236 



BIOLOGICAL PHYSICS 



as well as of its sympathetic partner; as an example of that 

 provision, there is established a system of discharging, 

 from within the systemic nervine structures, the results of 



.m it 



fit 



IV.V 



FIG. 98. LATERAL VIEW OK THE BRAIN OF AN EMBRYO CALF OF 5 CM. 

 (From Balfour, after Mihalkovics.) 



The outer wall of the left hemisphere is removed to show the interior of the lateral 

 ventricle ; /is, cut wall of the hemisphere ; sf, corpus striatum ; am. hippocampus 

 major; r/, choroid plexus of ventricle; fm, foramen of Monro; op, optic tract; 

 in, infundibulum ; nib, mid-brain; cb, cerebellum; iv.v, roof of fourth ventricle; 

 ps, pons Varolii ; with fifth nerve and Gasserian ganglion. 



structural " tear and wear," and, so, of maintaining a con- 

 dition of intra-cerebro-neural health and material sweetness, 

 of the whole nervature. 



FIG. 99. BRAIN OF THE HUMAN EMBRYO OF THREE MONTHS. NATURAL 

 SIZE. (From Kolliker. ) 



In i the view is from above, the upper part of the cerebral hemispheres and mesence- 

 phalon having been removed, f, fore part of the divided wall of the hemisphere ; 

 _/', hind part of the same which becomes the hippocampus turned in ; cst, corpus 

 striatum ; tho, thalamus opticus. 



In 2 the lower surface is represented ; to, tractus opticus ; and in front of this the 

 olfactory bulbs and tracts ; cm, single mass of the corpora mammillaria not yet 

 divided ; /, pons Varolii. The cerebellum and medulla oblongata, mo, are seen 

 behind and to the sides in both figures. 



These " ways and means " we have already described at 

 some length, so we here, only recall attention to the double 

 processes of differentiation and union which take place 

 simultaneously at the posterior and anterior extremities, 

 of the neurenteric canal. Thus, at the anterior extremity 





