THE MESENCEPHALON OR MIDBRAIN 



615 



Before this Hensen and Volckers had observed, in substantial agreement 

 with the findings of v. Monakow., that stimulation at the posterior end of 

 the floor of the third ventricle gave movements of accommodation, and at a 



GrMK 



VngF 





FIG. 272. Frontal section through the anterior quadrigeminal body of a 32-34 weeks' human 

 fetus, after Bernheimer. The section passes through the lateral chief nucleus, the small- 

 celled medial nucleus (KeM), the large-celled median nucleus (Gr.MK), the extra-nuclear 

 course of the medial and lateral fibers (Ung F, and Ug. F) of the third nerve, and the last bit 

 of the extra-nuclear course of the crossed lateral fibers (GF). QGF, transverse sections of 

 crossed fibers arising from behind and above. 



