Technical Note

In routine work in neural pathology it is ohen desirable to harden portions of the central nervous system in bulk, and to preserve the tissue in such a way as to make it suitable for subsequent microscopical Study. The necessity of precise fixation of delicate histological details is especially felt in the new line of cytological pathology in which the effects of certain diseases of the nervous system are to be sought in alterations of the ganglion cells. To meet these indications a comparatively cheap fixing fluid is demanded which will penetrate considerable masses of tissue with rapidity, which will produce a desirable degree of hardening, which will permit of subsequent staining by a variety of dyes, and, above all, which will faithfully preserve the most delicate structural details. The necessity for a reagent of this kind has been felt by the workers in the :Pathological Institute of the :New York State ttospita]s* in the treatment of the large amount of neurological material which is finding its way to this laboratory, and at present Lang's solution of corrosive sublimate is used, though it has not proven entirely satisfactory. A fresh human brain is subdivided after Meynert's method, placed in the sublimate solution for 48 hours, washed in running water, and treated with ascending alcohols till a strength of 80 per cent is reached. Tincture of iodin is added to exhaust the sublimate. The chief drawback to this otherwise excellent