532 MATERIA MEDIC A AND THERAPEUTICS. 



2. That the irritation of the cutaneous nerves will modify 

 in a simple reflex way, through the centres in the brain and 

 cord, the circulation and nutrition generally, of the parts 

 beneath; the impression which passes in being immediately 

 reflected along the vascular or trophic nerves. 



3. That possibly the irritation of the local nerves and 

 vessels may affect the vaso-motor and trophic centres in the 

 brain and cord, presiding over the area of skin ; and that this 

 disturbance may so influence a neighbouring trophic centre (say 

 of a joint) as to produce through it a change in the nutrition 

 of the tissues (such as a joint) in the neighbourhood of the 

 area to which the irritant was applied. 



4. That vesicants and pustulants may produce a flow of 

 plasma or pus, which will relieve the blood or tissues of 

 organised or other poisons, which are the cause of the disease. 

 This is the old humoral view, founded on the pathology that 

 " humours of the blood " are the origin of disease. 



III. PATHOLOGICAL RELATIONS AND THERAPEUTICS. The 

 pathological conditions which we seek to influence by counter- 

 irritants belong to various systems, which have been already 

 discussed. The same remark holds true of the therapeutical 

 applications of the principles just examined. All that 

 remains to be done here is to enumerate the chief morbid 

 conditions which may be treated by counter-irritation. These 

 are, (1) Subacute or chronic inflammation, with or without 

 unnatural growth, of parts in direct vascular connection with 

 the skin ; e.g. of a joint or bone. (2) Congestion or inflamma- 

 tion in neighbouring viscera; e.g. of the lungs. (3) Pain in 

 deep or distant parts, such as neuralgic, cardiac, or renal pain. 

 (4) Spasm, or other morbid activity in deep muscular struc- 

 tures, such as lumbago and vomiting. (5) Central nervous 

 disturbances such as syncope and hysteria. 



Baths and Allied Measures. The principles 

 on which the use of baths depend are in a great measure 

 identical with those which we have already discussed, and do 

 not require to be repeated. If the student will carefully bear 

 in mind the relations of the vessels and nerves of the skin to 

 the body heat, circulation generally, and nervous system, he 

 will readily appreciate the subject of baths from the following- 

 tables, which give a list of the most common baths, 

 together with their action and principal uses succinctly 

 arranged. 



