And  let  us  also  keep  in  view  how  the  reparative  processes  may  illus-
trate the  laws  of  ordinary  nutrition  ;  and  especially  observe  that  they
furnish  evidence  of  the  nature  of  the  formative  process  exercised  in  the
complete  organism.  I  mentioned  in  a  former  lecture  (p.  45)  that,  in
naany  instances  of  repair  and  reproduction,  the  formation  of  the  new
replacing  structures  cannot  be  ascribed  to  an  assimilative  force,  or  to
the  development  of  tissue-germs  derived  from  the  injured  or  lost  parts.
The  completeness  of  repair  after  injury,  and  the  extent  to  which  it  is
sometimes  accomplished,  become  thus  most  striking  evidences  of  the
principle  that  the  formative  process  is,  in  the  completed  organism,  the
same  and  continuous  with  that  which  actuated  the  formation  of  the
original  tissues  in  the  development  of  the  germ  and  embryo.  There  is
in  every  considerable  process  of  repair  a  re-making  of  a  part  ;  and  the
new  materials  assume  the  specific  form  and  composition  of  the  part  that
they  replace,  through  the  operatign  of  no  other,  or  otherwise  directed,
force,  than  that  through  which  that  part  was  first  made.  For,  in  all
grave  injuries  and  diseases,  the  parts  that  might  serve  as  models  for  the
repairing  materials  to  be  assimilated  to,  or  as  tissue-germs  to  develop
new  structures,  are  lost  or  spoiled  ;  yet  the  eflfects  of  such  injury  and
disease  are  recovered  from,  and  the  right  specific  form  and  composition
are  regained.  In  all  such  cases,  the  reproduced  parts  are  formed,  not
according  to  any  present  model,  but  according  to  the  appropriate  spe-
cific form  ;  and  often  with  a  more  strikingly  evident  design  towards  that
form  as  an  end  or  purpose  than  we  can  discern  in  the  natural  construc-
tion of  the  body.
