^'"oc7'i?83^™'}  ^^^^'^      CiuGhona  Bark  521 
Bat  if,  as  is  often  now  the  case,  the  shaving  is  merely  superficial 
and  carried  all  around  the  tree  the  result  is  entirely  different ;  in  this 
case  there  is  little  or  no  formation  of  cellular  tissues  to  replace  that 
removed,  a  fresh  epidermis  forms,  but  apparently  the  circulation  is 
carried  on  in  the  remaining  fibrous  tissue,  Avhich  in  fact  seems  to  be 
developed  further.  The  alteration  in  the  composition  of  the  alkaloid 
which  is  so  characteristic  of  the  true  renewal  does  not  take  place  in 
this  case ;  if  there  is  any  change  it  is  rather  in  the  direction  of  an 
increase  of  the  cinchonidine  instead  of  quinine. 
The  subject  is  not  merely  interesting  from  the  light  it  throws  upon 
Mclvor's  process,  but  it  is  one  of  great  commercial  importance.  Unless 
the  shaving  process  is  so  carried  on  as  to  produce,  at  least  in  part,  the 
beneficial  results  of  the  older  process  of  renewal  it  will  lead  to  grievous 
disappointment,  for  the  trees  seem  to  suffer  more  from  the  wrong 
treatment  than  from  the  right. 
It  is  to  be  feared  that  in  many  cases  the  temptation  to  get  a  quick 
return  from  the  plantation  by  over-frequent  and  unskilful  shaving  is 
risking  not  only  the  quality  of  the  crop  but  the  health  of  the  trees. 
Some  planters  are  even  advocating  a  return  to  the  barbarous  system  of 
coppicing ;  but  it  is  difficult  to  believe  that  this  will  generally  be  the 
case,  with  the  strong  evidence  before  their  eyes  of  the  benefits  to  be 
obtained  by  the  more  scientific  system  of  treatment. 
I  do  not  venture  into  the  vexed  questions  of  hybrids  and  species  in 
red  bark ;  but  when  I  find  that  "  red  bark  "  can  be  obtained  yielding 
up  to  4  and  5  per  cent,  of  quinine  from  natural  bark,  I  am  very  sure 
that  there  is  a  great  field  for  skill  in  the  selection  or  cultivation  of 
cinchonas.  There  is  much  to  be  learned  in  these  matters.  In  the  last 
drug  sales,  some  samples  of  bark  marked  "hybrid'^  gave  4  per  cent, 
of  quinine,  while  others,  also  hybrid,'^  gave  only  1  per  cent,  of 
quinine. 
It  is  evidently  no  easy  matter  to  distinguish  by  the  eye  the  different 
varieties  of  trees  which  produce  red  bark  of  widely  different  quality. 
Some  time  ago  I  analyzed  a  number  of  samples  of  bark  from  indi- 
vidual trees,  sent  me  by  J.  A.  Campbell,  Esq.,  from  Ceylon.  They 
were  renewed  bark  from  trees  giving  red  bark  of  very  fine  quality ; 
the  plants  were  all  from  the  same  nurseries,  and  were  supposed  to  be 
of  identical  quality. 
I  found,  however,  that  they  varied  very  widely  in  the  richness  of 
the  bark,  as  will  be  seen  from  the  following  table: 
