57  Q 
Analagous  results  were  obtained  with  the  sera  of  guinea-pigs  g 
and  12  withdrawn  a  few  hours  before  their  death.  It  is  evident, 
therefore,  that  the  addition  of  the  sera  of  guinea-pigs  3,  g  and  12 
(without  complement)  to  normal  guinea-pig  serum  caused  no  greater 
decrease  in  the  activating  power  of  the  latter  than  occurred  when  the 
normal  guinea-pig  serum  was  diluted  to  a  similar  degree  with  O’g  per 
cent.  NaCl  solution. 
Possibly  the  diminution  or  absence  of  complement  in  the  serum  of 
animals  dying  from  trypanosomia.sis  might  be  due  to  an  absorption  of 
the  complement  by  the  trypanosomes  which  at  the  time  of  death  were 
usually  present  in  the  peripheral  blood  in  very  great  numbers.  The 
fact,  however,  that  in  the  earlier  stages  of  the  disease,  even  when  the 
tiypanosomes  were  sw-arming  in  the  peripheral  circulation  no  diminution 
of  haemolytic  complement  wuis  noticed  contravenes  this  explanation. 
Moreover,  guinea-pigs  13  and  15,  infected  with  T.  gambiense  and 
T.  eqmperdum  respectively,  exhibited  a  considerable  decrease  in 
haemolytic  complement  in  the  scrum  w'ithdrawm  a  few  hours  before 
ueatn,  although  the  blood  contained  only  one  or  twm  trypanosomes  to 
the  microscopic  held.  In  this  connection  also,  w-e  have  failed  in  our 
attempts  to  remove  in  viiro  the  haemolytic  complement  from  normal 
guinea-pig  serum  by  the  addition  of  large  numbers  of  w^ell-w'ashed 
trypano.somes  obtained  from  heavily  infected  animals. 
CONCLUSIONS 
The  results  obtained  confirm  those  of  Hartoch  and  Yakimoff,  that 
in  most  cases  of  experimental  trypanosomiasis,  a  marked  diminution 
or  total  disappearance  of  the  haemolytic  complement  can  be  observed 
for  a  few  hours  before  the  animal’s  death. 
This  decrease  of  the  haemolytic  complement  is  limited  to  the  last 
stages  of  the  disease,  and  is  not  met  witli  in  the  earlier  stages,  even 
wdren  the  blood  is  sw-arming  wuth  trypanosomes. 
The  serum  of  an  animal  m  the  last  stages  of  the  disease,  at  a  time 
when  it  contains  no  haemolytic  complement,  has  no  inhibitory  effect 
upon  the  activating  powder  of  the  complement  of  normal  serum. 
The  piesence  of  numerous  trypanosomes  in  the  blood  cau.ses  of 
itself  no  diminution  of  the  haemolytic  complement,  and  secondly  it  is 
not  possible  to  absorb,  in  viiro,  the  complement  from  normal  serum 
by  the  addition  of  numerous  trypanosome.s. 
