Am.  Jour.  Pharm. 
April,  1909. 
Enzymes  of  Cow's  Milk. 
177 
solution  a  reddish-brown  precipitate  of  iodine,  which,  in  appearance, 
resembles  the  precipitate  formed  when  the  iodine  solution  is  added 
to  a  solution  of  an  alkaloid. 
A  saturated  solution  of  ether  alone  will  not  precipitate  in  this 
manner,  neither  will  acid,  or  water  and  acid  together.  The  addition 
of  an  equal  volume  of  water  at  once  dissolves  the  precipitate. 
The  necessity  of  guarding  against  this  condition  will  be  apparent 
to  all  those  interested  in  alkaloidal  work.  If  this  test  is  used  where 
ether  is  the  solvent  the  acidulated  solution  should  be  diluted  with 
water  before  applying  the  test.  It  is  still  better  to  add  the  iodine  first, 
and  if  a  precipitate  is  obtained  add  water,  when  it  will  disappear  if 
caused  by  the  ether. 
University  of  Illinois  School  of  Pharmacy. 
THE  ENZYMES  OF  COW'S  MILK. 
By  Joseph  W.  England. 
Milk  is  not  simply  a  mixture  of  chemical  compounds.  It  is  an 
organized  tissue,  as  much  so  as  blood.  In  fact,  the  resemblance  is 
so  close  that  it  could  be  called  "  white  blood."  It  contains  not  only 
fat,  proteids,  sugar,  salts,  and  water,  but  also  the  elements  that  go  to 
make  up  blood.  Among  these  may  be  mentioned  the  enzymes  or 
ferments.  The  presence  of  these  bodies  has  been  known  for  a 
decade  or  more,  but  their  physiological  significance,  in  the  growth 
and  development  of  the  tissues  of  the  body,  has  been,  apparently, 
entirely  overlooked. 
The  function  of  food  is  not  only  nutritional,  but  also  develop- 
mental ;  that  is,  it  furnishes  not  only  pabulum  for  the  tissues,  but 
stimulates  the  growth  and  development  of  the  digestive  tract,  espe- 
cially in  infants  and  growing  children.  Milk,  and  probably  other 
foods  also,  furnish  enzymes  that  promote,  in  some  degree  at  least, 
the  development  of  the  digestive  tract.  The  reason  why  unboiled 
milk  is  superior  to  boiled  milk,  as  an  infant  food,  is  because  it  con- 
tains enzymes  or  ferments  that  assist  digestion ;  in  other  words,  it  is 
autodigestive,  while  in  boiled  milk,  the  enzymes  have  been  destroyed, 
and  its  autodigestibility  lost. 
The  power  of  ferments  for  work  is  remarkable.  As  Abderhalden 
states  (Physiological  Chemistry,  1908,  46)  :  "  They  are  never  found 
as  end  products  of  the  reactions.  They  remain  unchanged.  The 
smallest  amount  suffices  to  repeat  the  same  reaction  a  countless 
