MODEL OF MEDULLATED TRACTS IN BABY's BRAIN 119 



tivum passing through the red nucleus. Emerging from the cere- 

 bral end of the red nucleus is a great mass of medullated fibres 

 (see fig. 3), which soon divides into two bundles, a dorso-lateral 

 mass which is Forel's BaTh, (no. 12), and a more ventral and 

 medial bundle which is Forel's Feld H. The dorso-lateral bundle 

 which is Forel's BaTh is a composite of possibly three elements, 

 first, a part of the medial lemniscus, secondly, possibly fibres 

 from the red nucleus and thiidly, a small bundle (no. 16), which 

 comes from the nucleus colliculi inferioris and runs to the center 

 median of Luys. This bundle is readily seen in its connections 

 in the section of the baby's brain in fig. 7, no. 16. It is readily 

 identified in sagittal sections of the adult by the angle the bundle 

 makes with the main mass of BaTh (see no. 12, fig. 7). The sec- 

 tion of the adult brain (fig. 8), is, however, just too far lateral to 

 show the two bundles as separate tracts. The bundle from the 

 inferior colliculus to the center median of Luys is described by 

 Dejerine,^ under the confusing name of "the arm of the inferior 

 colliculus," a term which should be reserved for the fibres con- 

 necting the inferior colliculus with the medial geniculate body. 

 Dejerine, however, makes the distinction, in fact, and notes, that 

 the bundle in question enters the center median of Luys. The 

 true brachium quadrigeminum inferius connecting the inferior 

 colliculus with the medial geniculate body is non-medullated at 

 birth, and lies farther lateralward so that it is seen only from the 

 side (no. 25, fig. 9). 



The bundle BaTh (no. 12), then consisting of a part of the 

 leminscus, the tract from the inferior colliculus and possibly of 

 fibres from the red nucleus enters the cup shaped nucleus (no. 

 15, figs. 8 and 11), and the center median of Luys (no. 14). 

 In connection wdth these nuclei it is interesting to note that 

 Sachs^ found that in degeneration experiments involving the 

 center median of Luys and the cup-shaped nucleus, there were 

 no efferent fibres to the cortex nor to the mesencephalon; that 

 the efferent fibres all ran to the other nuclei of the thalamus, 



* Dejerine, Anatomic d. centres Nerven, Tome 2, 1901, p. 72. 



* Sachs, On the Structure and Functional Relations of the Optic Thalamus. 

 Brain, August, 1909, vol. 32, page 146. 



