626 NERVOUS SYSTEM. 



may not present any disorder in the muscular movements. These facts are 

 in accord with the results of experiments upon the lower animals. 



The phenomena observed in 'the few cases of cerebellar inco-ordination 

 which have been carefully observed are notably different from those presented 

 in simple locomotor ataxia. In cerebellar disease, the gait is staggering, 

 much as it is in alcoholic intoxication. The chief difficulty seems to be in 

 maintaining the equilibrium in progression, even with the greatest care and 

 closest attention on the part of the patient. With the idea in mind that 

 there is a co-ordinating centre for the muscles of progression, and that this 

 centre acts imperfectly, it seems as though an efficient effort at co-ordination 

 were impossible. In locomotor ataxia, patients seem to make co-ordinating 

 efforts, but the paths by which these efforts find their way to the muscles are 

 disturbed and the co-ordinating process, which is more or less automatic in 

 health, requires peculiar care and attention. By the aid of the sense of sight 

 and by artificial supports, progression may be safely though irregularly accom- 

 plished. The movements are jerky, and each step seems to require a distinct 

 act of volition. It is possible to imagine that in disorganization of the paths 

 of co-ordination in the spinal cord, the co-ordinating centre may act in some 

 degree through the motor paths in the direct and crossed pyramidal tracts 

 of the cord. It is certain that the want of normal co-ordinating power is 

 supplemented by ordinary voluntary acts and by the sense of sight. 



Vertigo is not a necessary accompaniment of cerebellar ataxia. Disease 

 of the semicircular canals of the internal ear (Meniere's disease) is attended 

 with vertigo, and this is the main cause of the disturbances of equilibrium. 



Connection of the Cerebellum with the Generative Function. The fact 

 that the cerebellum is the centre for equilibration and the co-ordination of 

 certain muscular movements does not necessarily imply that it has no other 

 office. The idea of Gall, that " the cerebellum is the organ of the instinct 

 of generation," is sufficiently familiar; and there are facts in pathology 

 which show a certain relation between this nerve-centre and the organs of 

 generation, although the view that it presides over the generative function is 

 not sustained by the results of experiments upon animals or by facts in com- 

 parative anatomy. 



In experiments upon animals in which the cerebellum has been removed, 

 there is nothing pointing directly to this part as the organ of the generative 

 instinct. Flourens removed a great part of the cerebellum in a cock. The 

 animal survived for eight months. It was put several times with hens and 

 always attempted to mount them, but without success, on account of want of 

 equilibrium. In this animal the testicles were enormous. This observation 

 has been repeatedly confirmed, and there are no instances in which the cere- 

 bellum has been removed with apparent destruction of sexual instinct. In 

 a comparison of the relative weights of the cerebellum in stallions, mares 

 and geldings, Leuret found that, far from being atrophied, the cerebellum in 

 geldings was even larger than in either stallions or mares. 



In certain cases of disease or injury of the cerebellum, irritation of this 

 part has been followed by persistent erection and manifest exaggeration of 



