Skip to main content

Full text of "A first report on the relations between climates and crops"

See other formats 


^^^ 


^^0*= 


LIBRARV 

OF   THE 


University  of  California. 

GIFT  OF- 


Class 


♦^ 


UI.LETIN  > 


No.  3r..     W.  B.  No.  342. 


»rl<'t',  )8J|.60. 


U.  S.  DEPARTMENT  OF  AGRICULTURE. 

WEATHER     BUREAU. 


A  FIRST  REPORT 

ON 

THE  RELATIONS  BETWEEN  CLIMATES 
AND  CROPS. 

BY 

CLEVELAND    ABBE. 


PREPARED  UNDER  THE   DIRECTION  OK 

WILLIS  L.  MOORE, 
Chief  United  States  Weather  Bureau. 


WASHINGTON: 

GOVERNMENT    PRINTING     OFFICE. 
1905. 


LETTER  OF  TRANSMITTAL. 


United  States  Department  of  Agricui '"ure, 

Weather  Bureatt,  Office  of  Chief, 

Washington^  D.  6'.,  August  /,  1905. 
Hon.  James  Wilson, 

Secretary  of  Agnculture^  Washington,,  D.  C. 
Sir:   I  have  the  honor  to  submit  the  manuscript  of  a  first  report, 
by  Prof.  Cleveland  Abbe,  on  the  Relations  Between  Climates  and 
Crops,  and  to  recommend  its  publication  as  a  bulletin  of  the  Weather 
Bureau. 

This  paper  is  not  designed  as  an  original  investigation,  but  as  a 
summary  of  the  views  of  the  best  experimentalists  and  observers,  so 
far  as  those  had  been  published  up  to  1891.  A  continuation  of  this 
study,  bringing  the  subject  up  to  date,  is  contemplated:  but  as  the 
]Miblication  of  this  first  portion  has  been  frequently  requested,  it 
seems  wise  not  to  delay. 

The  author  has  intended  to  notice  onlj^  those  investigations  that 
have  given  precise  information  as  to  specific  plants  or  crops  and  spe- 
cific localities,  and  has  made  a  thorough  search  of  all  the  more  impor- 
tant literature,  in  so  far  as  it  was  accessible  to  him;  it  is  believed 
that  the  numerous  extracts  given  by  him  will  be  gratefully  received 
by  those  who  have  not  access  to  the  same  volumes. 

The  work  is  prepared  with  the  idea  that  it  will  be  especially  useful 
to  the  teachers  of  the  agricultural  colleges  and  the  investigators  of 
the  agricultural  experiment  stations.  Therefore  only  a  limited  edition 
is  recommended. 

As  the  memoir  points  out  the  importance  of  a  climatic  laboratory 
and  the  methods  that  must  be  pursued  in  order  to  evolve  new  varieties 
of  crop  plants  adapted  to  special  climatic  conditions,  I  can  but  con- 
sider that  yon  will  recognize  this  memoir  as  a  proper  contribution  to 
igriculture  from  the  Weather  Bureau. 

Very  respectfully,  Willis  L.  Moore, 

Chief  U.  S.  Weather  Bureau. 
Approved : 

James  Wilson. 

Secretar'y. 

(3) 


PREFACE. 


Several  experts  in  agricnltnral  science  having  stated  to  me  their 
need  of  a  systematic  summarv  of  the  present  state  of  our  knowledge 
with  regard  to  the  specific  influence  of  climate  in  agriculture  and  its 
relation  to  or  absolute  effect  on  the  percentages  of  the  resulting  har- 
vest, and  the  subject  being  one  in  which  I  had  long  been  interested, 
I  therefore  presented  the  matter  to  the  Chief  Signal  Officer,  who 
thereupon  issued  an  instruction,  dated  February  25,  1891,  authorizing 
me  to  prepare  this  work,  completing  it  before  June  30  of  that  year. 
The  present  report  is  a  rapid  compilation  from  a  wide  range  of 
sources,  and  presents  a  preliminary  view  of  the  condition  of  our 
knowledge  at  that  time  as  to  the  effect  of  climate  upon  the  gi'owth 
and  distribution  of  our  staple  crops.  As  far  as  practic?Mc  I  have 
presented,  in  the  words  of  the  respective  authors,  the  results  of  their 
own  investigations  on  the  points  at  issue,  my  owm  duty  being  not  to 
undertake  any  extensive  original  study,  but  to  merely  connect  their 
results  together  in  a  logical  manner,  to  collect  data  for  future  general 
use,  and  to  suggest,  or  stimulate,  further  inquiry  on  the  points  here 
presented.  I  regi'et  that  the  report  could  not  have  been  published 
in  1891,  as  many  of  the  ideas  presented  therein  have  by  delay  thus 
been  withheld  from  their  practical  applications  to  the  benefit  of 
agriculture. 

As  the  study  of  phenology  and  agriculture,  in  the  modern*  spirit, 
has  been  cultivated  for  over  a  century  in  Europe,  much  of  our  knowl- 
edge must  be  drawn  from  European  literature,  which  is  really  far 
too  extensive  to  be  satisfactorily  summarized  in  the  time  and  space 
at  my  disposal.  Originally  it  was  my  hope  to  introduce  into  this 
report  a  sunnnary  of  the  large  and  sadly  scattered  literature  of 
American  phenology,  including  the  dates  of  l)lossoming  and  ripening 
both  of  natiA'e  and  cultivated  ])lants,  enlarging  the  work  already  done 
in  this  line  by  F.  B.  Hough  for  the  State  of  New  York;  but  I  did  not 
succeed  in  completing  this  part  of  the  work,  and  reserve  it  for  a 
future  occasion.  Requests  for  phenological  observations  in  the 
United  States  have  been  frequently  made  since  1800.  and  large  collec- 
tions of  data  exist  in  manuscript  and  print  sufficiently  extensive  to 
justify  the  hope  that  they  may  prove  worthy  of  a  study  as  elaborate 

(5) 


6 

as  that  which  European  observations  have  received  at  the  hands  of 
the  lamented  Linsser. 

The  very  extensive  problem  suggested  by  the  title  of  this  report 
involves,  first,  a  general  study  of  meteorology  in  its  relations  to 
vegetable  and  animal  life;  second,  the  determination  of  the  effect  of 
climate  upon  the  growth  and  distribution  of  staple  crops;  third,  the 
determination  of  the  climatic  conditions  and  the  localities  best  suited 
to  the  growth  of  special  varieties  of  plants  and  seeds;  fourth,  the 
statistics  of  the  extent  of  the  areas  best  adapted  to  each  of  the  more 
important  crops;  fifth,  the  separate  and  the  combined  effects  of  tem- 
perature, rainfall,  and  sunshine,  both  in  their  normal  and  abnormal 
proportions,  upon  the  annual  yields  of  the  staple  crops.  But  such 
study  necessitates  great  labor  and  much  time,  and  as  the  first  step 
in  any  such  investigation  consists  in  the  critical  examination  of  the 
work  already  done  by  others,  in  order  to  prevent  unnecessary  dupli- 
cation and  avoid  the  troubles  that  others  have  experienced,  therefore 
the  reader  must  consider  this  first  report  as  only  a  brief  introduction 
to  our  knowledge  of  the  relations  between  climates  and  crops. 

Three  ways  are  generally  recognized  as  affording  our  only  methods 
of  advancing  our  knowledge  of  our  subject,  viz,  physiological,  experi- 
mental, and  statistical.  I  shall  therefore  endeavor  to  present  the 
question  of  climates  and  crops  from  these  three  points  of  view. 

1.  The  physiological  studies  of  many  botanical  physiologists,  under 
the  leadership  of  Prof.  Julius  von  Sachs,  of  the  Botanical  Institute 
at  Wiirzburg,  Germany,  have  given  us  an  insight  into  the  method 
of  growth  of  plants  and  the  conditions  upon  which  successful  agri- 
culture must  depend.  Their  conclusions,  based  upon  microscopic 
examination,  delicate  measurements,  and  detailed  study  of  all  the 
minutiae  in  the  life  of  a  plant,  have  given  occasion  to  the  development 
of  what  ma}^  be  called  a  theory  of  vegetable  life,  which,  however,  is 
still  fclr  from  having  reached  a  perfect  stage  of  development.  Under 
this  head  I  have  collected  observations  relative  to  the  germination 
of  seeds,  the  flow  of  the  sap,  the  action  of  sunlight  on  the  leaves,  the 
absorption  of  moisture  by  the  roots,  the  transpiration  from  the  leaves, 
the  ripening  of  the  seeds,  the  nutritious  value  of  the  crop,  and  the 
acclimatization  of  plants. 

2.  The  experimental  method  of  determining  the  relations  of  crops 
and  climates  is  that  practiced  at  agricultural  experiment  stations 
and  also  in  the  botanical  or  biological  laboratories  that  are  so  plen- 
tiful in  the  United  States  and  in  Europe.  In  these  institutions 
special  seeds  are  sown  with  special  care,  either  in  the  open  air  in  small 
plats  of  ground  or  in  culture  pots  in  rooms  where  the  temperature, 
moisture,  and  other  conditions  are  under  control.  The  numerous  ab- 
stracts that  I  have  presented  in  this  report  tend  to  show  the  effect  of 
varying  conditions  upon  the  resulting  crops,  and  I  must  agree  heartily 


with  De  Candolle  in  his  plea  for  a  climatic  laboratory.  It  is  evident 
that  in  such  an  institution  one  may  reproduce  to  perfection  the  cli- 
matic conditions  under  which  a  given  seed  was  grown,  and  thus 
insure  a  maximum  crop;  or.  on  the  other  hand,  by  successive  culti- 
vations, under  successive  slight  changes  in  the  artificial  climate,  may 
so  modify  the  seed  as  to  produce  a  new  variety  with  a  fixed  habit  of 
growth  adapted  to  any  natural  climate  that  the  farmer  has  to  deal 
with.  The  laws  of  acclimatization  that  naturally  follow  from  Lins- 
ser's  investigations,  and,  in  fact,  from  general  experience  in  all  parts 
of  the  world,  point  to  this  as  a  most  important  field  of  future  useful- 
ness. It  is  thus  that  we  may  hope  to  accelerate  the  natural  course, 
which,  on  the  one  hand,  has  already  produced  grains  adapted  to  the 
Russian  steppes,  and,  on  the  other,  will  eventually  evolve  those 
adapted  to  the  vicissitudes  of  our  own  arid  regions  and  i30ssibly  our 
severe  Alaskan  climate. 

3.  The  statistical  method  of  ascertaining  the  effect  of  a  climate  on 
the  resulting  crop  consists  in  comparing  the  statistics  of  the  succes- 
sive annual  harvests  in  the  country  at  large  with  the  statistics  of  the 
prevailing  climatic  conditions.  At  the  close  of  this  report  I  have 
given  a  large  collection  of  data  of  this  kind,  sufficient,  I  think^  to 
ihow  that  this  method  is  very  unsatisfactory  because  of  our  ignorance 
3f  the  many  details  that  must  be  considered  in  discussing  the  statis- 
tical figures.  I  have  compiled  these  elaborate  tables  for  the  United 
States  from  the  data  given  by  the  former  Statistician  of  the  Depart- 
ment of  Agriculture,  Mr.  J.  R.  Dodge,  and  his  able  assistant,  Mr. 
Snow,  and  have  indicated  a  method  of  treating  these  figures  which 
will,  I  think,  eventually  give  us  the  best  results  that  they  are  capable 
of  affording,  and  will  be,  perhaps,  sufficiently  accurate  for  the  needs 
of  the  farmer,  the  merchant,  and  the  statesman,  but  Avhich  can  scarcely 
respond  to  the  exact  demands  of  agricultural  physics.  The  great  col- 
lection of  data  given  in  the  reports  of  the  Tenth  and  Eleventh  cen- 
suses of  the  United  States  for  the  crop  years  1879  and  1889  will, 
I  hope,  tempt  some  one  to  an  extended  study  for  those  years. 

I  shall  not  devote  much  space  to  the  question  of  the  relative  influ- 
ence of  forests  and  cultivated  fields  on  the  temperature  and  moisture 
of  the  local  air.  This  has  become  a  special  studv  on  the  part  of  those 
devoted  to  forestry,  and  the  papers  of  Professor  Ebermayer  (1873), 
Muttrich  (1880),  Nordlinger  (1885),  and  others"  teem  with  figures  to 
show  that  in  the  heart  of  an  extensive  forest  the  mean  daily  varia- 
tions of  temperature  or  the  range  from  minimum  to  maximum  is,  on 
the  average,  from  2°  to  5°  C.  less  than  in  the  open  air  just  outside  the 
forest,  while  a  similar  difference  of  only  1°  to  2°  C.  exists  for  the 


.he  full  titles  of  the  works  referred  to  in  this  report  will  be  found  in  section 
Bibliography,"  Part  IV. 


annual  ranges  of  temperature.  Some  attempts  have  also  been  made 
to  show  that  in  a  forest  region  more  rain  falls  than  in  adjacent  open 
fields ;  but  this  I  shall  not  further  consider,  as  I  have  elsewhere  shown 
that  the  measured  differences  are  all  due  to  the  influence  of  the  wind 
on  the  catch  of  the  rain  gage  and  have  nothing  to  do  with  rainfall 
itself.  All  reliable  observations  show  that  the  percentage  of  moisture 
in  the  soil  is  larger  under  the  forest  than  in  the  open  air,  and  all 
investigations  show  that  the  temperature  of  the  soil  is  far  more  uni- 
form under  the  forest  than  in  the  full  sunshine. 

The  proper  conclusion  to  draw  from  these  forest  studies,  in  so  far 
as  they  relate  to  the  question  of  the  influence  of  climate  on  crops,  is 
simply  that  plants  growing  within  the  influence  of  a  forest  have  a 
somewhat  different  climate  from  those  growing  in  the  open  field. 
The  amount  of  this  influence  will  become  a  proper  study  when  any 
important  crop  is  cultivated  within  a  forest  or  under  its  influence, 
which,  however,  is  not  now  generally  the  case. 

The  inverse  question  as  to  the  influence  upon  general  atmosj^heric 
phenomena  of  the  temperature  and  moisture  of  the  thin  layer  of  quiet 
air  within  a  region  covered  with  a  forest  is  one  that  may  be  relegated 
to  the  future  as  being  of  minor  importance  in  dynamic  meteorology 
and  of  still  less  importance  in  agricultural  climatology. 

On  the  other  hand,  the  distribution  and  quality  of  forest  trees 
affords  a  very  important  illustration  of  climatic  influence.  Indeed, 
the  forests  themselves  furnish  a  most  important  crop  of  lumber  and 
firewood,  perhaps  the  most  valuable  crop  recorded  in  the  statistics 
of  the  countrj^,  and  one  whose  relation  to  climate  must  be  imj)ortant, 
but,  unfortunately,  the  statistics  of  annual  forest  growth  are  not  yet 
available  for  this  stud}'.  I  have,  therefore,  deferred  the  considera- 
tion of  this  branch  of  our  subject  to  a  future  date,  when  perhaps 
American  forestry  will  be  more  fully  developed. 

I  shall  omit  the  consideration  of  theories  and  experiments  as  to  the 
artificial  improvement  of  the  weather,  especially  the  production  of 
rainfall,  protection  from  hail  and  lightning,  and  the  amelioration  of 
our  hot  winds.  Although  this  subject  is  alluring,  I  hope  the  common 
sense  of  the  agricultural  community  will  eventually  indorse  my  con- 
viction that,  for  the  present,  our  wisest  plan  is  to  confine  our  study 
closely  to,  first,  the  influence  of  sunshine,  heat,  moisture,  and  atmos- 
phere on  the  growth  of  plants,  on  the  nature  of  the  seed,  and  on  the 
character  of  the  crops;  second,  the  influence  of  the  quality  of  the  seed 
itself  and  of  the  richness  of  the  soil  on  the  crop ;  third,  how  to  choose 
our  seed,  cultivate  the  ground,  and  protect  the  plant  from  frost,  birds, 
insects,  fungi,  etc.,  so  as  to  secure  a  good  crop  in  spite  of  adverse 
natura.  climatic  conditions. 

In  general,  I  have  labored  to  put  my  data  and  conclusions  before 
(he  reader  so  fully  that,  if  a  student,  he  may  utilize  this  report  as  a 


basis  for  further  generalizations,  or,  if  a  farmer,  he  may  derive  many 
suggestions,  hints,  and  rules  by  which  to  improve  his  methods. 

Very  few  appreciate  the  extensive  range  of  edible  plants,  but  the 
lists  given  by  E.  L.  Sturtevant  (Agr.  Sci.,  Vol.  III.,  p.  174)  suggest 
that  we  have  in  the  botanical  world  an  almost  unexplored  field  from 
which  to  recover  for  the  use  of  civilized  man  an  endless  variety  of 
foods  and  fruits  unknown  to  our  present  cuisine  and  table.  Sturte- 
vant enumerates  in  detail  the  210  natural  orders  of  plants  recognized 
i)y  botanists  from  the  days  of  Linn?eus  to  those  of  Bentham  and 
]  looker.  These  orders  include  8,849  genera  and  110,GG3  species,  and 
Sturtevant  shows  that  the  edible  plants  include  only  4,283  species, 
repr(>senting  170  of  these  orders,  so  that  only  about  3^  per  cent  of  the 
known  species  of  plants  are  now  being  used  as  food — most  of  them, 
of  course,  to  a  very  slight  extent,  only  as  auxiliaries  to  the  princij^al 
foods. 

The  food  plants  extensively  cultivated  by  man  include  only  1,070 
species;  that  is  to  say,  less  than  1  per  cent  of  all  known  species  are 
cultivated  anywhere  throughout  the  known  world,  and  those  actually 
in  ordinary  use  in  European  and  American  kitchen  gardens  represent 
only  211  species.  The  preceding  numbers  all  refer  to  the  phenogams, 
but  Sturtevant  gives  supplementary  lists  covering  the  lower  order  of 
plants. 

Therefore  it  would  seem  that  the  present  condition  of  agriculture 
and  the  present  extent  of  our  available  vegetable  foods  is  limited  not 
so  much  by  our  climate  and  soil  as  by  our  ignorance  of  the  laws  of 
nature  affecting  plant  life.  We  may  not  control  the  clinuite,  but  we 
may  rear  natural  plants  and  adopt  rational  methods  of  modifying 
them  by  cultivation  until  they  and  we  become  quite  independent  of 
the  vicissitudes  of  drought  and  frost. 

In  conclusion  I  gratefully  acknowledge  the  enthusiastic  assistance 
that  I  have  received  from  Mrs.  R.  S.  Hotze  as  translator,  and  Mr. 
E.  R.  Miller  in  the  preparation  of  the  index. 


CONTENTS. 


Page. 

Letter  of  Tr.u^smittal 3 

Preface -  5 

Table  of  Contents -  -  11 

Part  I.— Laboratory  Work,  Physiological  and  Experimental. 

Chapter  I.  General  Remarks 15 

The  vital  principle— Cellular  and  chemical  structiire 15 

General  relations  of  the  seed  and  plant  to  the  air  and  the  soil *  18 

Importance  of  climatic  laboratories  (De  CandoUe) 23 

Chapter  II.  Germination 28 

Influence  of  uniform  temperature  on  germination  of  seed  ( De  CandoUe) .  28 

Influence  of  temperature  and  moisture  on  germination  (Sturtevant) 37 

Influence  of  light  and  heat  on  germination  (Pauchon) 37 

Chapter  III.  The  Temperature  of  the  Soil 53 

Observations  at  Houghton  Farm  and  Geneva.  N.  Y.,  by  Penhallow  . .-  53 

Observations  by  Goff  53 

Observations  of  temperature  of  manured  soils  in  Japan  by  Georgeson  _  54 

Influence  of  rain  on  temperature  of  the  soil  at  Munich  (K.  Singer) 54 

Soil  temperatures  as  affected  by  surface  slope  and  covering  (Wollny)  _ .  57 

Soil  temperatures  observed  at  Greenwich,  England 58 

Soil  temperatures  observed  at  Brookings,  S.  Dak 59 

Soil  temperatures  observed  at  Auburn,  Ala 61 

Soil  temperatures  observed  at  Pendleton,  Oreg 62 

Soil  temperatures  observed  at  Montreal.  Canada 63 

Methods  of  measuring  soil  temperatures  (Whitney;  Emory;  Menden- 

hall) 65 

Chapter  IV.  The  Infllt:nce  of  Sunshine  on  Assimilation  and  Trans- 
piration   67 

Chemistry  of  assimilation  (Abbott) 67 

Sunshine  and  transpiration  (Marie- Davy:  Deherain) '  69 

Annual  distribution  of  svmshine  ( Humboldt)       72 

^otal  quantity  of  heat  required  to  ripen  grain  ( Boussingault) 73 

The  sunshine  and  heat  required  to  ripen  grain  (Tisseraud )    73 

>,,^^The  sunshine  and  heat  required  to  form  chlorophyl  (Marie-Davy) 75 

Influent'e  of  absorbent  media  on  chlorophyl  (Engelmann) 77 

Influence  of  the  .supply  of  sap  (Laurent) 77 

Climate  and  the  location  of  chlorophyl  cells  (Guntz) 77 

The  influence  of  cloud  and  fog  ( Marie-Davy) 78 

Influence  of  shade  on  development  (Hellriegel) . 79 

Influence  of  long  and  short  waves  of  light  ( Vochting;  Sachs) 79 

Influence  of  dryness  and  sunlight  on  development  of  tubers  (Knight; 

Langeuthal;  Wollny) 80 

(11) 


12 

Page. 
Chapter  V.  The  Methods  of  Measuring  Direct  or  Diffuse  Sunshine 

AS  to  Intensity  or  Duration . 81 

Theoretical  relation  of  direct  and  diffused  sunshine  (Clausius) 81 

Total  insolation,  direct  and  diffused  (Marie-Davy)  ,  ^  ^   . . 82 

Theoretical  formulae  for  actinometer  (Arago-Davy:  Marie- Davy:  Fer- 

rel)  87 

Intensity  and  duration  of  sunshine  at  Montsouris  (Marie-Davy)  89 
Relative  total  heat  received  from  sun  and  sky  diiring  any  day  by  hori- 
zontal surfaces  ( Aymonnet) 90 

^-~ilelative  total  heat  received  during  certain  months  (Aymonnet) 92 

Photo-chemical  intensity  of  sunshine  (Bunsen:  Roscoe) . 92 

Photographic  intensity  of  sunshine  ( Vogel:  Weber) 95 

Marchand's  self-registering  chemical  actinometer 96 

Comparison  of  Marchands  and  Marie- Davy's  results  (Radau) 96 

Violle's  conjugate  bulbs 97 

Bellani"s  radiometer  or  vaporization  actinometer  (Descroix) 97 

Arago"s  cyanometer  and  Desain's  thermo-electric  actinometer -99 

Duration  of  sunshine — 

Recorded  at  United  States  Signal  Service  stations 99 

Recorded  at  Winnipeg,  Manitoba .  - .  . 100 

Total  possible  duration  of  sunshine,  by  decades  (Schott;  Libbey) 101 

Chapter  VI.  Moisture  of  the  Soil 104 

In  general        ... 104 

Evaporatio..  from  the  surface  of  fresh  water  in  evaporometer  (Descroix; 

^^-_^              ?erald;  Piche;  Riissell) 104 

Culti \  ation  diminishes  surface-soil  evaporation  (Sturtevant) 108 

Percol.^tion  ( Welitschkowsky;  Whitney;  Goff ) 100 

Available  moisture  ( Wollny;  Haberlandt:  Seignette) 110 

Transpiration  (Hoehner:  Wollny;  Risler;  Marie-Davy:  Perret) 112 

Relation  of  plants  to  moisture  of  soil  ( Wollny) .    114 

Relation  of  water  to  crops   (Ilionkoff:   Haberlandt;   Hellriegel;   Fitt- 

bogen;  Birner;  Heinrich;  Wollny;  Sorauer) ^..  116 

Rainfall  and  sugar  beets  (Briem;  Grassmann) 125 

Chapter  VII.  Miscellaneous  Relations 128 

Rapid  thaws ,  , 128 

Wind :. 129 

The  organic  dust  of  the  atmosphere  (Serafina;  Arata)  130 

Atmospheric  electricity  ( Wisliczenus;  Marie-Davy) 131 

Chapter  VIII.  Relation  of  Plants  to  Atmospheric  Nitrogen 133 

In  general 133 

"The  amount  of  nitrogen  brought  down  by  the  rain  to  the  soil  (Marie- 
Davy:  Muntz:  Marcano) 133 

Nitrogen  directly  absorbed  by  soil  (Schloesing) 136 

Fixation  of  nitrogen  by  plants  (Hellriegel  and  Wilfarth;  Breal;  Lawes 
and    Gilbert;    Frank;   Berthelot;   Heraeus;   Warini;ton;  Maquenne; 

Wheeler;  Leone;  Woods;  Petermann;  Pagnoul;  Salkowsky) 136 

Chapter  IX.  Relations  of  Crops  to  Manures  and  Fertilizers,  and 

Rotation 162 

Artificial  fertilizers  and  manures  (Sanborn;  Ohio;  Ladd;  Prize  crops 

of  1889) 162 


13 

Part  II.— Open  Air  Work— Experience  in  Natural  Climates. 

Page. 

Chapter  X.  Phenology _ 167 

The  relation  of  temperature  and  sunshine  to  the  development  of  plants— 
Thermometric  and  actinometrie  constants  (Reaumur;  Adanson;  Hum- 
boldt: Boussingault:  Gasparin;  Lachmann:  Tomaschek;  Kabsch; 
Sachs;  Deblanchis;  Hoffmann:  Herve  Mangon:  Belland;  Marie-Davy; 

Georges  Coutagne:  Van  Tieghem;  Lippincott) 168 

Studies  in  phenology — 

Quetelet 181 

Fritsch - -.- 189 

Linsser 211 

Applications  of  Linsser's  results 233^ 

Dove ---- -.-.  234 

Hoffmann 236 

Marie-Davy  (1877;  1878;  1882;  1888;  1890)- 243 

Angot  (I,  1882;  II,  1886;  III,  1888;  IV,  1890) 278 

Requests  for  phenological  observations  of  uncultivated  plants  (Smith- 
sonian ;  Hoffmann ) 290 

Chapter  XI.  Acclimatization  and  Heredity 295 

Grape  (Fritz)  295 

Grasses  (Sporer) •. .  299 

Cereals  (Brewer) 300 

Cotton  (Hammond) 305 

Beans  (De  Candolle) ^ . . ' 306 

Pepper  (Sturtevant)  ...  ^-"'-^  307 

Kentucky  blue  grass  (Hunt) .--iV,  307 

Chapter  XII.  Relation  of  Special  Crops  to  Special  Features  of 

Climate  and  other  Influences 309 

Beets  and  potatoes  (Briem) 309 

Sugar  beets  ( Durin) 310 

Grasses  (Ladd;  Holten) 310 

Cereals  (Richardson) 312 

Wheat— General  relation  to  climate  and  soil  (Brewer) 314 

Cultivation  of  cereals— Experiments  at  Brookings,  S.  Dak. — Wheat- 
Barley — Oats— Maize — Meteorologica!  ^ecord  for  1888  and  1889 318 

Maize- 
Indiana  331 

New  York  (Plumb) 332 

Missouri  (Schweitzer) 333 

Pennsylvania  (Frear  and  Caldwell)  333 

Illinois  (Hunt) 334 

Maize  and  peas— New  York  (Sturtevant) 335 

Sorghum— United  States  (Wiley  and  Stone) _  _ 337 

Oats- 
Kansas  337 

Ohio _ 338 

Freezing  of  plants  and  seeds  (Detmer)  338 

ijuries  and  benefits  due  to  wind-breaks 340 

hunderstorms  and  ozone 341 

Tuning  versus  climate 341 

/"heat,  temperature,  and  rain  in  England 341 

agar  crop  and  rain  in  Barbados 344 


14 

Part  III.— Statistical  Farm  Work. 

