444 
Observations  on  Parasitic  Fungi. 
infected  by  this  fungus  have  a sickly  green  colour,  with  a whitish 
cast.  Although  the  most  dreaded  by  agriculturists,  it  appears  to 
be  the  most  easily  prevented,  by  pickling  the  seed  grain,  of  which 
there  are  two  or  three  well-known  methods. 
Uredo  segetum — Smut  (fig.  4)  occupies  the  ovary  in  the  same 
way  as  the  last;  but  ruptures  it  usually  before  the  ear  is  pro- 
truded from  the  sheath  ; which  appears  at  length  covered  with  a 
smutty  powder,  containing  the  black  opaque  sporidia,  which  are 
much  larger  than  those  of  U.  caries,  but  without  their  unpleasant 
odour.  This  generally  destroys  the  entire  ear  ; but  as  the  sporidia 
easily  burst,  and  are  always  washed  oft’  by  rain  before  harvest, 
farmers  do  not  probably  calculate  their  loss  to  be  so  great  from 
this  fungus  as  it  sometimes  is  : for  I have  seen  fields  in  which 
nearly  one-filth  of  the  ears  were  rendered  abortive  by  it.  It 
appears,  therefore,  that  the  means  employed  effectually  in  pre- 
venting the  Bunt  do  not  produce  the  same  result  upon  this  species. 
Spermoedia  clavus — Ergot,  on  rye  and  other  grasses,  after 
frequent  investigations  by  men  of  science,  still  remains  in  doubt 
whether  it  be  a perfect  fungus,  or  a monstrous  form  of  the  grain, 
caused  by  fungi  or  insects.  Having  recently  found  many  Ergots 
on  the  black  bent,  Alopecurus  agrestis  (Tab.  F.  1),  and  examined 
them  carefully  while  fresh,  I find  their  pruinose  coating  to 
consist  of  small  white  blisters,  which  at  length  burst,  and  tufts 
of  moniliform  spicula  protrude  in  all  directions  (Tab.  F.  2). 
These  being  exceedingly  delicate,  break  up  under  the  least 
friction,  and  are  dispersed ; but  the  joints  of  which  they  are 
composed  (fig.  3)  being  glutinous,  adhere  to  the  parts  on  which 
they  fall.  Mr.  E.  J.  Quekett  has  given  several  beautiful  draw- 
ings of  this  fungus,  which  M.  Leveille  has  named  Sphacelia 
segetum,  from  its  producing  gangrene.  The  ovule  of  the  grain 
is  no  doubt  impregnated  by  the  spores  of  this  fungus  being 
carried  up  in  the  sap  in  the  same  manner  as  those  which  contain 
Bunt  and  Smut;  and  its  presence  causing  a constant  irritation 
and  struggle  on  the  part  of  the  plant  to  throw  it  off,  distortion 
and  enlargement  of  the  grain  is  the  result.  Insects  produce 
galls  by  similar  means ; and  branches  of  the  juniper-tree  are 
enlarged  to  twice  their  natural  size  where  attacked  by  Podisoma 
juniperi;  and  the  stems  of  Shepherd’s  purse,  where  infested  by 
Botrytis  parasitica  (Tab.  B.),  are  swollen  to  four  times  the  size 
of  the  parts  adjoining.* 
The  common  bean  is  attacked  in  most  seasons  by  Puccinia 
fabae  (2  Z>),  which  checks  its  growth  and  lessens  its  produce ; but 
I believe  it  suffers  much  more  from  insects. 
* I lately  found  a number  of  Ergots  amongst  barley  in  London.  Parties  should 
be  cautious  as  to  what  uses  sucli  samples  are  applied ; indeed  the  sale  of  them  should 
lie  prohibited  altogether. 
