AFebVuary,Pih9a ™" )  Occurrence  of  Mould  in  Cocoa  Butter.  113 
An  accidental  contamination  with  dirt  was  at  first  suspected,  but 
on  microscopical  examination  the  dark  material  was  found  to  consist 
of  innumerable  hyphae  of  various  kinds,  and  greenish  blue  conidia 
of  a  fungus.  It  was  difficult  to  identify  the  individual  genera  in 
this  mass,  so  sterile  prune-juice  agar  medium  was  prepared,  poured 
into  Petri  dishes,  and  subsequently  inoculated  from  various  parts  of 
the  infected  material.  In  this  way  colonies  of  the  moulds  were  ob- 
tained and  Penicillium  glaucum  and  pink  yeast  were  found  to  occur, 
but  the  greater  part  of  the  original  mass  was  found  to  consist  of  a 
species  of  Aspergillus.  A  pure  culture  of  the  latter  was  obtained, 
and  it  is  believed  to  be  Aspergillus  oryzcc.  According  to  Lafar2 
this  species  is  of  practical  importance  as  a  saccharifying  fungus,  and 
has  been  cultivated  for  centuries  in  Japan  for  the  production  of  sake 
from  rice.  It  grows  rapidly  on  a  large  variety  of  liquid  and  solid 
media,  and  is  easily  cultivated  even  at  room  temperature,  the  op- 
timum being  above  300  C.  The  peculiarities  of  the  conidiophores, 
sterigmata,  and  conidia  enable  the  species  to  be  distinguished  with 
comparative  ease  from  most  others,  but  it  is  similar  to  Aspergillus 
flaws,  except  that  in  the  latter  the  walls  of  the  hyphse  and  conidio- 
phores bear  irregular  outgrowths.  The  clavate  or  spherical  globule 
exhibits  no  definite  line  of  demarcation  from  the  smooth  stem.  The 
sterigmata  are  radial,  and  bear  numerous  large  spherical  conidia 
measuring  about  0.006  Mm.  in  diameter. 
On  breaking  open  the  block  of  infected  butter,  drops  of  clear 
liquid,  apparently  water,  were  observed  to  be  present  in  some  of 
the  larger  vesicles.  Chemical  examination  showed  the  infected  part 
to  contain  0.13  per  cent,  of  moisture,  and  it  was  thought  possible 
that  the  spores  of  the  fungi  had  found  their  way  into  the  butter  by 
this  means.  To  settle  this  question,  the  following  investigation  of 
the  conditions  of  growth  of  Aspergillus  was  carried  out :  Cocoa 
butter  in  sterilized  Petri  dishes  was  inoculated  from  the  infected 
butter,  and  it  was  found  that  the  mould  would  not  grow  on  ordinary 
cocoa  butter  at  any  temperature  from  room  temperature  up  to  33 0 
C,  which  is  its  melting  point. 
Evidence  of  the  facilitating  influence  of  water  on  the  growth  of 
the  mould  in  the  infected  block  was  then  sought  by  preparing  a  series 
of  sterile  Petri  dishes,  and  into  them  placing  (a)  ordinary  cocoa 
butter,  (b)  sterilized  cocoa  butter,  and  (c)  solidified  emulsion  of 
cocoa  butter  and  water  (containing  about  30  per  cent,  of  water). 
2  Tech.  Mycol,  1910,  Vol.  II.,  Pt.  II.,  p.  308. 
