316 



G. E. COGHILL 



R.M 



Aud.V 



R.VII' 



Fig. 22 Early flexure stage (No. 550, section 1-2-14). X 200 The plane of 

 section of this figure is illustrated in figure 16. It illustrates a longitudinal sec- 

 tion of the medulla oblongata, in which the entrance of the trigeminal root ap- 

 pears (R.V). There is a short ascending trigeminal tract {Tr.asc.V) and a 

 descending trigeminal tract {Tr.des.V) which reaches to the level of the middle 

 of the auditory vesicle (Aud.V) The ventricular pits opposite the entrance of 

 the roots are conspicuous features of such a section. 



Figs. 23 to 28 Early flexure state (No. 473, sections 1-5-14 to 19). X 500. 

 These figures are from six successive sections of the series from which figure 2 

 was made, and show the relations of the root bundles of the seventh and eighth 



