98  Boric  Acid  and  a  New  Boric  Preparation  J(Am-^%¥rm 
of  Streptococcus  pyogenes  when  6  per  cent,  was  present ;  for  stopping 
anthrax  bacilli  9  per  cent,  was  required ;  typhus  bacilli  did  not 
develop  under  the  influence  of  7  per  cent.  Cholera  spirilli  were  the 
most  sensitive,  for  3  per  cent,  arrested  their  development.  Mould 
fungi  ceased  to  grow  in  the  presence  of  4  per  cent.  But  much 
smaller  quantities  of  boric  acid  delayed  the  development  for  many 
days,  and  in  some  cases — especially  the  bacilli  of  anthrax — indica- 
tions of  degeneration  were  observed  in  the  bacilli  themselves.  In 
order  to  ascertain  how  much  boric  acid  one  must  add  to  the  culti- 
vation medium,  in  order  to  prevent  development  of  all  bacteria,  the 
author  mixed  several  materials  known  to  favor  the  growth  of  micro- 
organisms— earth,  sewer  water,  putrified  blood,  etc.,  and  inoculated 
with  this  mixture  a  series  of  cultivation  glasses  containing  serum 
and  broth  and  also  boric  acid  in  gradually  increased  proportions, 
keeping  the  glasses  in  an  ordinary  incubator.  The  glasses  with  the 
least  proportion  of  boric  acid  (1  per  cent.)  quickly  became  clouded, 
owing  to  the  development  of  numerous  micro-organisms  of  various 
kinds;  more  slowly  the  next  glass,  which  contained  2  per  cent,  of 
boric  acid,  began  to  show  some  appearances,  but  not  for  three  weeks, 
and  then  the  clouding  was  only  slight  ;  the  other  glasses  which 
contained  2^  to  3  per  cent,  of  boric  acid  remained  without  any 
bacterial  growth,  only  a  few  fungi  were  developed  in  them.  It  may 
be  assumed  that  in  blood-serum  and  broth  the  growth  of  all  bac- 
teria is  prevented  by  the  addition  of  2^  per  cent,  of  boric  acid. 
In  using  boric  acid  therapeutically,  whether  in  substance  or  in 
solution,  it  should  be  present  in  excess  so  as  to  render  the  wound 
unfit  for  the  settlement  and  growth  of  micro-organisms.  The  modes 
of  application  must  vary  with  the  varied  conditions,  which  are 
described  by  the  author. 
Boric  acid  is  devoid  of  irritating  properties ;  it  does  not  inter- 
fere with  the  properties  of  the  tissues ;  it  is  comparatively  devoid 
of  poisonous  properties,  70  grams  per  day  having  been  given  inter- 
nally. It  takes  T^ru-  to  of  body  weight  to  kill  mice.  It 
is  four  or  five  times  less  poisonous  than  carbolic  acid  and  resorcin 
and  salicylic  acid.  Borax  is  not  affected  by  the  soft  tissues  with 
which  it  comes  in  contact. 
After  its  use  the  author  never  saw  inflammation  or  formation  of 
pus  take  place  ;  suppuration  quickly  disappears,  the  tendency  to  the 
formation  of  granulations  in  wounds  is  rather  kept  back  than  encour- 
