CIASS IV. 2. 1. 10. OF ASSOCIATION. 403 



as to resist venesection, opiates, bark, blisters, mucilages, 

 and all the usual methods employed in coughs. It was for a 

 time supposed to be the hooping cough, from the violence of the 

 action of coughing; it continued two or three weeks, the patient 

 never being able to sleep more than a few minutes at once during 

 the whole time, and being propped up in bed with pillows night 

 and day. 



As no fever attended this violent cough, and but little expec- 

 toration, and that of a thin and frothy kind, I suspected the 

 membrane of the lungs to be rather torpid than inflamed, and 

 that the saline part of the mucus not being absorbed, stimulated 

 them into perpetual exertion. And lastly, that though the lungs 

 are not sensible to cold and heat, and probably therefore less mo- 

 bile, yet, as they are nevertheless liable to consent with the tor- 

 por of cold feet, as described in species 6 of this Genus, I sus- 

 pected this torpor of the lungs to succeed the gout in the feet, or 

 to act a vicarious part for them. 



10. Vertigo rotatoria. In the vertigo from circumgyration 

 the irritative motions of vision are increased; which is evinced 

 from the pleasure that children receive on being rocked in a 

 cradle, or by swinging on a rope. For whenever sensation arises 

 from the production of irritative motion with less energy than 

 natural, it is of the disagreeable kind, as from cold or hunger; 

 but when it arises from their production with greater energy 

 than natural, if it be confined within certain limits, it is of the 

 pleasurable kind, as by warmth or wine. With these increased 

 irritative motions of vision, I suppose those of the stomach are 

 performed with greater energy by direct sympathy; but when 

 the rotatory motions, which produce this agreeable vertigo, are 

 continued too long, or are too violent, sickness of the stomach 

 follows; which is owing to the decreased action of that organ 

 from its reverse sympathy with the increased actions of the or- 

 gan of vision. For the expenditure of sensorial power by the 

 organ of vision is always very great, as appears by the size of 

 the optic nerves; and is now so much increased as to deprive the 

 next link of association of its due share. As mentioned in Spe- 

 cies 6 of this Genus. 



In the same manner the undulations of water, or the motions 

 of a ship, at first give pleasure by increasing the irritative mo- 

 tions belonging to the sense of vision; but produce sickness at 

 length by expending on one part of the associated train of irrita- 

 tive actions too much of that sensorial power, which usually served 

 the whole of it; whence some other parts of the train acquire too 

 little of it, and perform their actions in consequence too feebly 2 

 and thence become attended with disagreeable sensation, 



