170  Koch's  Lymph  and  its  Dilutions.      {Am April,"  i89iarm" 
As  regards  Mr.  Reuter's  view  "  that  the  lymph  is  a  neutral  solu- 
tion of  the  hydrochlorate  of  an  alkaloidal  "body,  possibly  a  ptomaine," 
since  auric  chloride,  and  iodine  and  potassium  iodide  solutions  each 
gave  precipitates  with  the  acid  solution,  the  statement  seems  doubt- 
ful, since  solutions  of  iodine  and  potassium  iodide,  mercuric  chloride, 
and  potassio-mercuric  iodide — all  alkaloidal  precipitants — do  not 
precipitate  the  neutral  solution.  Further,  Brouardel  and  Boutiny's 
test  for  ptomaines  (of  potassium  ferric  cyanide  and  ferric  chloride), 
fails  to  reveal  their  presence. 
Strong  nitric  acid  by  the  "  contact  method,"  or  the  dilute  acid 
solution  placed  in  a  very  narrow  tube  and  the  upper  part  heated, 
showed  the  absence  of  albumen.  The  absence  of  peptones  was 
indicated  by  the  Biuret  test  (of  KHO,CuS04  in  very  dilute  solution, 
etc.  Red  or  pink  color,  in  the  absence  of  albumen).1  With  the 
Biuret  test,2  however,  the  pure  violet  color  of  albuminoids  (with  no 
tinge  of  pink  or  red),  was  produced,  just  as  it  had  been  previously 
obtained  with  Fehling's  solution. 
To  summarize,  then,  there  are  present  sodium  chloride,  water, 
glycerin  and  albuminoids,  the  latter  probably  in  the  form  of  certain 
micro-organisms  or  their  products,  or  both,  and  proteids.  If  the 
lymph  is  made  by  "culture"  and  there  are  proteids  present  for  the 
growth  and  development  of  the  colonies,  it  would  presuppose  that 
the  finished  product  should  also  contain  peptones,  but  the  chemical 
reaction  for  peptones  is  negative.  It  seems,  then,  probable  that  the 
peptones,  necessarily  present  if  the  "culture"  has  contained  proteids 
and  micro-organisms,  have  been  removed  by  precipitation  with 
sodium  chloride  or  some  peptone  precipitating  compound  and 
filtered.  Hence,  the  negative  result  for  peptones  with  the  Biuret  test 
in  the  finished  product.  It  is  probable,  also,  that  the  proteids  have 
likewise  been  removed;  leaving  a  saline,  watery,  glycerin  extract 
of  the  micro-organisms,  or  their  products,  or  both. 
The  lymph  used  in  the  above  examination  was  obtained  by  the 
Philadelphia  Hospital  through  Minister  Phelps,  U.  S.  Minister  at 
Berlin,  and  was  kindly  furnished  me  by  Dr.  D.  E.  Hughes,  Chief 
Resident  Physician  of  the  Philadelphia  Hospital. 
1  Clinical  Diagnosis,  Jaksch  and  Cagney,  p.  211. 
2  It  may  be  of  interest  to  state  that  the  Biuret  test,  in  the  absence  of  albumen, 
produces  a  red  or  pink  color  when  peptones  are  present ;  a  violet  color  when 
albuminoids  exist,  and  a  reddish-violet  color  if  there  be  present  both  albu- 
minoids and  peptones.    Albumen  alone  gives  a  blue  color. 
