Connections of the red nucleus are complex and hard to elucidate in histologic series of the normal human brain. The difficulties arise from a number of natural conditions. The nucleus occupies a central position in the tegmentum, where it is closely surrounded by ascending and descending fiber tracts. In man the nucleus consists of three parts, of which the medial and lateral are greatly enlarged, while the large cells of the posterior part are markedly reduced in number.1 The posterior and lateral parts are traversed by a large mass of fibers of the brachium conjunctivum. Each of the three parts of the red nucleus is related to a descending fiber tract, only one of which, the rubrospinal tract, crosses near its origin. Moreover, the oral end of the red nucleus is enclosed in the prerubral field H, or nucleus campi Foreli, composed of neuropil and cells, which marks the