SENSORY GANGLIA. CONSENSUAL AND EMOTIONAL ACTIONS. 335 



than those resulting from mere Reflex action. One of the most remarkable 

 phenomena exhibited by such a being, is the power of maintaining its equili- 

 brium, which could scarcely exist without consciousness. If it be laid upon 

 the back, it rises again; if pushed, it walks. If a Bird thus mutilated be 

 thrown into the air, it Hies; if a Frog be touched, it leaps. It swallows food 

 and liquid, when they are placed in its mouth; and the digestive operations, 

 the acts of excretion, &c., take place as usual. In the case of a Pigeon ex- 

 perimented on by Malacorps, which is recorded by Magendie, there appears 

 sufficient proof of the persistence of a certain amount of sensation. Although 

 the animal was not affected by a strong light suddenly made to fall upon its 

 eyes, it was accustomed, when confined in a darkened or partially-illuminated 

 room, to seek out the light parts; and it avoided objects that lay in its way. 

 In the same manner, it did not seem to be affected by sudden noises; but at 

 night, when it slept with closed eyes and its head under its wing, it would 

 raise its head in a remarkable manner, and open its eyes, on the slightest 

 noise ; speedily relapsing into a state of complete unconsciousness. Its 

 principal occupation was to prune its feathers and scratch itself. The con- 

 dition of such a being seems to resemble that of a Man, who is in a slumber 

 sufficiently deep to lose all distinct perception of external objects, but who is 

 yet conscious of sensations, as appears from the movements occasioned by 

 light or by sounds, or from those which he executes to withdraw the body 

 from an uneasy position.* 



436. Among the ganglia of special sensation, the functions of the Optic 

 Lobes, or Corpora Quadrigemina, have been chiefly examined. The re- 

 searches of Flourens and Hertwig have shown, that their connection with 

 the visual function, which might be inferred from their anatomical relations, 

 is substantiated by experiment. The partial loss of the ganglion on one 

 side produces partial loss of power and temporary blindness on the opposite 

 side of the body, without necessarily destroying the mobility of the pupil; 

 but the removal of a larger portion, or complete extirpation of it, occasions 

 permanent blindness and immobility of the pupil, with temporary muscular 

 weakness, on the opposite side. This temporary disorder of the muscular 

 system sometimes manifests itself (as already stated) in a tendency to move on 

 the axis, as if the animal were giddy. No disturbance of consciousness ap- 

 pears to be produced; and Hertwig states that he never witnessed the con- 

 vulsions, which Flourens mentions as a consequence of the operation, and 

 which were probably occasioned by his incision having been carried too 

 deeply. These results are confirmed by pathological phenomena in Man; 

 for there are many instances on record, in which blindness has been one of 

 the consequences of diseased alterations in one or both tubercles ; and in 

 some of the cases, in which the lesion extended to parts seated beneath the 

 tubercles, disturbed movements were observed. No definite conclusions can 

 be drawn, either from experiment or from pathological observation, in regard 

 to the functions of the Thalami Optici and Corpora Striata; but there is 

 nothing in these sources of information to oppose the views already offered, 

 which are based on other foundations. 



437. Emotional fictions. There appears strong reason for regarding the 

 Ganglionic tract, which is the instrument of Consensual actions, as the imme- 

 diate centre also of those movements which directfy result from the excite- 

 ment of the Emotions. Several considerations tend to establish this position. 



It must not be forgotten that, in such experiments, the severity of the operation will of 

 itself occasion a suspension or disturbance of the functions of parts that remain ; so that the 

 loss of a power must not be at once inferred from the absence of its manifestations. But the 

 persistence of a power, after the removal of a particular organ, is a clear proof that it canuot 

 be the peculiar attribute of that organ. 



