168 
TUMOURS IN THE BRAIN. 
ing the retrograde movement, which is often a negative sign 
only of immobilite , I observed — 1st, That the animal presented 
other symptoms which denoted a derangement of the func- 
tions of sensation, and to such a degree that a skilful man would 
not be able to make him obey him, or direct him to the right 
or to the left, or make him to go forwards. 2d, If on his legs 
being placed in any particular position, the animal should not 
endeavour to move them, although certain methods of excite- 
ment are used— noise, for example. 3d, If his eyes remained 
fixed and open. 4th, If the horse, after having taken a 
mouthful of forage, and having commenced to masticate it, 
should suddenly stop, and, after some time, commence again. 
I should, therefore, condemn as wimobile a horse which 
would refuse to execute backward movements, or to im- 
mediately adjust his fore legs, they having been previously 
crossed; if also he should be observed to keep the eyes fixed, 
and to rest during the mastication of the forage, it being but 
partly taken into his mouth. 
The most striking and constant symptom of what I under- 
stand by immobilite is a peculiar appearance or state of icliotism , 
characterised especially by a fixedness of the eyes, and by the 
slight attention paid by the animal to what passes around 
him. This condition of the animal is always accompanied by 
abnormal modifications, or momentary suspensions of the 
movements of a particular class of muscles having relation to 
life, whence results immobilite , for a given time, of the parts 
whose function it is to produce motion, and consequently the 
impossibility, or at least a great diffiulty, in the perfect loco- 
motion of the animal. ' 
There are, then, several kinds of immobile horses — those 
which cannot be made to go backwards, as also those which 
cannot be made to advance ; and others again in which it is 
difficult to make them turn round. There are some which 
go forwards irresistibly, and others which it is impossible to 
stop when they begin to recede. All refuse to obey the 
wishes of the conductor, and all are unfit for service, and 
dangerous to use. 
I therefore see nothing which can prevent this interpreta- 
tion of the expression immobility, as used in the text of the 
law of 20th May. This interpretation is at least impartial. 
I repeat that I have never opened a horse decidedly immobile , 
without finding lesions more or less manifested, although 
various, in the viscera of the cranium. One day I made the 
autopsy of an immobile horse, (about 2 5 years old) with M. 
Calmed, and did not discover any lesion ; but M. Calmeil dis- 
covered a very marked adherence between the two layers of 
