Despite the Behring therapeutic serum and the protective vaccine developed by Behring, the field of diphtheria immunity has always interested various research experts. Their efforts were all directed toward developing safe, _active_ immunity. 48. (LV. 137) As early as 1902 DZIERGOWSKY (Dziergowsky, quoted from Seeligmann and Happe: The Position of the Active Protective Vaccine against Diphtheria. Result of Hygiene 11, 1930) reported on several experiments to protect human beings against diphtheria by a number of subcutaneous injections with a gradually increasing dose of Diphtheria-Toxin. * * * * * 49. (LV. 138) BLUMENAU (Blumenau, page 137) worked on this principle in 1909. He soaked cotton wads in undiluted toxin and placed them alternately in the right and then in the left nostril of children from 3-12 years of age. He attained an antitoxin titer increase of up to 10 A.E. per ccm. of serum. 50. (LV. 139) BANDI and GAGNONI worked with killed bacteria (Bandi and Gagnoni, page 137). They injected measles convalescents with a 4-day-old crush of diphtheria bacilli cultures on agar which had been killed at 55° Centigrade * * *. 51. (LV. 141) BOEHME and RIEBOLD (Boehme and Riebold, One Way of Active Immunization against Diphtheria, Munich Medical Weekly 1924, 232) were the first to use living diphtheria bacilli for vaccination of human beings. After extensive experiments on guinea pigs, they proceeded to experiment on human beings. They used a diphtheria lymph, which they named Diphcutan, a mixture of living, highly toxic diphtheria bacilli cultures in N_{a}C1. Sixty-two persons were vaccinated with this lymph with 10-20 scratches each on the upper arm. Those vaccinated were— 22 children from 1½-5 years of age, 11 children from 6-10 years of age, 17 children from 10-15 years of age, 2 youths from 15-20 years of age, and 9 adults from 20-50 years of age. * * * * * 52. (LV. 142) EBERHARD (Eberhard, Contributions toward active Immunization against Diphtheria. Hygiene Journal 105, page 614) tested 4 different vaccines produced by the Marburger Behringwerke for their suitability for immunization of humans and for use in public vaccination stations. * * * * * 53. (LV. 143) BAYER used the lymph suggested by BOEHME and RIEBOLD (Bayer, On active Immunization against Diphtheria. Yearbook of Infant Therapeutics 1925, 273) and vaccinated 87 children with it * * *. 54. (LV. 144) MUELLER and MEYER (Mueller and Meyer, Diagnosis and Immunization of children threatened with Diphtheria. Journal of Infant Therapeutics 39, 405, 1925). They also checked the experiments by BOEHME and RIEBOLD with the same methods, vaccinated 53 children who had shown a positive reaction to the SCHICK test. * * * * * _TYPHUS_