Page. 

Chapter  XIII.  The  Crops  and  Climates  of  the  United  States 351 

Variability  of  results  from  plat  experiments 353 

Effect  of  variations  in  method  of  cultivation  and  in  quality  of  seed  for 

different  regions  and  years 355 

Effect  of  variations  in  dates  of  seeding  and  harvesting 358 

Brief  summary  of  conclusions 363 

Part  IT. 
Chapter  XIV.  Authorities: 

Catalogue  of  periodicals  and  authors  referred  to 365 

General  index  _ - -  - - .       377 


A  FIRST  REPORT  ON  THE  RELATIONS  BETWEEN 
CLIMATES  AND  CROPS. 


PART  I.-LABORATORY  WORK,  PHYSIOLOGICAL  AND  EXPERI- 
MENTAL. 


Chapter  I. 

GENERAL   REMARKS. 

It  is  not  possible  to  conceive  of  an  intelligent  solution  of  the  com- 
plex problems  offered  by  plant  life  in  the  ojjen  air  and  cultivated 
fields  without  first  considering  the  innumerable  experiments  that 
have  been  made  by  experimental  botanists.  It  is  therefore  necessary 
for  the  student  and  the  practical  man  alike  to  know  something  of  the 
laws  of  growth,  as  presented  in  the  elaborate  treatises  by  Sachs,  Vines, 
Goodale,  and  others.  I  will  at  i3resent  simply  collate  those  special 
results  that  bear  upon  crojjs  as  the  final  object  of  agriculture  and 
confine  myself  very  closely  to  the  relation  between  the  crop  and  the 
climate,  in  order  to  avoid  being  drawn  into  the  discussion  of  innumer- 
able interesting  matters  which,  although  they  may  affect  the  crop, 
yet  are  understood  to  be  outside  the  province  of  climatology.  By 
this  latter  term  I  understand  essentially  the  influence  on  the  plant  of 
its  inclosure,  i.  e.,  the  sky  or  sunshine,  soil,  temperature,  rainfall,  and 
the  chemical  constitution  of  the  air,  either  directly  or  through  the 
soil. 

THE  VITAL  PRINCIPLE— CELLULAR  AND  CHEMICAL  STRUCTURE. 

The  growth  of  a  plant  and  the  ripening  of  the  fruit  is  accomplished 
by  a  series  of  molecular  changes,  in  which  the  atmosphere,  the  water, 
and  the  soil,  but  especially  the  sun,  play  important  parts.  In  this 
irocess  a  vital  principle  is  figuratively  said  to  exist  within  the  seed  or 
•lant  and  to  guide  the  action  of  the  energy  from  the  sun,  coercing 
he  atoms  of  the  soil,  the  water,  and  the  air  into  such  new  chemical 
ombinations  as  will  build  up  the  leaf,  the  woody  fiber,  the  starch, 
he  pollen,  the  flower,  tlie  fruit  and  the  seed. 

(15) 


16 

A  climate  that  is  favorable  to  a  special  crop  is  one  whose  vicissi- 
tudes of  heat  and  rain  and  sunshine  are  not  so  extreme  but  that  they 
can  easily  be  utilized  by  the  sunbeams  in  building  up  the  plant.  An 
unfavorable  climate  is  one  whose  average  conditions  or  whose  extreme 
vicissitudes  are  such  that  the  vitality  of  the  plant — namely,  its 
power  to  grow — can  not  make  headway  against  them.  In  extreme 
cases,  such  as  frosts,  sudden  thaws,  and  great  droughts,  the  climate 
may  even  destroy  the  organic  material  that  had  already  been  formed 
in  the  plant. 

No  plant  life,  not  even  the  lowest  vegetable  organism,  is  perfected 
except  through  the  influence  of  the  radiation  from  the  sun.  It  may 
need  the  most  intense  sunlight  of  the  Tropics,  or  it  may  need  only 
the  diffuse  and  faint  light  within  dark  forests  or  caves.  Heat  alone 
may  possibly  suffice  for  the  roots  and  certain  stages  of  gi'owth,  but  a 
greater  or  less  degree  of  light — i.  e.,  energy  delivered  in  short-wave 
length  or  rapid  periodic  oscillations — is  necessary  for  the  eventual 
maturity.  The  radiation  from  any  artificial  light,  especially  the 
most  powerful  electric  light,  will  accomplish  results  similar  to  that 
of  sunlight;  therefore,  it  is  not  necessary  to  think  that  life  or  the 
vital  principle  is  peculiar  to  or  emanates  from  the  sun,  but  on  the 
contrary  that  living  cells  utilize  the  radiations  or  molecular  vibra- 
tions so  far  as  possible  to  build  up  the  plant. 

We  know  nothing  about  the  nature  of  this  vital  principle,  but  we 
can,  by  the  microscope,  demonstrate  that  the  essential  ultimate  struc- 
ture of  the  plant  or  seed  is  a  minute  cell,  namely,  a  very  thin  skin 
or  film  or  membrane  inclosing  a  minute  portion  of  matter  consisting 
of  mixed  liquids  and  solids.  This  skin  is  called  the  wall  of  the  cell ; 
in  the  early  groAvth  of  the  cell  its  inclosed  liquid  is  called  the  proto- 
v'  ism.  By  crushing  many  such  young  cells  we  may  obtain  enough 
\  iither  part  to  make  a  chemical  examination  and  find  that  the  cell 
wall  is  a  complex  chemical  substance  called  cellulose,  composed  of 
carbon,  hydrogen,  and  oxygen.  By  molecules  this  compound  is 
CisHgyO.s;  by  weight  cellulose  has  C  44.44,  H  6.17,  O  49.39  per  cent. 
As  the  cells  become  older  their  walls  become  thicker  and  are  incrusted 
internally  with  additional  matters,  such  as  gums,  resins,  etc.,  until 
the  cell  wall  refuses  to  perform  its  original  functions.  Such  old 
cells  are  not  easily  digested  by  man  or  animals  and  are  not  considered 
as  food  or  reckoned  among  the  food  crops,  but  young  cells  in  suc- 
culent stems,  leaves,  and  fruits,  or  the  crushed  cells  of  seeds  and 
grains,  are  nutritious  food.  Flax,  cotton,  jute,  straw,  wood  pulp, 
and  many  other  mature  dried  cells  form  the  important  crops  of  textile 
fibers. 

The  protoplasm  within  the  cell  is  generally  an  albuminous  com- 


17 

pound  or  nlbimiinoid,  vi/,  besides  liavino-  carbon,  hvdro<>en,  and  oxy- 
i>:on.  it  also  contains  considerable  nitrogen  and  a  littl(^  snli)hnr  or 
phosphorus  or  iron  or  other  substances,  thus  fonnino-  all>nnien,  whose 
chemical  constitution  is  expressed  by  the  approximate  molecular 
formula  C,M,,,^,,0,.^,.  or  by  weight  C  53,  H  7,  N  IG,  O  22,  S  1 
per  cent.  Possibly  this  molecular  formula  is  more  properly  written 
3(C^.4H3yNB08),  plus  the  addition  of  sulphur  compounds  such  as  to 
make  the  Avhole  become  as  before  written.  Mulder  supposed  that  a 
certain  substance  which  he  called  proteine,  and  whose  composition  is 
supposed  to  be  C.joHobN^Oio,  is  the  basal  molecule  of  albumen;  two 
such  molecules,  Avith  additional  quantities  of  nitrogen,  hydrogen,  and 
oxygen,  combined  with  a  little  sulphur,  phosphorus,  iron,  or  other 
mineral,  make  up,  according  to  him,  the  constitution  of  the  ordinary 
albuminoid.     But  his  views  are  not  considered  altogether  acceptable. 

The  constituent  chemical  elements  contained  in  cellulose  are  ]:)i'e- 
cisely  the  same  as  those  of  starch,  wdiose  fornuda  is  Ci;Hi,/)-,,  but 
the  arrangement  of  the  atoms  and  molecules  among  themselves  is 
undoubtedly  very  different,  so  that  the  physical  and  chemical  proper- 
ties of  starch  and  cellulose  are  very  diti'erent.  Starch,  diastase,  and 
cellulose  may  be  considered  as  substances  composed  of  molecules 
whose  internal  structures  are  respectively  more  and  more  complex; 
in  the  molecules  of  each  of  these  substances  the  carbon,  hydrogen, 
and  oxygen  are  in  the  same  proportions  relative  to  each  other  both 
by  number  and  by  weight,  but  a  molecule  of  diastase  has  twice  and 
one  of  cellulose  three  times  as  many  atoms  as  a  molecule  of  starch. 
The  composition  of  pure  Avater  is  represented  by  the  molecular 
formula  HoOj,  or  by  Aveight  H  11,  O  89,  so  that  starch  may  be  consid- 
ered as  a  compound  of  0  atoms  of  carbon  Avith  5  molecides  of  Avater. 
From  the  same  point  of  vieAv  diastase  Avould  be  compounded  of^l'2 
atoms  of  carbon  and  10  molecules  of  water,  Avhile  cellulose  aa'  ^;d 
consist  of  18  atoms  of  carbon  and  15  molecules  of  water.  These  three 
substances  are  therefore  called  carbohydrates,  as  though  carbon  com- 
bined Avith  Avater  Avere  to  be  considered  as  carbon  combined  Avith 
liydric  acid.  This  term  is  not  to  be  confounded  Avith  the  Avord  "  hydro- 
carbon," which  is  applied  to  any  compound  of  hydrogen  and  carbon, 
Avhich,  Avhen  combined  Avith  Avater  or  other  molecules,  forms  a  vei-y 
different  series  of  chemicals,  such,  for  example,  as  C,tH„,  Avhicli  is  a 
hydrocarbon  and  Avhen  combined  with  4  molecules  of  Avater  or  hydric 
oxide  forms  alcohol,  making  the  latter,  as  it  were,  a  hydrate  of  a 
hydrocarbon. 

The  approximate  percentages  by  weight  of  the  cellulose  found  in 
plants  and  vegetables  dried  at  a  temperature  of  212°  F.  iuid  the  per- 
2667—05  M 2 


18 

centage  of  albuminous  compounds  for  air-dried  crops  are  given  as 
follows : 


Plant. 

Cellulose 

(dried  at 

212°). 

Albumi- 
noids (air 
dried). 

Plant. 

Cellulose 
(dried  at 

212°). 

Albumi- 
noids (air 
dried). 

1.1 
3.0 
5.5 
8.0 
10.3 
1.5.0 

11-20 
10-16 
12-16 

ii-ir 

10-14 
22-36 

24-41 

Wheat  kernels 

Red  clover  hay 

34.0 
23.0 
40.0 
48.0 
54.0 

12-20 

Barley  kernels 

Oat  straw 

Wheat  straw...., 

Rye  straw 

3-  4 

Buckwheat  kernels 

3-  4 

Peas 

This  crude  chemical  analysis  of  the  walls  and  of  the  contents  of  the 
crushed  cells  tells  us  nothing  of  the  life  that  had  previously  resided 
in  the  uncrushed  organisms,  but  prepares  us  for  the  statement  that 
the  development  of  a  plant  implies  a  great  amount  of  work  done 
among  the  molecules  in  rearranging  them  into  the  places  where 
tliey  are  needed.  These  molecules  come  from  the  simpler  atoms  in 
the  soil,  the  air,  and  the  rain  water,  but  the  force  and  energy  that 
does  the  work  of  building  them  up  comes,  so  far  as  we  know,  from  the 
sunshine.  It  is  a  case  of  the  transformation  of  energy.  Within  the 
cells  of  a  plant  the  molecular  energy,  or  the  so-called  "  radiant 
energy,"  that  would  otherwise  produce  the  phenomena  of  heat  and 
light  is  transformed  into  chemical  activity  and  produces  the  new 
molecular  compounds  that  we  use  as  food.  We  and  other  animals 
can  not  produce  these  compounds  in  our  own  bodies,  but  we  can  utilize 
them  if  they  are  not  injured  in  the  process  of  cooking. 

GENERAL   RELATIONS   OF   THE   SEED   AND   PLANT   TO   THE   AIR 
AND  THE   SOIL. 


RESPIRATION. 

It  is  known  that  in  the  act  of  germination  the  seed  absorbs  oxygen 
from  the  air  contained  in  the  interstices  of  the  soil  and  that  very  few 
seeds  will  germinate  when  the  soil  and  the  water  are  deprived  of  air 
or  free  oxygen. 

As  to  the  full-grown  plant,  it  is  commonly  said  to  absorb  carbonic- 
acid  gas  from  the  air  through  its  leaves  and  to  exhale  oxygen.  The 
investigations  of  Moisson  tend  to  modify  this  statement  and  show 
that  at  low  temperatures  there  is  more  oxygen  absorbed  than  there 
is  carbonic-acid  gas  produced,  while  at  high  temperatures  the  reverse 
is  true.  For  each  plant  there  is  a  certain  temperature  at  which  each 
volume  of  carbonic-acid  gas  absorbed  is  replaced  by  an  equal  volume 
of  oxygen  exhaled  by  the  leaves.  Thus  in  the  case  of  the  Pinus 
pinaMer  for  every  100  volumes  of  oxygen  absorbed  there  are  50 
volumes  of  carbonic-acid  gas  exhaled  at  0°  C.  temperature,  but  77 
volumes  at  13°  C.  and  114  volumes  at  40°  C. 


19 

Evidently  this  whole  process  of  respiration  depends  largely  upon 
the  temperature  of  the  air  and  is  more  active  as  the  temperature 
increases.  It  goes  on  both  in  darkness  and  in  light,  but  with  this 
difference — that  in  darkness  more  carbonic-acid  gas  is  given  out  than 
the  oxygen  that  is  absorbed,  whereas,  on  the  other  hand,  under  the 
influence  of  light  more  oxygen  is  given  out  than  the  carbonic-acid 
gas  that  is  absorbed.  Both  these  processes  are  stimulated  by  heat. 
The  assimilation  or  nutrition  of  the  plant  depends  upon  this  me- 
chanical influence  of  light  in  disengaging  oxygen  and  "  fixing  "  the 
carbon  of  the  gas  in  the  cells  of  the  plant.  Plant  respiration  is 
accompanied  by  two  distinct  but  correlated  phenomena,  Avhich  are 
defined  by  Marie-Davy  (1882)  as  "evaporation"  and  "transpi- 
ration." 

Eva-pofation. — This  is  a  purely  physical  phenomenon.  All  bodies 
lose  water  from  their  external  surfaces  when  in  contact  with  dry  air, 
and  do  so  faster  in  proportion  as  the  wind  is  stronger  and  the  air 
is  drier.     Evaporation  takes  place  for  dead  and  living  surfaces  alike. 

Transpiration. — This  is  a  physiological  and  not  a  purely  physical 
phenomenon.  It  occurs  only  in  living  plants  and  under  the  influence 
of  light ;  it  is  independent  of  the  dryness  of  the  air  a'hd  is  only  indi- 
rectly dependent  on  temperature.  It  is  intimately  connected  with 
assimilation,  since  by  its  means  materials  are  furnished  to  complete 
the  work  of  the  growth  of  the  plant. 

DRYNESS,   TEMPERATURE,  AND   VELOCITY  OF  THE  WIND. 

The  evaporation  from  the  leaves,  the  flow  of  sap,  and  the  develop- 
ment of  the  plant  depend  almost  as  much  on  the  wind  and  the  dry- 
ness of  the  air  as  they  do  on  the  temperature  of  the  air  considered  by 
itself,  since  all  these  are  necessary  in  order  to  bring  the  supply  of 
nutritious  water  up  to  the  leaf.  Therefore,  the  temperature  of  the 
air  must  not  be  considered  as  the  only  important  climatic  element  con- 
trolling vegetation.  At  the  time  of  the  bursting  of  the  buds  in  the 
spring,  when  no  leaves  are  on  the  trees  and  when  the  respiration  of 
the  plant  and  the  evaporation  are  at  their  miniminn,  the  temperature 
and  dryness  of  the  air  have  their  least  influence,  while  the  tempera- 
ture and  moisture  of  the  soil  may  have  their  maximum  relative  im- 
portance. These  latter  are  the  elements  that  determine  how  much 
water  shall  be  absorbed  and  pushed  upward  as  sap.  It  is  under  the 
influence  of  this  upward  ])ressure  of  the  sap  that  the  sunlight  manu- 
factures the  first  buds  and  leaves.  The  temperature  of  the  air  flowing 
among  the  branches  and  buds  may  have  any  value  Avithout  seriously 
affecting  the  development  of  the  plant,  provided  it  is  above  freezing 
and  below  a  destructive  temperature,  such  as  120°  F.,  and  above  a 
destructive  dryness,  such  as  5  or  10  per  cent  of  relative  humidity. 
Ordinarily  a  warm  spring  day  implies  a  warm,  moist  soil  and  a  warm, 


20 

moist  atmosphere.  Man  naturally  observes  first  the  latter  feature, 
which  is  so  important  to  him,  and  then  associates  it  with  the  budding 
of  the  plant,  but  he  recognizes  his  mistake  when  he  considers  that  the 
plant  is  firmly  established  in  the  earth  and  that  its  nourishment  and 
growth  must  depend  primarily  on  the  condition  of  the  soil  and  roots. 

TEMPERATURE   AND   MOISTURE   OF   THE   SOIL. 

The  temperature  of  the  soil  a  short  distance  below  the  immediate 
surface  does  not  depend,  by  way  of  cause  and  effect,  priniarily  on  the 
temperature  of  the  air.  It  is  not  warmed  or  cooled  appreciably  by 
conduction  of  atmospheric  heat,  but  by  direct  absorption  or  loss  of 
the  radiation  that  falls  upon  it.  To  a  slight  extent  (perhaps  5  per 
cent)  this  sunshine  is  reflected  from  the  surface  particles  of  the 
ground  according  to  the  laws  of  simple  reflection;  the  remainder  is 
absorbed  by  the  surface  and  warms  it.  This  warmed  surface  layer 
immediately  radiates  back  a  small  quantit}^  (10  per  cent)  as  long- 
waves  into  the  atmosphere  and  through  that  into  space,  since  the 
atmosphere  does  not  absorb  these  long  waves,  but  it  gives  up  a  larger 
part,  perhaps  ^0  per  cent,  by  conduction  to  the  adjacent  lowest 
layer  of  air,  which  being  thus  warmed  quickly  rises  and  by  convection 
distributes  this  50  per  cent  of  heat  throughout  the  atmosphere,  whence 
it  is  eventually  radiated  back  into  space.  The  remaining  40  per  cent 
of  the  solar  heat  is  by  conduction  carried  downward  through  the  solid 
earth;  a  large  portion  is  consumed  in  the  evaporation  of  soil  water 
and  returns  to  the  atmosphere  with  the  aqueous  vapor ;  the  rest  goes 
on  downward,  warming  up  the  soil  until  it  arrives  at  a  layer  30  to  50 
feet  below  the  earth's  surface,  where  the  gi'adient  of  temperature 
just  in  front  of  it  is  the  same  as  that  just  behind  it.  Here  the  heat 
would  accumulate  and  push  its  way  still  deeper  were  it  not  that  by 
this  time,  in  most  cases,  the  diurnal  and  annual  changes  of  tempera- 
ture at  the  earth's  surface,  where  this  heat  wave  started,  have  brought 
about  a  deficiency  just  below  the  earth's  surface;  consequently  the 
heat  that  had  reached  the  depth  of  30  or  50  feet  now  finds  the  tem- 
perature gradient  just  above  it  beginning  to  reverse,  wherefore  this 
heat  begins  to  flow  back,  upward,  and  outward.  In  this  manner  the 
temperature  of  the  ground  increases  downward  to  a  depth  of  a  few 
yards  during  certain  months  and  then  upward  during  other  months, 
in  diurnal  and  annual  fluctuations  interspersed  with  irregular 
changes,  depending  on  cloud  and  wind  and  rain,  all  of  which  are  easily 
recognized  by  examining  any  system  of  curves  representing  the  earth 
temperatures  at  different  depths  throughout  the  year. 

The  ground  is  warmed  by  the  air  only  in  case  the  temperature  of 
the  surface  soil  is  lower  than  that  of  the  air,  and,  although  this 
happens  frequently,  yet  the  quantity  of  heat  thereby  communicated 


21 

to  the  ground  is  comparatively  slight,  owing  to  the  slow  conduc- 
tivity of  the  soil  and  the  small  specific  heat  of  the  atmosphere.  This 
point  has  been  carefully  developed  by  Maurer,  of  Zurich  (1885). 
But  when  rain  and  snow  fall,  then  the  latent  heat  formerly  con- 
tained in  the  atmospheric  vapor  is  qniclvly  given  to  the  surface  soil 
and  directly  conducted  deeper  into  the  ground,  and  the  latter  is 
warmed  or  cooled  according  as  the  rain  or  snow  is  warmer  or  cooler 
than  it.  In  general,  the  warming  of  the  soil  by  warm  rain  is  less 
important  than  the  cooling  by  cold  rains,  melting  snows,  and  evapo- 
rating wine's, 

CLOUDINESS. 

AATien  clouds  intervene  the  soil  receives  a  smaller  proportion  of 
direct  solar  heat,  and  the  proportion  diminishes  as  the  thickness  of 
the  cloud  layer  increases  or  as  the  jjroportion  of  cloudy  sky  to  clear 
sky  increases.  We  may  adopt  the  approximate  rule  that  the  warm- 
ing elfect  of  the  sunshine  is  inversely  as  the  cloudiness  of  the  sky 
within  45°  of  the  zenith;  thus  for  a  sky  covered  by  10  cumulus  or 
10  stratus  the  direct  solar  heat  at  the  ground  is  0;,  for  10  cirrus  or 
cirro-cumulus  or  cirro-stratus  the  solar  heat  is  about  5,  while  for  0 
cloudiness  the  radiation  that  the  observer  receives  is  10. 

SOIL    THERMOjMETERS. 

The  motions  of  the  clouds  do  not  affect  the  sum  total  of  the 
intensity  of  the  sunshine,  but  the  variations  of  cloudiness  are  so 
important  that  it  is  best  to  make  use  of  some  form  of  sunshine 
recorder  or,  better  still,  some  form  of  integrating  actinometer  as  a 
means  of  determining  the  relative  effectiveness  of  the  sunshine  for 
any  hour  or  day.  If  any  such  instrument  shows  that  during  any 
given  hour,  with  the  sun  at  a  known  altitude,  the  duration  of  the 
effectiveness  of  the  sunshine  was  the  nth  part  of  the  maximum  value 
for  clear  sky,  then  we  may  assume  that  the  heating  effect  of  the  sun 
on  the  surface  of  the  soil  was  the  nth  part  of  its  maximum  value 
and  may  thus  ascertain  and,  if  need  be,  approximately  compute  the 
irregularities  of  the  diurnal  waves  of  heat  that  penetrate  the  soil. 
But  these  ii-regularities  are  directly  shown  by  thermometers  buried 
in  the  soil  at  different  dejjths,  and  the  observation  of  such  soil  ther- 
mometers is  an  essential  item  in  the  study  of  climate  and  vegetation. 
The  absence  of  these  observations  has  necessitated  much  labor  in 
unsatisfactory  efforts  to  obtain  the  approximate  soil  temperatures 
from  the  ordinary  observations  of  air  temperature,  radiation  ther- 
mometers, clouds  and  sunshine. 

Fortunately  the  agricultural  experiment  stations  of  the  United 
States  have  begim  the  observation  of  soil  temperatures  as-  distin- 


22 

guished  from  the  deep-earth  temperatures  that  have  for  a  century 
past  interested  the  student  of  terrestrial  physics  but  do  not  affect 
agriculture.  I  shall  hereafter  give  a  synopsis  of  such  records  so  far 
as  they  are  available  to  me ;  but  so  much  agricultural  data  has  been 
collected,  both  in  Europe  and  America,  without  corresponding  soil 
temi3eratures  that  we  also  need  the  data  and  methods  that  may  be 
used  for  estimating  soil  temperatures  from  ordinary  meteorological 
observations. 

SUNSHINE. 

Climatology  usually  considers  the  temperature  of  the  air  as  given 
by  thermometers  that  are  shaded  from  the  effect  of  sunshine;  this  is 
the  temperature  of  the  air  very  nearly  as  given  by  the  whirled  or 
ventilated  or  sling  thermometers  and  is  that  which  is  needed  in 
dynamic  meteorology.  But  the  sunshine  produces  important  chem- 
ical effects  besides  its  thermal  effects,  and  these  have  no  simple  rela- 
tion to  each  other.  It  is  therefore  very  important  that  we  have  some 
method  of  recording  the  duration,  intensity,  and  quality  of  the  total 
or  general  radiation  that  the  plant  receives  from  the  sun  and  from 
the  sun  and  the  sky  combined.  Up  to  the  early  i^art  of  the  nine- 
teenth century  the  optical  and  thermal  effects  of  sunshine  were  spoken 
of  as  due  to  certain  imponderable  forces  called  light  and  heat  that 
were  supposed  to  be  combined  in  the  complex  solar  rays,  but  which 
can  be  separated  from  each  other.  But  we  now  believe  it  to  be  cor- 
rect to  speak  of  the  sunshine  as  a  complex  influence,  a  radiation  of 
energy,  whose  exact  nature  is  problematical,  but  whose  mechanical 
effects  when  it  acts  upon  terrestrial  matter  w^e  know,  measure,  and 
study  as  the  phenomena  of  light,  heat,  electricity,  gravitation,  chem- 
ism,  and  vitality. 

DISTRIBUTION  OF  CLIMATIC  ELEMENTS  RELATR-E  TO  THE  LIFE  OF  THE 
PLANT. 

As  before  stated,  plants  respire  during  both  day  and  night.  The 
pores  of  the  leaves  are  always  absorbing  and  emitting  gases,  but 
when  the  sun  shines  on  thedeaves,  and  more  especially  with  the  help  of 
the  yellow  part  of  the  solar  spectrum,  the  chlorophyl  in  the  leaf  cells 
is  able  to  decompose  the  carbonic  acid  absorbed  by  the  plant,  retain- 
ing carbon  and  rejecting  the  oxygen. 

So  long  as  the  plant  absorbs  more  carbon  from  the  air  and  more 
nitrogen  from  the  soil  than  it  loses  by  any  process  it  is  continually 
increasing  its  leaf  surface  and  the  nutrition  in  its  sap,  laying  up  a 
store  of  nutrnnent  for  future  use.  This  process  ceases  in  the  case  of 
annual  plants  when  the  seed  or  grain  or  fruit  begins  to  ripen;  from 
this  time  forward  the  seed  makes  a  steady  draft  upon  the  nutriment 
already  stored  up  in  the  plant  which  goes  to  perfect  the  seed.     In 


23 

this  season  of  its  growth  the  phmt  really  needs  less  water  than  before, 
but  still  its  roots  have  the  same  power  of  absorbing  water,  and  if  the 
sap  is  thus  diluted  there  results  a  seed  or  fruit  that  is  heavy  with  an 
excess  of  water.  Of  course  this  water  will  dry  out,  if  it  has  an 
opportunity,  after  the  harvest,  but  if  it  has  no  opportunity,  on  account 
of  damp  weather,  it  Avill  remain  in  the  seed  and  render  the  latter  more 
subject  to  injury  from  fungi,  whose  spores  are  always  floating  in  the 
air  seeking  a  moist  nidus  or  resting  place  favorable  to  their  growth. 
Such  moist  seeds  give  a  heavy,  green  harvest,  but  a  light  dried  crop. 

