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the susceptibility of the nervous system. The result was that 
the power of the ganglia of the sympathetic nervous system to 
conduct, transfer and radiate the effects of impressions, was no 
longer controlled by the superior force in the cerebro-spinal 
centres, and instead of tranquil even harmonious action in the 
various organs as in perfect health, we had convulsive and pain- 
ful movements. After referring to the effects of irritation and 
section of branches of the sympathetic, the next step in his 
argument was that in the disorder under consideration there 
was first of all contraction of the vessels of the brain (probably 
the middle cerebral artery), and so a diminished supply of blood 
produced by excited action of the sympathetic, and that the 
exhaustion of the sympathetic following on this excitement 
causes the dilatution of the vessels and the headache. This he 
supported by various cases and comparisons. He next discussed 
the question, why the disorder might be sometimes unilateral 
and sometimes bilateral, and lastly, why in some cases there is 
(i) disturbance of vision without headache following, (1) dis- 
turbance of vision followed by headache, and (iii) headache 
preceded by disordered sensation, but not by disturbed vision ; 
all of which he maintained were explicable by the theory which 
he had advanced. 
Prof. Humpury said that he had experienced a sudden 
attack of hemiopia, which was probably of somewhat similar 
origin; that on another occasion he had been conscious of 
considerable mental disturbance, accompanied by dilatation of 
a pupil. This he believed due to the eye being accidentally 
touched by a little atrophine, and that the mental disturbance 
was merely nervous sympathy. 
Mr Trotter asked whether Dr Latham could suggest any 
cause for the peculiar complicated figure appearing in this 
disorder. 
Dr LaruHam said he could not explain the special form.’ 
Prof. MILLER stated that he himself had sometimes seen the 
