IMMUNITY AND ADAPTATION. 147 



to be some objection to applying it to cases in which the sub- 

 stance causing the immunization or adaptation is derived from 

 the same animal in which the antibody is produced. Antibodies 

 have been experimentally produced only in such cases in which 

 certain substances derived from one animal were injected into 

 another animal and usually those belonging to a different species. 

 The experimental proof has, however, been given that in certain 

 cases iso-antibodies can be produced, by the injection of animal 

 cells or animal products into other animals of the same species. 

 Furthermore it could be shown that such antibodies may act not 

 only on the cells of another animal of the same species but even 

 on the analogous cells of its own body. This for instance was 

 found in the case of the spermotoxins. An antibody against 

 its own spermatozoa can be produced in the same animal which 

 has been injected with spermatozoa of another animal of the same 

 species. Whether the spermatozoa are able to produce anti- 

 bodies if they are injected into the same animal from which they 

 are derived, has apparently not yet been investigated ; but it 

 appears not unlikely that it might succeed. Such an experiment 

 gave negative results in the case of the blood cells which are 

 however normally circulating in the blood. Certain other facts 

 point to the conclusion that such autoantibodies may be formed 

 without experimental interference under natural pathological and 

 even normal conditions. If one kidney becomes chronically 

 diseased by experimental interference so that tissue of the kidney 

 is being resorbed, the serum seems to assume properties, injuri- 

 ous to kidney tissue of the same animal. If we inject such serum 

 into the circulation of another animal of the same species, albu- 

 minuria appears as a sign that the kidneys have been injured. 

 Even if this observation should be open to a different interpreta- 

 tion, there are other facts which suggest a similar conclusion. 

 It is certain that such digestive ferments as trypsin pass normally 

 into the circulation and may be excreted by the kidney. As 

 might be expected from what has been said before, an anti- 

 trypsin exists in the serum, or the serum has antitryptic proper- 

 ties, just as the snake blood contains antitoxin against snake 

 venon. 



Glaessner found even that the tryptic power of the serum varies 