Thus  it  happens  that  the  distribution  of  atmospheric  heat,  and 
moisture,  as  to  time,  is  quite  important  in  its  effect  on  the  local  harvest. 

Apparently  the  time  of  ripening  of  the  harvest  depends  wholly 
upon  the  chronological  distribution  of  water  and  sunshine,  but  the 
quantity  and  quality  of  the  harvest,  which  are  the  important  practi- 
cal results  to  the  farmer,  depend  upon  the  nutrition  carried  into  the 
plant  by  the  water  that  is  absorbed  by  the  roots. 

IRRIGATION. 

The  determination  of  the  right  time  for  irrigation  and  of  the 
proper  quantity  of  water,  in  order  to  produce  the  best  crop  in  soil 
of  a  given  richness  is  the  special  problem  of  those  planters  who 
depend  mostly  upon  irrigation  for  successful  agriculture.  In  general 
it  may  be  said  that  our  ordinary  seeds  have  long  since  been  selected 
and  acclimatized  with  a  view  to  success  in  a  climate  where  abundance 
of  moisture  is  available  at  the  proper  season.  Hence  our  crops  are 
not  so  likely  to  be  injured  by  excess  of  rain  as  by  deficienc}^  or 
drought.  Therefore  in  almost  every  section,  from  the  Rocky  Moun- 
tains to  the  Atlantic,  the  highest  success  can  only  be  attained  by  mak- 
ing provision  for  artificial  irrigation  in  times  of  drought.  The  exact 
times  and  quantities  of  irrigating  water  depend  upon  the  seed,  the 
soil,  and  the  evaporation,  which  latter  is  due  to  dryness  of  the  air,  the 
velocity  of  the  wind,  and  the  character  of  the  soil ;  but  when  artificial 
watering  or  irrigation  is  needed  to  supi^lement  natural  rain  one  must 
seek  to  ai^proximate  as  closely  as  practicable  to  the  conditions 
presented  in  the  countries  where  the  seed  originated,  and'  especially 
the  conditions  presented  during  the  seasons  in  which  the  given  seed 
produced  the  best  crops. 

IMPORTANCE  OF  CLIMATIC  LABORATORIES. 

The  studies  that  we  are  entering  upon  are  greatly  facilitated  by 
experiments  on  a  moderate  scale  under  conditions  that  are  under  the 
control  of  the  investigator,  and  free  from  the  irregularities  of  open- 
air  agriculture.  The  laws  of  nature  can  only  be  found  out  by  ques- 
tioning nature,  as  it  were,  by  means  of  test  experiments.     Our  present 


24 

needs  in  this  respect  are  even  more  urgent  no^Y  than  the}^  were  thirty 
years  ago,  and  I  can  not  do  better  than  to  reprint  and  indorse  the 
following  appeal  first  made  in  an  address  by  A.  de  Candolle  in  1866 : 

It  appears  to  me.  however,  that  botanic  gardens  can  l^e  made  still 
more  useful  in  carrying  out  physiological  researches.  For  instance, 
there  is  much  yet  to  be  learned  on  the  mode  of  action  of  heat,  light, 
and  electricity  upon  vegetation.  I  pointed  out  many  of  these  defi- 
ciencies in  1855  in  my  Geographic  Botanique  Raisonnee.  Ten  years 
later  Prof.  Julius  Sachs,  in  his  recently  published  and  valuable  work 
on  Physiological  Botany,  remarks  much  the  same  deficiencies,  not- 
withstanding that  some  progress  has  been  made  in  these  matters. 
The  evil  consists  in  this,  that  when  it  is  desired  to  observe  the  action 
of  tem])erature,  either  fixed  or  varied,  mean  or  extreme,  or  the  effect 
of  light,  it  is  exceedingly  difficult,  and  sometimes  impossible  (when 
ol)-ervations  are  made  in  the  usual  manner),  to  eliminate  the  effects 
of  the  constant  variations  of  heat  and  light.  In  the  laboratory  it  is 
possible  to  operate  under  more  exactly  defined  conditions,  but  they 
are  rarely  sufficiently  persistent ;  and  the  observer  is  led  into  error  by 
growing  plants  in  too  contracted  a  space,  either  in  tubes  or  bell 
glasses.  This  last  objection  is  apparent  when  it  is  wished  to  ascertain 
the  influence  of  the  gases  diffused  in  the  atmosphere  around  plants, 
or  that  of  the  plants  themselves  upon  the  atmosphere. 

Place  plants  under  a  receiver,  and  they  are  no  longer  in  a  natural 
condition;  leave  them  in  the  open  air,  and  the  winds  and  currents, 
produced  at  each  moment  of  the  day  by  the  temperature,  disperse 
the  gaseous  bodies  in  the  atmosphere.  Everyone  is  aware  of  the 
numerous  discussions  concerning  the  more  or  less  pernicious  influence 
of  the  gases  given  off  by  from  certain  manufactories.  The  ruin  noAv 
of  a  manufacturer,  noAv  of  a  horticulturist,  may  result  from  the 
declaration  of  an  expert ;  hence,  it  is  incumbent  on  scientific  men  not 
to  pronounce  on  these  delicate  questions  without  ■substantial  proof. 

With  a  view  to  these  researches,  of  which  I  merely  point  out  the 
general  nature,  but  which  are  immensely  varied  in  details,  I  lately 
put  this  question:  ''Could  not  experimental,  greenhouses  be  liuilt, 
in  which  the  temperature  might  be  regulated  for  a  prolonged  time, 
and  be  either  fixed,  constant,  or  variable,  according  to  the  wish  of  the 
observer?"  My  question  passed  unnoticed  in  a  voluminous  work 
where,  in  truth,  it  Avas  but  an  accessory.  I  renew  it  now  in  the  pres- 
ence of  an  assembly  admirably  qualified  to  solve  it.  I  should  like, 
were  it  possible,  to  have  a  greenhouse  placed  in  some  large  horticul- 
tural establishment  or  botanic  garden,  under  the  direction  of  some 
ingenious  and  accurate  physiologist  and  adapted  to  experiments  on 
vegetable  physiology;  and  this  is,  within  a  little,  my  idea  of  such  a 
construction : 

The  building  should  be  sheltered  from  all  external  variations  of 
temperature,  to  effect  which  I  imagine  it  should  be  in  a  great  meas- 
ure below  the  level  of  the  ground.  I  Avould  have  it  built  of  thick 
brickwork,  in  the  form  of  a  vault.  The  upper  convexity,  which  would 
rise  above  the  ground,  should  have  two  openings — one  exposed  to  the 
south,  the  other  to  the  north — in  order  to  receive  the  direct  rays  of. 
the  sun,  or  diffused  light.  These  apertures  should  each  be  closed  by 
two  very  transparent  glass  windows,  hermetically  fixed.  Besides 
which,  there  should  be  on  the  outside  means  of  excluding  the  light, 


25 

in  order  to  obtain  complete  darkness,  and  to  diminish  the  influence 
of  the  variations  of  temperature  when  lif^ht  is  not  required.  By 
sinking  it  in  the  ground,  by  the  thickness  of  its  walls,  and  by  the 
covering  of  its  exterior  surfaces  with  straw,  mats,  etc.,  the  same 
fixed  degree  of  temperature  could  be  obtained  as  in  a  cellar.  The 
vaulted  building  should  have  an  underground  connnunication  with 
a  chamber  containing  the  heating  and  the  electrical  apparatus.  The 
entrance  into  the  experimental  hothouse  should  be  through  a  passage 
closed  by  a  series  of  successive  doors.  The  temperature  should  be 
regulated  by  metallic  conductors,  heated  or  cooled  at  a  distance. 
Engineers  have  already  devised  means  by  which  the  temperature  of 
a  room,  acting  on  a  valve,  regulates  the  entry  or  exit  of  a  certain 
amount  of  air,  so  that  the  heat  regulates  itself.  Use  could  be  made  of 
such  an  apparatus  when  necessary. 

Obviously,  with  a  hothouse  thus  constructed^  the  growth  of  plants 
could  be  followed  from  their  germination  to  the  ripening  of  their 
seeds,  under  the  influence  of  a  temperature  and  an  amount  of  light 
perfectly  definite  in  intensity.  It  could  then  be  ascertained  how  heat 
acts  during  the  successive  phases  from  sowing  to  germination,  from 
germination  to  flowering,  and  from  this  on  to  the  ripening  of  the 
seed.  For  dilferent  species  various  curves  could  be  constructed  to 
express  the  action  of  heat  on  each  function,  and  of  which  there  are 
alread}'  some  in  illustration  of  the  most  simple  phenomena,  such  as 
germination,  the  growth  of  stems,  and  the  course  of  the  sap  in  the 
interior  of  certain  cells.  We  should  then  be  able  to  fix  a  great  num- 
ber of  those  minima  and  maxima  of  temperature  wdiich  limit  phys- 
iological phenomena.  Indeed,  a  question  more  complicated  might 
be  investigated,  toward  the  solution  of  which  science  has  already 
made  some  advances,  namely,  that  of  the  action  of  variable  tempera- 
tures; and  it  might  be  determined  if,  as  appears  to  be  the  case,  these 
temperatures  are  sometimes  beneficial,  at  other  times  injurious,  ac- 
cording to  the  species,  the  function  investigated,  and  the  range  of 
temperature.  The  action  of  light  on  vegetation  has  given  rise  to 
the  most  ingenious  experiments.  Unfortunately  these  experiments 
have  sometimes  ended  in  contradictory  and  uncertain  results.  The 
best  ascertained  facts  are  the  importance  of  sunlight  for  green  col- 
oring, the  decomposition  of  carbonic-acid  gas  by  the  foliage,  and 
certain  phenomena  relating  to  the  direction  or  position  of  stems  and 
leaves.  There  remains  much  yet  to  learn  upon  the  effect  of  diffused 
light,  the  combination  of  time  and  light,  and  the  relative  importance 
of  light  and  heat.  Does  a  prolonged  light  of  several  days  or  weeks, 
such  as  occurs  in  the  polar  regions,  produce  in  exhalation  of  oxygen, 
and  in  the  fixing  of  green  matter,  as  much  effect  as  the  light  distrib- 
uted during  twelve-hour  periods,  as  at  the  equator  ?  No  one  knows. 
In  this  case,  as  for  temperature,  curves  should  be  constructed,  show^ing 
the  increasing  or  diminishing  action  of  light  on  the  performance  of 
each  function;  and  as  the  electric  light  resembles  that  of  the  sun, 
we  could  in  our  experimental  hothouse  submit  vegetation  to  a  con- 
tinued light. 

A  building  such  as  I  propose  w^ould  allow  of  light  being  passed 
through  colored  glasses  or  colored  solutions,  and  so  prove  the  effect 
of  the  different  visible  or  invisible  rays  which  enter  into  the  compo- 
sition of  sunlight.  For  the  sake  of  exactness  nothing  is  superior  to 
the  decomposition  of  the  luminous  rays  by  a  prism,  and  the  fixing  the 


rays  by  means  of  the  heliostat.  Xevertheless,  a  judicious  selection 
of  coloring  matters  and  a  logical  method  of  performing  our  experi- 
ments will  lead  to  good  results.  I  will  give  as  proof  that  the  recent 
most  careful  experiments  concerning  the  action  of  various  rays  upon 
the  production  of  oxygen  by  leaves  and  upon  the  production  of  the 
green  coloring  matter  have  only  confirmed  the  discoveries  made  in 
183G,  without  either  prism  or  heliostat,  by  Professor  Daubeny,  from 
which  it  appears  that  the  most  luminous  rays  have  the  most'  i^ower. 
next  to  them  the  hottest  rays,  and  lastly  those  called  chemical. 

Doctor  Gardner  in  1843,  Mr.  Draper  immediately  after,  and  Dr. 
C.  M.  (juillemin  in  1857,  corroborated  by  means  of  the  prism  and  the 
heliostat  the  discovery  of  Doctor  Daubeny,  which  negatived  the 
opinions  prevalent  since  the  time  of  Senebier  and  Tessier,  and  which 
were  the  results  of  erroneous  experiments.  It  was  difficult  to  believe 
that  the  most  refrangible  rays,  violet,  for  instance,  which  act  the 
most  on  metallic  bodies,  as  in  photometrical  operations,  should  be 
precisely  those  which  have  least  effect  in  decomposing  the  carbonic- 
acid  gas  in  plants  and  have  the  least  effect  over  the  green  matter  in 
leaves.  Notwithstanding  the  confirmation  of  all  the  experiments 
made  by  Doctor  Daubeny,  when  repeated  by  numerous  physicists  and 
by  more  accurate  methods,  the  old  opinions,  appearing  more  probable, 
still  influenced  many  minds  till  Prof.  Julius  Sachs,  in  a  series  of  very 
important  experiments,  again  affirmed  the  truth.  It  is  really  the 
yellow  and  orange  rays  that  have  the  most  power,  and  the  blue  and 
violet  rays  the  least,  in  the  phenomena  of  vegetable  chemistry,  con- 
trary to  that  which  occurs  in  mineral  chemistry,  at  least  in  the  case 
of  chlorid  of  silver.  The  least  refrangible  rays,  such  as  orange  and 
yellow,  have  also  the  twofold  and  contrary  property,  such  as  pertains 
also  to  white  light,  and  which  produces  the  green  coloring  matter  of 
leaves  or  bleaches  them  according  to  its  intensity.  It  is  these,  also, 
which  change  the  coloring  matter  of  flowers  when  it  has  been  dis- 
solved in  water  or  alcohol.  Those  rays  called  chemical,  such  as  violet 
and  the  invisible  rays  beyond  violet,  according  to  recent  experiments 
confirmatory  of  those  of  ancient  authors — those  of  Sebastian  Pog- 
gioli  in  1817  and  those  of  C.  M.  Guillemin — have  but  one  single 
well-ascertained  effect,  that  of  favoring  the  bending  of  the  stem 
toward  the  quarter  from  which  they  come  more  decidedly  than  do 
other  rays;  yet  that  is  an  effect  perhaps  more  negative  than  positive 
if  the  flexure  proceeds,  as  many  still  believe,  from  what  is  going  on  on 
the  side  least  exposed  to  the  light. 

The  effect  upon  vegetation  of  the  nonvisible  calorific  rays  at  the 
other  extremity  of  the  spectrum  has  been  but  little  studied.  Accord- 
ing to  the  experiments  we  have  on  this  subject,  they  would  appear  to 
have  but  little  power  over  any  of  the  functions;  but  it  would  be 
Avorth  while  to  investigate  further  the  'calorific  regions  of  the  spec- 
trum by  employing  Doctor  Tyndall's  process — that  is,  by  means  of 
iodine  dissolved  in  bisulphide  of  carbon — which  permits  no  trace  of 
visible  light  to  pass. 

How  interesting  it  would  be  to  make  all  these  laboratory  experi- 
ments on  a  large  scale !  Instead  of  looking  into  small  cases  or  into 
a  small  apparatus  held  in  the  hand  and  in  which  the  plants  can  not 
well  be  seen,  the  observer  would  himself  be  inside  the  apparatus  and 
could  arrange  the  plants  as  desired.  He  might  observe  several 
species  at  the  same  time — plants  of  all  habits,  climbing  plants,  sensi- 


27 

tivo  plants,  thoso  with  colored  foliage,  as  well  as  ordinary  plants. 
The  experiment  might  he  prolonged  as  long  as  desirahle.  and  j)rob- 
ably  unlooked-for  i-esnlts  would  occur  as  to  the  form  or  color  of  the 
organs,  particularly  of  the  leaves. 

Permit  me  to  recall  on  this  sul)ject  an  experiment  made  in  18r);5  by 
Professor  von  Martins.  It  will  interest  horticulturists,  now  that 
plants  with  colored  foliage  become  more  and  more  fashionable. 
Professor  von  ISIartins  placed  some  plants  of  Amdidnflixs  tricolor 
for  two  months  under  glasses  of  various  colors.  Under  the  yellow 
glass  the  varied  tints  of  the  leaves  were  all  preserved.  The  red 
glass  rather  impeded  the  development  of  the  leaves  and  produced  at 
the  base  of  the  limb  yellow  instead  of  green;  in  the  middle  of  the 
upper  surface,  yellow  instead  of  reddish  brown,  and  below,  a  red 
spot  instead  instead  of  purplish  red.  With  the  blue  glasses,  which 
allowed  some  green  and  yellow  to  pass,  that  which  was  red  or  yellow 
in  the  leaf  had  spread,  so  that  there  only  remained  a  green  border  or 
edge.  Under  the  nearly  pure  violet  glasses  the  foliage  became  almost 
uniformly  green.  Thus,  by  means  of  colored  glasses,  provided  they 
are  not  3'ellow.  horticulturists  may  hope  to  obtain  at  least  temporary 
eflFects  as  to  the  coloring  of  variegated  foliage. 

The  action  of  electricity  on  foliage  is  so  doubtful,  so  difficult  to 
experiment  upon,  that  I  dare  hardly  mention  it ;  but  it  can  easily  be 
understood  how  a  building  constructed  as  proposed  might  facili- 
tate experiments  on  this  subject.  Respecting  the  action  of  plants  on 
the  surrounding  air  and  the  influence  of  a  certain  composition  of  the 
atmosphere  upon  vegetation,  there  would  be  by  these  means  a  large 
field  open  for  experiments.  Nothing  would  be  easier  than  to  create 
in  the  experimental  hothouse  an  atmosphere  charged  with  noxious 
gas  and  to  ascertain  the  exact  degree  of  its  action  by  day  and  by 
night.  An  atmosjjhere  of  carbonic-acid  gas  might  also  be  created, 
such  as  is  supposed  to  have  existed  in  the  coal  period.  Then  it  would 
be  seen  to  what  extent  our  present  vegetation  would  take  an  excess 
of  carbon  from  the  air,  and  if  its  general  existence  was  inconven- 
ienced by  it.  Then  it  might  be  ascertained  what  tribes  of  plants 
could  bear  this  condition  and  what  other  families  could  not  have 
existed,  supposing  that  the  air  had  formerly  had  a  very  strong  pro- 
portion of  carbonic-acid  gas. 

In  hopes  of  realizing  this  idea  of  a  complete  botanic  laboratory,  the 
author  spent  his  vacation  of  1893  in  the  botanic  gardens  and  green- 
houses of  Harvard  University.  On  his  return  to  Washington  Pro- 
fessor Riley  kindly  offered  him  every  convenience  and  space  in  the 
insectary  of  the  Department  of  Agriculture.  His  800  experimental 
plants  of  wheat  and  maize  were,  therefore,  brought  hither  from  Cam- 
bridge, Mass.  But  unforeseen  difficulties  arose,  and  it  is  to  be  hoped 
that  the  idea  of  an  experimental  laboratory  for  botanic  study  may 
be  carried  out  by  abler  hands. 


Chapter  II. 

GERMINATION. 

INFLtTENCE  OF  UNIFORM  TEMPERATURE    ON    GERMINATION   OF 

SEED. 

The  results  of  his  own  experiments  on  the  germination  of  seeds  at 
different  temperatures  were  published  by  De  Candolle  (1865).  His 
object  was  to  determine  the  effect  of  long  exposures  at  low  tempera- 
tures as  compared  with  short  exposures  at  high  temperatures.  He 
eliminated  various  sources  of  complication  and  extended  the  observa- 
tions made  by  Burckhardt  (1858).  Great  pains  were  taken  to.  keep 
the  seeds  at  a  uniform  temperature;  the  water  with  which  they 
were  wetted  was  previously  brought  to  the  temperature  required  by 
the  experiment.  The  first  wetting  was  quite  copious.  The  seeds 
were  first  covered  with  a  thin  layer  of  sand  and  the  wettings  fre- 
quently washed  them  bare,  but  no  difference  was  observable  in  the 
epoch  of  germination  for  naked  and  covered  seeds,  showing  that  the 
temperatures  in  the  inclosures  were  very  uniform.  The  thermometers 
were  carefully  reduced  to  a  standard  Centigrade  and  their  readings 
are  probably  correct  within  a  tenth  of  a  degree.  The  moment  of 
germination  is  a  delicate  point  to  fix  and  is  somewhat  arbitrary. 
The  embryo  changes  within  the  seed  before  any  change  shows  itself 
on  the  outside.  De  Candolle  takes  as  the  moment  of  germination  that 
when,  the  spermoderm  being  broken,  the  radicle  begins  to  issue 
forth.  Burckhardt  in  his  experiments  took  as  the  epoch  of  germina- 
tion the  moment  when  the  cotyledons  show  themselves;  but  in  De 
Candolle's  opinion  this  is  rather  an  epoch  of  vegetation  than  the 
epoch  of  germination.  It  would  perhaps  be  well  to  consider  this 
phenomenon  when  we  compare  the  same  species  under  different  con- 
ditions; but  it  varies  very  much  from  one  species  to  another,  since 
certain  plants  remain  for  a  long  time  recurved  under  the  earth  or 
with  their  cotyledons  imprisoned  in  the  remnants  of  the  spermoderm. 

The  seeds  experimented  on  were  as  follows : 

Crucif erae Lepidium  sativum . 

Do Sinapis  alba. 

Do Iberis  amara. 

Polemoniaceae Collomia  coccinea. 

Linaceae Linum  usitatissimum. 

Cucnrbitaceae Melon  ( cantaloupe) . 

RanuncTilaceae Nigella  sativa. 

Pedalinefe Sesamum  orientate. 

Legiiminoseae Trifolium  repens. 

Gramine;e Zea  mays,  var.  precoce. 

Amarantaceae Celosia  cristata. 

(28) 


29 

The  conclusions  which  De  Ctuulolle  draws  from  his  experiments  arc 
as  follows : 

(a)  at  a  constant  temperature  ok  0°  c. 

From  the  7th  of  March  to  the  Uth  of  April — that  is  to  say,  in  35 
days'  exposure  to  this  temperature — the  following  seeds  did  not  ger- 
minate at  all :  Collomi<(,  Lepidium^  Linum^  Zea  ?nays,  Melon,  Nlgella, 
Sesatmnn,  Trifoliunu  Celosia. 

The  only  species  which  did  germinate  was  Sinapw,  the  various 
seeds  of  which  germinated  in  from  11  to  17  days,  the  latter  seemed 
to  De  Candolle  to  be  the  more  proper  value  of  the  time. 

(b)  at  temperatures  from  1.4°  to  2.2°  c. 

Collomia  and  Celosia  did  not  germinate  in  35  days;  Lepidium  and 
Linum  germinated  in  30  and  34  days,  respectively,  under  ^average 
temperature  of  1,8°.  Zea  mays  and  Nigella  did  not  germinate  in  35 
days;  Sesa7num  did  not  germinate  in  35  days;  Sinapls  germinated  in 
16  days,  at  an  average  temperature  of  1.9°. 

(c)     AT   temperatures    VARYING    BETWEEN    2.6°    AND   3.2°    C. 

Collomia  did  not  germinate  in  36  days;  Lepidium,  about  one-half 
of  the  seeds  germinated,  on  the  twelfth,  sixteenth,  and  thirty-first 
daj^s,  respectively;  Linum  germinated  on  the  seventeenth  and 
eighteenth  days,  at  an  average  temperature  of  3.1°  ;  Zea  mays  did  not 
germinate  in  36  days;  Nigella  did  not  germinate;  Sesamum  did  not 
germinate.  Three  Sinapis  seeds  germinated  on  the  ninth,  one  more 
on  the  seventeenth  day.  A  new  sowing  of  Sinapis  gave  one  seed 
germinating  on  the  sixth  day.  AfterAvards  the  temperature  was 
alloAved  to  rise  gradually,  but  the  seeds  which  had  not  germinated 
before  came  to  nothing, 

(d)  at  temperatures  from  4.2°  to  6.1°  c. 

About  one-half  the  Collomia  seeds  germinated  on  the  seventeenth 
day,  at  an  average  temperature  of  5.35° ;  Lepidium  germinated  abun- 
dantly on  the  eighteenth  day ;  Zea  mays  did  not  germinate ;  about  one- 
fifth  of  the  Linnm  seeds  germinated  on  the  seventeenth  day  (average 
temperature  4.8°)  ;  Nigella,  Sesamum,  and  Sinapis  did  not  germinate. 

Possibly  the  moisture  was  too  large  in  series  (c)  and  (d). 

(e)   at  temperatures  between  5.4°  and  6°  v. 

Some  Collomia  seeds  germinated  in  14  days;  Lepidium  germinated 
freely  on  the  fifth  day;  LJnum  germinated  freely  on  the  sixth  day; 
Zea  mays  did  not  germinate  in  36  days ;  Nigella  germinated  in  twenty- 
seventh  day;  Sesamum  did  not  germinate  in  36  days;  Sinapis  germi- 


30 

nated  abundantl}'  the  fourth  day:  Iheris  germinated  the  fourteenth 
day;  Trifolium  germinated  the  tenth  day;  Melon  did  not  germinate 
in  36  days. 

(r)    TEMPERATURES   ABOUT   9.2°    C. 

Collomia  germinated  in  6f  days  after  sowing;  Lepidium  germi- 
nated the  third  day ;  Linum,  1  seed  began  to  germinate  the  second  day, 
several  others  the  fourth;  Mays,  1  seed  germinated  the  tenth  day,  2 
others  the  twelfth  day,  and  others  afterAvards;  Melon  did  not  germi- 
nate; Nigella  germinated  the  fifteenth  day;  Sesamum  did  not  germi- 
nate; Sinaj)ls  germinated  at  the  end  of  3i  days;  Iheris  germinated 
the  sixth  day ;  some  Trifolium  seeds  germinated  the  fifth  day,  others 
the  sixth,  eighth,  etc. 

(g)    TEMPERATURES   FROM    12°    TO    13°    C. 

For  the  first  three  days  the  average  temperature  of  the  soil  was 
12.9°.  The  individual  results  were  as  follows:  Collomia  germi- 
nated from  the  sixth  to  the  seventh  day ;  Lepidium  germinated  after 
about  If  days  (in  a  second  experiment  at  12.9°  C.  it  germinated  in  If 
days  as  before)  ;  Linum  germinated  in  about  2f  days  (in  a  second 
experiment  at  13.5°  it  germinated  at  the  end  of  If  days)  ;  2  Mays 
seeds  out  of  17  germinated  at  the  end  of  the  fifth  day,  and  half  of 
them  had  germinated  on  the  seventh  day;  Melon  did  not  germinate 
during  60  days ;  a  quarter  of  the  Nigella  seeds  germinated  the  ninth 
day;  Sesamum  germinated  abundantly  at  the  close  of  the  ninth  day; 
Sinapis  germinated  after  If  days  (in  a  second  experiment  it  germi- 
nated in  about  40  hours,  the  average  is  41  hours  under  a  temperature 
of  12.9°  C.)  ;  Iheris  germinated  in  3^  to  4  days;  Trifolium  seeds 
sprouted  unequally  at  the  end  of  the  third  day  (a  second  experiment 
gave  3  hours  less  than  3  days,  or  69  hours,  under  a  temperature 
of  13°). 

