ix MID- AND INTEE-BEAIN 523 



movements noted by Magendie, and the hemiplegia described by 

 other authors, do not occur, though there is diminution of muscular 

 power on the opposite side. These symptoms disappear after a 

 few days. 



When the unilateral ablation involves the posterior part of 

 the thalamus or the pulvinar there seems to be total blindness of 

 the eye on the opposite side, which apparently persists as long as 

 the animal survives. When the excision of the pulvinar is bi- 

 lateral the dog appears to be blind in both eyes; immediately 

 after the operation its behaviour is similar to that of a dog in 

 which both eyeballs have been removed, but there is not absolute 

 permanent blindness. In fact, the animals had hardly recovered 

 from the operation when both began to walk, and they soon learned 

 to orientate themselves, to recognise the objects near them, and 

 thus to avoid them in walking. 



Among Lo Monaco's experiments great importance attaches 

 to that performed on a dog in which the pulvinar was destroyed 

 on both sides, causing atrophy of the corpora quadrigemina and 

 the external geniculate bodies. In this animal there were obvious 

 visual disturbances that persisted during the eleven months that 

 it survived. 



The dog exhibited a graver disturbance of vision than the 

 psychical blindness due to extirpation of both cortical visual 

 centres, but less than the blindness that results from extirpation 

 of both eyeballs. 



In addition to visual disturbances there is, according to Lo 

 Monaco, a unilateral or bilateral affection of taste in dogs deprived 

 of the pulvinar on one or both sides, shown by the fact that one or 

 other half of the tongue, or the entire taste surface, is insensitive 

 to the bitterness of a saturated solution of quinine. 



The sense of smell is also disturbed in dogs that have lost their 

 pulvinar ; they only perceive the odour of meat when it is placed 

 near their nostrils, while a dog blinded by extirpation of the eyes 

 recognises it at a much greater distance. 



Lo Monaco found painful, thermal, and muscular sensibility 

 intact in dogs after removal of the pulvinar. After destruction of 

 the mesial or anterior nucleus of the thalamus, on the contrary, 

 tactile sensibility and muscular energy are reduced on the contra- 

 lateral side ; but not permanently, as no trace of diminution can 

 be recognised after a few days. The circus movements to the 

 opposite side are only seen during the first days after the operation, 

 and evidently depend on the prevailing action of the muscles of the 

 side operated on, or of the side on which the thalamus is more pro- 

 foundly and extensively injured. 



Anatomical examination of the brains of the dogs whose 

 thalamus was operated on by Lo Monaco almost entirely confirms 

 the functional lesions observed during life. In a case of removal 



