283 



As has been said, the first model is a series of sections. The 

 second shows the surface form on the one side, and the structures just 

 beneath the surface on the other. It corresponds to Plates I and II 

 in the Atlas. The third model is designed to show the motor cerebral 

 nuclei and nerves on the one side and the sensory on the other as 

 in Plates III and IV of the Atlas. It relates the gray matter of the 

 cord to that of the medulla. The fourth shows the deeper structures 

 which make the foundation as frame work, namely the medial and 

 lateral lemnisci, the corpus trapezoideum, and the fasciculus longi- 

 tudinalis medialis. It relates the white matter of the cord to that of 

 the medulla. 



Comm.coliinf. ^rach-.conj. 



VentriculusQuartus. 



' ^Tu.fun-cun. 



Fig. 1. 



In as much as the model was made from the brain of a new-born 

 babe, some of the fibre tracts are not yet medullated. The most im- 

 portant of these are the pyramids and the brachium pontis. These 

 two structures lie near the surface, however, and are easily shown 

 schematically. The course of the pyramidal tract is shown by heavy 

 wires on models II and IV, while the position of the brachium pontis 

 is indicated on model II. 



The first model consists of six sections, so mounted as to cor- 

 respond in position with models II — IV. The outlines of this sections 

 are drawn on model II. 



The drawings of the sections correspond with a series of sections 



19* 



