AmjJu°"imMm'}      Serum  Treatment  of  Hay  Fever.  329 
reported  by  Dunbar  and  his  students.  To  these  should  be  added 
the  experiences  acquired  last  summer.  The  object  of  this  paper, 
written  at  the  request  of  Professor  Liebreich,  is  to  discuss  briefly  the 
question  of  the  serum  treatment  of  hay  fever. 
The  conception  that  hay  fever  is  caused  in  persons  disposed  to  it 
by  pollen  is  found  in  the  older  literature  on  the  subject,  especially  in 
the  English.  The  proof,  however,  has  been  brought  by  Dunbar's 
exact  experiments  for  the  pollen  of  a  considerable  number  of  plants. 
These  experiments  have  been  verified  by  numerous  investigators, 
both  in  the  Old  and  the  New  World.  The  following  is  a  list  of 
plants  the  pollen  of  which  are  the  cause  of  hay  fever:  Syringa  vul- 
garis, Secale  cereale,  Avena  sativa,  Hordeum  sativum,  Avena  flaves- 
scens,  Oryza  sativa,  Calamagrostis  larceolota,  Calamagrostis  mon- 
tana,  Calamagrostis  Halleriana,  Dactylis  glomerata,  Poa  pratensis, 
Anthoxanthum  odoratum,  Eriophorum  vaginatum,  Cynosurus  cris- 
tatus,  Phalaris  arundinacea,  Lolium  perenne,  Holcus  lanatus 
Alopecurus  pratensis,  Aira  caespitosa,  Brachypodium  silvaticum, 
Agropyrum  repens,  Festuca  elatior,  Festuca  gigantea,  Triticum 
sativum,  Bromus  mollis,  Lonicera  caprifolium,  Convallaria  majalis, 
Polygonatum  multiflorum,  Oenothera  biennis,  Brassica  Napus,  Car- 
duus  acanthoides,  Leucanthemum  vulgare,  Solidago  odora,  Solidago 
nemoralis,  Solidago  canadensis,  Centaurea  Cyanus,  Chrysanthemum, 
Aster,  Zea  Mays,  Carex  vulgaris,  Carex  intermedia,  Carex  arenaria, 
Carex  paniculata,  Carex  glauca,  Carex  alba,  Carex  verna,  Atrip- 
lex  hortense,  Ambrosia  trifida,  Ambrosia  artemisiaefolia,  Ambrosia 
elatior,  Ambrosia  maritima,  Xanthium  macrocarpum,  Iva  xanthifolia, 
Spinacia  oleracea. 
In  connection  with  this  list,  and  to  the  completion  of  which  work 
is  unceasingly  continued,  it  may  be  observed  that  the  hay  fever  of 
Europe  and  the  June  cold  of  North  America  is  principally  produced 
by  the  pollen  of  grasses,  the  widely  spread  and  dreaded  Autumnal 
cold  of  North  America  is  caused  by  the  pollen  of  ragweed  (Ambro- 
sia) and  of  goldenrod  (Solidago),  also  of  asters  and  chrysanthe- 
mums. Right  here  it  may  be  stated  that  in  this  paper  we  shall  not 
be  able  to  go  into  further  details  concerning  the  autumnal  cold  of 
America. 
From  the  pure  active  pollens  a  protein-like  substance  has  been 
isolated  according  to  Dunbar's  directions  by  precipitation  with  salt 
and  alcohol.  This  substance  is  highly  toxic  when  applied  to  patients 
