8o 



KARL FOLKERS 



TABLE X 

 Extrinsic Factor in Pernicious Anemia 



Effect of daily administration of various substances together with 150 

 cc. of neutralized normal human gastric juice (Castle and associates, 1944) 



plement for case 99 and a meat extract for case 100, a positive response 

 resulted as evidenced by a rise in the red blood cell count and the reticu- 

 locyte peak. It was concluded that the extrinsic factor for pernicious 

 anemia was not identical with folic acid, xanthopterin, or any of the 

 known B vitamins. 



Much effort has been devoted to the isolation of the antipernicious 

 anemia factor in liver. The factor may be multiple. The properties of 

 the concentrates of this factor as studied by five groups of investigators 

 are given in Table XI. The properties of the concentrates differ con- 

 siderably. For example, the carbon content varied from 41 to 53 % , and 

 the nitrogen content varied from 10 to 15%. The molecular weight of 

 one preparation was believed to be in the range of 2000-5000. Two of 

 the materials were reported to have amino nitrogen, but none was found 

 in the material of another group. The fraction of Dakin and his asso- 