(h)    TEMPERATURES    OF   ABOUT    17°    C. 

Lepidium  (mean  of  two  experiments)  germinated  in  1^  days,  under 
17.05° ;  Linum,  mean  of  2  experiments,  germinated  in  3  daj^s,  tem- 
perature 17.05°  C. ;  Trifolium,  2  experiments,  germinated  in  2.6 
days,  temperature  17.05°  C. ;  Sinapas,  mean  of  3  experiments,  germi- 
nated in  1.7  days,  temperature  17.2°;  Collomia,  1  experiment,  under 
16.9°  germinated  in  5^  days;  Mays,  1  experiment,  germinated  in  3f 
days,  temperature  16.9°  C. ;  Melon,  1  experiment,  began  to  germinate 
in  9i  days,  temperature  16.9° ;  Nigella,  1  experiment,  germinated  the 
sixth  day,  temperature  16.9°;  Sesamum.  1  experiment,  germinated 
the  third  day,  temperature  16.9°;  Iheris,  1  experiment,  germinated 
the  fourth  day,  temperature  16.9°. 


31 

(l)    TEMPERATURES    OF    ABOUT   20°    TO    21°    C. 

Lepidium  gerniinated  in  38  hours  under  21.1° ;  Linum  gerniinated 
in  36  hours  under  21.1° ;  Mays  began  to  germinate  in  42  hours  under 
21.1°;  Nigella  germinated  in  4^  days  under  21.1°;  Sesamum  germi- 
nated in  about  33  hours  under  21.1° ;  Sinapis  germinated  in  22  hours 
on  the  average  under  21.1°;  some  TrifoUum  seeds  germinated  in  42 
hours  under  21.1°;  Ihcrh  germinated  in  2^  days  under  20.4°;  only 
one  CoUomia  seed  germinated  in  15^  days  under  19.6° ;  2  Melon 
seeds  out  of  10  germinated  in  68  hours  under  19.4°. 

(k)    TEMPERATURES    FROM    24°    TO    25°    C. 

Lhiuiii  germinated  in  38  hours  under  25.05°  ;  Mays,  1  seed  in  12  ger- 
minated in  23  hours  (half  the  seeds  had  germinated  within  44  hours 
under  25.05°)  ;  Melon,  2  seeds  in  10  germinated  in  44  hours,  the  others 
subsequently'^  under  25.05° ;  Sesamum  germinated  in  from  21  to  22^ 
hours  under  25.05°  (a  second  exj)eriment  gave  22^  hours  under  24.6°)  ; 
Sinapis  germinated  in  about  36  hours  under  25.05°;  TrifoUum  ger- 
minated in  42  hours  under  25.05° ;  Nigella  and  Iheris  observations 
accidentally  lost;  Lepidium,  2  seeds  in  10  germinated  at  the  end  of 
the  sixth  day,  and  the  majority  of  the  seeds  between  the  sixth  and 
seventh  day  under  a  mean  temperature  of  23.65°.  A  repetition  gave 
38  or  39  hours  under  a  temperature  of  21.1°;  a  third  repetition  gave 
16  hours  under  a  temperature  of  26.5°,  but  which  unfortunately  ran 
up  to  43°  during  a  few  hours.  De  Candolle  concludes  that  there  was 
some  accident  or  mistake  as  to  the  first  experiment,  and  therefore 
rejects  it ;  jjrobably  the  w^rong  seed  was  sown.  He  adopts  for  Lepid- 
ium 38  hours  under  21.1°  C.  Golloinia  did  not  germinate  until  the 
twenty-seventh  day,  when  2  seeds  sprouted  under  an  average  tem- 
perature of  21.5°. 

(l)     TEMPERATURES    OF    ABOUT    28°  C. 

Two  Lepidium  seeds  germinated  in  39  hours,  but  the  greater  part 
not  at  all  in  4  days ;  Linum.,  1  seed  germinated  at  the  end  of  2|  days,  3 
seeds  by  the  end  of  the  third  day,  but  the  majority  not  at  all ;  Mays,  1 
seed  germinated  in  36  hours,  and  the  majority,  with  vigor,  in  48 
hours;  Melon,  1  seed  germinated  at  the  end  of  the  third  day,  and  the 
majority  in  3J  days;  Sesamum  germination  began  in  22  hours,  and 
began  to  be  abundant  in  25  or  26  hours  (a  repetition  gave  1  seed 
germinated  in  31  hours  under  a  temperature  of  27.5°  C.)  ;  Sinapis,  2 
seeds  out  of  10  germinated  at  the  end  of  the  third  day,  a  third  seed 
6  hours  later,  and  the  rest  did  not  germinate;  a  few  TrifoUum  seeds 
germinated  at  the  end  of  the  third  day ;  Collomia  and  Nir/ella  did  not 
germinate  in  8  days;  a  few  Trifolimn  and  Linum  seeds  germinated 
in  8  days  under  a  temperature  of  34°. 


32 

(m)    TE]MPERATURES    from    -iO^    TO   41°    c. 

Two  Sesamum  seeds  germinated  in  10^  hours  under  40.7°,  and  the 
others  immediately  after;  3  Melon  seeds  germinated  in  04  hours 
under  40.6°  ;  none  of  the  other  seeds  germinated  at  all  in  4  days. 

(n)  higher  temperatures. 

MM.  Lefebure  (1800)  and  Edwards  and  Colin  (1834)  have  shown 
that  most  seeds  undergo  an  alteration  at  a  temperature  of  50°  C,  so 
that  they  will  not  germinate  after  that,  even  Avhen  put  under  most 
favorable  conditions.  Some  seeds  when  kept  dry  can  be  warmed  in  a 
stove  almost  to  the  point  of  combustion,  but  in  water  they  lose  the 
power  of  germination  at  55°  or  50°,  or  perhaps  lower.  In  humid 
soil  the  seed  is  altered  in  proportion  to  the  abundance  of  the  water 
and  the  temperature  of  the  soil.  Thus,  in  De  Candolle's  above-given 
experiments,  the  seeds  being  kept  quite  wet  could  lose  the  power  of 
germinating  under  50°  and  perhaps  under  34°,  as  some  of  the  pre- 
ceding experiments  show,  without,  hoAvever,  precisely  defining  this 
limit.  Therefore  De  Candolle  only  experimented  on  the  seeds  of 
Sesamum  at  high  temperatures  with  the  following  results:  The 
temperature  varied  from  50°  to  57°  C.  The  seeds  were  watered 
copiously.  One  seed  in  5  germinated  in  25.7  hours  at  an  average 
temperature  of  51.5°  C.  On  repeating  the  experiment,  3  seeds  in  12 
germinated  at  the  end  of  6  days,  and  2  subsequently,  but  the  majority 
did  not  germinate,  the  temperature  having  averaged  44°  C.  during 
the  first  26  hours  and  20°  C.  during  the  remainder. 

For  ease  of  study  I  have  collected  most  of  De  Candolle's  results  for 
each  of  the  eleven  plants,  respectively,  into  the  following  small  tables : 

Tables  showing  results  of  De  Candolle" s  experimenis  on  the  genu iiiat ion  of  seeds 
at  different  temperatures. 


lepidium  sativum. 


Temper- 
ature. 

Time. 

Temper- 
ature. 

Time. 

Temper- 
ature. 

Time. 

°C'. 
1.8 
2.9 
5.3 
5.7 

30  days. 
12  days. 
18  days. 
5  days 

°C. 
9.2 
12.9 
17.05 
21.1 

3  days. 
1.75  days. 
1.5  days. 
38  hours. 

26.5 

28.0 

16  hours. 
39  hours. 

SINAPIS  ALBA. 


0.0 
1.9 
2.9 
5.7 

17  days. 
16  days. 
9  davs. 
4  days. 

9.2 
12.9 
17.2 
21.1 

3.5  days. 
41  hours. 

Do.          i 
22  hours. 

25.05 
28.0 

,36  hours. 

72    and   78 

hours. 

33 

IBERIS  AMARA. 


Temper- 
ature. 

Time. 

Temper- 
ature. 

Tim,.       iTemper- 

Time. 

5.7 

9.2 

U  days. 
6  days. 

12.9 
'          16.9 

1:   -a 

3.6  days.                 20.4 
4  days.          1 

2.75  days. 

COLLOMIA  COCCINEA. 


5.:i5  ir  days. 
5. 7  14  days. 
9.3  I  6. 75  days. 


12.9  6.5  days. 
16. 9  5.5  days. 
19. 6  15. 5  days. 


27  days. 


LESrUM  USITATISSIMUM. 


1.8     34  days. 
3. 1     17  days. 
4.8           Do. 
5.7     6  days. 

9.2       2-4  days.              21.1    1  36  hours. 
12.9       2.75  days.            25. 05    38  hours. 
13.5    !   1.75  days.             28.0      %-3days. 
17.05  1   3  days.                 34.0      8  days. 

MELON   (CANTALOUPE). 

16.9    9.25  days. 
19.4     68  hours. 

25.06 
28.0 

44  hours. 
3.1  days. 

_L 

40.6 

94  hours. 

NIGELLA  SATIVA. 


5.7 

27  days. 
15  days. 

12.9 
16.9 

9  days. 
6  days. 

21.1 

4.25  days. 

SESAMUM  ORIENTALE. 

12.9  !  9  days. 
16.9     3  days. 
21. 1     3:^  hours. 

25. 05  21-22i  hrs. 

24. 6  22.V  hours. 
28.0      22^26  hours. 

27.5 
40.7 
51.5 

31  hours. 
101^  hours. 
25.7  hours. 

TRIFOLIUM  REPENS. 

.5.7 
9.2 
12.9 

10  days. 
5-6  days. 
72  hours. 

13.0 
17.  a5 
21.1 

69  hours. 
2.6  days. 
42  hours. 

25.05 
28.0 
34.0 

42  hours. 
72  hours. 
8  days. 

ZEA  MAYS. 

9.2     1(1-12  days. 
12.9     5-7  days. 
16.9  1  3.75  days. 

21. 1       42  hours. 
25.tt5     23-44  hours. 

28.0 

36  and   48 
hours. 

De  Canclolle's  general  conclusions  are  as  follows : 

(1)  Contrary  to  the  opinions  of  early  investigators,  such  as  De 
Seynes  (1863)  and  Edwards  and  Colin  (1834),  it  is  now  proven  that 
some  seeds,  and  probably  others,  do  germinate  in  water  at  the  tempera- 
ture of  0°  C. 

(2)  There  is  a  minimum  temperature  at  which  each  species  germi- 
nates.    These  temperatures  are  as  follows : 

Sitiapis  alba  germinates  at  0°  C,  and  possibly  below  this  tempera- 
ture if  the  water  can  be  kept  liquid. 
2667—05  M 3 


34 

Lepidium  and  Linum  did  not  germinate  at  0°  C,  but  did  germinate 
•at  1.8°  C. 

CoUomia  did  not  germinate  at  3°  C  but  did  germinate  at  5.3°  C. 

Xigella^  Iheris,  and  Trifolhim  repens  did  not  germinate  at  5.3°  C.. 
but  did  germinate  at  5.7°  C. 

Mays  did  not  germinate  at  5.7°  C,  but  did  germinate  at  9°  C. 

Semmum  did  not  germinate  at  9°  C,  but  did  germinate  at  13°  C. 

Melon  did  not  germinate  at  13°  C..  but  did  germinate  at  17°  C. 

Malvaceae,  Gossypium  lierhaceum ;  variety  not  specified:  Some  cot- 
ton seeds  on  which  experiments  had  been  made  two  years  before 
would  not  then  germinate,  but  did  germinate  at  this  time  at  40°  C. 

Raphanus  sativus  (radish)  :  Lefebure  had  shown  that  these  seeds 
germinate  at  5°  or  6°  C.  as  their  minimum  temperature. 

Trltkum  (winfer  wheat),  Hordeum  (barley),  Secede  cereale  (rye)  : 
All  of  these  Graminese  germinated  at  7°  C,  according  to  Edwards 
and  Colin,  but  this  is  probably  not  their  minimum,  for  certainly 
barley  will  germinate  at  a  lower  temperature  by  prolonging  the 
experiments.  i 

We  conclude,  therefore,  that  each  species  has  a  minimum  tempera- 
ture at  which  it  germinates,  and  the  ordinary  experience  of  the  farmer 
would  suggest  this,  but  in  his  work  one  can  hardly  decide  whether 
seeds  sown  too  early  in  the  springtime  are  simply  retarded  by  specific 
low  temperatures  or  Avhether  germination  is  quite  impossible.  These 
present  experiments  show  that  if  the  temperature  is  too  low,  then 
germination  is  prevented.  In  calculations  on  the  relation  of  temper- 
ature to  vegetation,  one  must  consider  only  facts  deduced  from  pro- 
longed, constant  temperatures.  In  the  stud}'  of  growth  under  natural 
conditions  one  must  consider  certain  temperatures  as  useless  and 
ineffective  as  concerns  the  germination  of  certain  species  of  plants. 
There  are,  moreoA^er,  other  facts  that  show  that  the  same  rule  holds 
good  for  leafing,  flowering,  and  maturing. 

According  to  De  Candolle's  experim.ents,  the  species  that  require 
high  temjDeratures  as  minima  for  germination  are  all  from  warm 
countries.  Such  species  can  not  flourish  in  cold  countries,  for  if  they 
do  germinate  there  this  happens  too  late  in  the  springtime  and  they 
can  not  ripen  their  fruits  before  winter.  Among  the  species  which 
germinate  at  low  temperatures  there  are  some  that  can  exist  in  tem- 
perate climates,  but  these  do  not  extend  very  far  toward  polar  regions, 
either  for  reasons  foreign  to  the  germination  or  else  because,  having 
germinated  too  early,  the  delicate  shoots  are  killed  by  frost. 

(3)  There  is  for  each  seed  a  maximum  temperature  beyond  which 
germination  is  impossible.  The  above  experiments  determine  such 
maxima  approximately  as  follows  : 

Nigella  does  not  germinate  if  the  mean  temperature  exceeds  28°  C. 
CoUomia  does  not  germinate  if  the  mean  temperature  exceeds  28°  C. 


35 

Trifolium  repens:  Very  few  soods  o-onuinato  at  28°  C,  and  prob- 
ably none  at  80°  C. 

Mays:  Probably  the  upper  limit  is  35°  C,  althoun:li  one  seed  <i;er- 
iiiinated  after  being  exposed  to  50°  C. 

Melon  will  stand  40°  C,  but  it  is  probable  that  above  42°  C.  ger- 
mination is  impossible. 

Sesamum  will  stand  40°  C,  and  jmssibly  45°  C.,  the  latter  being  the 
upper  limit. 

These  upper  limits,  as  I  have  before  said,  depend  very  much  on  the 
moisture,  and  on  account  of  the  difKculty  of  the  experiment  I  have 
not  endeavored  to  obtain  great  exactness. 

Lepidium  and  Linum :  According  to  the  experiments  of  Burck- 
hardt,  some  of  these  seeds  have  germinated  after  an  inunersion  of 
half  an  hour  in  Avater  at  50°  C,  but  not  after  half  an  hour  in  water 
at  60°  C. 

Raphanus  satirus  (radish)  :  Lefebure  shows  that  these  seeds  ger- 
minate in  moist  earth  at  a  maximum  temperature  of  38°  C. 

Triticum  (winter  wheat),  Triticum  (spring  wheat),  Hordeum 
(barley),  Secale  cereale  (rye),  and  Avena  (oats)  germinate  per- 
fectly at  40°  C,  partially  at  45°  C,  and  not  at  all  at  50°  C. 

(4)  The  range  between  the  maximum  and  min^'nium  temperatures 
at  which  germination  is  possible  differs  appreciably  for  these  various 
species.  Evidently  a  small  range  is  a  condition  unfavorable  to  an 
extensive  geographical  distribution. 

(5)  Marked  diU'erences  are  observable  between  seeds  of  the  same 
species  and  coming  from  the  same  place.  This  is  well  known  to  the 
farmer  and  strongly  afl'ected  some  of  the  preceding  observations. 
The  seeds  of  the  same  plant  or  the  same  capsule  are  not  identical 
physically  nor  chemically.  But  if  the  temperature  and  moisture  are 
those  most  favoral)le  to  germination,  many  seeds  will  sprout  simul- 
taneously, whereas  near  the  maximum,  and  especially  the  minimum, 
temperature  the  seeds  germinate  very  irregularly  and  many  of  them 
not  at  all. 

(G)  The  structure  of  the  seeds,  especially  the  presence  and  nature 
of  the  albumen  within  them,  ought  to  exert  a  definite  influence,  but 
the  small  number  of  species  that  De  Candolle  experimented  ujion 
does  not  allow  of  extensive  generalizations. 

The  species/ having  little  or  no  albumen — viz,  Sinap/'s,  Lepidiimi, 
and  Linnm — germinate  at  very  low  temperatures.  Those  having  the 
next  larger  amounts  of  albumen — viz,  Nhjclla,  Collotiiin,  and  Zea 
7)i(iys — germinate  at  about  5°  C. ;  but  Sesamutn,  which  has  l^ut  little 
albumen,  requires  10°  or  12°  C. 

At  17°  or  18°  C.  all  these  seeds  germinate  well,  but  the  length  of 
time  required  increases  somewhat  as  the  albinnen  increases,  showing 
that  the  latter  exerts  a  retarding  influence.     The  order  of  germina- 


36 

tion  at  this  temperature  is  as  folloAvs:  Lejndinm^  1.5  da3^s;  Sinapis, 
1.7  days;  TrifoIiu?n,  2.6  days;  Sescunum,  8  days;  Linu7n,  3  days; 
Iheris,  4  days;  Zea  mays,  3.75  days;  CoUomia,  5.5  days;  Nigella,  G 
days;  Melon,  9.25  days. 

(7)  The  relation  between  temperature  and  the  time  required  for 
germination  is  such  that  the  time  is  shortest  at  a  certain  best  tempera- 
ture for  each  seed  and  increases  to  infinity  or  impossibility  as  we 
depart  from  that  temperature  toward  the  maximmn  and  minimum 
limiting  temperatures.  All  calculations  of  the  sums  of  daily  tem- 
peratures, both  in  geographical  botany,  in  agriculture,  and  horticul- 
ture, are  complicated  by  hypotheses  and  affected  by  many  causes  of 
inaccuracy,  so  that  De  Candolle  hesitates  to  draw  very  precise  con- 
clusions from  his  laborious  experiments.  However,  he  shows  that 
if  the  duration  required  for  germination  as  expressed  in  days  is  mul- 
tiplied by  the  corresponding  temperature  expressed  in  degrees  Centi- 
grade we  shall  then  obtain  much  more  consistent  figures  if  the  tem- 
peratures are  counted  from  the  minimum  for  each  plant  instead  of 
from  the  zero  of  the  Centigrade  thermometer.  The  tables  on  pages  32 
and  33  give  the  temperatures  and  the  durations  in  days,  as  observed  by 
De  Candolle  for  the  species  experimented  upon  by  him.  For  three  of 
these  he  adopts  as  the  starting  point  of  his  calculations  the  following 
minimum  temperatures — viz,  for  Lepidium,  1°  C. ;  for  Trifolium 
repeiiH,  5.5°  C. ;  for  Sesamum.,  11°  C. 

(8)  "Wlien  seeds  are  subject  to  variable  temperatures,  as  occurs  to 
a  slight  degree  in  these  experiments,  and  to  a  still  larger  degree  in 
nature,  the  so-called  useless  or  ineffective  temperatures  may  be  in 
fact  unfavorable  and  even  retard  the  germination,  since  moisture  con- 
tinues to  be  absorbed  into  the  seed,  although  the  latter  can  make  no 
use  of  it. 

(9)  There  is  some  analogy  between  the  germination  of  seeds  and 
the  hatching  of  eggs.  Thus  Millet  and  Robinet  have  shown  that  the 
hatching  of  the  eggs  of  the  silk  worm  requires  at  least  a  temperature 
of  9°  C.,  and  that  as  the  temperature  increases  above  this  the  num- 
ber of  days  required  to  hatch  diminishes  faster  than  required  by  a 
constant  sum  total,  so  that  at  a  temperature  of  20°  C,  ten  days  accom- 
plishes more  than  twenty  days  will  do  at  a  temperature  of  10°.  This 
shows  an  influence  of  the  minimum  temperature  similar  to  that  for 
the  seeds  of  plants. 


An  entirely  analogous  case  has  been  worked  out  by  the  author  with 
regard  to  the  hatching  of  the  eggs  of  the  grasshopper  when  deposited 
in  the  soil  of  our  western  j^lains.  The  details  of  this  study  will  be 
found  in  the  First  and  Second  Reports  of  the  United  States  Ento- 
mological Commission,  and  afford  an  illustration  of  the  possibility 
of  making  from  meteorological  data  a  prediction  as  to  the  hatching 


87 

of  the  e<rgs  of  this  pest,  such  as  may  «juide  the  farmer  in  his  sowing 
or  i)lanting-  so  that  the  young  phint  may  escape  the  ravages  of  the 
young  insects. 

INFLUENCE    OF    TEMPERATURE    AND    MOISTURE    ON  GERMINA- 
TION. 

The  influence  of  temperature  and  moisture  on  the  sprouting  of  seeds 
has  been  studied  by  Sturtevant  at  Cornell  University  (Agr.  Exp. 
Sta.,  Bull.  Xo.  7),  with  results  generally  confirming  those  of  De  Can- 
dolle.  Sprouting  occurs  better  with  a  uniform  than  with  a  variable 
temperature,  so  that  the  method  of  Quetelet,  which  requires  us  tx) 
take  account  of  the  squares  of  the  temperatures,  is  no  better  than  that 
which  considers  the  simple  temperature.  The  rapidity  of  sprouting 
diminishes  with  the  decrease  of  temperature.  The  percentage  of 
seeds  that  sprout  does  not  depend  uj^on  the  uniformity  of  the  tem- 
perature. Sprouting  takes  place  more  rapidly  in  a  rather  dry  soil, 
but  a  decidedly  wet  soil  is  injurious.  By  soaking  the  seed  before 
planting  it,  the  interval  between  planting  and  sprouting  is  dimin- 
ished, but  not  between  soaking  and  sprouting;  hence  the  total  time 
required,  and  the  total  percentage  of  sprouting  seeds  is  not  much 
affected  by  the  soaking.  The  exposure  to  light  during  germination 
retards  some  seeds,  but  does  not  affect  others.  Actual  planting  in  the 
field  may  give  50  per  cent  less  germinations  than  given  by  similar 
geeds  planted  in  experimental  pots  under  control. 

INFLUENCE    OF   LIGHT   AND   HEAT    ON   GERMINATION. 

Pauchon  (1880)  summarizes  the  results  of  the  studies  of  many 
authors  on  the  relative  influence  of  light  and  heat  on  the  germination 
of  seeds  and  the  growth  of  plants.  The  following  section  is  condensed 
from  liim : 

Edwards  and  Colin  (1834)  state  that  in  their  day  little  was  knowu 
as  to  the  influence  of  light  and  air  on  the  green  matter  and  on  the 
respiration  of  plants;  since  then,  however,  it  ma}'  be  considered  as 
established  that  the  life  of  a  plant  varies  in  proportion  to  the  adapta- 
tion of  the  plant  to  its  surroundings.  The  study  of  the  influence  of 
light  may  be  said  to  have  begun  with  Lavoisier,  who  thought  that  the 
light  directly  combined  with  certain  parts  of  the  plant  producing 
the  green  leaves  and  colored  flowers,  and  that  without  light  there 
could  be  no  life.  Similarly  Moleschott  (1850),  at  Zurich,  affirms  that 
in  general  everything  that  breathes  or  moves  draws  its  life  from  the 
light  of  the  sun. 

Boussingault  (1870),  controverting  a  statement  of  Pasteur,  main- 
tains that  the  growth  of  nnishrooms  and  mold  in  the  dark  is  not  an 
exception  but  a  confirmation  of  the  general  rule,  and  that  if  the  solar 


light  should  be  cut  off  both  the  plants  having  chlorophyl,  and  also  the 
plants  that  do  not  have  it,  would  disappear  from 'the  surface  of  the 
globe. 

Berthelot,  in  his  essay  on  the  mechanics  of  chemistry  as  based  on 
thermochemistry,  shows  that  the  action  of  the  light  is  demonstrated 
by  the  formation  of  complex  chemical  effects,  isomeric  changes,  and 
more  complex  reactions.  For  instance,  the  combination  of  free  oxygen 
is  stimulated  in  a  great  many  cases  by  the  action  of  light,  as  is  shown 
by  the  bleaching  of  fabrics  of  any  kind  exposed  to  the  air  and  by  the 
oxidation  of  volatile  oils.  All  the  oxidizing  in  reactions  brought 
about  by  the  action  of  light  is  exothermic — that  is  to  say,  there  is  a 
loss  of  energy  in  the  transition  from  the  compound  body  to  its  ele- 
mentary components  and  a  disengagement  of  heat.  The  light  plays 
the  role  of  a  determining  agent.  On  the  other  hand,  when  a  complex 
body  is  built  up  in  the  cells  of  a  plant,  by  drawing  in  elementary 
bodies  from  the  atmosphere  and  soil,  the  reaction  is  endothermic,  and 
solar  heat  is  absorbed  and  rendered  latent  in  the  plant. 

Sachs,  Wiesner,  and  Mikosh  would  seem  to  have  established  the 
principle  that  the  formation  of  the  green  matter  of  a  plant  is  not 
dependent  wholly  on  the  light  as  such,  but  also  demands  a  certain 
temperature,  varying  between  0°  and  35°  C.,  for  the  various  plants  of 
Europe.  They  show  also  that  an  increase  in  the  temperature  of  the 
atmosphere,  with  equal  increase  of  light,  increases  the  rapidity  of 
the  fornuition  of  the  chlorophyl  up  to  a  certain  maximum  tempera- 
ture, and  that  in  proportion  as  the  temperature  departs  from  this 
favorable  maximum,  either  above  or  below,  the  formation  of  the  green 
matter  becomes  less  and  less  active,  until  when  the  limits  0°  or  35°  C. 
are  exceeded  it  ceases  altogether.  But  the  temperature  most  favor- 
able for  the  formation  of  chlorophyl  under  the  action  of  light  has 
but  little  connection  with  the  temperature  that  promotes  the  further 
action  of  the  chlorophyl  after  it  has  been  formed  within  the  plant. 
Thus  Timiriazeff  (1880)  shows  that  the  activity  of  the  chlorophyl 
consists  in  the  absorption  of  certain  radiations ;  but  in  order  that  these 
radiations  may  act  it  does  not  suffice  merely  that  they  should  be 
absorbed;  it  is  further  necessary  that  there  should  be  a  very  consid- 
erable intensity  of  heat,  in  order  to  furnish  to  the  chlorophyl  the 
definite  number  of  calories  necessary  for  the  decomj^osition  of  the 
carbonic-acid  gas  taken  in  from  the  atmosphere. 

