IMMUNOLOGY AND SELF-SAVING CATALYSTS 141 



their proper injection or by their introduction through invading 

 organisms or viruses in an attack of a disease. The U. S. Army 

 uses immunization to protect against cholera, smallpox, tetanus, 

 typhoid fever, typhus, and yellow fever, and sometimes against 

 diphtheria, influenza and some forms of pneumonia. 



Chemically, antibodies are proteins present in blood serum, 

 whose physical properties class them primarily with the globulin 

 fraction of the serum; they are globulins according to electro- 

 phoretic studies by Arne Tiselius and E. A. Kabat; 2 but their 

 peculiar specificities are not necessarily and exclusively due to 

 chemical differences, as so many assumed. The paper and metal 

 industries show how many lasting contours may be impressed on 

 sheets without involving chemical change. The ultracentrifugal 

 work of The Svedberg 3 (Nobel prize, 1927) indicates the molecular 

 weights of some antibodies and other large molecules: 



Serum globulin (horse) 68,000— 167,000 



Serum albumin (horse) 70,000 



Antipneumonococous globulin (horse) 910,000 



Serum globulin (man) 176,000 



Antipneumococcus (man) 195,000 



Lactoglobulin 41,000 



Pepsin 35,500 



Insulin 46,000 



Catalase 250,000 



Urease 480,000 



Hemocyanins (various sources) 400,000 — 8,700,000 



But these "molecules" are not spheres. A. Neurath 4 makes the 

 following estimates: Rabbit pneumococcus antibody, 37A x 338A; 



horse pneumococcus antibody, 20-47A x 950A. J. R. Marrack 

 reports 5 that on immunization there may be an increase in serum 

 protein, mainly in the globulin fraction. 



Apart from these immune bodies developed from the introduc- 

 tion of the specific antigen, the blood serum may carry, as the 

 result of genie or humoral inheritance, a number of natural anti- 

 bodies to some antigens; and such inherited immunities may in 

 some cases be important factors in survival. Huge numbers of 

 various American, Mexican, and South American tribes suc- 

 cumbed to smallpox, and measles decimated the natives of Pacific 

 islands among whom natural immunity to this disease was rare if 

 not non-existent. 



