Chap. XL] THE BRAIN AND NERVES. 227 



4. The nerve-centres correlate these transmitted impressions. 



5. The spinal cord contains, besides transmitting-fibres, many 

 centres of reflex action for the performance of simple or complex 

 organic actions. 



6. The medulla oblongata contains a centre for such vital 

 reflex actions as are connected with the regulation of the 

 heart-beat, with breathing, and the distribution of the blood- 

 supply. 



7. The sympathetic is usually held to be a subsidiary system, 

 largely occupied with regulating the calibre of certain blood- 

 vessels. 



8. The cerebellum is probably largely occupied with the co- 

 ordination of muscular movements. 



9. The optic lobes are probably centres for vision and the 

 adjustment of the visual apparatus. 



10. The thalami (of the rabbit) are regarded as centres by 

 which sensory impressions are transmitted, while the corpora 

 striata are centres by which motor impulses are transmitted. It 

 is possible that purely responsive non-original acts require no 

 higher centres than these. 



11. The cerebral hemispheres are definitely involved in 

 original and intelligent actions. 



12. Accompanying and associated with, or perhaps identical 

 with, certain nerve-actions (neuroses) going on within the body, 

 there are, in all probability, certain feelings (psychoses) about 

 which, in the frog, the pigeon, and the rabbit, we can know 

 little. 



