I 
DIFFUSION  OF  GERMS,  ETC.  341 
DIFFUSION  OF  GERMS,  (PANSPERMIA,)  RESEARCHED  UPON 
SPONTANEOUS  GENERATION. 
We  recently  gave  our  readers  the  views  of  this  question 
entertained  by  Pouchet ;  many  scientific  men  have  pronounced 
against  the  conclusions  of  this  zoologist,  and  have  referred  the 
origin  of  the  vegetable  mycoderms  obtained  by  him,  where  the 
atmospheric  air  was  excluded,  to  microscopic  germs  floating  in 
the  air,  and  which  are  so  small  that  they  may  be  introduced  into 
the  apparatus,  despite  the  precautions  taken  to  exclude  them. 
According  to  this  theory  it  is  necessary  to  suppose  that  the  air 
is  full  of  these  germs,  therefore  Pouchet  has  undertaken  to 
submit  the  atmospheric  air  to  microscopic  examination.  He  has 
not  found  either  germs  or  spores  of  infusoria  in  the  dust  sus- 
pended in  the  air,  but  he  has  found  a  great  number  of  grains  of 
starch.  The  air  of  great  cities  and  other  inhabited  places, 
contains  many  of  these  starch  grain.>^,  which^  according  to  him, 
one  might  take  to  be  eggs  of  infusoria,  or  germs  of  mycoderms. 
He  has  found  them  among  the  dust  of  old  cathedrals,  and  even 
from  dust  obtained  from  Egyptian  mummies,  and  the  chambers 
of  the  pyramids,  as  well  as  among  the  ruins  of  Grecian  temples. 
Yet  there  must  be  something  in  the  air  which  has  escaped 
recognition  by  the  microscope,  for  by  causing  a  quantity  of  air 
to  pass  through  a  tube  containing  calcined  asbestos,  and  intro- 
ducing some  of  this  material  into  liquids  which  previously  had 
access  only  to  calcined  air,  and  which  consequently  contained 
no  trace  of  vegetation,  Pasteur  has  been  able  to  develop  muce- 
dines.  We  have  seen  the  apparatus  of  this  chemist  in  use  at 
the  Ecole  N'ormale  de  Paris.  This  apparatus  is  remarkable  for 
its  simplicity  and  its  precision,  and  it  is  Impossible  to  object  to 
his  conclusions,  for  they  preclude  the  possibility  on  the  part  of 
nature  to  continue  her  creative  work  in  connection  with  elements 
purely  mineral,  or  to  animate  them  with  the  organic  influence. 
This  chemist  has  already  informed  us,  that,  in  order  that 
vegetation  may  be  developed,  or  fermentation  produced,  there  is 
required  a  liquid  containing  water,  a  salt  having  ammonia  as  a 
base,  a  carbonaceous  substance,  and  a  phosphate  ;  the  air  is 
necessary  only  for  the  moment  while  we  introduce  into  the  flask 
some  spores  of  penicilium,  or  a  little  dust  obtained  from  the  air 
