708 NERVOUS SYSTEM. 



of the encephalic ganglia, with the cerebrum ; by the middle peduncles, the two lateral 

 halves of the cerebellum are intimately connected with each other ; and, by the inferior 

 peduncles, the cerebellum is connected with the posterior columns of the spinal cord. 

 We shall see, when we come to study the functions of the cerebellum, that its connection 

 with the posterior white columns of the cord is a point of great interest and importance. 



General Properties of the Cerebellum. There is now no difference of opinion among 

 physiologists, with regard to the general properties of the cerebellum. Flourens, who 

 made the first elaborate and satisfactory observations upon the cerebellum in living 

 animals, noted, in all of his experiments, that lesion or irritation of the cerebellum 

 alone produced neither pain nor convulsions ; and the same results have followed the 

 observations of all modern physiologists who have investigated this question practically. 

 We have ourselves frequently exposed and mutilated the cerebellum in pigeons and have 

 never observed any evidence of excitability or sensibility. From these facts, we must 

 conclude that the cerebellum is inexcitable and insensible to direct stimulation, at least 

 as far as has been shown by direct observations. It is not impossible, however, that 

 future experiments may reverse this generally-received opinion ; particularly in view of 

 the recent observations of Fritsch and Hitzig, already cited, which show that certain 

 parts of the cerebrum are excitable, and that the excitability of the encephalic centres 

 rapidly disappears in living animals, as the result of pain and hemorrhage. We should 

 note, also, the experiments of Budge, who observed movements in the testicles and vasa 

 deferentia, in males, and in the cornua of the uterus and in the Fallopian tubes, in females, 

 following irritation of the cerebellum. 



Functions of the Cerebellum. 



There are still the widest differences of opinion among physiologists, with regard to 

 the functions of the cerebellum, mainly for the reason that the experiments upon the 

 lower animals, though in themselves sufficiently definite, are apparently contradicted by 

 pathological observations upon the human subject. There should be no such discrep- 

 ancy between well-conducted experiments and carefully-observed cases of disease or 

 injury ; for it is certain that the functions of the cerebellum present no essential differ- 

 ences in different animals, at least in man, the mammalia, and birds. It is necessary, 

 therefore, for the physiologist, by carefully analyzing and correcting the results obtained 

 by direct experimentation and by applying to the study of pathological observations the 

 facts elicited by these experiments, to endeavor to harmonize the real or apparent con- 

 tradictions ; for, as we have often had occasion to remark, there are no exceptions to 

 the laws to which the functions of similar classes of animals are subordinated ; and 

 observations and experiments, apparently discordant, will always be found, as our posi- 

 tive knowledge advances, to present differences in the conditions under which the phe- 

 nomena have been observed. To apply this idea to the functions of the cerebellum, it may 

 be safely assumed that it is impossible for this organ to preside directly and exclusively 

 over muscular coordination in birds and the inferior mammals, and, in man, to pos- 

 sess different functions. With regard to the cerebrum, man possesses, not only a higher 

 degree of development of certain intellectual faculties than the inferior animals, but is 

 endowed with others, such as the power of articulate language. But, in man and in the 

 higher orders of animals, the general properties and functions of the muscular system are 

 essentially the same. To take one of the most generally-accepted views of the functions 

 of the cerebellum, if this be the centre for muscular coordination in birds and mammals, 

 it has the same office in man, although it may possess additional functions not found 

 lower in the scale of animal life. Keeping in view, then, the desirability of bringing 

 into accord the results of experiments and of pathological observations, we shall first 

 study carefully the phenomena which follow injury or extirpation of the cerebellum in 

 the lower animals. 