In  general,  under  ordinary  conditions  light  is  indispensable  to  the 
formation  of  chlorophyl.  To  this  general  law  there  are  a  few  appar- 
ent exceptions,  as  folloAvs:  The  embryos  of  the  genera  Pinus  and 
Thuya  have  their  cotyledons- colored  an  intense  green  at  the  moment 
of  germination,  even  when  they  have  been  or  appear  to  have  been 
completely  deprived  of  the  action  of  light.  So  also  Avith  a  certain 
number  of  phanerogams  in  which  the  embryo  is  protected  by  thick 


39 

integuments;  finally,  the  fronds  of  certain  ferns  have  a  green  color, 
even  Avhen  they  grow  in  complete  darkness.  With  regard  to  the  seeds 
of  Acer,  Asfraf/dliis,  Celtic,  and  Raphawis,  it  has  been  shown  by  J. 
B()hm  that  when  they  germinate  in  darkness  they  do  not  acquire  any 
green  color;  Flahault  (1879)  has  obtained  the  same  result  for  the 
seeds  of  the  Viola  trk-oloi\i\\Q  Acer pscudoplat(inui<.^-c\\\([  the  Geranium 
hicidum.  Similarly  as  to  the  other  seeds  above  enumerated  the  stud- 
ies of  Sachs  and  Flahault  render  it  probable  that  in  most  cases  there 
was  stored  uj)  in  the  seed  certain  reserve  nutrition,  which  reserve, 
originally  formed  under  the  action  of  light,  can  subsequently  in  the 
act  of  germination  temporarily  replace  the  further  direct  action  of 
light.  It  would  thus  seem  that  in  no  case  can  dark  heat  truly  replace 
the  action  of  sunlight. 

On  the  other  hand,  light  can  replace  heat  in  the  process  of  vegeta- 
tion. This  was  first  shown  by  De  Candolle,  and  a  striking  illustra- 
tion is  quoted  by  Moleschott  (185G),  who  shows  that  by  the  influence 
of  light  during  the  resplendent  nights  of  the  polar  regions  the  har- 
vests ripen  in  a  short  time,  while  many  days  of  our  autumn  heats 
in  lower  latitudes  scarcely  suffice.  It  is  the  quantity  of  light  and 
the  quality  of  the  radiations  that  these  plants  receive  that  enable 
certain  cereals,  such  as  barley  and  oats,  to  be  cultivated  as  far  north 
as  70°  of  latitude.  The  observations  of  Schleiden  on  the  potato,  of 
De  Candolle  on  the  radiola,  and  of  Haberlandt  (186())  on  oats,  shoAv 
that  there  exist  decided  differences  in  the  quantities  of  heat  neces- 
sary to  the  development  of  different  species  of  vegetables  under  differ- 
ent latitudes,  and  that  the  most  important  cause  of  these  differences  is 
the  quantity  of  light  which  these  plants  receive.  De  Candolle,  in  his 
botanical  geography,  says  the  effect  of  light  is  shown  in  the  northern 
limits  of  certain  species ;  thus  the  radiola  is  perfected  by  a  total  sup- 
ply of  heat  represented  by  2,225  day-degrees  in  the  Orkneys  at  59° 
north,  but  by  a  total  of  1,990  day-degrees  at  Drontheim,  latitude 
north  63°  25';  the  difference  (235)  corresponds  to  the  fact  that  the 
longest  da}^  is  1]  hours  longer  at  Drontheim  than  in  the  Orkneys, 
which  increased  sunlight  enables  the  plant  to  comjilete  its  growth 
better  under  the  same  temperature. 

Wheat  furnishes  a  still  more  striking  example.  It  begins  to  vege- 
tate when  the  temperature  in  the  shade  is  about  ()°  C.  and  observation 
has  shown  that  it  requires  the  following  day-degrees  to  ripen :  At 
Paris  in  138  days,  total  shade  temperature  1,970°  C. ;  at  Orange,  117 
days,  total  shade  temperature  1,601°  C. ;  at  Upsala,  122  days,  total 
shade  temperature  1,546°  C. ;  at  L3^nden  (North  Cape),  72  days, 
total  shade  temperature  675°  C.  Or,  if  we  use,  not  the  shade  temper- 
atures, but  those  of  a  thermometer  exposed  to  the  full  sunshine,  as 
is  done  by  Gasparin,  then  the  above  figures  become  at  Orange,  2,468 
day-degrees;  Paris,  2,433  day-degrees;   Lynden,   1,582  day-degrees. 


40 

These  remarks  of  De  Candolle  with  reference  to  germination  are 
equally  applicable  to  the  whole  period  of  growth  of  the  piant. 

As  to  the  method  of  calculating  the  sum  total  of  temperatures 
De  Candolle  found  that  it  may  be  conducted  in  two  ways,  either  by 
adding  together  all  the  mean  daily  temperatures  above  0°  C.  or  by 
omitting  the  useless  degrees  and  adding  all  the  others.  This  last 
method  would  seem  to  be  the  most  logical,  but  can  rarely  be 
employed,  owing  to  our  ignorance  of  that  minimum  temperature 
below  which  all  must  be  omitted.  On  the  other  hand,  if  we  consider 
that  a  plant  which  vegetates  between  10°  C.  and  30°  C.  has  a  maxi- 
mum at  20°  C,  and  if  we  seek  the  coefficients  of  growth  correspond- 
ing to  each  successive  degree  of  temperature,  we  find,  as  Boussingault 
has  shown,  that  these  coefficients  vary  for  each  degree  as  we  depart 
above  or  below  the  temperature  most  favorable  to  vegetation. 

Similarly  De  Candolle  (1865)  has  shown  that  near  the  minimum 
and  near  the  maximum  temperatures  the  rate  of  germination  is  more 
difficult,  and  therefore  slower,  than  at  the  intermediate  or  best  tem- 
peratures; consequently,  both  in  germination  and  in  subsequent  veg- 
etation, it  is  necessary  to  recognize  the  fact  that  calculations  of  the 
•sums  of  heat  in  connection  with  the  study  of  the  geographical  distri- 
bution of  plants  are  complicated  with  hypotheses  and  many  sources 
of  error. 

Schuebeler  (1862)  shows  that  cultivated  plants  in  northern  coun- 
tries have  more  highly  colored  flowers,  larger  and  greener  leaves,  and 
larger  seeds,  which  are  more  highly  colored  and  richer  in  essential 
oils,  than  those  of  southern  regions.  Bonnier  and  Flahault  (1878) 
have  shown  the  same  facts  for  uncultivated  plants.  Both  these 
authors  attribute  this  result  to  the  prolonged  action  of  sunlight, 
and  the  latter  shows  that  the  A^ariations  are  exactly  proportional  to 
the  duration  of  sunlight.  In  Flahault's  more  recent  observations  he 
shows  that  there  must  necessarily  exist  a  relation  between  the  quan- 
tity of  carbonic  acid  decomposed  and  the  quantity  of  carbonaceous 
matters  formed  by  the  plant,  and  that  in  general  the  sunlight  has  a 
very  remarkable  inifluence  on  vegetation  since  it  compensates  in  a 
large  measure  for  the  deficiency  of  temperature. 

It  is,  furthermore,  to  this  influence  of  light  that  Pauchon  attributes 
the  singular  fact  that  plants  cultivated  in  high  latitudes  are  endowed 
with  a  vegetating  power  greater  than  that  of  southern  countries,  so 
that  when  transported  to  the  south  their  seeds  ripen  sooner  than  those 
of  the  southern  plants.  This  subject  has  been  especially  studied  by 
Tisserand  in  his  memoir  on  vegetation  in  high  latitudes,  as  cited  by 
Grandeau  in  his  work  on  nutrition  of  plants.  According  to  Tis- 
serand a  plant  behaves  in  northern  latitudes  as  a  more  highly  per- 
fected machine  and  one  that  performs  better  than  southern  jdants. 
In  regions  where  it  has  neither  time  nor  heat  it  gains  in  activity  and 


41 

in  the  speed  with  which  it  perfects  its  own  growth.  It  seems  to 
Pauchon  that  we  may  properly  interpret  this  phenomenon  if  we 
admit  that  a  seed  transported  from  the  north  to  the  soutli  finds  itself 
in  climatic  conditions  more  favorable  to  the  development  of  the 
embryo  which  it  contains  and  of  the  plant  which  is  to  follow.  What 
the  action  of  light  loses  in  duration  in  proportion  as  we  move  toward 
the  equator  it  gains  in  intensity.  It  may  be  that  the  cause  of  this 
increased  activity  is  due  to  the  larger  size  of  the  northern  seeds  or  to 
their  greater  richness  in  the  essential  oils.  Pauchon  thinks  that  the 
embryo  of  such  a  seed  should  not  be  compared  to  a  more  perfect 
machine;  it  is  rather  an  identical  machine,  but  better  nourished  by 
the  reserve  of  combustible  and  nutritive  material  in  the  perisperm. 
Possibly  the  abundance  of  essential  oils  contained  within  the  seed 
contributes  to  furnish  to  the  embryo  in  northern  countries  the  mate- 
rials for  the  oxidation  that  is  necessary  in  order  to  maintain  its  tem- 
perature during  germination  and  to  struggle  against  the  severity  of 
the  climate. 

Tisserand  (1876)  has  shown  that  the  rye  cultivated  in  northern 
Norway  has  not  the  same  chemical  composition  as  that  of  France  and 
Algeria,  and  that  in  general,  as  we  go  northward,  or  as  we  rise  above 
the  level  of  the  sea,  or  as  the  temperature  lowers  without  diminishing 
the  quantity  of  light,  we  see  the  starch  in  the  grain  increase  relatively 
to  the  nitrogenous  components.  Wheat  grown  at  Lynden  ( North  Cape) 
has  a  smaller  proportion  of  gluten  than  the  wheat  of  France,  and  the 
latter  less  than  the  wheat  of  Africa.  On  the  other  hand,  barley 
raised  at  Alten,  on  being  sown  at  Vincennes  on  the  7th  of  April  by 
Tisserand,  was  ripe  on  the  18th  of  June,  or  thirty-seven  days  in 
advance  of  French  barley,  so  that  in  order  to  mature  it  required  a 
sum  total  of  heat  far  less  than  the  French  barley.  The  reverse  is 
true  when  southern  grains  are  carried  north  and  sown  in  colder 
climates.  Therefore,  as  Marie-Davy  has  remarked,  plants  become 
acclimated  more  or  less  rapidly  according  to  their  own  nature  and 
the  extent  of  the  climatic  variations  that  are  imposed  upon  them;  the 
climate  produces  in  them  a  functional  change  which  corresponds  to 
an  organic  change  the  nature  of  which  often  escapes  our  observation. 
It  is  therefore  not  necessary  that  each  phase  of  vegetation  should 
corresj3ond  to  a  constant  sum  of  heat  in  very  different  climates. 
That  which  it  is  important  for  us  to  know  is  what  are  the  limits 
between  which  this  sum  total  can  vary,  for  the  same  s})ecies  of  i)lant 
under  different  climates. 

The  general  fact  that  the  quantity  of  nitrogen  contained  in  the 
seeds  increases  as  we  approach  the  warmer  climates  leads  to  the 
hypothesis  that  the  formation  of  albuminous  reserves  within  the  seed 
takes  place  in  proportion  to  the  temperature,  and  that  the  formation 
of  starch  and  other  reserves  takes  i^lace  in  proportion  to  the  duration 


42 

of  the  light  and  the  action  of  the  chlorophyl  of  the  leaves.  As  we 
pass  from  the  pole  to  the  equator  the  luminous  intensity  of  the  sun- 
light increases  from  a  hundred  to  a  thousand,  but  its  duration  dimin- 
ishes during  the  growing  season  from  a  hundred  at  the  poles  to  fifty 
at  the  equator.  ^Vmong  the  special  investigations  into  the  action  of 
sunlight  Ave  note  that  of  Timiriazelf  (1877),  who  has  shown  that  a 
very  intense  light,  after  traversing  a  certain  thickness  of  green-leaf 
cells,  has  no  further  action  on  the  phenomena  of  the  reduction  or 
decomposition  of  carbonic-acid  gas;  in  other  words, it  acts  the  same  as 
darkness  would  do.  On  the  other  hand,  Paul  1  jert,  by  exposing  plants 
to  the  action  of  light  which  had  been  sifted  tlirough  a  solution  of 
chlorophyl,  invariably  found  that  the  development  of  the  green  mat- 
ter of  the  leaf  was  completely  arrested;  inversely,  he  found  the  green 
matter  produced  to  its  normal  amount  when  the  plant  received  only 
light  that  had  been  filtered  through  a  solution  of  iodine  in  bisulphide 
of  carbon,  which  solution,  as  we  know,  cuts  off  all  visible  rays,  but 
allows  the  red  and  infra-red  to  pass  through  with  great  freedom. 
This  would  seem  to  demonstrate  that  chlorophyl  is  formed  by  the 
action  of  the  red  portion  of  the  spectrum. 


As  to  the  effect  of  light  on  the  germination  of  seeds,  Pauchon 
(1880)  gives  a  critical  summary  of  views  by  different  authors,  from 
which  we  condense  the  following : 

Miesse  (1775),  from  observation  on  the  Camelina  {Myagricni  sati- 
vum), concludes  that  the  seeds  grow  in  darkness  the  same  as  in  full 
daylight,  and  that  light  does  not  seem  to  influence  this  stage  of 
vegetation. 

Senebier  (178'2),  from  observations  on  seeds  of  lettuce  and  beans, 
some  of  which  were  exposed  to  the  full  sunlight,  others  to  sunlight 
after  filtering  through  a  thickness  of  Avater,  others  in  the  dark,  and 
others  in  red,  violet,  and  yellow  light,  respectively,  reached  the 
conclusion  that  light  was  injurious;  but  his  results  were  not  decisive, 
because  of  his  neglect  to  observe  exactly  the  temperatiu'es  under 
different  conditions. 

Ingenhousz  (1787)  exposed  an  equal  number  of  mustard  seeds  in 
places  receiving  different  amounts  of  light.  He  himself  concluded 
that  the  light  of  the  sun  is  as  injurious  to  vegetation  at  the  beginning 
of  its  life  as  it  is  advantageous  to  vegetation  in  the  fullness  of  its  life. 
But  a  more  careful  consideration  of  Ingenhousz's  experiments  shoAvs 
that  the  moisture  and  the  temperature  in  his  seA^eral  localities  varied 
so  much  as  to  preA'ent  any  serious  conclusion  as  to  the  action  of  light 
itself. 

Bertholon  (1789),  in  an  article  on  the  effect  of  electricity,  shows 


43 

that  up  to  that  time  it  had  not  been  proven  whetlier  the  germination 
of  the  seeds  was  att'ected  by  light  or  by  humidity.  His  own  experi- 
ments convinced  him  that  the  hitter  was  more  important. 

Senebier  (1800)  maile  acUlitional  experiments  on  peas  and  beans, 
sowing  tliem  in  sponges,  which  were  kept  equally  moist,  all  inclosed 
under  glass  covers,  so  that  no  evaporation  could  take  place.  Some 
were  exposed  to  sunlight  and  some  were  kept  in  the  dark,  but  those 
which  were  in  the  dark  germinated  much  sooner  than  those  in  the 
light.  But  in  such  experiments  as  these  the  sources  of  error  are 
numerous,  and  the  fact  that  there  was  no  renewal  of  the  air  under 
these  covers  was  especially  unfavorable  to  germination.  In  fact, 
Leclerc  (1875)  has  shown  that  under  the  influence  of  mercurial 
vapor,  as  it  existed  in  Senel)ier's  experiments,  a  large  portion  of  seeds 
are  killed,  so  that  with  our  present  knowledge  we  can  not  accept 
Senebier's  conclusions. 

Lefebure  (1800),  having  finally  accepted  the  conclusions  of  Sene- 
bier and  Ingenhousz  relative  to  the  injurious  influence  of  light  on 
germination,  repeated  the  experiments,  but  also  observed  the  tem- 
peratures more  carefully,  and  in  addition  sought  to  determine  the 
effect  of  light  that  had  passed  through  plates  of  white,  green,  black, 
red,  and  blue  glass;  but  he  added  little  to  our  knowledge,  although 
he  himself  concluded  that  the  seeds  under  white  glass  w^ere  retarded. 

Th.  de  Saussure  (180-1)  endeavored  to  ascertain  whether  the  influ- 
ence observed  by  others  was  due  to  light  or  heat,  and  he  concluded 
that  nothing  demonstrates  that  light  has  an  injurious  influence  inde- 
pendent of  the  heat  that  accompanies  it. 

Keith  (1816)  made  no  observations  himself,  but  controverted  the 
conclusions  of  De  Saussure. 

Boitard  (18*29)  sowed  the  auricula  seeds  in  three  flower  pots,  but 
the  conditions  as  to  temperature  and  moisture  are  not  sufficiently 
known  to  justify  us  in  drawing  any  conclusion. 

A.  P.  de  Candolle  (188-2)  says:  " 

I  do  not  deny  that  darkness  may  be  useful  in  germination,  but  T  do 
deny  that  it  is  necessary  to  think  that  light  has  no  action  on  germina- 
ti(m.  Analogy  indicates  this,  theory  confirms  it.  and  experience  dem- 
onstrates it. 

According  to  De  Candolle,  'light  favors  the  decomposition  of  car- 
l>onic  acid,  but  germination  demands  the  formation  of  carbonic 
acid;  therefore  darkness  will  favor  germination.  This  theory 
thus  enunciated  by  De  Candolle  has  been  accepted  by  many  authors 
Avithout  proper  experimental  basis. 

Ch.  Morren  (1832)  experimented  upon  water  cresses  grown  under 
different  colored  glasses.  He  concluded  that  as  darkness  favored  ger- 
mination, so  the  individual  colors  of  the  spectrum,  acting  each  hy  itself, 
have  a  special  influence  that  favors  germination  in  such  a  way  that 


44 

those  colors  that  have  the  greatest  ilkiminating  power  are  those  that 
least  favor  germination. 

Ad.  Brongniart  (1832)  announced  as  the  results  of  his  experiments 
that  the  retarding  influence  of  light  depends  not  only  on  the  illumi- 
nating power  of  the  colored  light,  but  on  the  relative  quantitj^  of  white 
light  that  passes  through  the  different  colored  glasses.  In  all  these 
experiments  the  seeds  were  seA^ral  millimeters  below  the  surface  of 
the  soil,  so  that  the  colored  lights  did  not  affect  the  seeds  directl3%  but 
indirectl}'  through  the  soil  whose  temperature  and  moisture  and 
evaporation  may  easily  be  of  predominating  importance. 

Ph.  A.  Pieper  (ISS-t),  Meyen  (1837),  ^Zantedeschi  (1846),  and 
Belhomme  (1854)  have  all  experimented  on  the  growth  of  seeds 
under  colored  glasses;  but  the  sources  of  error  incident  to  this 
method  of  observation  prevent  us  from  drawing  any  conclusion  as  to 
the  influence  of  light  itself. 

Ville  (1865)  says  that  the  injurious  effect  of  solar  radiation  on 
germination  is  the  result  of  the  heat  onh?^  and  that  the  effect  of  the 
light  is  inappreciable.  For  aquatic  plants  whose  seeds  germinate  in 
the  Avater,  darkness  seems  decidedl}^  favorable  to  germination,  but  it 
acts  only  in  an  indirect  manner  by  preventing  the  warming  of  the 
water  and  the  disengagement  of  the  oxygen  that  is  dissolved  in  this 
water. 

Charles  Darwin  (1877)  says  that  certain  species  of  seeds  do  not 
grow  well  when  they  are  exposed  to  the  light,  even  the  diffuse  light  of 
a  room. 

Duchartre  (1877)  considers  the  action  of  darkness  as  a  secondary 
influence,  useful  but  not  at  all  essential  and  concerning  which  there 
has  been  too  much  exaggeration. 

Faivre  (1879)  has  shown  that  the  appearance  of  the  primordial 
latex  occurs  at  a  moment  when  the  radicle  is  only  a  few  milliuieters 
long  and  when  the  cotyledons  are  still  inclosed  in  the  seed  envelopes 
and  have  not  yet  received  the  action  of  light.  He  notes  that  under  a 
yellow  light  obtained  by  transmitting  sunlight  through  a  solution  of 
bichromate  of  potash  the  seeds  develop  their  chlorophyl  and  their 
latex  more  rapidly,  and  consequently  have  a  shorter  period  of  ger- 
mination than  under  a  blue  light  obtained  by  transmitting  sunlight 
through  a  solution  of  the  ammoniacal  oxide  of  copper. 

Detmer  (1880)  has  consecrated  an  extensive  Avork  to  the  study  of 
the  germination  of  seeds,  and  states  that  concerning  the  action  of 
light  we  are  still  ignorant  as  to  whether  it  is  direct — that  is  to  say. 
whether  it  stimulates  the  storing  up  of  new  substances  in  the  vege- 
table tissue  or  whether,  on  the  contrar}^,  it  strengthens  the  persist- 
ence within  the  cells  of  some  special  process  having  a  more  or  less 
intimate  relation  to  the  phenomena  of  growth  and  which  can  only 


45 

proceed  in  darkness.  Detmer  adds  a  few  historical  references,  viz, 
Humboldt  (1704),  according  to  whom  seeds  sprout  more  easily  in 
darkness  than  in  light;  Fleischer  (1851),  Heiden  (1859),  and  Nobbe 
(who  all  consider  solar  rays  as  having  no  action  on  the  seeds),  and, 
finally,  Plunt  (1851),  who  considers  that  light  retards  geruiination. 

After  this  preliminary  historical  survey,  Pauchon  communicates 
the  results  of  his  own  experiments  as  to  the  influence  of  light  on  ger- 
mination on  the  following  twenty-two  species  of  plants : 

C'rucifern' :  Ijeguiuinosejp : 

Brassica  napus.  Aracbis  hypogjipa. 

Iberls  amara.  Dolichos  lablab. 

Lepidium    sativum.  Rubiace;p : 

Sinapis  alba.  Coffea  arabica  var.  Rio. 

Raphauns  sativum.  Spilantlies  fiisea. 

Rammeulace.v :  Heliaiitlius  aimuus. 

Delpbiiiium  Consolida.  ,  Cartbauuis  tinctorius. 

Nigella  sativa.  MalvaceiP : 
Cucurbitacete :  Hibi^icus  estuleutus. 

Ciicurbita     uielo     var.     melon  I'olygoiiace.-e : 

vert.  Fagopyrum  esculentum. 

Papaveracefe :  Liuat-eip : 

Papaver  somuiferum.  Linum  usitatissimum. 

F.nphorbiacejp  :  Bignoniacea^  or  Pedaliaceae: 

Rieinns  communis.  Sesamum  orientale. 

Gramineai:  Liliace.-p: 

Zea  mays.  Pancratium  maritinunn. 

After  deducting  doubtful  results  or  failures  Pauchon  gives  the 
following  conclusions  (see  p.  131  of  his  work  above  quoted)  : 

(1)  In  22  experiments  germination  occurred  first  in  the  light;  in 
26  experiments  it  occurred  first  in  the  dark. 

(2)  Five  times  we  obtained  duplicate  results  favorable  to  the 
light  for  the  same  species  of  plants  {Arachis^  Zea  m/ii/s,  Dolic/io.Sj 
Sinapis,  and  Linum).  Eight  times  these  duplicate  results  were 
favorable  to  specimens  kept  in  the  dark  {HelianthuH,  Delphiti'nini, 
Pancratium,  Ricinus,  and  Papaoer).  In  one  case  {Linum)  two  re- 
sults were  obtained  favoring  light  and  two  favoring  darkness. 

(3)  Among  the  22  species  of  plants  used  in  the  experiments  14  gave 
mixed  results  equally  favorable  whether  placed  in  the  light  or  the 
dark. 

(4)  Amoug  the  8  other  varieties  only  1  gave  negative  resuhs  (Cof- 
fea)  ;  3  gave  results  favorable  to  light  {Cuatrhita,  Spilauthes,  and 
Carthaniiis)  ;  4  gave  results  favorable  to  darkness  {Del phhihim.  Pan- 
cratium, Lepidium,  and  Nigrlln). 

It  appeared  to  Pauchon  impossible  to  draw  any  conclusion  what- 
ever from  these  facts.  Should  we  be  astonished  at  this?  The  prob- 
lem  is  certainly  much  more  comj^lex  than   appears  at  first  sight. 


46 

There  i^^  every  rea^-on  to  suppose,  for  example,  that  the  action  of  light 
is  not  the  same  under  all  the  conditions  of  temperatnv.?,  A\hich  ob- 
tained during  these  experiments.  Here  again,  however,  we  ai'e  con- 
fronted by  the  unknown;  because,  in  order  to  draw  from  these 
researches  the  consequences  which  might  flow  from  them  it  would  be 
necessary  to  know  precisely  the  thermic  conditions  favorable  to  the 
germination  of  each  species.  Unfortunately  this  is  a  very  important 
gap  to  be  still  filled  up,  as  the  work  accomplished  in  this  direction 
gives  only  approximate  results  limited  to  a  very  small  number  of 
different  kinds  of  seeds.  On  the  other  hand,  looking  to  facts  of 
another  order,  mentioned  further  on  in  this  work,  we  think  that  we 
may  be  allowed  to  suppose  that  the  influence  of  light  can  only  be 
favorable  to  germination  when  it  acts  at  temperatures  below  that 
which  is  most  favorable  to  germination.  A  considerable  number  of 
observations  already  cited  would  seem  to  be  in  accord  with  this  view 
of  the  subject.  But  unfortlmately  the  many  contradictions  that  we 
observed  in  our  results  do  not  allow  us  to  accept  this  opinion  as  based 
upon  a  solid  foundation. 

Pauchon  then  goes  on  as  follows : 

Another  reason,  however,  induces  me  to  admit,  only  with  many 
reserves,  the  results  of  experiments  whose  critical  epoch  is  the  visible 
development  of  the  embryo.  A  method  based  on  this  special  observa- 
tion does  not  appear  to  me  capable  of  furnishing  a  really  scientific 
basis  for  the  determination  of  the  question  before  us.  The  process  of 
germination  is  not,  in  reality,  as  simple  a  phenomenon  as  the  greater 
number  of  botanists,  perhaps  too  easily,  take  for  granted.  Its  com- 
l^lexity  is  even  so  great  that  one  can  not  judge  of  the  actual  develop- 
ment of  the  germ  of  the  plant  and  of  the  degree  of  its  physiological 
activity  by  the  external  characters  observable  by  the  eye,  such  as  the 
bursting  of  the  spermoderm  and  the  more  or  less  rapid  protrusion 
of  the  radicle.  I  do  not  hesitate  to  say,  according  to  observations 
frequently  repeated,  that  this  is  an  empirical  process  and  entirely 
deceptive  in  the  particular  case  that  we  are  dealing  with.  Although 
it  may  be  capable  of  furnishing  valuable  results  when  av(>  wish  to 
judge  of  the  influence  of  some  one  of  the  fundamental  conditions  of 
germination,  it  becomes  utterly  insufficient  when  it  is  a  question  of 
observing  the  more  delicate  and  fugitive  influences,  such  as  that  of 
light.  I  have,  in  fact,  in  the  course  of  chemical  researches,  given  in 
the  next  chapter,  demonstrated  that  for  the  same  stage  of  apparent 
development  the  absorption  of  oxygen  by  the  seeds  in  the  process,  oi 
germination  varies  to  a  large  extent  Avith  the  temperature,  and  has 
no  relation  to  the  external  growth  of  the  embryo.  It  is,  howevei'. 
not  surprising  that  the  development  of  the  embryo  continues  in  the 
interior  of  the  seed  for  a  much  longer  time  in  one  seed  tlian  in 
another  of  identical  appearance;  the  unknown  and  variable  relation 
between  the  reserved  nutrition  and  the  rudimentary  vegetable  is 
probably  the  explanation  of  these  hitherto  unex])lained  peculiarities. 

