Am'M°aUyr;  i92iarm" }     Scientific  and  Technical  Abstracts.  359 
Trypanocidal  Action  of  Arsenic  and  Antimony  Com- 
pounds.— Quantitative  studies  by  Carl  Voegtlin,  Homer  W  Smith, 
and  others,  into  the  power  of  certain  drugs  to  sterilize  an  infected 
animal  are  the  subject  of  the  recent  report  to  the  U.  S.  Public  Health 
Service.  Specifically,  the  studies  were  directed  to  ascertaining  the 
minimum  dose,  injected  intravenously,  of  certain  compounds  of 
arsenic  and  antimony  (important  in  the  treatment  of  relapsing  fever, 
syphilis,  sleeping  sickness,  etc.),  which  would  prove  lethal  to  the 
majority  of  white  rats  that  had  been  infected  with  trypanosoma,  and 
also  the  minimum  dose  that  would  prove  effective  in  destroying  the 
parasites. 
The  minimum  effective  dose,  below  which  the  drug  failed  to 
destroy  the  parasites,  was  found  to  be  fixed  partly  by  the  reaction 
between  the  drugs  and  the  parasites,  and  partly  by  the  rate  at 
which  the  drug- was  absorbed  by  the  tissues  of  the  host'.  Thus,  sub- 
effective  doses  antimonyl  lactate  ceased  to  act,  not  when  they  had 
killed  a  certain  number  of  parasites,  but  when  absorption  by  the  host 
had  lowered  their  concentration  below  their  "threshold." 
Differences  in  the  effectiveness  of  different  arseno  and  pentra- 
valent  compounds  are  held  to  depend  on  the  ease  with  which  they  are 
oxidized  or  reduced  in  the  body,  oxidation  or  reduction  being  neces- 
sary before  they  can  exert  their  chief  toxic  action. 
The  authors  hold  that,  although  the  results  otained  do  not  indi- 
cate with  absolute  accuracy  the  clinical  value  of  a  compound,  they  do 
furnish  a  valuable  quantitative  comparison  with  other  compounds. 
Utility  of  Antiplague  Vaccines. — That  the  utility  of  vac- 
cines and  serums  in  antiplague  work  is  at  the  best  not  proved  is 
asserted  by  G.  W.  McCoy  and  C.  W.  Chapin  in  a  recent  report  of 
the  U.  S.  Public  Health  Service.  Antiplague  vaccine  was  first  used 
on  man  in  1897  by  Haffkins,  who  used  .old  killed  broth  cultures  in 
large  doses  and  claimed  that  marked  reduction  in  the  attacks  of  the 
disease  resulted.  Other  observers  report  much  less  brilliant  results, 
possibly  as  later  work  suggests,  because  different  strains  of  the 
plague  organism  affect  the  efficiency  of  the  vaccine.  Innoculation  by 
living  virulent  cultures  has  been  found  promising  by  other  workers, 
but  its  value  has  not  been  demonstrated.  Vaccination  is  not  known  to 
have  ever  controlled  a  plague  outbreak. 
