The Mid-Winter Meetings. 183 



and its external medullated lamina. The bundles running to this nucleus represent 

 the main tract to the cortex, for from the lateral surface of the ventro-lateral nucleus 

 a large bundle of well-meduUated fibers passes to the cortex of the lower part of the 

 posterior central gyrus. The sensory path is almost entirely broken in the lateral 

 nucleus. The dorsal segment of the medial lemniscus, Forel's Bath, passes to 

 the centre median of LuY and to the cup-shaped nucleus. 



The motor path is medullated only down to the cerebral peduncle. It makes 

 connections with the lenticular nucleus, the hypothalmic nucleus and the substantia 

 nigra. The model shows that the motor and sensory paths are parallel throughout 

 the brain stem. The sensory path is always dorsal to the motor. In the medulla, 

 the paths are- adjacent, in the pons, they are separated somewhat by the cells of 

 the nuclei pontis; in the midbrain and hypothalmic region, the substantia nigra 

 and hypothalmic nucleus come in between the two paths, while in the thalamus 

 and subcortical regions, they are adjacent. 



In the thalamus, the nuclei that contain medullated fibers from the medial lem- 

 niscus are the lateral nucleus, the centre median of LuY, and the cup-shaped nucleus. 

 The lateral geniculate body and the pulvinar have medullated optic fibers, while 

 the medial and anterior nuclei contain no medullated fibers whatever. The fascicu- 

 lus retroflexus stands out very clearly, however, passing through the lower border 

 of the medial nucleus. 



Development of the Inter-forebrain Commissures in the Human Embryo. By 

 George L. Streeter, Wistar Institute of Anatomy, Philadelphia. 

 A morphological study of the corpus callosum, anterior commissure and the 

 commissure of the hippocampus, based on a series of wax-plate reconstructions 

 of human embryos varying from 80 to 150 mm. in length. All three structures 

 cross the median line in that portion of the brain wall developed from the lamina 

 terminalis. In 80 mm. embryos, the corpus callosum consists of a round bundle 

 of fibers lying directly on the commissure of the hippocampus, representing the 

 condition found in non-placental animals. The succeeding growth consists in the 

 lengthening of the fornix and caudal migration of the hippocampal commissure, 

 the latter remaining in close relation to the caudal end of the corpus callosum, 

 which, in the meantime, by increase in number of fibers has extended anterior to 

 the anterior commissure and posterior so as to deck over the region of the third 

 ventricle. The formation of a cavity in the septum lucidum occurs in embryos 

 of about 95 mm. The anterior or olfactory division of the anterior commissure 

 does not enter the olfactory bulb but is traced to the cortex dorsal to the bulb. 



The Relations of the Frontal Lobe in the Monkey. By E. LiNDON Mellus, 



Anatomical Laboratory, Johns Hopkins University. 



The Terminal Distribution of the Eighth Cranial Nerve in Man. By Joseph H. 

 Hathaway, Cornell University Medical College, Ithaca, N. T. 



Statistical Studies of the Brachial Plexus in Man (A Preliminary Note). By 



Abram T. Kerr, Cornell University Medical College, Ithaca. 



These studies are based on the record of 175 plexuses dissected and drawn by 



students, mostly in the Johns Hopkins Medical School, some in Cornell. The 



records were verified in order of time by Drs. Elting, Bardeen, and Kerr. This 