Although  the  researches  given  in  tl-ris  chapter  do  not  give  any  posi- 
tive result  on  the  subject  of  my  work,  I  have  preserved  them  .nid  pub 


47 

lish  thorn  hero  in  order  to  explain  to  observers  the  defects  of  an 
experimental  process  to  which,  in  the  futnre,  they  wonld  themselves 
have  been  tempted  to  resort :  this,  moreover,  seems  to  me  the  more 
iisefnl  in  that  np  to  this  time  this  danger  does  not  seem  to  have  struck 
the  attention  of  botanists.  On  the  other  hand,  my  observations  con- 
lain  some  new  data  relative  to  the  temperatures  favorable  for  the 
L'ormination  of  certain  exotic  seeds. 

In  consequence  of  the  conclusions  to  which  we  have  thus  been  led, 
it  would  be  useless  to  study  the  action  of  the  different  portions  of  the 
solar  spectrum  on  the  apparent  progress  of  germination.  How,  in 
fact,  can  we  suppose,  in  view  of  the  contradictory  results  already 
obtained  for  the  condition  of  light  and  of  darkness — that  is  to  say, 
for  the  most  extreme  conditions — that  the  employment  of  the  same 
method  can  reveal  a  dift'erence  of  action  for  the  various  portions  of 
the  spectrum  ? 

Is  it  then  necessary,  after  this  first  fruitless  attempt,  to  give  up  the 
solution  of  the  problem,  or  shall  we  seek  it  by  another  and  better 
method?  It  is  this  latter  alternative  that  I  have  adopted  in  that  I 
have  taken  for  the  basis  of  a  new  series  of  observtions  the  variations 
of  a  physiological  process  that,  in  an  almost  mathematical  manner, 
measures  the  germinal  activity  of  the  vegetable  embryo,  namely,  the 
respiration. 

After  giving  the  details  of  his  experiments  on  respiration  of  plants, 
Pauchon  draAvs  the  following  conclusions  (p.  166)  : 

The  laws  brought  prominently  forward  by  the  results  of  these 
experiments  are : 

(1)  Light  exercises  a  constant  and  more  or  less  marked  accelerat- 
ing influence  upon  the  absorption  of  oxygen  by  seeds  in  the  i)rocess  of 
germination.  All  the  experiments  made  in  a  strong  light  have  not, 
liowever.  the  same  value  in  demonstrating  this  fact.  But  if  we  have 
doubts  about  the  precision  of  the  results  furnished  by  experiments 
in  which  germination  did  not  invariably  take  place  (and  we  believe 
that  we  have  shown  by  some  preparatory  experiments  that  these 
results  have  at  least  a  relative  value),  this  certainly  is  not  the  case 
with  experiments  Nos.  2  and  8,  in  which  all  the  seeds  did  germinate. 
Thus  experiment  No.  2  shoAved  in  favor  of  light  a  result  as  to  the 
oxygen  absorbed  twice  as  great  as  that  given  by  the  seeds  placed  in 
the  dark.  In  the  same  way  in  experiment  No.  S  this  superiority 
reaches  to  one-third  of  the  quantity  of  oxygen  absorbed  by  the  seeds 
placed  in  the  dark.  Finally,  the  other  experiments,  and  particularly 
those  classed  under  Xos.  3.  6,  and  7,  further  confirm  the  generality  of 
this  action  of  light,  which  we  will,  besides,  find  again  in  a  second 
series  of  experiments  reported  hereafter,  several  of  which  have  shown 
unanimity  of  germination  in  both  cases. 

(2)  There  exists  a  relatirm  between  the  degree  of  light  and  the 
((uantity  of  oxygen  absorljed.  Thus,  in  a  diffuse  light  this  accelerat- 
ing influence  shows  itself  in  a  most  marked  manner  when  the  sky 
is  very  clear,  and  the  solar  radiation  reaches  us  in  its  greatest  inten- 
sity. Such  was  the  case  in  exix'riments  Nos.  2  and  8.  Whenever  the 
sky  is  cloudy  this  action  is  more  and  more  weakened  and  ceases 
altogether  when  the  sun  is  coni])letely  veiled,  as  in  stormy  weather, 
so  that  there  is  a  semiobscurity. 


48 

However,  in  all  the  experiments  where  the  final  result  has  been 
favorable  to  the  action  of  light  T  have  convinced  myself  that  a  cloudy 
sky  for  twelve  hours  always  showed  itself  in  the  amount  of  the 
absorption  of  oxygen  in  such  a  manner  that  the  examination  of  these 
figures,  noted  day  by  day,  would  almost  serve  to  show  the  state  of 
the  atmosphere  during  the  day  which  preceded  the  observation.  A 
very  conclusive  instance  of  this  action  is  given  us  by  experiment 
No.  4  of  the  second  series,  in  which  the  state  of  the  sky  being  care- 
fully observed  it  showed  very  marked  changes. 

(8)  The  accelerating  influence  exercised  upon  seeds  exposed  to  the 
action  of  light  during  the  day  did  not  stop  at  night;  it  continued  to 
act  in  the  dark  with  an  equal,  sometimes  even  with  a  greater  intensity. 
I  will  cite  as  examples  experiments  Nos.  3,  4,  6,  7,  and  8,  wdien  obser- 
vations made  twice  a  day,  morning  and  evening,  allowed  of  examin- 
ing the  fact  I  state.  How  can  we  explain  this  persistent  action  of 
light?  One  hypothesis  only  can  be  admitted.  A  portion  of  the 
action  of  the  light  absorbed  by  the  grain  during  the  day  is  stored  up 
by  it  and  used  by  it  at  night  to  accelerate  its  respiration.  The  i)roof 
of  this  is  that  the  diiferences  of  elevation  [or  quantities  of  absorbed 
oxygen]  shown  in  the  morning  by  the  instruments  for  seeds  kept  in 
the  dark  are  always  below  those  shown  by  the  instruments  and  plants 
in  the  light.  The  influence  of  the  light,  then,  continues  for  a  certain 
time,  at  least  several  hours,  even  after  the  light  itself  has  ceased  to 
act;  on  the  other  hand,  however,  this  action  is  not  exerted  immedi- 
ately. There  is  one  other  phenomenon  that  we  have  demonstrated 
by  our  experiments.  Suppose  the  sky  to  be  very  clear;  the  differ- 
ences in  favor  of  light  are  only  apparent  after  two  or  three  days 
and  become  much  more  marked  toward  the  end  of  the  experiment; 
that  is  to  say,  in  proportion  as  the  daily  action  of  sunlight  is  more 
and  more  frequently  repeated. 

(4)  I  should  also  call  attention  to  still  another  peculiarity,  viz, 
that  the  difl'erences  in  the  quantities  of  oxygen  absorbed  in  the  dark 
and  in  the  light  were  generally  much  greater  at  the  beginning  of 
these  researches  than  in  the  later  experiments,  and  particularly  in 
those  of  the  second  series.  The  temperature  appears  to  me  to  be  the 
only  element  that  varied  in  these  experiments.  There  must  there- 
fore be  a  more  intense  respiratory  action  exercised  by  light  at  low 
temperatures,  and  this  influence  would  become  weakened  at  high  tem- 
peratures. This  fact  would  be  in  entire  agreement  with  the  demands 
of  physiology.  It  is  easy  of  comprehension  that  a  scarcity  of  heat 
should  be  counterbalanced  by  the  action  of  light,  which  furnishes 
for  the  reaction  of  the  respiratory  organs  the  force  that  they  could 
not  obtain  from  an  insufficient  temperature.  On  the  contrary,  when 
the  heat  is  intense  the  intervention  of  the  light  is  no  longer  neces- 
sary, the  first  cause  bcMiig  suffirieut  to  excite  the  process  of  germina- 
tion in  the  protoplasm  of  the  seeds. 

(5)  This  action  of  light  seems  to  difi'er  a  little  accordmg  as  it  acts 
upon  seeds  containing  albumen  or  those  without  albumen.  In  the 
case  of  the  albuminous  seeds  of  the  castor-oil  plant  the  advantage  was 
much  more  apparent  in  favor  of  those  exposed  to  the  light,  which 
advantage  appeared  to  me  much  less  decided  for  the  seeds  without 
albumen,  such  as  the  haricot  bean.  Nevertheless,  as  the  experiments 
were  not  invariable  in  their  results,  the  cause  of  the  variations  ob- 


49 

served  can  also  be  accounted  for  by  attributinij  thoni  to  certain  dif- 
ferences in  the  atmospheric  conditions. 

(6)  The  more  considerable  absorption  of  oxys^en  by  seeds  under 
the  influence  of  li^iht  explains  the  fact  that  asparagine  (the  medium 
for  the  conveyance  of  the  reserved  albuminous  substances  in  the  ger- 
mination of  leguminous  plants)  only  disappears  in  plants  exposed 
to  the  light  and  continues  present  in  those  raised  in  the  dark.  The 
comj^arative  researches  of  Pfeller  (1ST2)  upon  the  chemical  com- 
position of  asparagine  ajid  other  substances  showed  that  asparagine 
is  poorer  in  carbon  and  in  hydrogen  and  richer  in  oxygen  than 
legumine  and  other  albuminoids.  The  transformation  of  leguniine 
into  asi:)aragine  is  accompanied  by  the  absorption  of  a  certain  quan- 
tity of  oxygen.  On  the  other  hand,  it  is  effected  only  by  the  influ- 
ence of  light,  the  reason  being  that  light  increases  the  quantity  of 
oxygen  absorbed,  and  therefore  exerts  only  an  indirect  influence  on 
this  change,  as  had  already  been  surmised  even  when  we  were  not 
acquainted  with  the  reasons. 

(7)  Other  new  and  important  conclusions  become  apparent  from 
these  experiments  and  those  which  follow,  and  although  they  have 
no  direct  connection  with  the  subject  of  my  work  I  think  it  will  be 
well  to  designate  them  briefly. 

The  quantity  of  ox^'gen  aljsorbed  in  a  certain  space  of  time  by  a 
seed  in  process  of  germination  varies  very  considerably  according  to 
the  temperature;  it  increases  with  it,  as  has  been  alreadj^  proved  in 
treating  of  the  respiration  of  i^lants  in  the  dark.  The  general  results 
of  mv  experiments,  and  particularly  of  Nos.  9  and  10,  leave  no  doubt 
of  this  fact.  We  can  therefore  easily  understand  what  errors  haA'e 
been  committed  by  those  experimentalists  who  have  given  calcula- 
tions of  this  absorption  of  oxygen  by  certain  seeds  without  taking 
into  consideration  the  conditions  as  to  temperature.  Their  figures 
have  no  value  whatever,  particularly  in  vicAv  of  a  fact  stated  by  me 
several  times  alread}^  viz,  that  the  quantity  of  oxygen  absorbed  by  a 
seed  is  not  at  all  in  proportion  to  its  apparent  development,  but,  on 
the  contrary,  undergoes  considerable  variation,  depending  upon  the 
influence  of  the  external  agents  affecting  the  phenomenon.  x\ccord 
ing  to  my  observations,  this  quantity  may  vary  as  two  to  one,  or  even 
more,  in  two  plants  of  identically  the  same  weight,  but  placed  in  dif- 
ferent thermic  conditions  from  the  commencement  of  their  germina- 
tion to  the  emerging  of  the  rootlet.  From  this  point  of  view,  then, 
the  plant  acts  like  a  complete  organism,  its  respiratory  action  being- 
accelerated  or  retarded  always,  however,  within  physiological  limits, 
like  those  of  an  animal  under  the  influence  of  certain  exterior  changes. 

Having  thus  shown  that  germinating  seeds  absorb  more  oxygen  in 
the  light  than  in  darkness,  Pauchon  conducted  some  experiments  to 
determine  the  ratio  betw^een  the  oxygen  and  the  carbonic  acid,  and 
draws  the  following  conclusions  (see  page  182  of  his  work)  : 

Experiments  Nos.  3  and  4  have  a  real  value  for  the  solution  of  the 
problem  brought  forward  in  this  part  of  my  work.  As  to  the  partial 
results  given  by  experiments  Xos.  1,  2,  and  5,  their  accuracy  can  not 
be  doubted;  therefore  I  shall  make  use  of  them  as  confirmatory  docu- 
ments. I  must  repeat  that  the  numbers  used  for  the  proportions  of 
2667—05  M 4 


50 

carbonic  acid  are  a  little  smaller  than  the}'  should  be  in  reality,  in 
consequence  of  peculiarities  inherent  to  the  method  and  already 
explained;  but  as  this  diminution,  which  is  almost  insignificant,  is 
equally  present  in  all  the  quantities,  the  result  is  that  the  numerical 
quantities  are  always  comparable,  akhough  the  ratio  may  be  dimin- 
ished in  an  inappreciable  degree.  Finally,  I  may  add  that  the  con- 
clusions which  follow  are  only  applicable  to  plants  under  precisely 
the  same  conditions  as  those  under  which  my  experiments  were 
conducted. 

( 1 )  I  note,  first,  that  experiments  Nos.  8  and  4  confirm  in  the  most 
l^recise  manner  the  general  fact  of  the  accelerating  influence  exer- 
cised by  light  upon  the  absorption  of  oxygen;  but,  these  experiments 
having  been  carried  out  at  a  higher  mean  temperature,'the  differences 
in  the  quantity  of  oxygen  absorbed  in  the  light  and  in  the  dark  are 
generally  less  than  in  the  first  series  of  experiments. 

(2)  As  to  the  exact  relative  quantities  of  carbonic  acid  exhaled, 
it  was  a  little  more  for  the  castor-oil  plant  in  the  dark  than  in  the 
light,  the  contrary  being  the  case  for  the  scarlet  runner  bean.  From 
this  we  might  conclude  that  the  influence  of  light  produces  doubly 
favorable  effects  upon  the  germination  of  the  castor-oil  i^lant.  (a)  by 
increasing  the  absorption  of  oxygen  and  {b)  by  diminishing  the 
exhalation  of  carbonic  acid,  thereby  increasing  the  gain  of  oxygen 
by  reducing  the  expenditure  of  carbon  and  oxygen.  (It  must  not 
be  forgotten,  in  this  explanation,  that  one  volume  of  carbonic  acid  gas 
contains  one  volume  of  oxygen.)  From  this  particular  point  of 
view  the  scarlet  runner  bean  seems  to  be  less  favored  than  the  castor- 
oil  plant,  although  the  excess  of  the  quantity  of  carbonic  acid  exhaled 
by  either  placed  in  the  light  is  nearly  insignificant  when  compared 
with  that  exhaled  by  the  same  species  kept  in  the  dark. 

CO. 
(o)  In  tlie  dark  the  ratio     T)  ^'  as  determined  l>y  four  experiments 

divided  equally  between  the  seed  of  the  castor-oil  plant  and  those  of 
the  haricot  bean,  was  at  least  a  third  more  in  favor  of  the  latter  thari 
the  ratio  obtained  for  the  castor-oil  plant.  The  length  of  the  experi- 
ment appears  to  me  to  have  exercised  a  certain  influence  upon  this  ratio. 
Thus,  for  the  castor-oil  plant  the  figures  reached  0.586  in  experiment 
No.  2,  which  lasted  about  four  days,  and  0.7T1  in  experiment  No.  8, 
which  lasted  five  days.  The  same  was  the  case  with  the  haricot  bean : 
the  result  was  1.138  for  experiment  No.  4,  which  terminated  during 
the  fourth  day,  and  1.034  for  experiment  No.  5.  which  was  prolonged 
until  the  sixth  day.     In  a  word,  the  prolongation  of  the  experiment 

tends  to  render  the  ratio  -t^  equal  to  unity.     With  tiie  duration  of 

the  experiment  this  ratio  rises  in  those  cases  Avhere  it  is  below  1,  but 
diminishes  where  it  is  above  1,  until  the  seed  is  consumed  and  the 
period  of  vegetation,  properly  so  called,  arrives,  during  M'hich  latter 
time  the  final  limit  may  be  reached  when  the  quantities  of  oxygen 
absorbed  and  the  carbonic  acid  exhaled  balance  perfectly. 

(4)  In  the  light   the  ratio    -    -    is    about    a    third    more    for    the 


51 

haricot  boan  than  for.  the  castor-oil  phuit.  Hut  the  sum  obtained  iu 
oxperiinont  No.  i2  was  very  much  below  that  stated  in  experinienl 
No.  5.  The  duration  of  this  experiment  and  its  prolongation  until 
the  api:)roach  of  the  vegetating  ])eriod  ai)pears  to  me  to  account  foi- 
this  ditt'erence.  This  hypothesis  is  supported  by  the  results  of  (wperi- 
ments  Xos.  1  and  4,  the  first  having  lasted  six  days  and  the  other  less 
than  four. 

(5)  By  comparing  the  ratio     -^■-'  for  similar  expei'iments  made  in 

the  light  and  in  the  dark,  Ave  see  that  there  is  alwaj^s  a  ditt'erence  of  a 
quarter  of  the  value  of  this  ratio  in  favor  of  the  dark;  or,  in  other 
words,  a  seed  placed  in  the  dark  always  exhales  more  carbonic  acid 
for  the  same  quantity  of  oxygen  absorbed  than  a  seed  kej)t  in  the 
light,  even  although  sometimes,  as  we  showed  in  experiment  No.  8,  the 
absolute  quantity  of  carbonic  acid  exhaled  is  less  in  the  light  than  it  is 
in  the  dark.  Finally,  while  in  the  light  the  carbonic  acid  released 
is  always  much  less  in  quantity  than  the  oxygen  absorbed,  the  con- 
trary may  be  the  case  in  the  dark,  where  the  absolute  amount  of  car- 
bonic acid  may  even  exceed  the  absolute  quantity  of  oxygen,  as  is 
proved  in  experiment  No.  4,  where  the  absorption  of  oxygen  87.36 
corresponds  to  an  exhalation  of  42.54  of  carbonic  acid. 

(6)  In  order  to  consider  the  influence  exerted  upon  the  ratio -^^  by 

the  nature  of  the  grain  itself  under  diiferent  conditions  as  to  light 
and  darkness,  it  is  only  necessary  to  consult  the  conclusions  which 
precede,  and  note  the  marked  ditferences  that  distinguish  the  albumi- 
nous and  oily  seed  of  the  castor  oil  from  the  nonalbuminous  and 
starchy  haricot  bean. 

(7)  The  facts  which  precede  complete  the  explanation  already 
given  of  the  transformation  of  legumin  into  asparagin  under  the 
influence  of  light.  In  general,  the  absorption  of  a  greater  quantity 
of  oxygen  only  assures  the  formation  of  asparagin  in  so  far  as  the 
amount  of  carbonic  acid  exhaled  is  less  than  the  amount  of  oxygen 
absorbed;  since  asparagin  is  poorer  in  carbonic  acid  and  richer  in 
oxygen  than  legundn,  all  the  conditions  favorable  to  that  formation 
are  to  be  found  demonstrated  in  the  results  of  experiment  No.  4,  with 
seeds  exposed  to  the  light.  It  is  very  probable  that  a  portion  of  the 
oxA'gen  which  had  disappeared  and  that  was  not  found  as  carbonic 
acid  was  absorbed  by  the  albuminoids  when  forming  asparagin,  and 
we  know  from  other  sources  that  this  substance  seems  to  form  in  the 
majority  of  seeds  during  the  process  of  germination. 

This  absorption  of  oxygen  during  the  period  of-  germination  is 
still  greater  in  the  castor-oil  seed  than  in  that  of  the  bean.  The  oily 
seed,  therefore,  seems  to  be  more  favored  by  nature  from  a  i)hysio- 
logical  point  of  view. 

(8)  We  might  be  tempted  to  compare  the  ratio    ^.  '\  obtained  during 

the  time  of  germination,  with  the  same  ratio  during  the  period  of 
vegetation.  But  the  sum  for  the  vegetating  epoch  has  only  been 
precisely  fixed  in  the  dark,  which  for  green  plants  is  entirely  an  ab- 
normal state.     As,  on  the  other  hand,  it  is  impossible  to  gauge  exactly 


52 

the  quantity  of  oxygen  absorbed  and  the  amount  of  carbonic  acid 
exhaled  by  a  phmt  placed  in  the  light  and  under  natural  conditions, 
it  will  easily  be  understood  why  we  refrain  from  making  any  com- 
parison until  we  are  in  possession  of  iill  the  data  necGSi^ary  to  carry 
out  the  calculation. 

(9)  The  facts  which  precede  convince  me  that  the  seeds  of  uncul- 
tivated plants  germinating  in  the  light  are,  all  other  conditions  being- 
equal,  better  distributed  than  the  seeds  of  cultivated  plants;  that 
they  possess  a  greater  germinating  power,  an  advantage  which  in- 
creases their  chances  for  ulterior  development. 


Chapter  III. 

THE  TEMPEEATURE  OF  THE  SOIL. 

OBSERVATIONS   AT   HOUGHTON    FARM   AND    GENEVA,  N.  Y.,  BY 
D.  P.  PENHALLOW. 

Ill  reference  to  the  value  of  soil  temperatures,  Penhallow  states 
(Agr.  Sci..  Vol.  I,  p.  78)  : 

A  jsroper  knowledo-e  of  the  temperature  of  the  soil  must  serve  to 
o-uide  us  in  reference  to  the  time  of  planting  particular  seeds  and  the 
depth  at  which  they  should  be  planted,  as  determined  by  the  condition 
and  character  of  the  soil.  When  the  farmer  gently  packs  the  earth 
over  the  planted  seed  he  derives  a  measure  of  benefit  in  the  higher 
temperature  of  the  soil  at  that  place,  whereby  germination  is  accel- 
erated. Similarly,  we  can  understand  that  cultivation  during  periods 
of  excessive  heat  must  tend  to  avert  some  of  the  evil  results  otherwise 
following  from  an  excess  of  temperature.  Moreover,  in  seasons  of 
great  or  even  of  ordinary  dryness  a  judicious  system  of  irrigation 
must  be  of  the  greatest  advantage,  not  only  as  supph'ing  needed  fluids 
for  the  general  functions  of  gTowth,  but  as  reducing  the  otherwise 
high  tem})erature  of  the  soil  to  a  degree  that  is  well  within  the  danger 
limit  and  consistent  with  normal  growth. 

Penhallow  also  shows  from  observations  at  Houghton  Farm  and  at 
Geneva,  X.  Y.,  that  all  layers  of  the  soil  within  8  inches  of  the  surface 
have  temperatures  that  depend  not  merely  upon  absorption  of  solar 
heat  but  also  upon  the  cooling  due  to  radiation  and  evaporation. 
The  depression  due  to  evaporation  amounts  to  about  8°  C.  on  the 
average  of  the  warmer  half  of  the  year  and  is  even  more  than  this 
when  hot  days  and  strong  dry  winds  produce  an  excessive  evaporation. 

OBSERVATIONS   BY   E.   S.   GOFF. 

E.  S.  Goff  adduces  observations  to  show  that  the  temperature  of  the 
water  at  the  time  when  it  enters  into  the  roots  from  the  soil  has  some 
relation  to  the  temperature  of  the  stem  of  the  plant  for  a  short 
distance  above  the  surface  soil,  and  that  the  distance  up  the  stem  to 
which  this  temperature  is  felt  depends  upon  the  rajiidity  of  the  flow 
of  the  sap,  and  therefore  ultimately  on  the  rapidity  of  transpiration 
from  the  leaves.     (Agr,  8ci.,  Vol.  I,  p.  134.) 

(53) 


54 


OBSERVATIONS  OF  TEMPERATURE  OF  MANURED  SOILS  IN  JAPAN 
BY  GEORGESON. 

Soil  temperature  must  to  some  extent  be  aifected  by  the  heat  given 
out  by  decaying  manure  and  vegetation.  On  tliis  subject  Mr.  C.  C. 
Georgeson  describes  some  experiments  being  made  at  Tokyo,  Japan 
(Agr.  Sci.,  Vol.  I,  p.  251),  from  which  it  appears  that  the  tempera- 
ture immediately  after  applying  the  manure  was  from  2°  to  5°  F. 
higher  than  in  the  unmanured  soil,  and  this  excess  steadily  dimin- 
ished, but  was  still  appreciable  at  the  end  of  two  months.  The  2° 
of  excess  occurred  when  the  manure  was  applied  at  the  rate  of  10 
tons  per  acre,  and  the  5°  of  excess  when  applied  at  a  rate  of  80  tons 
per  acre. 

INFLUENCE    OF     RAIN    ON     TEMPERATURE     OF    THE     SOIL    AT 
MUNICH.     (K.   SINGER.) 

The  study  of  the  earth  temperatures  at  considerable  depths  is  a  prob- 
lem for  terrestrial  physics,  but  for  agricultural  purposes  we  need  only 
consider  the  temperature  of  the  soil  within  4  or  at  most  8  feet.  The 
work  of  Karl  Singer  (1890)  is  sufficiently  instructive  to  justify  the 
presentation  of  his  general  results  for  use  in  studying  the  phienolo- 
gical  phenomena  of  Europe.  In  a  simple  diagram  Singer  sum- 
marized at  a  glance  the  mean  temperature  of  the  soil  at  any  depth 
between  1  and  7  meters  for  any  day  of  the  year,  as  it  results  from  an 
average  of  thirty  years  of  observations  at  the  observatory  at  Bogen- 
hausen,  near  Munich,  Bavaria.  The  series  of  observations  includes, 
in  fact,  four  sets  of  earth  thermometers,  two  of  which  were  on  the 
northwest  side  of  the  observatory  and  the  other  two  on  the  south- 
east side;  the  diagram  and  the  following  summary  of  results  relate 
to  the  average  of  the  pair  on  the  southeast  side.  Each  set  of  ther- 
mometers consisted  of  five,  whose  bulbs  were  buried  at  depths  of  4,  8, 
12,  16,  and  20  Bavarian  feet,  respectively,  or  1.2,  2.4,  3.6,  4.8,  and  5.9 
meters,  respectively.  The  lines  given  in  this  diagram  are  thermal 
isopleths,  viz,  curves  of  equal  temperature  for  successive  depths  and 
days,  the  days  being  represented  by  vertical  lines  and  the  depths  by 
the  horizontal  lines.  The  following  paragraphs  express  the  general 
results  of  Singer's  work  as  far  as  it  bears  upon  the  growth  of  plants: 


55 


(1)  The  normal  mean  temperature  of  the  earth  for  twenty-five 
years  (18()1-1885)  at  Booenhausen,  near  Ahniich,  at  certain  depths, 
is  as  follows : 


Tbermometov. 


No.  I.. 
No.  II. 
No.  m 
No.  IV 
No.  V- 


Depth. 

Mean 
temper- 
ature. 

Bavarian 
feet. 

Meters. 

"C. 

i.2 

1.3 

9.18 

8.2 

2.  .5 

9.16 

12.2 

3.6 

9.12 

16.2 

4.8 

9.12 

20.2 

6.0 

9.06 

Ampli- 
tude. 


C. 

11.(54 
7.64 
5.24 
3.48 
2.12 


(2)  The  mean  temperature  of  the  earth  at  a  depth  of  about  1  meter 
below  the  surface  exceeds  the  mean  temperature  of  the  air  |  at  a 
meter  above  the  surface]  by  more  than  -?°.  The  important  influence 
of  the  considerable  altitude  above  sea  level  of  the  place  of  observation 
is  to  be  recognized  in  this  result. 

