41 8  Germination  of  Gr  amine  c? 
carbohydrate  is  one  which  is  readily  assimilable  by  the  embryo, 
such  as  cane-sugar  or  maltose,  secretion  of  ferment  is  checked  or 
even  entirely  inhibited.  No  such  inhibitory  action  is,  however, 
produced  by  such  substances  as  mannitol  and  milk-sugar,  which  are 
entirely  without  nutritive  value.  The  authors'  experiments  in  this 
direction  point  to  the  secretion  of  the  amylo-hydrolytic  and  cyto- 
hydrolytic  enzymes  as  being  to  some  extent  starvation  phenomena. 
The  power  of  secretion  possessed  by  the  epithelium  is  in  some  way 
or  other  so  adapted  to  the  requirements  of  the  young  plants  as  to  be 
only  exercised  when  the  supply  of  tissue-forming  carbon  compounds 
begins  to  fail. 
The  authors  confirm  the  important  generalization  of  Sachs  that 
the  relation  of  the  embryo  to  the  endosperm  is  that  of  parasite  to 
host,  and  they  have  availed  themselves  of  this  relation  by  culti- 
vating the  embryo  upon  suitable  media  after  separating  it  from  its 
endosperm,  and  in  this  way  they  have  obtained  information  with 
regard  to  the  secretory  powers  of  the  embryo  and  the  chemical 
modifications  of  its  absorbed  nutriment,  which  it  would  have  been 
impossible  to  obtain  by  any  other  means. 
The  results  of  cultivating  the  excised  embryos  upon  various 
nutrient  solutions,  more  especially  of  the  carbohydrates,  are 
recorded,  and  it  is  shown  that  whilst  cane-sugar,  invert-sugar, 
dextrose,  laevulose,  maltose,  raffinose,  galactose  and  glycerol  have 
all  more  or  less  nutrient  value,  milk-sugar  and  mannitol  do  not  in 
any  way  contribute  to  the  growth  of  tissue  in  the  young  plant.  Of 
all  the  substances  tried,  cane-sugar  has  by  far  the  greatest  nutritive 
power.  Maltose,  although  the  natural  food  of  the  embryo  when 
attached  to  its  endosperm,  is  decidedly  inferior  in  this  respect  to 
cane-sugar.  This  is  shown  to  be  due  to  the  fact  that  maltose 
directly  it  is  absorbed  by  the  growing  embryo  becomes  transformed 
into  cane-sugar  by  the  living  cells,  and  in  this  form  is  passed  from 
cell  to  cell.  When  cane-sugar  is  supplied  ready  formed  to  the 
young  plantlet  there  is  manifestly  a  saving  of  energy  to  the  living 
cell  which  receives  its  nutriment  in  a  form  in  which  it  is  directly 
available  for  its  requirements. 
An  examination  of  the  sugars  produced  during  the  germination 
and  of  their  mode  of  distribution  in  the  grain  have  convinced  the 
authors  that  the  transformed  starch  of  the  endosperm  is  absorbed  by 
the  embryo  in  the  form  of  maltose;  and  that  the  seat  of  production 
/  Am.  Jour.  Pharm. 
\        Aug.,  1890. 
