yiii PREFACE. 



Thus the pain of the bowels from worms is caused by 

 the increased action of the membrane from the stimu- 

 lus of those animals; but the convulsions, which some- 

 times succeed these pains in children, are caused by 

 the consequent volition, and belong to another class. 



To discover under what class any disease should be 

 arranged, we must first investigate the proximate cause; 

 thus the pain of the tooth-ach is not the cause of any 

 diseased motions, but the effect; the tooth-ach there- 

 fore does not belong to the class of Sensation. As the 

 pain is caused by increased or decreased action of the 

 membranes of the tooth, and these actions are owing 

 to the increase or decrease of irritation, the disease is to 

 be placed in the class of Irritation. 



To discover the order it must be inquired, whether 

 the pain be owing to increased or defective motion of 

 the pained membrane; which is known by the concomi- 

 tant heat or coldness of the part. In tooth-ach with- 

 out inflammation there is generally a coldness attends 

 the cheek in its vicinity; as may be perceived by the 

 hand of the patient himself compared with the opposite 

 cheek. Hence odontalgia is found to belong to the or- 

 der of decreased irritation. The genus and species 

 must be found by inspecting the synopsis of the second 

 order of the class of irritation. See Class I. 2. 4. 12. 



This may be further elucidated by considering the 

 natural operation of parturition; the pain is occasioned 

 by the increased action or distension of the vessels of 

 the uterus, in consequence of the stimulus of the fetus; 

 and is therefore caused by increased irritation; but the 

 actions of the abdominal muscles in its exclusion are 

 caused by the pain, and belong to the class of increas- 

 ed sensation. See Class II. 1.1.12. Hence the dif- 

 ficulty of determining, under what class of diseases 

 parturition should be arranged, consists in there being 