(3)  The  decrease  of  the  annual  amplitude  with  increasing  depth 
for  the  adopted  interval  of  -i  Bavarian  feet,  or  1.17  meters,  amounts 
to  1:2.18°  C,  or  very  nearly  one-third  of  the  original  amplitude  of 
the  atmospheric  temperature.  The  amplitude  aP  in  centigrade  de- 
grees at  the  dei^th  P  in  meters  is  represented  by  log  aP=1.2()"20 — 
0.1508  P.  Whence  we  compute  the  amplitudes  given  in  the  last  col- 
umn of  the  preceding  table. 

(4)  The  epoch  of  the  occurrence  of  the  extreme  and  mean  tempera- 
tures for  the  highest  thermometer,  No.  I,  are :  Minimum,  2d  of  ^larch ; 
first  mean,  21st  May;  maximum,  24th  August;  second  mean,  loth 
November.  These  are  therefore  separated  from  each  other  by  inter- 
vals of  about  2f ,  3,  2f,  3^  months,  respectively.  P^or  each  step  down- 
ward of  4  feet,  or  1.2  meters,  in  depth,  the  occurrence  of  the  epoch  of 
extreme  temperature  is  retarded  on  an  average  21  da^^s  and  that  of  the 
mean  temperature  24  days;  therefore  an  almost  uniform  distribu- 
tion of  these  dates  is  brought  about  down  to  a  depth  of  20.2  feet, 
or  ()  meters,  where  the  minimum  occurs  on  the  23d  of  INIay,  the  first 
mean  on  the  24th  August ;  the  maximum  ITtli  November,  and  the 
second  mean  on  the  24tli  February. 

(5)  The  actual  temperatures  of  the  ground  from  18G1  to  1889.  at 
the  upper  stage  of  4.2  feet,  or  1.3  meters,  or  thermometer  No.  I,  did 
not  fall  below  2°  C.  or  rise  above  17°  C.  At  the  lower  levels  they 
ranged  between  4°  and  14°,  5°  and  13°,  6°  and  12°,  7°  and  11°,  respec- 
tivel}'. 

(6)  By  a  careful  consideration  of  the  state  of  the  weather  it  is  pos- 
sible in  every  case  to  account  for  the  connection  between  the  fluctua- 
tions of  the  temperature  of  the  air  and  that  of  the  earth. 

The  following  generalizations  refer  to  the  climate  of  the  South 
Bavarian  Plateau  only  and  to  the  four  .seasons  of  the  year: 

(7)  In  mild  and,  as  usual,  rainy,  winter  months,  there  is  no  mate- 
rial rise  in  the  temperature  of  the  earth  relative  to  the  average  tem- 
perature curves,  particularly  at  great  depths,  but  generally  a  lowering 
of  temperature. 


56 

(8)  Mild,  and  at  the  same  time  dry,  winters  are  associated  with  a. 
tendency  of  the  earth  temperature' to  rise  above  the  average. 

(9)  The  earth  temperatures  exhibit  a  tendency  to  fall,  if  not  al- 
read}'  too  low,  during  winters  in  which,  with  alternate  freezing  and 
thawing,  the  mean  temperature  is  below  the  normal. 

(10)  In  the  same  way  even  a  covering  of  snow  can  only  to  a  lim- 
ited extent  prevent  the  cooling  of  the  earth  when  severe  cold  follows 
the  mild  and  rainy  weather  of  the  first  part  of  winter. 

(11)  In  continuous  severe  winters,  on  the  contrary,  wdien  even 
December  generally  brings  a  permanent  covering  of  snow,  the  nega- 
tive departure  of  the  earth  temperature  is  either  limited  to  the  higher 
strata  or  is  unimportant. 

(12)  A  warm  spring,  which,  as  a  rule,  brings  only  a  moderate  quan- 
tity of  rain,  causes  a  relatively  decided  rise  of  the  earth  temperature. 

(13)  When  a  cold  and  rainy  late  winter  is  directly  succeeded  by 
warm  spring  months,  the  temperatures  of  only  the  upper  strata  of 
the  ground  rise,  wdiile  those  of  the  low^er  strata  may  fall  still  further 
below  their  normal  values. 

(14)  In  certain  w^arm  and  at  the  same  time  rainy  springs  the  earth 
teniperatures  remain  on  an  average  unchanged  with  respect  to  the 
nonnal  for  the  cold  rain  counterbalances  the  warm  weather.     C.  A.] 

(15)  An  exceptionally  cold  spring,  which  is  generally  distinguished 
by  heavy  snow^s,  is,  with  few  exceptions,  accompanied,  and  to  a  con- 
siderable depth,  by  a  notable  low^ering.  of  the  temperature  of  the 
ground  in  comparison  wath  its  normal  temperature. 

(16)  In  cold  and  at  the  same  time  dry  spring  weather  the  relative 
lowering  of  the  temperature  of  the  ground  will  generally  be  incon- 
siderable if  it  has  not  been  preceded  by  an  immediate  very  rainy 
season. 

(17)  A  warm  summer  is  always  accompanied  by  a  high  temperature 
of  the  ground  or  by  a  rise  of  its  temperature.  The  increase  is  the 
more  decided  the  more  the  excess  in  the  temperature  of  the  air  is 
accompanied  by  a  large  quantity  of  rain,  or  has  been  immediately 
preceded  by  it.  In  warm  and  comparatively  dry  summers  the  rise 
of  the  earth's  temperature  does  not  perceptibly  exceed  the  normal. 

(18)  The  relative  lowness  of  the  temperature  of  the  soil  which  fol- 
lows without  exception  a  cool  summer  generally  extends  down  only 
to  a  comparatively  moderate  depth,  scarcely  to  4  meters.  Those 
months  in  which  we  find  it  extending  to  G  meters  will  be  found  to 
have  been  at  the  same  time  rainy  months. 

(19)  A  warm  autumn,  with  very  few  exceptions,  causes  a  corre- 
sponding small  rise  in  the  temperature  of  the  soil,  but  this  may  even, 
on  the  contrary,  become  a  fall  wdien  the  late  autunni,  by  reason  of 
much  rain,  resembles  a  mild  type  of  winter. 

(20)  Low  air  temperature  is  generally  accompanied  in  autumn  by 
an  excess  of  rain,  the  consequence  of  which,  as  regularly  and  fre- 
quently observed,  is  a  falling  in  the  temperature  of  the  earth. 

(21)  In  the  rarer  cases  of  cool  and  dry  autumns  there  is  observed 
only  a  very  inconsiderable  influence  on  the  temperature  of  the  earth. 

(22)  The  dampness  of  the  soil  is  (under  the  climatic  influences 
prevailing  in  ^funich)  sufficient  to  allow^  the  variations  in  the  tem- 
perature of  the  air  in  winter  and  spring  to  exercise  a  decided  influence 
upon  those  of  the  soil,  whereas  in  summer  an  excess  of  rain  would  be 


57 

necessary  to  accomplish  this,  and  that,  too,  to  a  greater  deofree  if  the 
soil  l)e  covered  with  vegetation.  The  ])henomena  of  autunni  geniu-ally 
resemble  closely  those  of  sunnner. 

(28)  In  general  the  fluctuations  in  the  temperature  of  the  earth 
are  not  less  dependent  on  the  precipitation  than  on  the  variations  in 
the  temperature  of  the  air. 

SOIL,   TEMPERATURES    AS  AFFECTED    BY    SURFACE    SLOPE   AND 
COVERING  (WOLLNY). 

In  reference  to  the  effect  of  the  slope  of  the  earth's  surface  on  the 
temperature  of  the  soil,  "Wollny  (1888,  p.  364)  has  made  an  extensive 
series  of  measurements  at  Munich  from  which  he  draws  the  following 
conclusions  in  continuation  of  those  published  by  him  in  1883.  His 
temperatures  were  measured  bihourly  at  a  depth  of  15  centimeters 
under  both  fallow  soil  and  grass  sod;  the  differences  referred  to 
amounted  to  3°  and  4°  F.  in  individual  cases,  but  on  the  average  to 
scarcelj^  1°  F. 

(1)  That  soil  whose  exposure  is  toward  the  south  is  the  warmest, 
then  comes  the  east,  then  the  west,  and  finally   the  north  exposure. 

(2)  The  southern  exposure  is  warmer  in  proportion  as  the  inclina-/^ 
tion  to  the  horizon  is  greater. 

(3)  The  difference  of  temperature  betw^een  the  north  and  south 
exposure  is  much  greater  than  between  east  and  west. 

(4)  The  difference  in  the  Avarming  of  the  soil  for  north  and  south 
exposures  is  greater  in  proportion  as  the  surfaces  have  a  greater 
inclination. 

AVollny  (1888,  p.  415)  has  also  investigated  the  influence  of  the 
covering  of  straw  and  chaff  on  tlie  temperature  and  moisture  of  the 
soil.     He  finds  the  following  conclusions: 

(1)  That  at  a  depth  of  10  centimeters  the  naked  soil  is  warmed 
more  with  rising  air  temperatures  and  is  cooled  more  with  falling 
air  temperatures  than  under  any  one  of  the  different  forms  of  straw 
covering. 

(2)  That  the  variations  in  the  temperature  within  the  straw  litter 
are  very  much  less  than  in  the  earth. 

(3)  That  the  earth  is  in  general  somewhat  colder  than  the  material 
of  which  the  litter  is  made,  except  when  the  latter  is  moss. 

(4)  That  among  the  various  materials  forming  a  litter  the  pine^ 
needles  are  w^armed  the  most,  the  oak  leaves  and  the  fir-tree  needles 
are  less  warm,  while  the  litter  of  moss  is  the  coldest. 

The  different  temperatures  observed  were  as  follows,  on  the  average 
of  the  months  April  to  September:  Pine  needles,  lf).i)3''  C:  oak  leaves. 
16.62°  C;  fir  needles,  16.34°  C. ;  the  naked  soil  at  a  depth  of  10 
centimeters,  16.18°  C;  moss,  15.95°  C. 


58 

The  difference  between  the  morning  and  evening  temperatures 
shows : 

(1)  That  the  cooling  during  the  night  and  the  warming  (hiring 
the  day  is  appreciably  larger  for  the  naked  earth  than  for  the  various 
kinds  of  litter. 

(2)  That  the  pine  needles  warm  up  most  during  the  day  and  the 
moss  Avarms  up  least;  that  the  fir  needles  cool  most  during  the  night 
and  the  pine  needles  least. 

The  power  of  retaining  moisture  varies  with  the  different  kinds  of 
litter  as  follows : 

(1)  Any  litter  of  forest  leaves  or  needles  is  moister  than  the  earth, 
but  the  moss  is  less  moist  than  the  earth ;  the  gradation  is  from  oak 
leaves,  the  highest,  through  fir  needles  to  moss,  the  lowest. 

With  regard  to  evaporation  Wollny  shows  that  the  naked  earth 
loses  a  greater  quantity  of  moisture  by  evaporation  than  do  the 
various  kinds  of  litter. 

/'   (2)  That  the  moss  litter  evaporates  the  most,  but  the  litter  of  forest 
\ leaves  the  least. 

(3)  That  the  quantity  of  evaporation  is  greater  the  thinner  the 
layer  of  the  litter. 

In  general,  then,  the  litters  of  leaves  and  of  pine  needles  give  up 
the  rain  water  that  falls  upon  them  to  the  ground  beneath  in  larger 
proportion,  but  still  continue  to  be  very  moist  because  they  lose,  rela- 
tively, little  water  by  evaporation;  furthermore,  that  the  moss  litter 
is  distinguished  by  large  variations  in  its  contained  water  because 
it  has  on  the  one  hand  a  large  capacity  for  water  and  on  the  other 
hand  a  very  considerable  evaporating  power. 

SOIL  TEMPERATURES  OBSERVED  AT  GREENWICH,  ENGLAND. 

Among  the  limited  number  of  long-continued  series  of  observations 
of  temperatures  of  soil  near  the  surface  is  that  maintained  at  Green- 
wich Observatory,  England,  since  June,  1846.  This  series  embraces 
observations  at  considerable  depths  that  will  not  interest  the  student 
of  agriculture,  but  we  reproduce  in  the  following  table  the  results  of 
observations  at  1  inch  in  depth,  as  given  in  the  annual  volumes  of  the 
Greenwich  Observatory  for  1878,  and  as  given  in  J.  D.  Everett's 
memoir  of  1860.  These  soil  temperatures  can  be  used  in  any  sub- 
sequent study  of  English  crops  throughout  the  southern  half  of 
England  or  in  analogous  climates. 


59 

Monthly  and  nniiual  means  of  noonday  readings  of  a  Fahrenheit  thermometer 
whose  hulh  is  i  inch  hvioir  the  surface  of  the  soil /it  Green  icich  Ohsercatory. 


1847 

1848 

1849 

1850 

1851... 

1853 


1854. 
1855. 
ia56. 
1857. 


18«53. 
1S«4. 


1866. 
1867. 


1870. 
1871. 

1872. 
1873. 


■37.8 
37.4 
41.5 
36.7 
44.2 
42.8 
44.3 
40.6 
38.4 
41.5 
38.9 

42.4 
40.9 
:55. 5 
40.7 
43.2 
39.6 
.38.8 
44.1 
38.3 
39.4 
43.0 
40.1 
36.2 
41.6 
42.8 


38.0 

44.1 
j  43.6 
i  44.4 

42.7 
I  42.0 

37.0 
I  41.6 

!  3:^.4 
4;i.3 

40.7 
37.8 
4:15 
37.4 
42.6 
42.9 
43.2 
39.0 
38.9 
43.1 
46.1 
44.5 
46.8 
38.1 
42.0 
44.6 
3fi.4 


42.9 
44.6 
44.3 
41.9 
44.0 
43.0 
41.8 
45.3 
41.0 
41.7 
43.7 
42.2 
47.3 
42.1 
44.6 
45.6 
45.0 
43.2 
39.3 
42.0 
40.7 
45.9 
40.8 
42.5 
4.5.0 
45.0 
42.4 


40.38   41.40   4125   49. -^l 


Apr. 


47.2 
49.5 
46.3 
50.4 
48.5 
49.9 
47.4 
52.7 
48.9 
50.4 
48.3 
49.6 
49.3 
45.2 
47.7 
50.6 
51.1 
50.0 
53.3 
50.3 
49.9 
50.5 
51.5 
50.0 
49.6 
49.8 
48.5 


May 


June.  July- 


SB.  0 
61.6 
56.5 
53.0 
54.8 
55.1 
55.7 
54.2 
52.9 
52.6 
57.6 
54.3 
55.8 
56.7 
54.9 
57.8 
54.3 
56.3 
57.8 
52.8 
55.9 
59.8 
54.3 
56.1 
54.2 
53.4 
53.3 
5-).  54 


61.1 

61.7 
63.3 

64.1 
62.2 
59.4 
62.3 
59.8 
61.3 
63.0 
6.5.6 
68.6 
64.4 
58.2 
63.2 
60.0 

60.0 
64.4 
63.3 
61.4 
64.3 
58.6 
64.2 
58.4 
61.5 
61.2 


62. 08 


67.4 
65.0 
65.0 
65.2 
63.8 
71.0 
63.2 
64.4 
65.6 
64.8 
67.0 
64.5 
70.7 
61.3 
64.6 
62.6 
64.0 

66.1 
65.0 
62.6 
69.9 
86.2 
07.1 
63.7 
06.9 
66.0 


Aug 


64.7 

60.8 
65.2 
63.0 
65.5 
6.5.2 
64.1 
64.6 
66.0 
66.7 
67.9 
66.0 
66.7 
60.4 
66.2 
&3.5 
&3.9 
62.2 
62.5 
61.7 
64.1 
66.7 
63.2 
6:3.8 
66.6 
63.9 
65.2 


Sept. 


61.8 
58.7 
60.0 
61.1 
60.3 
61.6 
(50.9 
59.0 
62.5 
62.7 
59.7 
57.0 
60.3 
60.6 
57.6 
59.5 
65.6 
59.0 


54.6 
53.5 
53.0 
49.5 
.54.7 
50.2 
55.1 
52.9 
54.7 
54.5 
55.2 
54.2 
54.4 
52.4 
57.5 
54.3 
54.3 
54.0 
54.7 
5.5.2 
52.6 
52.2 
52.4 
52.9 
52.0 
50.8 
51.4 


48.7 
45.5 
46.5 
4S.7 
41.2 
.50.4 
44.9 
44.1 
44.3 
419 
48.8 
42.2 
44.3 
44.0 
419 
42.7 
48.0 
45.4 
47.5 
47.2 
45.2 
45.0 
45.8 
44.3 
41.2 
47.1 
45.7 


Dec. 


44.5 

45.5 
41.1 
42.7 
42.2 
4S.0 
38.0 
42.9 
38.3 
41.9 
46.6 
42.4 


42.6 
44.0 
45.6 
41.6 
45.1 
44.9 

47.0 
40.5 
38.1 
39.2 
43.0 


51.81 
52.33 
52.34 
51.. 52 
.51.98 
53.18 
51.18 
52.06 
50.47 
51.94 
53.57 
52.01 
53.15 
49.62 
.51.97 
52.11 
.52.  .56 
51.17 
51.83 
52.38 
51.43 
54.02 
52.00 
51.32 
50.73 
.52.36 
51.11 


51.97 


SOIL  TEMPERATURES  OBSERVED  AT  BROOKINGS,  S.  DAK. 


Ainoiig-  the  agricultural  experiment  stations  in  the  United  States 
whose  work  will  be  used  in  this  preliminar.y  report  are  some  whose 
observations  of  the  temperature  of  the  soil  will  be  needed  for  com- 
parison with  the  observations  on  the  growth  of  plants  and  resulting 
crops  or  for  denfonstrations  of  the  relations  between  the  temperature 
of  the  air  and  of  the  soil.  The  following  table  gives  for  Brookings, 
S.  Dak,,  the  daily  maximum  readings  of  the  thermometer  in  the  air 
and  shade,  the  daily  rainfall,  the  maximum  temperatures  of  the  soil 
at  depths  of  2  inches  and  12  inches  as  far  as  published  in  Experiment 
Station  Bulletin  No.  C  for  a  portion  of  the  summer  of  1888.  These 
figures  show  that  in  summer  and  for  the  growing  season  generally 
the  temperature  of  the  soil  near  the  surface  is  higher  than  that  of 
the  air  in  the  shade  only  when  the  sun  shines  on  it,  and  that  it  is 
lower  than  the  temperature  of  the  air  in  the  shade  only  when  the 
radiation  cools  it  at  nighttime  or  when  the  rain  falls  in  the  daytime 
and  is  for  a  short  time  followed  by  rapid  evaporation.     The  average 


60 


of  the  maximum  temperatures  i)f  the  air,  less  the  temperatures  of  the 
soil  at  2  p.  m.  at  a  depth'of  2  inches  was  2.3°  F.  in  July,  1888,  and 
3°  F.  in  August,  1888.  On  the  other  hand,  the  average  value  of  the 
maximum  temperature  of  the  air,  less  the  temperature  of  the  soil  at 
2  p.  m.  at  a  depth  of  12  inches  was  12°  F.  for  the  observations  here 
given,  scattered  through  July  and  August,  1888. 

Temperatures  at  Brookings,  /S'.  DaJc. 
[Lat.  44°  20'  N. ;  long.  96°  40'  W. ;  altitude,  1,000  feet.] 


Date,1888. 

Maxi- 
mum ail- 
tempera- 
ture. 

Daily 
rain- 
fall. 

Soil  tempera- 
tui-es  (read- 
ings at  2  p. 
m.). 

Date,  1888. 

Maxi- 
mum air 
tempera- 
ture. 

Daily 
rain- 
fall. 

Soil  tempera- 
tures (read- 
ings at  2  p. 

Depth 
inches. 

inches. 

Depth 
inches. 

Depth 
inches. 

op 

Inch. 

"  F. 

"  F. 

°F. 

Inch. 

°  F. 

o  p 

July  13 

69.0 

0  09 

69 

Aug.    tt 

63.0 

0.0 

63 

60 

U 
15 
16 
17 
19 

81.5 
81.0 
82.0 
79.0 
86.0 

.11 
.0 
.0 
.0 
.0 

81 

81 
71 

10 
11 
12 
13 

14 

60.0 
62.0 
74.0 
79.0 

75.0 

.40 
.01 
.0 
.0 
.50 

67 

23 

82.0 

.0 

84 

15 

69.0 

.20 

63 

24 

83.0 

.0 

86 

16 

72.0 

.0 

71 

25 

82.5 

.0 

84 

..-•_.... 

17 

73.0 

.0 

72 

26 

89.0 

.0 

83 

18 

82.0 

.0 

71 

27 
28 
2« 

88.0 
94.0 
89.0 

.0 
.0 
.0 

81 
85 
70 

67 
70 

19 

20 
21 

72.0 
80  0 
79.0 

.42 
.01 
.0 

70 

30 

101.0 

.23 

103 

76 

22 

82.0 

.0 

78 

78 

31 

73.0 

.0 

87 

ft5 

23 

83.0 

.0 

76 

71 

Aug.    1 

77.0 

.0 

76 

67 

24 

89.0 

.0 

77 

70 

2 

91.0 

.0 

85 

68 

25 

94.0 

.0 

82 

75 

3 
4 

83.0 

.0 
.0 

93 
85 

70 
71 

26 

84.0 
89.0 

.0 
.0 

84 

78 

5 
6 

7 

79.0 
76.0 
71.0 

1.27 
.12 
.0 

28 
29 
30 

82.0 

,      94.0 

78.0 

.0 
.0 
.0 

83 

77 

68 
67 

86 

71 

8 

76.0 

.28 

m 

64 

31 

69.0 

.0 

83 

68 

It  would  appear  that  the  reading  of  the  soil  temperature  is  fre- 
quently omitted  when  rain  falls;  this  is  a  bad  practice,  but  the  records 
suffice  to  show  us  that  in  this  dry  country  and  during  the  summer  time 
the  maximum  surface  temperatures  of  the  soil  will  not  differ  much 
from  the  maximum  temperatures  of  the  air,  while  the  soil  tempera- 
tures at  12  inches  will  closely  follow  the  mean  temperature  of  the 
air.  The  latter  mean,  viz,  one-half  the  sum  of  the  maximum  and 
minimum  record  for  any  day  is  greater  than  the  mean  temperature 
of  the  layers  of  soil  at  2  and  12  inches  depth,  as  observed  at  2  p.  m., 
by  about  6°  F.  ,  ' 


(>1 

SOIL   TEMPERATURES   OBSERVED   AT   AUBURN,    ALA. 

As  an  illustration  of  soil  temperatures  in  a  southern  locality  I 
have  chosen  the  following  record  for  1880  at  Auburn,  Ala.,  where 
the  agriculiural  experiment  station  has  maintained  three  sets  of 
buried  thermometers,  two  of  them  in  sandy  soils  on  hills  and  one  in 
moist  bottom  land  near  the  banks  of  a  small  stream.  It  appears 
from  these  records  that  the  dilt'erence  in  temperature  in  the  growing- 
season  between  the  so-called  "  cold  wet ""  and  ''  warm  dry "  soils 
averages  but  a  few  degrees;  in  fact,  I  doubt  whether  it  is  appreciable 
from  observations  having  the  accurac5^  of  those  here  given.  Thus 
at  3  inches  depth  and  during  the  warm  half  of  the  year  the  maxi- 
mum temperatures  on  the  hill  average  1°  F.  above  those  in  the 
bottom  land,  while  the  mininnim  temperatures  on  the  hill  average 
2°  F.  colder  than  4liose  of  the  bottom  lands.  The  temperatures  here 
given  are  the  averages  of  the  maxima  and  minima  and  are  taken 
from  successive  monthly  reports  and  from  Bulletin  No.  18  of  the 
Alabama  Agricultural  Experiment  Station.  In  these,  as  at  most 
other  United  States  stations,  the  correction  for  the  temperature  of 
the  long  stem  of  the  thermometer  still  remains  to  be  applied.  A  com- 
})arison  of  the  temperature  at  o  inches  depth  with  the  maximum 
and  minimum  air  temj^erature  shows  that  the  soil  is  Avarmer  than 
the  air  in  the  daytime  from  April  to  October,  inclusive,  and 
warmer  than  the  air  at  the  minimum  temperatures  throughout  the 
year.  This  latter  is  true  for  the  minimum  temperatures  of  the  soil 
down  to  a  depth  of  96  inches,  but  the  excess  of  maxima  temperatures 
of  the  soil  over  those  of  the  air  during  the  daytime  in  summer 
ceafses  a  little  below  (>  inches.  Evidently  the  temperature  of  the  soil 
is  sufficiently  high  to  allow  of  the  growth  of  some  form  of  vegeta- 
tion throughout  the  year. 

Edtrcinci  and  means  of  soil  tciiiiicrninrcs  for  1SS9,  as  ohscrrrd  a  I  Aiihiini,  Ala. 
[Lat.  :'.L'°.G  N.  ;   long.  85°. 4  W. ;   altitude,  T.i-2  feet.  | 


Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Det-. 

Air  iemjieratures. 

"  F. 

"F.     'F. 

"  F. 

"F. 

"  F. 

°  F. 

"  F. 

°  F. 

"  F. 

"F. 

°  F. 

Mean  air  temperature. . . 

46.9 

46.3     54.7 

62.5 

70.1 

76.1 

80.7 

77.6 

74.8 

62.3 

53.1 

57.8 

Mean  radiation  temper- 
ature 

39.7 
(i7.0 

36.8 
75.0 

43.2 

76.0 

65.6 

82.0 

57.2 

89.0 

65.8 
91.5 

7D.0 
98.0 

67.5 
92. 5 

65.2 
93. 0 

49.5 
82.0 

42.9 
76.0 

45.5 

Maximum  air  tempera- 
ture   

74.0 

Minimum  air  tempera- 

ZiJ) 
51.0 

16.5 
m.  5 

30.0 
54.0 

38.0 
62.0 

45.0 
63. 0 

46.0 

67.5 
73.5 

6:^.0 
72.5 

48.0 
78.(1 

38. 0 
t)0.() 

24.0 

29.0 

Maximum  terrestrial  ra- 
diation temperature . . 

59.5 

Minimum  terrestrial  ra- 
diation temperature . . 

21.0 

24.0 

32.0 

37.0 

43.0 

43.0 

60.0 

62.0 

48.0 

»).() 

:>2.i> 

;«i.  5 

62 


Extremes  and  means  of  .so/7  temperatures  for  18S9,  etc. — Continued. 


Jan. 

Feb. 

Mar. 

Apr. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Soil  temperature. 

SANDY  SOIL  ON  A  HILL; 
OFTEN        CULTIVATED 
DURING  CROPS. 

3-mch  depth: 

0  jr 

°F. 

°F. 

"  F. 

"  F. 

-  F. 

o  jr. 

°  F. 

°  F. 

"  F. 

°  F. 

"  F. 

Maximum. 

63.5 

69.0 

73.5 

82.5 

92.6 

96.0 

101.5 

95.0 

96.5 

84.6 

69.5 

69.0 

Minimum 

33.5 

32.0 

37.0 

48.5 

52.0 

52.0 

71.5 

69.5 

54.5 

45.0 

35.0 

85.0 

6-inch  depth: 

Maximum 

61.0     76.5 

68:5     79.5 

89.0 
56.0 

92.0 
56.0. 

