﻿36 
  

  

  In 
  order 
  to 
  show 
  how 
  conspicuously 
  the 
  characteristics 
  of 
  

   the 
  sexes 
  are 
  shown 
  in 
  these 
  sections 
  I 
  have 
  made 
  careful 
  

   drawings 
  of 
  two 
  of 
  them. 
  Figure 
  53 
  is 
  a 
  section 
  of 
  part 
  

   of 
  the 
  visceral 
  mass 
  of 
  the 
  female, 
  showing 
  nine 
  ovarian 
  

   follicles 
  cut 
  in 
  various 
  directions. 
  Each 
  follicle 
  contains 
  a 
  

   nearly 
  central 
  cavity, 
  and 
  around 
  this, 
  on 
  all 
  sides, 
  the 
  

   opaque 
  granular 
  eggs 
  project 
  from 
  the 
  basement 
  membrane 
  

   of 
  the 
  follicle, 
  to 
  wliich 
  they 
  are 
  attached 
  either 
  directly 
  or 
  

   by 
  long 
  stalks. 
  Each 
  egg 
  contains 
  a 
  large, 
  conspicuous, 
  oval, 
  

   transparent 
  nucleus, 
  and 
  a 
  single 
  nucleolus, 
  which 
  is 
  on 
  that 
  

   side 
  of 
  the 
  nucleus 
  which 
  is 
  nearest 
  the 
  point 
  of 
  attachment 
  

   to 
  the 
  membrane. 
  The 
  eggs 
  are 
  so 
  crowded 
  that 
  they 
  are 
  

   tiattened 
  and 
  rendered 
  polygonal 
  by 
  mutual 
  pressure, 
  and 
  in 
  

   some 
  places 
  there 
  is 
  a 
  very 
  regular 
  alternation 
  of 
  those 
  with 
  

   and 
  those 
  without 
  stalks. 
  

  

  Figure 
  G7 
  is 
  a 
  section 
  of 
  a 
  portion 
  of 
  the 
  visceral 
  mass 
  

   of 
  a 
  male, 
  as 
  seen 
  with 
  the 
  same 
  magnifying 
  power. 
  The 
  

   space 
  nearest 
  the 
  basement 
  membrane 
  of 
  each 
  follicle 
  is 
  

   here 
  occupied 
  by 
  a 
  thick 
  layer 
  of 
  small 
  cells, 
  the 
  mother 
  

   cells 
  of 
  the 
  spermatozoa, 
  and 
  the 
  centre 
  of 
  the 
  follicle, 
  instead 
  

   of 
  being 
  empty, 
  as 
  in 
  the 
  female, 
  is 
  filled 
  with 
  a 
  mass 
  of 
  sper- 
  

   matozoa, 
  which 
  have 
  been 
  set 
  free. 
  Some 
  of 
  the 
  follicles 
  

   shown 
  in 
  this 
  section 
  open 
  by 
  slightly 
  constricted 
  orifices 
  into 
  

   a 
  large 
  oval 
  duct, 
  with 
  a 
  lining 
  of 
  epithelial 
  cells. 
  These 
  

   ducts 
  are 
  filled 
  with 
  nearly 
  ripe 
  spermatozoa, 
  which 
  have 
  been 
  

   forced 
  into 
  them 
  from 
  the 
  follicles, 
  and 
  even 
  in 
  the 
  hardened 
  

   specimen 
  traces 
  of 
  the 
  movement 
  of 
  the 
  spermatozoa 
  from 
  

   the 
  cavities 
  of 
  the 
  follicles 
  into 
  that 
  of 
  the 
  duct 
  are 
  retained. 
  

   A 
  comparison 
  of 
  this 
  figure 
  with 
  the 
  one 
  just 
  described 
  shows 
  

   the 
  male 
  follicle 
  to 
  be 
  so 
  different 
  from 
  the 
  fenuile 
  follicle 
  in 
  

   structure 
  and 
  appearance 
  that 
  the 
  occurrence 
  of 
  a 
  male 
  folli- 
  

   cle 
  in 
  a 
  section 
  of 
  the 
  ovary, 
  or 
  of 
  a 
  female 
  follicle 
  in 
  a 
  section 
  

   of 
  the 
  testis, 
  could 
  not 
  escape 
  instant 
  detection, 
  and 
  it 
  is 
  also 
  

   plain 
  that 
  one 
  of 
  the 
  very 
  characteristic 
  ovarian 
  eggs 
  shown 
  

   in 
  Figure 
  53, 
  could 
  hardly 
  fail 
  to 
  attract 
  attention 
  at 
  once 
  if 
  

   it 
  should 
  occur 
  in 
  a 
  section 
  of 
  the 
  testis. 
  

  

  My 
  oi'servations 
  tend 
  to 
  show, 
  then, 
  that 
  the 
  sexes 
  are 
  sep- 
  

   arate 
  in 
  the 
  American 
  oyster 
  of 
  tiie 
  Chesapeake 
  Bay 
  during 
  

  

  