Am.  Jour.  Pharm.  ) 
January,  1920.  ) 
Current  Literature. 
53 
drying,  smear  downward,  on  the  following  fixing  solution:  corrosive 
sublimate  (saturated  aqueous  solution),  2  parts;  absolute  alcohol,  i 
part.  Fixation  is  complete  in  about  thirty  minutes.  The  smears 
are  then  placed  film  upward  in  iodized  alcohol  in  order  to  remove 
the  last  traces  of  sublimate,  washed  in  distilled  water  and  then 
stained  as  follows:  (i)  Soak  for  several  hours  in  a  4  per  cent,  solu- 
tion of  iron  alum  (made  with  violet  crystals) ;  (2)  wash  in  distilled 
water;  (3)  stain  in  Heidenhain's  hematoxylin  for  several  hours  (or 
over  night);  (4)  wash  in  distilled  water;  (5)  place  in  i  per  cent, 
iron-alum  solution  until  decolorization  has  reached  a  satisfactory 
stage;  (6)  wash  in  distilled  water  and  counter  stain  with  5  per  cent, 
aqueous  eosin  solution;  dehydrate  through  the  alcohols,  clear  in 
xylol,  and  mount  on  a  slide  in  Canada  balsam.  (Lancet,  London; 
through  Jour.  Amer.  Med.  Assoc.,  Dec.  6,  191 9.) 
The  Romanowsky  Stain. — Romanese  has  worked  out,  he  says, 
a  simple  and  reliable  substitute  for  the  Giemsa  method.  The  re- 
sults seem  to  be  the  same  with  it  as  with  the  original  Giemsa  fluid, 
while  the  ingredients  are  inexpensive  and  always  at  hand.  He 
dissolves  0.75  Gm.  methylene  blue  in  50  Cc.  of  95  per  cent,  alcohol 
and  50  Cc.  of  glycerin,  and  adds  3  Cc.  of  a  10  per  cent,  solution  of 
sodium  carbonate  in  distilled  water,  and  boils  for  fifteen  minutes. 
Then  he  adds  35  Cc.  of  a  i  per  cent,  alcoholic  solution  of  eosin  and 
boils  fifteen  minutes.  It  is  then  removed  from  the  fire  and  alcohol 
is  added  to  bring  the  total  amount  to  100  Cc.  It  is  then  set  aside, 
covered  closely,  for  a  week.  (From  Jour.  Amer. Med.  Assoc.,  October 
II,  1919.) 
Formic  Acid  in  the  Common  Nettle. — It  is  commonly  stated  in 
text  books  that  formic  acid  occurs  in  the  stinging  hairs  of  the  com- 
mon nettle  {Urtica  dioica),  but  there  is  no  satisfactory  proof  of  the 
statement.  When  nettles  are  cut  up  and  distilled  with  water  the 
reactions  for  formic  acid  in  the  distillate  are  obtained,  but  it  is  now 
known  that  various  parts  of  plants  yield  formic  acid  when  treated 
in  this  way;  therefore,  it  is  not  certain  that  the  formic  acid  comes  from 
the  stinging  hairs  of  the  nettles;  it  may  be  derived  from  the  general 
plant  tissues.  One  of  the  chief  chemical  reactions  of  formic  acid  is 
its  power  of  reducing  salts  of  silver  and  mercury,  but  that  s 
not  necessarily  conclusive  proof  in  this  case.  The  author  appears 
to  have  settled  the  point  definitely.    By  pressing  the  leaves  of  grow- 
