IN VIVO ACTIVITY 123 



tical application. Because of the activity of streptothricin and strepto- 

 mycin against gram-negative bacteria (460a, 597, 752) and because of 

 the lack of reliable chemotherapeutic agents active against these bac- 

 teria, the utilization of these substances in the treatment of certain dis- 

 eases caused by such bacteria becomes very significant (p. 243). Some 

 preparations, like actinomycetin, have been utilized in the preparation 

 of a bacterial hydrolysate (mycolysate) for vaccination purposes. 



