^ecimberfhi9™.'  )  Standardizing  Autogenous  Vaccines.  807 
Summary. 
Chronic  benzine  poisoning  is  uncommon,  but  may  occur.  The 
symptoms  complained  of  are  referable  almost  entirely  to  the  gastro- 
intestinal tract  and  the  central  nervous  svstem. 
FORMULAS  FOR  USE  IN  STANDARDIZING 
AUTOGENOUS  VACCINES.1 
By  Leo  R.  Tehon,  A.B., 
URBANA,  ILL.,  SERGEANT,  MEDICAL  DEPARTMENT,  U.  S.  ARMY. 
In  the  preparation  of  autogenous  vaccines,  we  used,  as  a  routine, 
W  right's  method  of  counting.  In  so  doing  I  have  experienced  some 
little  discomfort  in  handling  the  array  of  figures  usually  employed 
in  making  the  necessary  computations. 
As  a  short  cut,  the  formulas  here  given  have  proved  useful  and 
satisfactory,  it  being  entirely  unnecessary  to  compute  the  number 
of  organisms  per  cubic  centimeter  in  the  suspension.  The  result 
obtained  in  working  out  the  formulas  gives  the  number  of  cubic 
centimeters  of  the  suspension  of  organisms  needed  to  make  up  a 
desired  quantity  of  vaccine  which  will  contain  the  desired  number 
of  organisms. 
Formulas. 
Quantity  of  Vaccine. 
Millions  of  Organisms  per  Cc. 
1,000. 
.  500. 
200. 
10  CC. 
1.82  X  a 
0.909  X  a 
0.3636  X  a 
b 
b 
b 
15  CC. 
2.72  X  a 
1.36  X  a 
o.5454  X  a 
b 
b 
b 
25  CC. 
4-54  X  a 
b 
2.21  X  a 
b 
0.909  X  a 
b 
50  CC 
9-09  X  a 
4-54  X  a 
1.818  X  a 
b 
b 
b 
TOO  CC 
18.18  X  a 
9-C9  X  a 
3.64  X  a 
b 
b 
b 
In  computing  these  formulas  the  number  of  red  blood  cells  is 
arbitrarily  taken  to  be  5.5  million  per  cubic  millimeter;  ".a"  is  the 
average  number  of  red  blood  cells  obtained  from  the  count,  and  "  b  " 
is  the  average  number  of  organisms. 
1  From  Jour.  Amer.  Med.  Asso.,  October  4,  1919. 
