VARIETIES. 
75 
that  Herndon's  observations  have  revealed  the  existence  of  an  air-cast 
mould  of  the  Andes  in  the  higher  atmosphere.  He  further  suggests  that 
the  barometric  indications  on  the  leeward  or  Western  base  of  these  moun- 
tains should  be  less  than  normal,  and  from  some  data  in  his  possession  he 
believes  that  at  Lima  such  depression  exists,  yet  further  observations  are 
necessary  to  establish  this  fact.  We  have  been  informed  that  a  French 
traveller  over  the  same  route,  on  a  previous  occasion,  observed  the  gradual 
depression  of  the  boiling  point  as  he  sailed  down  stream,  which  so  annoyed 
him  that  he  destroyed  his  thermometer  as  valueless,  and  thus  by  not  con- 
tinuing his  observations,  deprived  himself  of  the  honor  of  first  discovering 
this  remarkable  phenomenon. 
Remarks  on  the  Potato  Disease.  Editor  of  the  Chemical  Gazette. — Sir  : 
During  the  course  of  the  last  few  months,  that  dreadful  scourge,  the  potato 
blight,  has  again  made  its  appearance  amongst  us,  and  has  already  com- 
mitted great  devastation  in  this  and  the  sister  island.  My  avocations 
having  lately  afforded  me  a  few  weeks  leisure,  I  determined  to  devote  it  to 
the  re-investigation  of  the  subject,  in  the  hope  of  ascertaining,  if  possible, 
the  cause  or  origin  of  the  disease,  as  well  as  a  means  of  curing  it  or  pre- 
venting its  occurrence.  I  will  not  now  occupy  your  time  and  space  with  a 
long  account  of  all  the  experiments  and  researches  that  I  have  made  with 
this  object,  but  will  content  myself  with  making  you  acquainted  with  the 
general  conclusions  at  which  I  have  arrived.    They  are  as  follows  : — 
1.  That  the  potato  blight  is  neither  directly  nor  indirectly  caused  by  the 
ravages  of  any  parasitical  insect. 
2.  That  it  is  the  effect  of  a  species  of  putrefactive  fermentation  or  in- 
cipient decomposition  of  the  nitrogenous,  i.  e.  albuminoid  constituents  of 
the  sap  or  cell-contents. 
3.  That  this  decomposition  is  either  directly  produced  by  a  peculiar 
fungus,  the  Botrytis  infestans — to  which  public  attention  has  been  already 
directed  by  other  writers — or,  what  is  in  my  opinion  a  still  more  probable 
supposition,  the  fungus  referred  to  only  makes  its  appearance  after  the  fer- 
mentative processes  have  been  in  action  for  some  time,  and  consequently  is 
an  effect,  and  not  the  cause  of  the  disease. 
4.  That  the  blight  has  been  in  some  measure  produced  by  the  long-con- 
tinued and  indiscriminate  use  of  animal  nitrogenous  manure,  which  has 
over-stimulated  the  potato  plant,  and  has  thus  rendered  it  more  susceptible 
of  disease,  and  has,  in  fact,  produced  the  same  effect  upon  it  that  alcoholic 
drinks,  when  taken  in  excess,  do  on  the  human  system  ;  that  is  to  say,  it 
has  injured  the  stamina  of  the  plant,  and  rendered  the  organism  more 
readily  affected  by  atmospheric  and  other  influences. 
5.  That  animal  or  highly-nitrogenous  organic  manures  should  be  used 
with  great  caution  in  the  cultivation  of  the  potato,  and  indeed  in  that  of  all 
root  crops  ;  the  best  manure  for  the  potato  plant  being  the  inorganic  com- 
pounds, such,  for  instance,  as  those  which  are,  or  were  at  one  time,  used  in 
parts  of  the  Continent. 
