348 
Blood  Examination. 
Am.  Jour.  Pharm. 
July,  1902. 
gained  is  of  more  importance  and  value  than  is  seemingly  the  case. 
Having  laid  too  much  stress  upon  this  point,  they  have  been  mis- 
taken in  their  deductions  and  have  often  found  conditions  opposite 
to  those  one  would  naturally  expect,  and  in  their  disappointment 
have  rejected  it. 
The  fourth  and  last  class  are  those  who  I  think  rightly  estimate 
this  clinical  phenomenon,  and  attribute  to  it  in  the  majority  of 
instances  its  true  value  as  being  one  symptom  that  goes  to  make  up 
the  completed  whole,  weighing  it  carefully  as  regards  the  other 
findings  in  each  individual  case  and  giving  to  it  only  the  considera- 
tion which  is  given  to  any  other  one  fact. 
Normal  human  blood  consists  of  plasma,  red  and  white  cells, 
blood  plates  and  blood  dust. 
The  red  cells  or  erythrocytes  are  bi-concave  discs  and  contain  no 
nucleus.  They  are  derived  in  extra-uterine  life  practically  almost 
entirely  from  the  red  bone-marrow.  In  the  early  and  late  stages  of 
the  fetus,  however,  they  are  found  developing  respectively  in  the 
newly  forming  capillaries,  the  liver  and  spleen.  The  number  of 
erythrocytes  averages  about  5,000,000  per  c.mm.  in  men  and  a 
slightly  less  number  are  found  in  the  blood  of  women.  Their  prin- 
cipal constituent  is  hemoglobin.  In  diseased  conditions  the  ery- 
throcytes may  be  altered  in  shape,  size,  number,  percentage  of 
hemoglobin  and  the  appearance  in  the  blood  of  nucleated  corpuscles 
(normoblasts  and  megaloblasts),  or  the  cells  themselves  may  contain 
micro-organisms. 
The  white  cells  or  leucocytes  are  colorless,  nucleated  bodies. 
They  are  derived  from  the  lymph  nodes,  spleen  and  marrow.  Their 
number  is  variously  estimated  from  5,000  to  10,000  per  c.mm.,  the 
average  ot  16  independent  observers  being  about  7,900.  These 
cells  are  divided  into  groups  and  named  in  accordance  with  their 
size,  shape  of  nucleus  and  reactions  to  acid,  basic  and  neutral  stains. 
The  principal  varieties  are  lymphocytes,  large  mononuclear  leu- 
cocytes, polynuclear  leucocytes  and  eosinophile  leucocytes  ;  and  are 
also  classed  as  basophile  cells,  neutrophile  cells  and  eosinophile 
cells. 
The  basophile  cells  are  the  lymphocytes  and  the  large  mono- 
nuclear leucocytes.  The  neutrophile  cells  are  the  polynuclear  leu- 
cocytes. The  eosinophile  cells  are  the  so-called  eosinophile  leu- 
cocytes. 
