

3. Direct observation (after dissection) of the muscles thrown into action by electrical excitation of the separate nerve roots. As a corollary to this, the question as to whether or no a single bundle of fibres representing a single simple movement in a nerve root ever remaius distinct in its course to the muscles it supplies, without inosculating with other nerve fibres, is dealt with. A further point determined is whether, when a muscle receives nerve fibres from more than one cervico-brachial nerve root, both nerve roots supply fibres to one and the same muscle fibre or not.

4. Alteration in the action of the fore limb in progression or in standing, evoked by section of a nerve root or roots.

5. Influence of section of a root or roots in excluding part of a

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