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the bronchial ramifications: this irritation, it will be replied, 

 affects the respiratory muscles sympathetically, and thus the 

 coughing is produced. 



10. Irritation is said to be the cause of our first symptom ; 

 and what produces irritation? it is excited by cold: with what, 

 then, is cold so related as to produce irritation? is it with the or- 

 ganic fibres? no, for cold never makes dead people cough ; is the 

 cold so related with the blood in the vessels of the part? no, for 

 there is always blood in the vessels of the part, and this blood 

 shall many times be surrounded by an atmosphere of the same 

 temperature, &c. yet it Will not produce a cough; or if this 

 answer should be excepted against, as it might, we will add, dead 

 vessels may be filled with blood, but we have no experience of 

 cough having been produced by a simple relation between blood 

 and air. This cough then takes place only during the presence 

 of life, and must therefore be considered as one of the phenomena 

 dependent upon life. 



11. What then shall we say of the state of irritation? merely 

 that it is a disordered or modified condition of life, which produces 

 those effects, those symptoms, which are just referred to it. 

 There are few terms more common in medical subjects than this 

 word irritation. A modified condition of the spirit is meant by it ; 

 it is employed to designate almost any modification, and by no 

 means a particular one: thus we say a part ulcerates because it is 

 irritated, as by a foreign body; or a wound is painful and secretes 

 bad matter, because it is in a state of irritation; or sympathetic 

 disorder of a system, as of the nervous, takes place from irritation 

 of one part; or a membrane, which would not otherwise secrete, 

 throws out mucus because it is irritated, &c. These are all 

 instances of irritation, yet the state which is the cause; the agent 

 producing different phenomena, though related alike with the 

 common material, must on this account consist in each of a diffe- 

 rent combination or assemblage of properties; in other words, the 

 irritation which makes a cancer spread is different from the irrita- 

 tion produced on the schneiderian membrane by a pinch of snuff. 

 If then we retain this word, or in our future use of it, let us under- 

 stand that it is designed to express a modified condition, liable to 

 much variety, of the spirit, and not one precise identity of it. 



12. To return to our symptom. The cough, it is said, is pro- 

 duced by irritation; the state of irritation, by a relation between 

 properties of life, the seat of which is in the membrane lining the 

 trachea, and the properties of the atmosphere. But the same 

 person may, many other times, have been exposed to the same 

 atmosphere, which has not before produced a cough; or many 

 other persons might at the same time have been exposed to the 

 stime atmosphere without such exposure being followed by our 

 symptom. If the atmosphere be the same in these instances of 

 different results, where must we look for the cause of the diversity? 

 We have no choice: we rawst look for the difference where alone 



