1GG THE HUMAN BODY. 



of the cerebral hemispheres. The front ends of these two 

 ventricles are seen in the vertical transverse section of the 

 brain represented in Fig. G8. 



The ventricles contain a small amount of cerebro- spinal 

 liquid and are lined by epithelium which is ciliated in 

 early life. 



Note. A frequent cause of apoplexy is a hemorrhage into 

 one of the lateral ventricles; the outpoured blood accu- 

 mulating and pressing uppn the cerebral hemispheres their 

 functions are suppressed and unconsciousness produced. 

 When a person is found in an apoplectic fit therefore the 

 best thing to do is to leave him perfectly quiet until medi- 

 cal aid is obtained: for any movement may start afresh a 

 bleeding into the ventricle which had been stopped by clots 

 formed in the mouths of the torn blood-vessels. 



Sections of the Brain. Having got a general idea of 

 the parts composing the brain, the best way to complete a 

 knowledge of its anatomy is to study sections taken in 

 various directions. Two such are given in Figs. 68 and G9. 

 Fig. 69 represents the right half of a vertical section of the 

 brain, taken from before back in the middle line and viewed 

 from the inner side. Above, the knife has passed between 

 the two cerebral hemispheres, in the longitudinal fissure, 

 without cutting either, and the convoluted inner surface of 

 the right one is seen. The sickle-shaped mass lower down, 

 Ccl 1 to Ccl* represents the cut surface of a connecting band 

 of white nervous tissue called the corpus callosum f which 

 runs across the middle line from one cerebral hemisphere 

 to the other and puts them in communication. SL the 

 septum lucidum, is a thin membrane which forms the inner 

 wall of the lateral ventricle of the hemisphere. Between 

 the two septa lucida on the sides (in the natural position 

 of the parts) and the corpus callosum above is inclosed a 

 narrow space known as the fifth ventricle. It is, however, 

 quite different from the remaining cerebral ventricles, not 

 being a continuation of the canalis centralis of the spinal 

 cord. The space beneath the septum lucidum and the 

 back part of the corpus callosum is the third ventricle, 

 which, lying in the middle line, has been laid open in the 



