Am. Jour.  Pharro. 
June,  1898. 
Mucilage  in  Plants. 
287 
The  origin  of  mucilage  as  an  "  Auscheidung  "  from  the  proto- 
plasm has  been  pointed  out  in  the  corms  of  various  species  of  Orchis, 
by  Frank,1  Meyer2  and  Hartwich.3  All  have  contributed  more  or 
less  confirmatory  researches  toward  this  end.  Frank  says  that  in  the 
young  cells  of  the  tuber  of  Orchis,  near  the  nucleus  occurs  a  bundle  of 
needle-like  crystals,  around  which  a  clear  mucilage  drop  is  formed. 
This  becomes  larger  and  larger,  and  finally  when  fully  grown  replaces 
the  protoplasm  and  nucleus,  and  occupies  the  lumen  of  the  cell. 
Arthur  Meyer,  on  the  other  hand,  claims  that  the  protoplasm  in 
Orchis  species  does  not  disappear,  but  that  it  is  to  be  found  in  the 
older  stages  of  the  cell,  and  that  the  peripherical  layer  of  proto- 
plasm secretes  the  mucilage  which  lodges  in  between  the  "  plasma- 
netz  "  (i.e.,  in  the  vacuoles).  Hartwich  confirms  the  labors  of  Meyer 
in  that  he  finds  the  peripherical  layer  of  protoplasm  in  the  latter 
stages  of  the  life  of  the  cell,  but  he  does  not  observe  the  "  plasma- 
netz."  He  also  says,  in  cells  of  Orchis  latifolia  and  0.  Morio  that  do 
not  contain  raphides,  the  mucilage  does  not  arise  in  the  middle  of 
the  cell. 
It  is  not  unlikely  but  that  in  all  of  the  plants  mentioned  as  having 
a  "  cell-contents  mucilage,"  and  which  contain  rhapides  of  calcium 
oxalate  as  scilla  (Fig.  6),  that  the  origin  is  similar  to  that  of  Salep, 
viz.,  as  an  "  Auscheidung  "  from  the  protoplasm4. 
In  Viola  tricolor,  L.,5  is  found,  as  has  been  previously  shown  by 
the  author,  peculiar  sub-epidermal  mucilage  cells,  which  occur  in  all 
the  leaf-like  elements  of  the  plant  with  exception  of  the  stamens. 
These  are  easily  ascertained  by  placing  fresh  specimens  of  the  leaf 
in  an  alcoholic  solution  of  methylene  blue  of  the  following  strength  : 
AIvCOHOUC  METHYLENE  BI^UE  SOLUTION. 
Methylene  blue   0*400  grammes. 
Alcohol  (95  per  cent.)   -  100 •  c.c. 
The  specimen  is  left  in  this  solution  for  at  least  several  hours, 
after  which  surface  or  transverse  sections  may  be  made  and  are 
transferred  to  a  slide  having  a  few  drops  of  the  following  mixture  : 
1  Pnngsheim" s  Jahr.f.  wiss.  BoL,  V,  p.  161. 
2  Arch.  d.  Pharm.,  1886,  p.  325. 
3  Arch.  d.  Pharm.,  1890,  p.  563. 
4  See  also  Tschirch,  loc.  cit.,  S.  109,  125. 
5  Inaugural  Dissertation,  Marburg,  1897. 
