738 MACHINERY OF COORDINATION. [BOOK in. 



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 m&y trust to deductions from structural arrangements, 

 we might be inclined to infer that the anatomical relations of 

 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 ana- 

 tomical relationships. We will, however, defer what else we 

 have to say on this point until after we have discussed the car- 

 rying out of voluntary movements. 



