vin THE HIND-BKAIN 431 



Study of the remote effects was only attempted very inadequately 

 by Flourens, and always on birds. Magendie (1828), Serres 

 (1826), and Bouillaud (1827) in their experiments followed more 

 or less on the lines of Kolando, Fodera, and Flourens. After 

 several years, experiments on the cerebellum were resumed by 

 N. Schiff (1858-59), Brown-Sequard (1859-60-61), E. Wagner 

 (1858-1860), Dalton (1861), Lussana (1862), Leven and Ollivier 

 (1862-63), Vulpian (1866), Weir - Mitchell (1869), Nothnagel 

 (1871), Ferrier (1878), and others. 



At the outset of our own researches on the cerebellum it 

 seemed to us advisable to extend our study to the higher mammals, 

 dogs and monkeys, in which the organ is more developed, but 

 which till then had rarely been employed for experiments on 

 account of the supposed technical difficulties. 



Our principal experiments may be divided into three series, 

 viz. investigation of animals after removal of the lateral half of 

 the cerebellum, of the vermis, and of the whole or almost the 

 whole of the organ. 



Before describing the results it seems advisable to make a few 

 preliminary remarks for the guidance of the student : 



(ft) Whatever the extent or degree of the cerebellar lesion, 

 whether it be symmetrical or asymmetrical, unilateral or bilateral, 

 complete or incomplete, the resulting symptoms are disturbances 

 of voluntary movement. 



(b) Unilateral lesions of the cerebellum produce disturbances 

 chiefly on the same side of the body; while the effects of re- 

 moving the so-called motor region of a cerebral hemisphere are 

 mainly crossed, i.e. on the opposite side of the body to that 

 operated on. 



(c) Whatever the nature of the cerebellar lesion, the true 

 phenomena of deficiency, i.e. those due directly to loss of the 

 cerebellum, are preceded by a brief period of functional exaltation ; 

 while in lesions of the cerebrum the phenomena of deficiency are 

 constantly preceded by a period of functional inhibition. To be 

 rigorously objective, we will refer to the immediate effects of 

 ablation of the cerebellum as " dynamic phenomena," leaving 

 undecided the question of whether they are produced by the 

 irritation of the operative traumatism or by the sudden cessation 

 of the influence of the cerebellum upon other portions of the 

 nervous system. 



(d) To the phenomena of cerebellar deficiency of the second 

 period there succeeds a third series of effects, which we have 

 termed " compensatory phenomena " ; these are due to the activities 

 of portions of the cerebellum that are left intact, or of other 

 cerebral centres. In the first case there is organic compensation, 

 which consists in the gradual diminution of the phenomena of 

 deficiency; in the second case there is functional compensation, 



