182 



LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



Burdach's column can be made out, but later, in the ninth foetal 

 month, the decussation of the fibres from the nuclei of Goll's 

 tract can also be seen. 



Let us compare the accompanying cut with Figs. 107 and 

 108. Behind the central canal lies the gray matter, which, at 

 this level, has become very much expanded laterally. In the 







FIG. 109. 



Section through the commencement of the medulla oblongata taken from a human 

 embryo of the 20th week. Notice the tracts from the columns of Burdach to the decus- 

 sation of the fillet, and the fibrae arciformes externse posteriores from the column of 

 (ioll, which will be described later on. Observe the situation of the direct lateral cere- 

 bellar tract. 



Kldnhim BaJin, CerebeHar tract. 

 Vorderhurn, Anterior horn. 



Oliv.-Zwwch.-ScTiicht, Inter-olivary layer. 

 Vordnr-Stranij-Bent, Remains of anterior column. 



funiculi gracilis et cuneati their respective nuclei have appeared, 

 and both are continuous with the gray matter. External to these 

 lies the substantia gelatinosa of the posterior horns, surrounded 

 by a thin stratum of medullary fibres (ascending root of fifth 

 nerve). The space in front of them, which, in Fig. 108, is oc- 

 cupied by the dark pyramidal fibres, appears clear because these 

 fibres have not yet become medullary. The remnant of the 



