138 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



have already called attention to the fact that the re- 

 spiratory movements are segmental processes. Goltz 

 has shown that those reflexes in which the muscles of 

 the arms are active are also segmental (2). During 

 the period of heat the male frog clasps the female 

 with his fore-limbs. If the head and back part of the 

 body of a male frog be amputated during this time, 

 so that only a piece consisting of the arms and the 

 segmental piece of the spinal cord belonging with the 

 arms remains, rubbing the skin on the ventral side of 

 this piece suffices to produce the clasping reflex. 



3. In considering the brain of Vertebrates we are 

 obliged to deal with the brain of the cold-blooded 

 animals, for the simple reason that in warm-blooded 

 animals we cannot well perform brain-operations in 

 the vicinity of the medulla oblongata without having 

 the respiration cease. In cold-blooded animals the 

 shock-effects are not so great. We have selected the 

 brain of the frog as a type because it has been worked 

 out the most carefully. It consists chiefly of the 

 cerebral hemispheres (GH, Fig. 35), thalamus op- 

 ticus (T/i., O), optic lobe, cerebellum (AT/), and 

 medulla oblongata. The diagram (Fig. 35) gives the 

 origin of the nerves of the brain (V-XI). It is our 

 aim to show in this chapter that the individual activi- 

 ties of the frog are dependent upon the segmental 

 ganglia and that we have no right to speak of " cen- 

 tres " for the single activities unless the word centre is 

 synonymous with the expression segmental ganglion. 



We will first consider the coordinated progressive 



