Am  jour.  Pharm. )  Hybridization  in  Plants.  251 
April,  1921.       )  J 
mainly  amongst  such  Monoeotyledonous  families  as  Liliacece  and 
Orchidacecc.  When  effected,  the  hybrid  progeny  is  often  desig- 
nated by  a  compound  generic  term.  Thus,  in  the  crossing  of  the 
Liliaceous  genus  Philesia  with  the  genus  Lapageria  of  the  same 
family,  the  resulting  hybrid  is  known  as  Philageria.  Similarly  in 
the  crossing  of  the  Orchids  Latlia  and  Catleya,  the  resulting  hybrids 
are  known  as  Laeliocattleya. 
Where  the  parent  forms  have  been  highly  cultivated  and  grad- 
ually modified  by  man  for  years  or  centuries,  the  resulting  progeny 
often  becomes  mixed  and  correspondingly  unstaple.  One  result 
of  this  has  been  that  our  most  abundant  garden  flowering  plants 
of  the  present  day  are  hybrids  of  extremely  mixed  type  and  often 
doubtful  parentage,  as  in  garden  pinks,  petunias,  tobaccos,  fuchsias, 
cresses  and  others.  These  all  tend  from  their  blended  parentage 
to  vary  or  sway  in  irregular  and  often  fortuitous  manner.  Such  is 
also  true  regarding  many  cultivated  varieties  of  a  single  species, 
e.  g.}  peas,  beans,  apples,  peaches,  potatoes  and  tomatoes. 
In  the  crossing  of  varieties  and  species  it  may  be  said  broadly 
that  the  hybrid  produces  the  characters  of  the  parents  in  blended 
manner  but  reduced  by  about  one-half  the  minutest  cell  details 
shown  by  both,  when  these  are  capable  of  blending.  Where  certain 
histological  details  in  one  parent  are  alone  present  and  absent  in 
the  other  parent,  such  may  appear  in  the  hybrid  but  reduced 
about  one-half.  For  example,  the  sepal  of  Philesia  is  devoid  of  a 
nectar  gland,  while  the  sepal  of  Lapigeria  has  a  large  nectar  gland. 
When  these  species  are  crossed  Philageria,  the  hybrid,  shows  sepals, 
each  of  which  is  found  to  possess  a  nectar  gland  one-half  the  size 
of  that  of  the  Lapigeria  parent. 
Again,  if  both  species  develop  diverse  histological  details,  these 
may  be  reproduced  side  by  side  in  the  hybrid,  but  each  reduced  by 
about  one-half.  Thus,  Gooseberry  leaf  epidermis  bears  long  unicellu- 
lar non-glandular  hairs.  Black  Currant  leaf  epidermis  is  devoid 
of  these,  but  has  volatile  oil  glands.  In  the  hybrid  between  these 
the  unicellular  hairs  and  the  volatile  oil  glands  are  reproduced,  but 
each  reduced  by  about  one-half. 
Similarly,  the  leaves  of  Myrica  cerifera  possess  numerous 
golden-yellow,  balloon-shaped  glands  and  orange-red  bowi-shaped 
glands  and  few  non-glandular  hairs  on  both  epidermises.  The 
leaves  of  Myrica  Carolinensis  show  numerous  golden-yellow,  bal- 
loon-shaped glands  on  the  lower  epidermis  and  few  or  none  of 
these  on  the  upper  epidermis,  while  numerous  non-glandular  hairs 
