Sclerosis of the Cornu Ammonis in Epilepsy.—Dr. W. L. Worcester (Journ. Nerv. and Ment. Disease, April and May, 1897) details his experience as to the frequency with which this lesion is found when systematically searched for, and discusses its relation to the pathology of epilepsy. He prefaces his own observations by a summary of previous ones, dating from those of Meynert in 1868. From these it would appear that the preponderance of authority is in favour of the view that the lesion in question is a result rather than a cause of the convulsions observed during life. Worcester's experience is based upon the appearances presented by the brains of forty-three epileptics, which he examined at the Arkansas and Danvers Asylums. In only nineteen of these was there an absence of any gross cerebral lesion. The one under consideration, namely, sclerosis of the cornu ammonis, was present on one or both sides in twenty cases, in eleven of which no other abnormality was found; while in nine it was accompanied by other and more extensive lesions which he believed had a common origin with it; and this association appeared to him to throw light on the nature of the connection between it and convulsions. Of these associated abnormalities the most frequent he found to be microgyria of an entire hemisphere. The histological characters of the diseased cornu ammonis seemed to have been remarkably uniform, and consisted of a general sclerosis, involving destruction of the neurons having their origin in the stratum pyramidale and nucleus fasciæ dentatæ. Such a condition the writer failed to note in a series of over a hundred and fifty brains of insane patients, save in those of epileptics. Exception, however, must be made to this generalisation, for the case of a patient dying subsequently to the printing of this monograph. It was that of a general paralytic in whom there was no history of epilepsy, nor had he suffered at all from convulsions; yet after death changes were noted identical with those above described. Still, the frequency of this condition in epileptics and its great rarity in those not subject to this disease, would seem to place it beyond the pale of mere coincidence. The question is whether the epilepsy causes the anatomical changes or they the epilepsy. The chief reason why the former view is held by the majority appears to be due, rather to the improbability of this convolution, from anything that is known, having any special relation to epilepsy, than to any definite theory as to the way in which epilepsy could bring about such changes in a single convolution. The writer himself would rather lean to the supposition that the condition of the cornu ammonis is the cause of the convulsions. In support of this view, he cites the fact that it is known that a cicatrix of the cortex may act as a focus of irritation, and gives references of evidence proving that irritation of the temporal lobe may excite convulsions. He does not wish it to be understood that he believes in this convolution having any special prerogative in this respect, but rather that a scar in any part of the cortex may have such an effect. Neither, also, would he assert that all epilepsies originate in any part of the cerebral cortex, for the certainty that epileptiform convulsions may be due to peripheral irritations and to toxæmic conditions is too clear.