CONVERSION  OF  MANNITE  AND  GLYCERINE  INTO  SUGAR.  453 
atorj.  On  the  12th  of  April,  1857,  the  liquid  contained  0.250 
grm.  of  true  sugar.  The  fragments  of  testicle  retained  their 
form  and  microscopic  appearance ;  some  almost  inappreciable 
traces  of  vegetation  were  discovered  on  careful  examination. 
When  washed  and  dried,  these  fragments  weighed  0.230  grm., 
so  that  they  had  lost  0.050  grm.  This  loss,  however,  is  rather 
apparent  than  real,  for  the  fresh  testicles  contain  a  certain  por- 
tion of  saline  and  other  substances  which  are  soluble  in  water, 
and  a  portion  of  the  tissue  becomes  disaggregated  and  soluble 
without  changing  into  sugar ;  all  these  products  are  calculated 
as  loss,  although  they  are  found  in  a  soluble  state,  and  partially 
coagulable  during  the  evaporation  of  the  liquid.  Taking  into 
account  these  various  circumstances,  and  the  proportion  of  sugar 
formed  in  the  preceding  and  other  experiments,  without  speak- 
ing of  the  analogies  of  composition  and  constitution  existing 
between  the  sugars  and  the  mannite  and  glycerine,  we  shall 
be  led  to  regard  the  sugar  thus  produced  as  resulting  principally, 
perhaps  exclusively,  from  the  transformation  of  the  mannite  or 
glycerine.  This  conclusion  is  also  confirmed  by  other  experi- 
ments, in  which,  without  perceptible  diminution,  the  testicular 
tissue  produced  the  conversion  of  mannite  into  sugar,  seven  times 
consecutively, 
These  facts  tend  to  assimilate  the  influence  of  the  testicular 
tissue  with  the  actions  of  contact  which  have  been  observed  in 
inorganic  chemistry,  and  this  is  confirmed  by  the  permanence  of 
the  microscopic  structure  of  the  tissue  in  the  course  of  the  ex- 
periments. These,  however,  are  probabilities  rather  than  a  de- 
monstration. In  fact,  the  animal  tissues  do  not  enjoy  that 
absolute  invariability  of  composition  which  often  characterizes 
the  mineral  compounds  acting  by  contact.  At  the  same  time 
that  the  tissue  acts,  it  becomes  continuously  altered;  it  is  decom- 
posed without  putrefaction,  as  shown  by  analysis. 
Thus  it  cannot  be  decided  positively  whether  the  tissue  operates 
by  the  action  of  contact  in  virtue  of  its  organic  structure,  or  its 
chemical  composition,  or  whether  the  very  fact  of  its  decomposi- 
tion does  not  exert  some  influence.  Lastly,  the  contact  of  the 
air,  without  which  these  experiments  would  not  succeed,  intro- 
duces a  new  complication,  for  it  allows  the  development  of  micro- 
scopic animal  vegetable  organisms  ;  this  could  never  be  altogether 
