194 FUNCTIONS OF THE BRAIN. 



Thus the structural and physiological evidence indicates, beyond reasonabi 

 doubt, that the vagus neuromeres (opercular and chilarial) and the five branchij 

 neuromeres of the marine arachnids have become consolidated into a single, compac 

 group, which in the vertebrates unites v\rith the hindbrain to form the posteric 

 part of the medulla. 



VII. The Cerebral Hemispheres. 



We have shown that in Limulus the hemispheres are primarily connecte 

 with the sensory nerves of but one sense organ, the olfactory. They contair 

 however, important secondary centers belonging to the visual and to the gustator 

 organs. They are true cerebral centers, both in structure and function, an' 

 are similar to the primitive hemispheres of vertebrates, in that they regulate o 

 control a large number of complex activities of which the several primary refle 

 centers lie in the more remote parts of the central nervous system. They, fo 

 example, exercise a tonic, or inhibitory, influence over the posterior part of th 

 brain and the cord, and they are the source of impulses that check, or maintain, o 

 coordinate, the walking and swimming movements, the leg movements in chewing 

 and the purposeful movements of the legs in removing local irritants. 



