274 



DETAILED SYNTHESIS. 



form of the skull and the different constitutions of its 

 three tables ; by the membranes within and on the out- 

 side of the skull ; by muscles ; by the skin, and by the 

 hair. 



657. IF A PORTION OF THE UPPER PART (Cerebrum) 

 OF THE BRAIN is SLICED OFF, the gray external tissue is 

 found to be only about an eighth of an inch thick, with- 

 in which the white tissue alone is found. 



658. IF THE GRAY SUBSTANCE SHOULD BE REMOVED 



FROM THE WHITE and spread out, it would present a fig- 

 ure several times larger than it now does ; that is, the 

 pia mater is several times the extent of the arachnoid. 



659. IT WILL BE OBSERVED that in the fissures the 

 convolutions are proportionately as numerous and the 

 anfractuosities as deep as described in ^[ 642. 



660. THE PROBLEM SOLVED BY THE ARRANGEMENT 



Fia I'.H. 



Fig. 191 represents the 

 brain sliced a little lower 

 than in the preceding figure. 

 1, the white tissue; 2, the 

 gray; 3, 4, the front and 

 back portions of the bridge 

 or corpus callosum, the mid- 

 dle portion being removed 

 and exposing the ventricles, 

 in which, and forming the 

 sides and floor of which, 

 ganglia are seen. Portions 

 of the brain are cut out to 

 show 7 and 6, extensions of 

 the ventricles; 8 is one of 

 the largest ganglia, and from 

 the white and gray substance 

 being in alternate layers, it 

 appears striped, hence its 

 name, striated body (corpus 

 striatum); 19, portion of 



thalamus; 14, hippocampus; 18, a plexus of capillary vessels (the choroid 



plexus). 



657. What ? 658. What extent of surface could be shown ? 659. What 

 in fissures? 660. What is - ? Dscribe Fig. 191. 



