852 



CHEMOTHERAPY 



have shown that while resistant races of trypanosomes are easily evolved, 

 the evidence is entirely against the probability of the development of arsenic- 

 resistant syphilitic spirochetes as the result of prolonged treatment with non- 

 sterilizing doses of salvarsau. Akatsu and Noguchi 1 have, however, in- 

 creased the tolerance of Treponema pallidum to salvarsan and neosal- 

 varsan five and-one-half times their original mark by cultivating the 

 spirochete in culture-media containing these drugs. 



With this brief discussion of the primary principles of chemotherapy, 

 which is really a very ancient method of treatment and dates from the 



time that chemicals were first 

 used for treating the sick, 

 but which has ' now emerged 

 from the darkness of pure em- 

 piricism into the light of a 

 science, we shall pass on to a" 

 consideration of salvarsan and 

 neosalvarsan. These two sub- 

 stances were not discovered as 

 the result of accident, but 

 were the outcome of exact 

 knowledge, logical thinking, 

 and carefully planned experi- 

 mentation. It is impossible 

 to tell what these discoveries 

 presage; certainly they open 

 up vast possibilities in the 



development of a specific therapy for all infections. One fact is cer- 

 tain: that while chance must ever play some r61e, future discoveries 

 will probably result only from prolonged, patient, and laborious study. 



FIG. 145. BLOOD OF SAME RAT EIGH- 

 TEEN HOURS AFTER INTRAVENOUS INJECTION 

 OF 0.0008 MG. SALVARSAN. 



SALVARSAN AND tiEOSALVARSAN IN THE TREATMENT OF SYPHILIS 



Historic. The administration of arsenic in protozoan infections has 

 long been a recognized method of treatment. The organic compound 

 of arsenic known as atoxyl (the sodium salt of para-aminophenylarsenic 

 acid) was first used in the treatment of trypanosomiasis, and although 

 this drug did not produce the results that were anticipated, it formed the 

 ; startmg-point for important researches in the preparation of organic 

 compounds of arsenic and their use in protozoan infections. On the 

 1 Jour. Exper. Med., 1917, xxv, 349. 



