Page:Proceedings of the Royal Society of London Vol 69.djvu/225

Rh Addendum on the Pyramidal Tracts. By C. S. SHERRINGTON.

The spinal degeneration resulting from ablation in the precentral gyms of the above-mentioned "hand "-area, discovers in the anthro- poid cord the human feature of a perfectly large direct ventral (Tiircksbiindel) as well as crossed pyramidal tract. The relative sizes of these tracts seem about the same as in man.

The homolateral or uncrossed lateral division of the pyramidal tract is also well seen. The crossed pyramidal degeneration from the hand area lesion is clearly traceable down to the lumbar region of the cord. In the lowest brachial segments there is obvious degeneration of fibres in the grey matter of the ventral horn of the crossed side. Some of the large nerve-cells there seem also degenerate.

A lesion at the top of the gyms precentmlis gave no ventral pyra- midal tract degeneration, and only a very slight uncrossed lateral pyramidal, although an extensive crossed lateral, that descends the whole length of the cord.

This expedition was one of those organised by the Joint Permanent Eclipse Committee of the Royal Society and Royal Astronomical Society, funds being provided from a grant made by the Government Grant Committee.

It was originally contemplated that the party should consist of Professor H. H. Turner and myself, and that we should occupy a station inland in Sumatra ; but when the former found himself unable to join in the expedition, it was decided not to appoint another observer in his stead, nor to fix upon the station to be occupied until there was an opportunity of learning about local conditions on the spot.

The expedition was to go to Padang, on the West Coast of Sumatra, and to this port I travelled in company with Mr. F. W. Dyson, who went out from the Royal Observatory, Greenwich. It was decided that we should travel out together, prepared either to join forces at one and the same camp, or to form two camps separated by a considerable distance, and our ultimate decision was to depend upon information which we expected to get from the Dutch authorities.

I had communicated with Major Muller, the Chief of the Survey