792 



CHEMOTHERAPY 



early stages of human syphilis by means of salvarsan administered early 

 in the proper manner and in correct dosage, but, unfortunately, it is 

 not true of the majority of cases, the difficulties increasing with the 

 duration of the infection. Fortunately, the investigations of Margulies 

 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 salvarsan. 



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 role, future discoveries 

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



FIG. 141. BLOOD OF SAME RAT EIGH- 

 TEEN HOURS AFTER INTRAVENOUS INJECTION 

 OF 0.0008 MG. SALVARSAN. 



SALVARSAN AND NEOSALVARSAN 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 

 starting-point for important researches in the preparation of organic 

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



