ASeiXrPhi9ri"' }  Active  Principle  of  Thyroid  Gland.  809 
out  cultivation.  The  average  shrub  is  about  25  inches  high.  Some 
plants,  however,  are  about  40  inches  in  height. 
"While  there  are  several  factories  making  candelilla  wax  in  this 
consular  district,  there  is  only  one  large  one  operating  at  present 
(with  a  daily  output  of  about  662  pounds  of  wax)  due  to  the  pres- 
ent low  price  obtaining  for  the  product  in  the  United  States. 
It  is  reported  that  another  large  factory  in  this  consular  district 
is  contemplating  opening  shortly. 
Methods  of  Extracting  the  JJrax. — After  the  shrub  is  pulled  out 
of  the  earth  it  is  placed  in  wooden  tanks  of  water  which  is  heated  to 
the  boiling  point.  At  the  moment  of  boiling  a  certain  proportion 
of  sulphuric  acid  is  put  in  the  tanks.  As  soon  as  the  acid  comes  in 
contact  with  the  wax  it  comes  to  the  surface  and  is  collected  and 
put  in  receptacles  until  it  congeals  :  it  is  then  put  in  another  tank 
where  steam  is  used  to  dissolve  the  wax.  adding  sulphuric  acid  a 
second  time.  The  wax  is  then  in  a  refined  state  and  is  allowed  to 
harden  in  certain  molds.  It  is  then  ready  for  shipment.  The  wax 
can  ajso  be  extracted  by  direct  fire. 
THE  ACTIVE  PRINCIPLE  OF  THE  THYROID  GLAXD.1 
In  our  issue  of  March,  1919  ('p.  67) ,  reference  was  made  to 
Kendall's  discovery  of  a  principle  of  the  thyroid  gland,  thyro-oxy- 
indol  or  Thyroxin,  believed  to  be  the  active  principle  of  the  gland. 
In  a  further  note  on  the  subject  (Endocrinology,  1919.  3.  156. 
Apr. -June')  :  the  same  author  reports  on  its  physiological  action.  A 
series  of  experiments  by  himself  and  others  show  that  the  action  of 
this  substance  is  probably  that  of  a  catalyst  which  bears  a  quantita- 
tive relation  to  the  production  of  energy  within  the  tissues.  The 
curve  representing  this  relation  is  a  straight  line  ;  that  is.  the  increase 
in  energv  production  with  an  increasing  amount  of  thyroxin  is  simply 
an  additive  one.  The  substance  appears  to  function  within  the 
tissues,  and  there  is  an  equilibrium  between  the  amount  in  the  tis- 
sues, the  amount  in  the  blood-stream,  and  its  source  of  supply,  the 
thyroid  gland.  The  entire  absence  of  the  substance  from  the  body 
does  not  produce  death,  but  merely  a  lowering  of  the  level  at  which 
energy  can  be  produced  by  the  animal  organism.    In  administering 
1  From  The  Prescribe^  October,  1919. 
