1020 MACHINERY OF COORDINATION. [BOOK in. 



has been left intact. Observations of this kind have disclosed 

 many interesting facts, besides the forced movements just referred 

 to, but they have not led to, and indeed could hardly be expected 

 to lead to, any clear views as to the point which we are now dis- 

 cussing. It does not follow that every part, injury or stimulation 

 of which interferes with coordinated movements, or gives rise to 

 definite, forced, or other movements, is to be considered as part 

 of the machinery under consideration. The corpora striata and 

 cerebral hemispheres form, as we have seen, no part of the 

 machinery, yet injury to them may disorder the machinery ; and 

 the fact that removal of, or injury to the cerebellum, disorders 

 the machinery is no proof by itself that the cerebellum is an 

 essential part of the machinery. 



If we may trust to deductions from structural arrangements, 

 we might be inclined to infer that the anatomical relations of 

 what we have called the tegmental region from the bulb upwards 

 point to its serving as the foundation of the machinery in 

 question. Behind, it has full connections with various parts of 

 the cord, while in front by means of the optic thalami and 

 anterior corpora quadrigemina, if not by other ways as well, it 

 is so far associated with the optic nerves that the path seems 

 open for visual impulses to gain access to it. To this foundation, 

 however, we must add the cerebellum, on account of its relations 

 to it, to the cord and to the bulb through the restiform bodies, 

 including its ties with the auditory nerve. And if we add the 

 cerebellum we must also probably add the pons. We may exclude 

 the pes of the crus, since this is composed exclusively of fibres 

 bringing the cerebral hemispheres, including the corpora striata, 

 into connection with the pons, bulb and cord, and so with the 

 coordinating machinery itself, as well as with other parts of the 

 nervous system. And observation as far as it goes supports this 

 deduction from anatomical relationships. We will, however, defer 

 what else we have to say on this point until after we have discussed 

 the carrying out of voluntary movements. 



