﻿GENETIC 
  PROGRESS 
  — 
  EAST. 
  289 
  

  

  idioplasm 
  or 
  germplasm 
  he 
  identified 
  with 
  the 
  chromatin 
  of 
  the 
  

   nucleus. 
  His 
  ultimate 
  physiological 
  unit, 
  the 
  biophore, 
  was 
  the 
  

   biological 
  atom 
  active 
  in 
  building 
  up 
  organic 
  characters. 
  Grouped 
  

   together 
  into 
  higher 
  units, 
  the 
  determinants, 
  these 
  corpuscles 
  con- 
  

   trolled 
  the 
  specialization 
  of 
  cells. 
  The 
  various 
  determinants 
  of 
  an 
  

   organism 
  made- 
  up 
  the 
  ids 
  contributed 
  by 
  past 
  generations. 
  The 
  

   ids, 
  if 
  more 
  than 
  one, 
  might 
  differ 
  slightly 
  among 
  themselves, 
  thus 
  

   governing 
  variation 
  within 
  the 
  species. 
  They 
  formed 
  the 
  chromo- 
  

   somes, 
  or 
  idants, 
  by 
  arrangement 
  in 
  a 
  linear 
  series. 
  

  

  Denying 
  the 
  inheritance 
  of 
  acquired 
  characters, 
  and 
  doing 
  much 
  

   toward 
  demolishing 
  the 
  fallacious 
  logic 
  put 
  forth 
  as 
  proof 
  at 
  that 
  

   time 
  by 
  adherents 
  in 
  the 
  belief, 
  Weismann 
  outlined 
  a 
  very 
  stimulat- 
  

   ing 
  conception 
  of 
  heredity 
  on 
  this 
  basis. 
  The 
  immortal 
  germ- 
  

   plasm 
  was 
  assumed 
  to 
  be 
  set 
  apart 
  at 
  a 
  very 
  early 
  cell 
  division 
  and 
  

   passed 
  along 
  unchanged 
  to 
  the 
  next 
  generation, 
  except 
  as 
  the 
  

   activities 
  of 
  the 
  living 
  units 
  produced 
  occasional 
  changes 
  in 
  its 
  

   constitution. 
  A 
  provision 
  for 
  accurate 
  equational 
  division 
  of 
  the 
  

   chromosomes 
  and 
  their 
  reduction 
  in 
  number 
  at 
  the 
  maturation 
  of 
  

   the 
  germ 
  cells 
  was 
  thus 
  demanded, 
  predicted 
  and 
  afterwards 
  

   realized 
  — 
  though 
  not 
  precisely 
  in 
  the 
  way 
  he 
  supposed 
  — 
  by 
  dis- 
  

   coveries 
  in 
  the 
  field 
  of 
  cytology. 
  

  

  Weismann 
  further 
  accounted 
  for 
  evolution 
  by 
  a 
  selective 
  struggle 
  

   between 
  the 
  determinants 
  of 
  the 
  germ 
  cells, 
  and 
  for 
  individual 
  

   development 
  by 
  a 
  qualitative 
  distribution 
  of 
  the 
  determinants 
  of 
  

   those 
  cells 
  set 
  apart 
  to 
  build 
  up 
  the 
  bodies 
  which 
  were 
  to 
  act 
  as 
  

   hostelries 
  for 
  the 
  immortal 
  germplasm. 
  

  

  With 
  Weismann 
  is 
  reached 
  the 
  peak 
  of 
  genetic 
  generalization 
  at 
  

   the 
  beginning 
  of 
  the 
  twentieth 
  century. 
  To-day 
  we 
  have 
  parted 
  

   company 
  with 
  him 
  in 
  many 
  particulars, 
  nevertheless 
  if 
  modern 
  

   genetic 
  theory 
  can 
  be 
  said 
  to 
  be 
  the 
  outgrowth 
  of 
  any 
  earlier 
  school, 
  

   the 
  Weismannian 
  school 
  must 
  be 
  given 
  the 
  preference. 
  As 
  Wilson 
  

   has 
  said, 
  he 
  brought 
  " 
  the 
  cell 
  theory 
  and 
  the 
  evolution 
  theory 
  into 
  

   organic 
  connection." 
  His 
  work, 
  besides 
  dispelling 
  many 
  old 
  wives' 
  

   notions 
  by 
  its 
  cutting 
  logic, 
  was 
  second 
  only 
  to 
  that 
  of 
  Mendel 
  in 
  

   making 
  genetics 
  an 
  experimental 
  science. 
  Morgan 
  credits 
  him 
  

   with 
  " 
  the 
  basis 
  of 
  our 
  present 
  attempt 
  to 
  explain 
  heredity 
  in 
  

   terms 
  of 
  the 
  cell 
  " 
  in 
  that 
  he 
  propounded 
  three 
  of 
  the 
  principles 
  

   upon 
  which 
  the 
  modern 
  Chromosome 
  Theory 
  is 
  founded. 
  

  

  WEISMANN 
  AND 
  MENDEL. 
  

  

  Some 
  may 
  see 
  an 
  inconsistency 
  in 
  ascribing 
  the 
  ground-work 
  of 
  

   current 
  ideas 
  of 
  heredity 
  to 
  Weismann, 
  and 
  yet 
  celebrating 
  the 
  re- 
  

   discovery 
  of 
  Mendel's 
  papers 
  as 
  the 
  true 
  break 
  between 
  the 
  old 
  

  

  