396  Myricacece  of  Eastern  United  States.   { ^™pJXvPi&iT' 
its  possible  pathogenic  relation  to  such  animals.  The  Actinomyces 
not  only  confines  itself  to  the  cortex  of  the  tubercular  roots ;  it  later 
works  its  way  into  the  tracheae  of  those  structures,  passes  into  the 
pitted  vessels  of  the  main  roots,  thence  into  those  of  the  stems,  and, 
conveyed  by  the  transpiration  stream  gradually  upward,  is  carried 
through  the  axes  of  catkins  so  as  finally  to  reach  the  flowers,  bracts, 
and  fruits.  In  these  it  confines  its  existence  to  the  part  corresponding 
to  the  mediocortex  of  the  root  tubercles ;  namely,  the  mesophyll  and 
outer  mesocarp  regions  respectively.  It  has  been  observed  by  the 
writer  in  its  most  luxuriant  form  in  the  cells  of  the  middle  fruit  wall 
of  the  various  species  studied.  Here  it  can  be  recognized  best  in  thin 
hand  sections  stained  with  safranin  and  methyl  green  in  the  form  of 
rosettes,  almost  filling  the  cell  lumina.  When  the  fruits  fall  to  the 
ground  and  subsequently  break  open  their  walls,  the  organism  proba- 
bly makes  its  way  from  the  infected  cells  into  the  soil,  where  it  spreads 
through  wide  areas,  infecting  the  roots  and  stems  of  other  Myricas 
and  producing  characteristic  lesions. 
In  Comptonia  asplenifolia,  while  Actinomyces  Myricarutn  is  the 
primary  infecting  agent  responsible  for  the  tubercles,  there  often 
appears  in  older  tubercles  a  mycelium-producing  fungus  with  non- 
septate  hyphae  probably  belonging  to  the  Oomycetes. 
As  for  the  roots,  so  for  the  stems  of  M.  cerifera,  M.  Caroliniensis, 
M.  Gale  and  Comptonia  asplenifolia,  a  careful  histological  study  has 
been  made  and  details  recorded. 
In  the  study  of  the  leaves  various  new  structural  details  have 
been  observed,  but  special  interest  attaches  to  the  presence  now  re- 
corded of  orange-red,  bowl-  to  saucer-shaped  glandular  hairs  specifi- 
cally characteristic  of  M.  cerifera  and  in  a  reduced  degree  of  M. 
Macfarlanei,  intermingled  with  golden-yellow  glandular  hairs  of 
Chevalier.   The  latter  only  are  present  in  M.  Caroliniensis. 
Exact  phytophenological  records  have  been  made  as  to  the  matura- 
tion of  the  floral  parts  and  the  period  of  blossoming  in  April  and  May. 
Spore  mother-cell  formation  is  completed  by  autumn  of  one  year, 
but  formation  of  tetrads  proceeds  in  the  different  species  studied 
from  mid- April  to  mid-May  in  the  Philadelphia  neighborhood. 
Careful  study  has  been  made  by  the  writer  of  stages  in  the 
development  of  the  fruits  of  M.  cerifera,  M.  Caroliniensis,  and  M. 
Macfarlanei.  These  will  be  described  as  one  category,  seeing  that 
they  closely  agree  with  each  other. 
In  early  June  the  maturing  wall  of  each  ovary  has  already  de- 
