The size of the great sciatic nerve renders complete laceration by a bullet of small calibre a matter almost of impossibility; hence complete division may almost be left out of consideration in the case of this nerve. On the other hand, partial division, perforation, and severe contusion are each and all favoured by the same factor. With an extended thigh the nerve is in a state of comparatively slight tension, and this may be still lessened if the knee be flexed. This factor, together with the density of the sheath of the nerve, favours the possibility of displacement, and this occurrence is more likely in the lower segment than in the upper, which is comparatively fixed in position. Clinical experience appeared to illustrate the importance of these anatomical factors, as the worst cases of sciatic injury that I saw were in connection with wounds of the buttock or the junction of that segment of the trunk with the thigh. The most striking observation with regard to the injuries of the great sciatic nerve was the comparatively frequent escape of the popliteal element and the severe lesion of the peroneal. This was so pronounced as to amount to as high a proportion of peroneal symptoms as 90 per cent., and often when the whole nerve was implicated the popliteal signs were of the irritative, the peroneal of the paralytic type. When bullets crossed the popliteal space, given wounds of equal severity in corresponding degrees of contiguity to the respective nerves, the peroneal element always suffered in greater degree. Again, the peroneal nerve symptoms were more obstinate and prolonged, and instances of ascending neuritis were more common than in the case of any other nerve of the lower extremity, and the trophic wasting of muscles was more marked. The peroneal nerve, therefore, acquires the same unenviable degree of importance in the lower extremity enjoyed by the musculo-spiral in the upper. Here, again, we are confronted with the fact that the peroneal element of the great sciatic nerve is the more prone to idiopathic inflammations or toxic influences, and hence we can only assume it to possess a special vulnerability. The peroneal element is of course somewhat the more exposed, as lying posterior; but it seems unreasonable to assume that so large a proportion of the injuries can implicate the posterior segment of the nerve as to make the startling difference in the incidence of degeneration explicable. In this relation we may bear in mind that the muscles supplied by this nerve suffer most in the degeneration subsequent to anterior polio-myelitis, and again that in cerebral hemiplegia or spinal-cord injuries they are the last to recover. Unfortunately no explanation of these remarkable facts, so forcibly impressed by the large series of cases with peroneal symptoms seen in a short time, is forthcoming.