NO.    5      MALE  GENITAr.TA  OF  ORTHOPTEROID  INSECTS— SNODGRASS         55 
segment  (A,  m)  evidently  is  protractile  against  the  ovipositor  base; 
the  short  ovipositor,  therefore,  serves  as  an  egg  conduct  leading  from 
the  gonopore  (Gpr)  on  the  end  of  the  genital  lobe  into  the  chamber  of 
the  oothecal  fold,  and  it  also  conveys  into  the  latter  the  formative 
material  of  the  ootheca  discharged  from  the  accessory  glands  opening 
between  the  bases  of  the  second  valvulae.  With  the  formation  of  the 
ootheca,  the  lateral  flaps  of  the  o5thecal  fold  are  pressed  upward 
against  the  roof  of  the  vestibulum,  and  thus  shut  off  the  oothecal 
chamber  from  the  cavity  containing  the  ovipositor,  except  for  the 
foramen  that  admits  the  end  of  the  ovipositor. 
Copulation  and  insemination. — There  can  be  little  doubt  that  many 
of  the  differences  in  the  male  genital  structures  between  Blatta  and 
Periplaneta  on  the  one  hand,  and  Blattella  and  related  genera  on  the 
other  are  correlated  with  the  differences  in  the  genital  apparatus  of 
the  females,  but  we  have  no  exact  information  on  the  interrelated 
functions  of  the  genital  organs.  Considering  how  intimate  some  of 
the  cockroaches  are  with  us,  it  is  disconcerting  to  find  how  little  we 
know  of  the  private  lives  of  cockroaches.  Several  investigators,  how- 
ever, have  revealed  something  of  their  mating  habits. 
It  has  long  been  known  that  male  roaches  are  provided  with  glands 
opening  on  the  back  of  the  abdomen ;  the  secretion  of  some  of  these 
glands  is  attractive  to  the  female  at  the  time  of  mating,  and  assists  the 
male  in  effecting  a  union  with  the  female. 
The  first  observation  on  dorsal  abdominal  glands  in  cockroaches 
was  made  by  Gerstaeker  (1861),  who  described  two  pairs  of  small, 
eversible,  glandular  vesicles  found  in  a  species  of  Corydia  between 
the  dorsal  and  ventral  plates  of  segments  /  and  //,  present  in  adult 
males  and  females,  but  not  in  nymphal  instars.  The  function  of  these 
glands  is  unknown,  and  the  occurrence  of  similar  glands  in  other 
species  has  not  been  determined.  In  Blatta  and  Periplaneta  a  pair  of 
small  glandular  pouches  occur  in  the  infolded  membrane  between 
the  tergal  plates  of  segments  V  and  VI.  These  glands  were  first 
described  in  Periplaneta  by  Minchin  (1889,  1890),  whose  observa- 
tions were  confirmed  by  Haase  (1889),  and  their  histology  has  been 
further  studied  by  Oettinger  (1906),  and  by  Koncek  (1924).  The 
walls  of  the  pouches  contain  glandular  cells,  and  their  inner  surfaces 
are  covered  with  small  hairs.  The  dorsal  glands  of  Blatta  and  Peri- 
planeta are  present  in  both  sexes  of  the  adult,  and,  according  to 
Oettinger,  in  all  stages  of  the  nymph.  They  are  regarded  as  odor- 
producing  organs  by  Haase  and  Oettinger.  It  is  possible  that  their 
secretion  has  a  sex  attraction  during  mating.  In  Blattella  and  related 
genera  the  back  of  the  male  abdomen  is  marked  by  two  deep  irregular 
