THE BRAIN. 483 



much better co-ordinated in the entire animal than when only 

 the spinal cord is left. It seems to be legitimate to infer that 

 the other parts of the brain contain the nervous machinery for 

 this work, which is usually aroused to action by the will, but 

 which an external stimulus may render active. All the connec- 

 tions, structural and functional, are present, except those on 

 which successful volition depends. The frog with the cord 

 only, sinks at once when thrown into water; when gently 

 placed on its back, it may and probably will remain in that 

 position, without an attempt at recovery. There is, in fact, 

 very limited power of co-ordination. 



Eemoval of the cerebral lobes in the bird is more likely to 

 be attended with difficulties, and conclusions must be drawn 

 with greater caution. 



But a pigeon may be kept alive after such an operation for 

 months. It can stand, balancing on one leg ; recover its posi- 

 tion when placed on its side; fly when thrown into the air; 

 it wHL even preen its feathers, pick up food, and drink water. 

 Its movements are such as we might expect from a stupid, drow- 

 sy, or probably intoxicated bird ; but it is plainly endowed with 

 vision, though not as good as before. But spontaneous move- 

 ments are absent, and the pecking at food, etc., must be consid- 

 ered as associate reflexes, and as such are very interesting, in 

 that they show how machine-like, after all, many of the appar- 

 ently volitional acts of animals really are. In a mammal so 

 great is the shock, etc., resulting from the operative procedure, 

 that the actual functions of the remaining parts of the brain, 

 when the cerebral convolutions are removed, are greatly ob- 

 scured ; nevertheless, little doubt is left on the mind that homol- 

 ogous parts discharge analogous functions. It can walk, run, 

 leap, right itself when placed in an unnatural position, eat when 

 food is placed in its mouth, and avoid obstacles in its path, 

 though not perfectly. Yet it remains motionless unless stimu- 

 lated ; all objects before its eyes impress it aUke if at all. The 

 animal evidently has neither volition nor intelligence. Now, if 

 any of the parts between the cerebrum and the medulla be 

 removed the creature shows lessened co-ordinating power; so 

 that the inference that these various parts are essential constitu- 

 ents of a complex mechanism, all the components of which 

 are necessary to the highest forms of muscular co-ordination 

 and probably other functions, is unavoidable. 



Since we are dealing with co-ordinated movements, we may 



