194 DEPRESSANTS TO PERIPHERAL NERVES 



Alypine often gives fine results in operations upon korses and is 

 said to be less toxic to them, or at any rate, does not produce such 

 symptoms of excitability, but it may be followed by swelling which 

 may last for several days. 



OTHER MEASURES FOR PRODUCING LOCAL 

 ANESTHESIA 



Atropine resembles cocaine somewhat but is much weaker in 

 action, but on the other hand is more readily absorbed from the intact 

 skin and may be used in liniments, ointments and plasters. 



Aconite first stimulates and then depresses the sensory nerves 

 without irritation. 



Aromatic Series. Many of the members of the aromatic series 

 possess an anesthetic action. This is particularly so of phenol, which 

 produces marked anesthesia even in dilute solution. Its application, 

 however, is often injurious, since it causes destruction of the skin and 

 may be absorbed in sufficient amounts to produce toxic symptoms. 

 It may be used for combined anesthetic and antiseptic action for such 

 operations as hypodermic injections, paracentesis, etc., in which 

 case the needle may be dipped in strong phenol, applied to the point 

 of introduction for a moment, then followed by an application of 

 alcohol to prevent serious destruction of tissue. All' the bodies of 

 this group show this double action. Acetanilid and antipyrine may 

 be used as a dusting powder for the combined anesthetic and anti- 

 septic action, but their action is not strong. 



Application of Cold. This in addition to anesthetic action 

 produces a local anemia. The anesthesia is complete but has the dis- 

 advantage of producing pain at first and may be followed by gan- 

 grene. This method of producing anesthesia is best done by spray- 

 ing the surface with a highly volatile liquid, such as ethyl chloride 

 or ether, but it may be produced in emergency by the application of 

 salt and ice. 



CounterirritantS. These first produce stimulation and then de- 

 pression of the nerves. Turpentine, menthol, camphor, alcohol, 

 chloroform, and all essential oils. 



Magnesium Salts. Meltzer and Auer (1905) discovered the 

 anesthetic action of the magnesium salts. They found that the ap- 

 plication of magnesium sulphate to nerve-trunks blocked conductivity 

 and abolished reflex excitability. They also found that a general 

 anesthesia, with abolition of the reflexes, may be produced by the 

 subcutaneous injection of magnesium salts (1.5 gm. of crystallized 

 magnesium sulphate per Kg. of body weight used as 25 per cent, 

 solution). The, same effect was produced when introduced intra- 



