416 JOHN H. STOKES 



Three other groups of vestibular connections are usually de- 

 scribed, namely, the internal arcuate fibers from the medial and 

 spinal nuclei, a bundle from Deiter's nucleus to the spinal cord, 

 and two groups of cerebellar connections, the medial and lateral 

 bundles. These groups are not capable of satisfactory recon- 

 struction in the opossum, and in fact distinct cerebellar groups 

 could not be definitely identified. 



In general the vestibular complex of the opossum corresponds 

 quite closely to the general conception outlined above. Several 

 points, however, require special notice. 



From time to time in the literature relating to the nuclei of 

 the floor of the fourth ventricle, stress has been laid upon the 

 separate anatomical identity of the nucleus intercalatus, and its 

 relation to the medial vestibular nucleus. A considerable number 

 of authorities regard the former as part of the latter. In a recent 

 paper ('03), already referred to, on the floor of the fourth ventri- 

 cle, Streeter in endeavoring to correlate external and internal 

 topography, discusses the status of the nucleus intercalatus. After 

 reviewing the opinions since Staderini and van Gehuchten, he 

 directs attention to the fact that Weigert preparations of the 

 human brain give no ground for differentiating the two. Other 

 methods of investigation however, show the question to be less 

 easily settled. He advances as evidence for giving the nucleus 

 intercalatus an identity of its own, among other things the exist- 

 ence of a neuroglia partition between it and the medial vestibular 

 nucleus, demonstrable by special neuroglia stains, and also certain 

 evidence from a brain in which one half of the cerebellum was con- 

 genitally absent, in which degenerative changes tending to estab- 

 lish the separateness of the two nuclei could be demonstrated. 

 This same question came up at the outset in the reconstruction 

 of the medial vestibular nucleus in the opossum. The use of 

 Weigert preparations may of course lay the work open to the 

 objection pointed out by Streeter, and the writer makes no pre- 

 tence of urging the finality of his conclusions on this point from 

 such evidence. None the less, he is obliged to confess that the 

 preparations upon which this work has been done offer not the 

 slightest excuse for differentiating the nucleus intercalatus from 



