276 DETAILED SYNTHESIS. 



with the same fluid as if they had not been thus placed. 

 These places are called ventricles. 



667. Remark. Dropsy of the Brain is apt to be a collection of 

 the fluid in the ventricles ; it may be outside the Brain, or it may be hi 

 both places. If outside the Brain, it can be reached by tapping through 

 the skull, which is a simple operation. 



668. WHITE FIBRES (commissures) EXTEND between 

 the cerebri, cerebelli, and other ganglia, and between 

 different parts of all the ganglia, by which communica- 

 tion is established and influences exerted, the whole be- 

 ing so woven together that intellections, emotions, sen- 

 sations, and volitions, can harmoniously and reciprocally 

 act on each other, as occasion may require. 



669. THE CEREBRI are the organs of the Intellect, 

 but by what method they act is not known. 



670. The central ganglia of the brain are organs 

 through which sensations are caused, and hence they 

 are called THE SENSORIUM. A part of these ganglia are 

 probably concerned in producing emotions, since they 

 can be excited despite the will by certain substances 

 swallowed or inhaled ; and substances that excite emo- 

 tions produce unusual circulation of Blood about some 

 of these ganglia. 



671. THE CEREBELLI are smoother at their surface 

 than the cerebri, and in this respect are like the central 

 ganglia. Cut across, they present in their centre, upon 

 section of either side, the white tissue branched like a 

 tree, hence called tree of life (arbor vitas). 



672. THE USE OF THE CEREBELLI is to harmonize 

 the action of all the muscles of the body, as is espe- 

 cially necessary in walking ; and by some they are also 

 thought to be the sensatory ganglia of muscular sensa- 

 tions ; but this is not certain, as they may perform the 

 office of influencing contractions .without necessarily ex- 

 citing sensations. 



667. Where is Cranial dropsy ? 668. How do - ? 669. What are - ? 670. What 

 is ? 671. Describe . 672. What is ? 



