THE SUBTIIALAMIC REGION, ETC. 



121 



lectures without demonstrating to you a specimen which has a 

 bearing upon this subject. 



In Fig. 70 we have a section through the anterior quadri- 

 geminal body, close to the posterior commissure, from a child 

 born during the ninth fcctal month. Every one of the fibres 

 which are medullary at this period is stained black by hsema- 

 toxylin. 



You will easily make out the features which we have just 

 described. Here your attention is, for the first time, called to a 



"Trut opt. 



FIG. 70. 

 Frontal section through the anterior quadrigeminal body of a 9 months' foetus. 



Bint. Langsb., Posterior longitudinal fasciculus. 0. S., Upper fillet. U. S.. Lower fillet. 



little circular bundle of transversely divided fibres lying between 

 the red nuclei, and marked b. It arises in the ganglion habe- 

 nulse and passes backward to a small ganglion which lies be- 

 tween the crura cerebri, and is called the ganglion inter- 

 pedunculare. In that situation the fibres decussate with those 

 of the opposite bundle before entering the ganglion. This 

 bundle is called the fasciculus retroflexus, or Meynert's bundle. 

 Its course is shown in Fig. 71. Compare also Fig. 59. 



You see in Fig. 70 a mass of fibres belonging to the lem- 

 niscus and passing around outside the red nucleus to the region 

 over the substantia nigra. In the crusta there is at the ninth 



