734 PRINCIPLES OF GENERAL PHYSIOLOGY 



other physical forces, have to be taken into account. In fact, many of the supposed 

 cases of extreme specificity have been found, on inquiry, to be due to factors other 

 than specific chemical relationship. 



The properties of certain individual drugs, of physiological interest, are 

 described in the text. Such are, acetyl-choline, strychnine, nicotine, pilocarpine, 

 atropine, hyoscine, veratrine, and ergotoxine. 



Certain substances of colloidal nature, probably all of protein constitution, 

 such as the bacterial toxins and foreign proteins, give rise to the production in the 

 blood of antibodies which are capable of neutralising, in various ways, the action 

 of the antigen injected. 



If an interval of not less than eight to ten days elapses after an injection of 

 one of these substances, the animal is found to be supersensitive to the antigen 

 (anaphylaxis). If an antigen usually innocuous, such as egg-white, is injected in 

 this sensitive state, severe symptoms are produced. 



Under certain conditions, the state of anaphylaxis is very specific, an isolated 

 organ reacting only to the actual antigen alone. But results obtained by Dale 

 indicate that the property is merely one of degree. Organs sensitised by one 

 antigen, under particular conditions, may react to a different substance. 



The theory of specific chemo-receptors does not give a satisfactory account of 

 the phenomena. The explanation appears to be in a colloidal precipitation 

 process at the surface of the sensitive cells, by which their semipermeability is 

 more or less destroyed. 



Immunity and anaphylaxis are closely related phenomena. 



Results have been obtained by Wooldridge, which show that tissue extracts 

 from normal animals can be obtained, which are capable of conferring immunity 

 in a similar way to the specific antitoxin obtained by bacterial inoculation. 



The facts connected with the increase of phagocytosis by the so-called 

 " opsonins " are, in all probability, to be explained by adsorption, causing changes 

 in surface tension. They are only to a limited degree specific. 



LITERATURE 

 Hormones. 



Bayliss and Starling (1904). 

 Starling (1905). 

 Gley (1911). 



Internal Secretions. 



Metzner (1913). 

 Elliott (1913, 1). 

 Biedl (1913). 

 Marshall (1910). 



Drugs. 



Barger and Dale (1910). 

 Straub (1912). 



Toxins and Antitoxins. 

 Burnet(1911). 



Anaphylaxis. 



Dale (1912). 



