576 IMMUNITY 



are distinct substances. These facts abundantly show how close an 

 analogy obtains between anti-bacterial and hsemolytic sera, and how 

 important a bearing hsemolytic studies have on the questions -of im- 

 munity in general. 



In addition to hcemolytic sera, anti-sera have been obtained by the 

 injection of leucocytes, spermatozoa, ciliated epithelium, liver cells, 

 nervous tissue, etc. The laws governing the production and properties 

 of these are identical, that is, each serum exhibits a specific property 

 towards the body used in its production i.e., dissolves leucocytes, im- 

 mobilises spermatozoa, etc. The specificity is, however, not so marked 

 as in the case of sera produced against red blood corpuscles ; thus a serum 

 produced against tissue cells is often hsemolytic ; this is probably due to 

 various cells of the body having the same receptors. Here again, when 

 the anti-serum produces no destructive effect on the corresponding cells, 

 the presence of an immune-body may be demonstrated by the increased 

 amount of complement which is taken up through its medium. It may 

 also be mentioned that each anti-serum usually exhibits toxic properties 

 towards the animal whose cells have been used in the injections, e.g., a 

 hsemolytic serum may produce a fatal result, with signs of extensive blood 

 destruction, hsemoglobinuria, etc., i.e., it is heemotoxic for the particular 

 animal ; a serum prepared by injection of liver cells has been found to 

 produce on injection necrotic changes in the liver in the species of animal 

 whose liver cells were used. These are mentioned as examples of a very 

 large group of specific activities. 



With regard to the sites of origin of immune-bodies our 

 information is still very deficient. Pfeiffer and Marx brought 

 forward evidence in the case of typhoid, and Wassermann in the 

 case of cholera, that the immune-bodies are chiefly formed in 

 the spleen, lymphatic glands, and bone-marrow. According to 

 certain workers of the French school, the chief source of anti- 

 substances acting on cells such as red blood corpuscles is the 

 large mononuclear leucocytes, whilst those acting on bacteria 

 are chiefly derived from the polymorpho-nuclear leucocytes (vide 

 p. 188). Another view is that immune-bodies are chiefly formed 

 by the large mononuclear leucocytes, whilst complements are 

 products of the polymorphs. That these cells are concerned in 

 the production of antagonistic and protective substances is almost 

 certain, though another possible source of wide extent, namely, 

 the endothelium of the vascular system, has been largely over- 

 looked. As yet, definite statements cannot be made on this point. 



(&) Opsonic Action. The presence of a substance in an 

 immune-serum which makes the corresponding organism sensi- 

 tive to phagocytosis was first demonstrated by Denys and Leclef 

 in 1895, in the case of an anti-streptococcal serum. They also 

 showed that the serum produced this effect by acting on the 

 organism, not on the leucocytes. It is, however, chiefly to the 

 researches of Wright and his co-workers that this subject has 

 come into special prominence. Wright and Douglas in their 



