FUNCTIONS OF THE BRAIN. 



33 



surface or when shaking himself, etc., etc. Sensibility of 

 all kinds seems diminished as well as motility, but of this I 

 shall speak later on. Moreoyer the dog tends in yoluntary 

 moyements to swerye towards the side of the brain-lesion in- 

 stead of going straight forward. All these symptoms gradu- 

 ally decrease, so that eyen with a yery seyere brain-lesion 

 the dog may be outwardly indistinguishable from a well dog 

 after eight or ten weeks. Still, a slight chloroformization 

 will reproduce the disturbances, eyen then. There is a cer- 

 tain appearance of ataxic in-coordination in the moyements 

 — the dog lifts his fore-feet high and brings them down with 

 more strength than usual, and yet the trouble is not ordi- 



Fig. 5.— Left Hemisphere of Dog's Brain, after Ferrier. ^. tlie fissure of Sj'lvius. B, 

 the crucial suli-iis. O, the olfactory bulb. /, //, /f/. /P, indicate the first, second, 

 third, and fourth external convoluiions respectively. (1), (4;, and (,5) are on the 

 sigmoid g3Tus. 



nary lack of co-ordination. Neither is there paralysis. 

 The strength of whateyer moyements are made is as great 

 as eyer — dogs with extensiye destruction of the motor zone 

 can jump as high and bite as hard as eyer they did, but 

 they seem less easily moved to do anything with the affected 

 parts. Dr. Loeb, who has studied the motor disturbances 

 of dogs more carefully than any one, conceiyes of them en 

 masse as effects of an increased inertia in all the processes 

 of inneryation towards the side opposed to the lesion. All 

 such moyements require an unwonted effort for their exe- 

 cution; and when only the normally usual effort is made 

 they fall behind in eff'ectiyeness.* 



* J. Loeb : ' Beitriige zur Pbysiologie des Giosshirns; Pfliiger's Ar- 

 chiv, xxxix. 293. I simplify the author's statement. 



