﻿74 
  Scientific 
  Intelligence. 
  

  

  zur 
  Demonstration 
  der 
  Symmetrieverhaltnisse 
  der 
  Krystalle 
  von 
  H, 
  

   Baumhauee 
  ; 
  pp. 
  36, 
  1 
  plate. 
  Leipzig, 
  1899 
  (W. 
  Engelmann). 
  — 
  

   The 
  author 
  takes 
  up 
  in 
  the 
  present 
  work 
  the 
  thirty-two 
  classes 
  

   of 
  crystals, 
  arranged 
  according 
  to 
  their 
  symmetry, 
  and 
  develops 
  

   the 
  relations 
  between 
  them 
  with 
  much 
  clearness 
  and 
  sharpness. 
  

   Since 
  fourteen 
  of 
  the 
  classes 
  have 
  no 
  plane 
  of 
  symmetry 
  and 
  

   twenty-one 
  have 
  no 
  center 
  of 
  symmetry, 
  he 
  prefers 
  to 
  base 
  the 
  

   fundamental 
  relations 
  upon 
  the 
  axes 
  of 
  symmetry. 
  Of 
  these 
  he 
  

   distinguishes 
  between 
  two 
  types, 
  the 
  " 
  Deckachsen 
  " 
  and 
  the 
  

   " 
  Spiegelachsen," 
  the 
  latter 
  being 
  the 
  axes 
  of 
  composite 
  sym- 
  

   metry 
  ; 
  these 
  are 
  further 
  defined 
  as 
  " 
  homogene 
  " 
  or 
  " 
  inhomo- 
  

   gene," 
  etc. 
  The 
  two 
  classes 
  of 
  the 
  triclinic 
  system 
  fall 
  into 
  an 
  

   anaxial 
  division, 
  and 
  the 
  remaining 
  thirty 
  into 
  the 
  axial 
  division 
  ; 
  

   the 
  latter 
  are 
  subdivided 
  into 
  the 
  monogonal, 
  digonal, 
  tetragonal 
  

   groups, 
  etc. 
  

  

  III. 
  Botany. 
  

  

  1. 
  How 
  are 
  seeds 
  affected 
  by 
  a 
  temperature 
  of 
  —250° 
  C. 
  f 
  — 
  Sir 
  

   W. 
  Thiselton-Dyer 
  gives 
  in 
  the 
  Proceedings 
  of 
  the 
  Royal 
  Society 
  

   (vol. 
  lxv) 
  a 
  very 
  interesting 
  account 
  of 
  his 
  experiments 
  with 
  seeds 
  

   under 
  the 
  influence 
  of 
  liquid 
  hydrogen. 
  They 
  are 
  especially 
  

   instructive 
  when 
  taken 
  in 
  connection 
  with 
  the 
  experiments 
  by 
  

   Messrs. 
  Browne 
  and 
  Escombe. 
  We 
  give 
  a 
  few 
  extracts 
  from 
  Sir 
  

   William's 
  paper. 
  

  

  "When 
  Professor 
  Dewar 
  first 
  suggested 
  the 
  experiment 
  to 
  me, 
  

   he 
  pointed 
  out 
  that 
  it 
  would 
  be 
  a 
  costly 
  one, 
  that 
  it 
  would 
  only 
  

   be 
  possible 
  to 
  operate 
  on 
  very 
  small 
  quantities 
  of 
  seeds, 
  and 
  that 
  

   the 
  number 
  of 
  kinds 
  must 
  also 
  be 
  few. 
  

  

  The 
  dozen 
  seeds 
  experimented 
  upon 
  by 
  Messrs. 
  Browne 
  and 
  

   Eseombe, 
  which 
  were 
  submitted 
  to 
  the 
  temperature 
  of 
  liquid 
  air 
  ? 
  

   were 
  apparently 
  selected 
  as 
  belonging 
  to 
  different 
  natural 
  fam- 
  

   ilies, 
  and 
  also 
  in 
  some 
  degree 
  as 
  to 
  their 
  composition.* 
  My 
  

   choice 
  was 
  much 
  more 
  restricted. 
  I 
  took 
  two 
  out 
  of 
  their 
  list 
  for 
  

   the 
  sake 
  of 
  comparison 
  : 
  barley 
  and 
  vegetable 
  marrow. 
  I 
  added 
  

   wheat, 
  which 
  had 
  more 
  than 
  once 
  been 
  made 
  the 
  subject 
  of 
  

   experiment. 
  This 
  gave 
  me 
  two 
  farinaceous 
  seeds 
  and 
  one 
  oily 
  

   one. 
  I 
  then 
  took 
  shape 
  and 
  bulk 
  into 
  account. 
  Wheat 
  and 
  bar- 
  

   ley 
  are 
  roughly 
  ellipsoidal 
  and 
  medium 
  in 
  size. 
  The 
  vegetable 
  

   marrow 
  is 
  relatively 
  large 
  but 
  flattened. 
  I 
  therefore 
  added 
  

   another 
  oily 
  seed, 
  mustard, 
  which 
  is 
  small 
  and 
  spherical. 
  I 
  fol- 
  

   lowed 
  Messrs. 
  Browne 
  and 
  Escombe 
  in 
  taking 
  a 
  pea, 
  which 
  is 
  also 
  

   spherical 
  in 
  shape 
  but 
  nitrogenous 
  in 
  composition. 
  Finally 
  I 
  

   sought 
  a 
  very 
  minute 
  seed, 
  and 
  pitched 
  upon 
  musk. 
  

  

  The 
  list 
  then 
  ultimately 
  stood 
  : 
  

  

  Brassica 
  alba. 
  

  

  Pisum 
  sativum. 
  

  

  Cucurbita 
  Pepo. 
  

  

  Mimulus 
  moschatus. 
  

  

  Triticum 
  sativum. 
  

  

  Hordeum 
  vulgar 
  e. 
  

  

  * 
  Roy. 
  Soc. 
  Proc, 
  vol. 
  lvii, 
  p. 
  161. 
  

  

  