98.0 
73.6 

92.5 
70.5 

92.5 
57.5 

83.5 
48.0 

68.5 
37.0 

65.0 

Minimum 

35.5 

34.5 

39.0 

60.0 

37.6 

24-inch  depth: 

Maximum 

52.5 

57.0 

58.5 

67.0 

76.6 

80.0 

86.0 

82.0 

89.5 

74.0 

65.5 

60.0 

Minimum 

46.5 

44.0 

49.0 

68.0 

64.5 

68.5 

77.0 

78.0 

72.0 

63.5 

52.0 

.50. 0 

48-inch  depth: 

Maximum 

53.5 
51.6 

53.0 
48.0 

56.5 
50.5 

63.0 
56.5 

71.5 
63.0 

75.0 
69.6 

79.5 
74.5 

79.0 
77.0 

84.5 
75.0 

74.5 
67.0 

69.0 
58.0 

60.6 

Minimum 

56.5 

96-inch  depth: 

Maximum 

59.5 

56.5 

56.0 

60.5 

62.5 

69.0 

73.0 

73.6 

76.6 

74.5 

70.0 

65.0 

Minimum 

56.5 

54.5 

54.5 

54.0 

60.0 

65.5 

69.0 

73.0 

73.6 

70.5 

64.0 

62.0 

BOTTOM  LAND  ON  BANK 
OF  SMALL  STREAM. 

3-inch  depth: 

Maximum 

60.5 

67.0 

69.0 

80.5 

92.5 

95.0 

101.0 

96.0 

96.0 

84.5 

71.6 

69.5 

Minimum 

35.5 

35.0 

41.5 

47.5 

6.5.0 

65.0 

74.0 

70.6 

66.5 

46.0 

34.0 

34.0 

6-inch  depth: 

Maximum 

58.5 

65.0 

66.6 

79.5 

88.0 

91.0 

97.5 

93.0 

92.0 

82.0 

69.0 

65.0 

Minimum 

39.0 

38.0 

44.0 

63.0 

69.0 

68.0 

76.0 

73.0 

60.0 

49.0 

37.0 

36.0 

24-ineh  depth: 

Maximum 

54.0 

57.6 

68.0 

67.5 

76.0 

80.0 

85.6 

82.0 

82.6 

74.5 

66.0 

60.0 

Minimum 

48.5 

46.0 

61.0 

58.5 

65.0 

69.5 

77.0 

78.5 

72.6 

63.0 

62.6 

50.  C 

48-inch  depth: 

Maximum 

54.5 

64.0 

57.0 

64.0 

71.0 

75.0 

79.5 

79.0 

79.0 

75.0 

68.0 

61.  ( 

Minimum 

52.5 

50.5 

51.5 

57.0 

63.6 

69.5 

74.5 

77.0 

75.0 

67.6 

59.0 

57.  t 

SOIL  TEMPERATURES  OBSERVED  AT  PENDLETON,  OREG. 

Among  the  United  States  experiment  stations  for  which  soil  tem- 
peratures have  been  published,  I  quote  the  following  observations 
made  by  Mr.  P.  Zahner,  voluntary  observer  at  Pendleton,  Oreg.,  (lat 
45°.7  N.;  long.  112°.2  W. ;  altitude,  1,122  feet),  because  it  represents 
a  climate  so  different  from  that  found  in  the  same  latitude  east  of  the 
Rocky  Mountains.  A  number  of  observations  of  diurnal  periodicity 
are  given  by  Zahner,  and  a  shorter  series  is  at  hand  for  Cor- 
vallis,  Oreg.  (lat.  44°. 5  N. ;  altitude,  150  feet).  The  comparison 
between  these  shows  that  the  Pendleton  air  and  soil  are  appreciably 
warmer  than  the  Corvallis  in  July,  August,  and  September,  but  colder 
in  November  and  probably  also  in  December.  In  general  the  maxi- 
mum soil  temperature  at  Pendleton  at  all  depths  follows  that  of  the 


G8 

daily  inaxiimiui  niT  teinperatuiv.  Kainl'all  lowers  the  temperature  of 
the  soil,  as  on  March  18,  1890,  at  8  inches  depth  by  2°  F.,  but  at  24 
inches  depth  by  0.5°  F.  At  12  inches  depth  th'e  soil  waA.not  frozen 
throughout  the  year,  but  at  8  inches  it  was  frozen  up  to  the  7th  of 
March.  The  soil  temperatures  were  read  daily  at  3  p.  m. ;  the  soil  was 
naturally  dry  and  light,  and  was  covered  with  a  thin  grass.  The 
thermometers  Avere  maximums  and  minimnms,  apjiarently  read  from 
above  ground  without  being  disturbed  in  their  positions. 


Obscrraiions  of  PcniUcton.  Ore;/.,  in  isno. 
[From  the  Monthly  Reports  of  the  Oregon  State  Weather  Bureau.] 


Air  temperature.  1 

Absolute  maximum  temper- 
ature  I 

Absolute  minimum  temper-  | 
ature...: - 

Mean  of  maximum  tempera- 
ture   

Mean  of  minimum  tempera-  | 
ture _ . 

Monthly  mean  temperature., 


Precipitation. 
Total  monthly  rainfalL 
.S'0(7  temperatiiri . 
4-inch  depth: 


00.0 

-16.0 

29.1 

13.0 
21.0 


"  F. 
58.0 


Maximum 
Minimum . 
Mean 

.s-inch  depth: 
Maximum 
Minimum. 
Mean 

12-inch  depth: 
Maximum 
Minimum. 
Mean 

24-in<h  depth: 
Maximum 
Minimum . 
Mean 


16.0 
26.7 

33.0 
20.0 
27.8 

34.0 
^.0 

:«i.4 


3:i.() 


mo 

26.0 
37.3 

44.0 
29.0 
36.6 

41.0 
33.0 

37.1 

40.0 
3.5. 0 


Mar. 

Apr. 

May. 

June. 

July.  Aug. 

Sept. 

Oct. 

"  F. 

°  F. 

"  F. 

op 

c  p 

"  F. 

°  F. 

"  F. 

70.0 

89.0 

91.0 

100. 0 

105.0 

99.0 

90.0 

73.0 

10.0 

21.0 

30.0 

36.0 

40.0 

44.0 

26.0 

24.0 

51.5 

67.9 

75.0 

76.6 

87.2 

88.5 

80.6 

64.5 

32.5 

36.6 

45.2 

49.4 

50.5 

49.1 

89.5 

34.8 

42.0 

52.2 

60.1 

63.0 

68.8 

68.8 

60.0 

49.6 

'2.04 

a0.17 

al..51 

a\.m 

a0.08 

"0.07 

aO.27 

aO.63 

55.0 

76.0 

81.0 

90.0 

92.0 

86.0 

80.0 

64.0 

:jo.o 

48.0 

60.0 

61.0 

74.0 

7.5.0 

62.0 

53.0 

44.9 

62.2 

72.3 

74.2 

84.6 

83.3 

73.2 

57.4 

49.0 

68.0 

72.0 

80.0 

83. 0 

78.0 

71.0 

60.0 

:w.o 

48.0 

59.0 

61.0 

72.0 

71.0 

64.0 

50.0 

40.9 

«6.5.3 

66.3 

68.4 

77.6 

75.8 

66.5 

53.  T 

46.0 

62.0 

67.0 

71.0 

78.0 

85.0 

70.0 

63.0 

a3.o 

46.0 

58.0 

60.0 

69.0 

71.0 

64.0 

51.0 

m.  8 

52.2 

63.1 

65.8 

73.7 

73.3 

&5.7 

54.7 

45.0 

58.0 

64.0 

66.0 

74.0 

73.0 

70.0 

64.0  1 

36.0 

45.0 

58.0 

61.0 

68.0 

71.0 

64.0 

54.0  ! 

40.1 

50.1 

60.9 

63.7     30.7 

71.7 

66.7 

57.3 

1 

°  F. 
68.0 
14.0 
.57.2 

23.6 
40.4 


53.0 
40.0 
45.8 

49.0 
38.0 
43.2 

51.0 
40.0 
45.2 

54.0 
44.0 
48.5 


SOIL  TEMPERATURES  OBSERVED  AT  MONTREAL,   CANADA. 

As  illustrating  temperatures  of  tlic  ground  in  a  very  cohl  locality. 
I  quote  the  work  of  Messrs.  C  II.  McLcod  and  1).  P.  Pciihallow.  of 
McGill  College  Ob.servatorv,  Montreal,  who  have  maintained  a  series 
of  observations  of  the  temperature  of  the  earth  by  liecquereFs  method, 
in  which  the  temperature  of  a  coil  of  wire  in  the  laboratory  is  !)rought 
to  ecpiality  with   the  temperature  of  a   similar  coil   buried   in   the 


64 

earth.  The  following  table  gives  the  mean  temperature  for  the  ten- 
day  periods  ending  on  the  dates  given  in  column  1  and  at  a  depth 
of  1  foot  below  the  surface  of  the  ground.  Temperatures  are  given 
by  them  for  other  depths,  as  also  for  the  air ;  the  total  rain  and  snow 
is  also  given.  An  investigation  of  the  connection  betw'een  earth 
temperature  and  the  development  of  vegetation  is  being  carried  on 
by  them,  but  as  no  results  have  as  yet  been  published  I  give  merely 
their  soil  temperatures  at  a  depth  of  1  foot,  which  usually  agree, 
within  a  degree  centigrade,  with  the  average  temperature  of  the  air 
for  ten  days. 

.yean  ioiiiicniturc  of  the  soil  at  a  depth  of  1  foot  for  periods  of  ten  days  at 
Montreal,  Canada. 


End  of  period. 

Average 
soil  tem- 
pera- 
tures. 

End  of  period. 

Average 
soil  tem- 
pera- 
tures. 

End  of  period. 

Average 
soil  tem- 
pera- 
tures. 

1888. 

"  C. 
6.3 
2.3 
0.4 
0.9 
0.8 
0.4 

0.5 

0.6 

0.2 

0.2 

-0.4 

-0.1 

-0.3 

-0.2 

-0.5 

-0.5 

3.7 

6.4 

12.7 

15.3 

14.7 

15.5 

18.8. 

19.2 

1889-Continued. 

July9-. 

July  19 

21.1 
20.4 
21.5 
21.2 
18.7 
18.9 
19.6 
18.4 
13.6 
11.0 
7.1 
5.0 
4.7 
4.3 
3.0 
1.2 
1.0 
0.9 

::! 

1.1 

0.8 
0.8 

1890— Continued. " 

March  6 

March  16 

"  C. 
1.0 

07 

July  29 

March  26 

0.4 

December  11 

Augusts 

August  18 

Aprils. 

April  15 

April  25 

0.5 

December  21 

■      0.6 

5.3 

1889. 

September  7 

September  17 

Septembers?.. 

October? 

May5.. 

May  15              

7.4 
9.1 

January  10 

May  25 

11.7 

June4 -. 

June  14 

15.0 

October  17 

15.5 

17.6 

July4 

July  14 

21.1 

November  16 

November  26 

December  6^. 

Decpimber  Ifi 

20.7 

July  24 

August  3 

August  13 

March  21_,.. 

20.7 

March  31 

21.7 

21.9 

December  26 

August  23. 

Septembers... 

September  12 

September  22 

18.7 

1890. 

Januarys.... 

January  15 

January  25 

February  4 

February  14 

February  24 

April  30 

16.5 

May  10              

17.2 

May  20 

14.9 

11.1 

May  30 

October  12 

10.1 

June  9 

8.8 

June  19 

Nov«Tnh«T  1 

6.8 



This  series  seems  to  show  the  powerful  influence  of  a  snow  covering 

to  keep  the  ground  from  cooling  to  very  Ioav  temperatures  during  the 

'inter.     The  minimum  temperatures  at  1  foot  depth  were  —0.5°  F. 

u,  ring  the  twenty  days  March  22  to  April  10,  1889,  and  +0.-!°  F. 

during  tlie  ten  days  March  17  to  2G,  1890. 


65 

METHODS  OF  MEASURING  SOIL  TEMPERATTTRES. 

As  it  is  very  iinportant  that  there  should  be  numerous  observations 
of  soil  temperature  available  for  af>:ricultural  study,  and  as  many 
persons  are  deterred  by  the  expensiveness  of  the  deep-earth  thermom- 
eters, I  would  call  attention  to  the  fact  that  agriculture  does  not  need 
to  consider  temperatures  at  depths  below  -i  feet  and  that  the  inex- 
pensive, excellent  system  of  thermometers,  made  by  Green,  of  New 
York,  has  been  recognized  as  the  standard  at  stations  in  the  United 
States ;  but  for  accuracy  and  convenience  nothing  can  exceed  the  ther- 
mophone  devised  by  Henry  E.  Warren  and  George  C.  Whipple,  of 
the  Massachusetts  Institute  of  Technology. 

Several  methods  of  measuring  deep-earth  temperatures  have  been 
most  thoroughly  studied  in  the  memoirs  of  Wild  and  Leyst,  of  St. 
Petersburg,  a  summary  of  which  I  have  prepared  and  will  submit 
at  another  time. 

The  soil  thermometers  constructed  by  Green  are  made  in  accordance 
with  suggestions  made  by  Milton  Wliitney,  of  the  South  Carolina 
Experiment  Station,  and  have  been  used  by  him. 

Wliitney  has  published  a  description  of  this  new  self-registering 
soil  thermometer  as  follows  (see  Agr.  Sci.,  Vol.  I,  p.  253;  Vol.  Ill, 
p.  261): 

This  is  a  modification  of  Six's  form  of  thermometer  in  which  the 
maximum  and  minimum  temperatures  are  registered  in  one  and  the 
same  instrument.  The  essential  features  of  the  thermometers  are  as 
follows:  A  cylindrical  bulb  6  inches  long,  filled  with  alcohol.  The 
bulb  is  protected  by  a  somewhat  larger  cylindrical  metal  tube,  con- 
taining numerous  holes,  and  is  to  be  placed  3  inches  below  the  surface 
of  the  soil — i.  e.,  so  that  the  bulb  will  extend  vertically  between  the 
depths  3  and  9  inches,  respectively,  in  the  soil.  The  tube  carrying 
the  alcohol  extends  some  6  or  8  inches  above  the  surface  of  the  ground, 
when  it  bends  twice  at  right  angles  and  descends  again  to  the  surface, 
bends  at  right  angles  twice,  crossing  the  main  stem,  and  is  carried  up 
aliout  G  or  8  inches  again,  where  it  terminates  in  a  bulb  partially  filled 
with  alcohol.  The  lower  bend  in  this  stem  carries  a  colunni  of  mercury 
Avhich  is  drawn  back  toward  the  bulb  when  the  alcohol  contracts,  and 
pushes  a  steel  index  up  to  the  minimum  temperature  on  a  scale  which 
reads  downward.  This  index  is  held  supported  in  the  alcohol  by  a 
little  spring  Avhen  the  alcohol  expands  and  the  mercury  leaves  it, 
while  another  index  is  pushed  up  to  the  maximum  temperature  by  the 
other  end  of  the  column  of  mercury.  The  indices  are  set  by  the  help 
of  a  magnet. 

The  advantages  claimed  for  this  instrument  are  that  it  gives  at 
once,  without  any  calculation,  the  mean  temperature  of  a  definite 
depth  of  soil,  for  which  we  now  use  at  least  three  thermometers, 
while  it  gives  in  addition  the  maximum  and  minimum  temperatures, 
and  need  only  be  read  once  a  day  instead  of  three  times,  as  at 
present.  *  *  * 
2667—05  M 5 


66 

Therinoineters  can  be  made,  of  course,  with  bulbs  longer  or  shorter 
than  the  one  described.  We  adopted  the  length  of  6  inches  placed  3 
inches  below  the  surface,  as  in  our  experience  that  represents  a  layer 
of  soil  in  Avhich  most  of  the  roots  of  the  cotton  plants  are  contained. 
We  expect  to  distribute  a  number  of  these  instruments  through  the 
State  [South  Carolina]  and  have  records  kept  for  us  near  signal- 
service  stations  in  our  typical  soils — a  method  wdiich  could  hardly 
have  been  arranged  with  the  old  form.  The  instrument  is  mounted 
on  a  neat  metal  backing,  and  is  made  by  H.  J.  Green,  of  New  York. 
It  cost  $10  without  packing  or  express  charges.  The  great  trouble 
about  the  instrument  is  the  danger  in  transportation  of  having  the 
index  get  doAvn  in  the  mercury  column.  For  this  reason  it  has  to  be 
transported  in  a  box  on  gimbals  to  swing  freely  w^ithin  a  larger  box, 
so  that  it  will  always  remain  upright.  We  had  such  a  box  made, 
capable  of  carrying  eight  or  ten  instruments,  for  $5. 

From  experiments  at  Houghton  Farm  (Agr.  Sci.,  Vol.  II,  p.  50) 
F.  E.  Emory  finds  that  the  thermoelectric  couple  and  galvanometer, 
as  used  by  Becquerel,  consumed  much  time  and  was  frequently  use- 
less owing  to  atmospheric  electricity  and  ground  currents.  Short- 
stem  graduated  thermometers,  with  bulbs  immersed  in  oil  and  fas- 
tened at  the  lower  end  of  a  light  w^ooden  rod,  gave  good  results  when 
the  temperature  at  the  thermometer  was  not  warmer  than  that  of  the 
overlying  soil  or  the  atmosphere ;  otherwise  a  circulation  of  air  takes 
place.  He  finds  that  the  telethermometer,  giving  a  continuous  rec- 
ord, answers  his  needs,  but  we  know  nothing  of  its  accuracy. 

T.  C.  Mendenhall  (1885)  describes  a  modified  form  of  thermometer 
for  observing  the  temperature  of  the  soil  at  any  depth,  which  he  calls 
the  "  differential  resistance  thermometer."  Experiments  w^ith  this 
instrument  at  Washington,  D.  C,  have  shown  him  that  it  is  miich 
less  troublesome  than  Becquerel's  electric  method,  but  still  too  trou- 
blesome to  be  recommended  to  any  but  persons  accustomed  to  electric 
measurements.  Mendenhall's  arrangement  consists  essentially  in  util- 
izing the  varying  resistance  of  a  platinum  wire  which  extends  from 
the  upper  end  of  an  ordinary  mercurial  thermometer  down  into  its 
bulb.  The  total  resistance  diminishes  as  the  temperature  rises  and 
allows  the  current  to  flow  through  less  platinum  but  more  mercury. 
The  changes  in  the  resistance  are  measured  by  the  galvanometer,  but 
he  hopes  to  substitute  for  this  the  telephone,  which  wdll  make  the 
apparatus  more  convenient  for  general  use. 

[It  is  desirable  that  this  or  Becquerel's  method  or  the  thermo- 
phone  be  provided  in  connection  with  the  ordinary  buried  long- 
stem  thermometers  in  order  that  by  an  annual  or  more  frequent  set 
of  comparative  observations  the  changes  in  the  zero  point  of  ordi- 
nary thermometers  may  be  detected. — C.  A.] 


Chapter  IV. 

THE  INFLUENCE   OF  SUNSHINE  ON   ASSIMILATION  AND  TRANS- 
PIRATION. 

CHEMISTRY  OF  ASSIMILATION  (ABBOTT). 

The  atmosphere  is  composed  of  about  79  per  cent  of  nitrogen  and 
21  per  cent  of  oxygen  when  we  consider  their  volumes,  but  77  per 
cent  of  nitrogen  and  23  per  cent  of  oxygen  when  we  consider  their 
relative  Aveights.  With  these  gases  there  are  mixed  small  quantities 
of  carbonic-acid  gas,  ammonia,  hydrocarbons,  and  other  impurities. 
With  this  ''  dry  atmosphere  "  there  is  intermixed  a  very  variable  quan- 
tity of  aqueous  vapor  or  moisture,  which  in  extreme  cases  may  amount 
to  as  much  as  5  per  cent,  by  weight,  of  the  dry  air.  These  are  the 
elements  that  are  to  be  compounded  by  sunshine  and  heat  in  the 
laboratory  of  vegetation. 

By  respiration  the  leaves  of  plants,  when  in  the  dark,  absorb 
ox3'gen  from  the  air  and  set  free  carbonic-acid  gas. 

By  assimilation,  as  shown  by  Garreau,  these  same  leaves  in  the 
sunshine  absorb  carbonic-acid  gas  from  the  air  and  set  free  oxygen, 
retaining  the  carbon  in  new  compounds.  Assimilation  is  a  process 
of  greater  intensity  than  respiration.  Respiration  is  a  process  analo- 
gous in  its  results  to  that  occurring  within  every  animal  organism, 
l)ut  assimilation  is  a  process  peculiar  to  the  plant  life. 

By  transjDiration  the  leaves  rid  themselves  of  the  superfluous  water 
that,  as  sap,  has  served  its  purpose  in  the  process  of  assimilation  by 
bringing  nourishment  from  the  soil  and  delivering  it  up  to  the  cells 
of  the  plant ;  a  small  portion  of  the  nourishment  and  of  the  water 
may  have  been  absorbed  by  the  cells  in  the  trunk  of  the  tree,  the  stem 
of  the  vine,  or  the  stalk  of  the  grain  and  grass,  but  the  majority  of 
the  water  is  removed  by  transpiration  at  the  surface  of  the  leaves  in 
order  to  make  room  for  fresh  supplies  of  sap.  Some  water  always 
remains  in  the  cells  of  the  seeds  and  grains  until  they  are  dried  after 
maturity,  but  a  well-dried  crop  contains  relatively  little  water.  This 
transpiration  is  stimulated  by,  and  almost  entirely  depends  upon,  the 
action  of  sunshine  on  the  leaves;  it  precedes  evaporation. 

Evaporation  is  not  transpiration;  the  former  takes  place  from  the 
surface  of  water  existing  either  in  the  moist  earth  or  in  films  on  leaf 
surface  or  in  larger  masses,  while  transpiration  takes  place  through 
the  cell  wall  and  is  a  process  of  dialysis,  an  endosmosis  and  exosmosis 

(07) 


68 

by  which  the  cell  takes  in  the  sap,  retains  what  it  needs,  and  then 
gets  rid  of  the  water  and  the  dissolved  substances  which  it  does  not 
need.  Thus  the  cell  wall  thickens  and  enlarges  and  the  contents  of 
the  cell  increase.  The  sap  enters  the  cell  from  that  side  of  the  cell 
which  is  turned  toward  the  interior  of  the  plant  or  adjacent  cells, 
and  the  rejected  water  penetrates  the  cell  wall  on  that  side  of  the  cell 
which  is  exposed  to  the  open  air,  and  especially  on  that  side  exposed 
to  the  sunshine ;  having  reached  the  outer  surface  of  the  cell  wall  on 
this  side  of  the  cell  it  is  then  evaporated.  This  endosmosis  by  which 
the  sap  enters  the  cell  on  one  side,  and  the  exosmosis  by  which  it  leaves 
the  cell  on  the  opposite  side,  constitute  the  fundamental  mechanics 
of  all  vital  activities;  the  chemistry  of  animal  and  vegetable  life 
differs  from  the  ordinary  chemistry  of  the  laboratory  in  that  the 
former  studies  the  behavior  of  the  cell  wall  toward  the  molecule, 
while  the  latter  studies  the  behavior  of  the  molecule  toward  the 
molecule.  An  interesting  contribution  to  the  development  of  this 
idea  of  the  chemistry  of  the  action  of  the  cell  is  contained  in  two 
papers  by  Miss  Abbott  (now  Mrs.  Michael,  of  Philadelphia),  pub- 
lished in  1887  in  the  Journal  of  the  Franklin  Institute;  from  the 
second  paper  I  take  the  following  extract : 

The  botanical  classifications  based  upon  morphology  are  so  fre- 
quently unsatisfactory  that  efforts  in  some  directions  have  been  made 
to  introduce  other  methods. 

There  has  been  comparatively  little  study  of  the  chemical  principles 
of  plants  from  a  purely  botanical  view.  It  promises  to  become  a  new 
field  of  research. 

The  Leguminosse  are  conspicuous  as  furnishing  us  with  important 
dyes,  e.  g.,  indigo,  logwood,  catechin.  The  former  is  obtained  prin- 
cipally from  different  species  of  the  genus  Indigofera,  and  logwood 
from  the  Hcematoxylon  campechianum^  but  catechin  from  the  Acacia 
catecliH. 

The  discovery  of  hrematoxylon  in  the  Saraca  indica  illustrates  very 
ivell  hoAv  this  plant,  in  its  chemical  as  well  as  botanical  character,  is 
related  to  the  Harndtoxylon  campechianum;  also,  I  found  a  sub- 
stance like  catechin  in  the  Saraca.  This  compound  is  found  in  the 
Acacias,  to  which  class  Saraca  is  related  by  its  chemical  position  as 
well  as  botanically.  Saponin  is  found  in  both  of  these  plants,  as  well 
as  in  many  other  plants  of  the  Leguminosfp.  The  Leguminosa'  come 
under  the  middle  plane  of  multiplicity  of  floral  elements,  and  the 
presence  of  saponin  in  these  plants  was  to  be  expected.     *     *     * 

From  many  of  the  facts  above  stated,  it  may  be  inferred  that  the 
chemical  compounds  of  plants  do  not  occur  at  random.  Each  stage 
of  growth  and  development  has  its  own  particular  chemistry. 


SUNSHINE  AND  TRANSPIRATION  (DEHERAIN  AND  MARIlS- 
DAVY). 

Studies  in  the  traiispinition  of  plants  were  made  in  Enjihind  as 
early  as  1691  by  S.  IL  Woodward,  who  oxiHM'iinonted  on  a(iuatic 
plants.  He  showed  that  the  consumption  of  water  by  the  plant,  or  the 
weight  of  water  evaporated  from  it,  varied  within  narrow  limits, 
while  the  growth  of  the  plant  under  the  same  temperature  and  sun- 
shine, varied  according  to  the  amount  of  nourishment  in  the  water; 
thus  of  pure  spring  water  170  grains  had  to  be  evaporated  in  order 
to  make  an  increase  of  1  grain  in  the  weight  of  the  plant,  but  only 
'M\  grains  of  the  rich  water  of  the  Thames  was  required  to  make  tlie 
same  increase  in  the  weight  of  the  plant. 

In  1848  Guettard,  experimenting  upon  a  creeping  nightshade, 
showed  that  a  plant  kept  in  a  warm  place  without  sunshine  would 
transpire  less  than  one  in  a  colder  place  with  sunshine. 

Deherain,  as  quoted  by  Marie  Davy  (1880,  p.  231)  introduced  the 
leaves  or  stems  of  a  living  plant  into  a  tube  suitably  closed;  under 
tliese  circumstances,  by  reason  of  the  small,  calm  space  of  air  sur- 
rounding the  leaves,  the  evaporation  in  the  ordinary  sense  would  be 
inappreciable,  but  the  transpired  water  was  found  to  increase  the 
weight  of  the  tube,  as  shown  in  the  accompanying  table. 

Sunshine  and  transpiration. 


Plant. 

Exposure. 

Temper- 
ature. 

Weight  of 

water 
transpired 
per  hour 
per  gram 
weight  of 
leaf. 

Wheat 

Sunshine 

22 
22 
19 
IG 
16 
22 
16 
28 
22 

Gram. 

Do 

.177 

Do 

Darkness 

Oil 

Barley 

Do 

Diffuse  light 

180 

Do 

.023 

Wheat 

Sunshine 

718 

Do 

Darkness 

028 

Do 

Sunshine 

703 

Do 

Diffuse  light 

Do 

Darkness 

(X)7 

The  effect  of  sunshine  in  stimulating  transpiration  is  very  clearly 
seen  by  a  study  of  these  figures.  The  small  trans])iration  from  the 
leaf  when  kept  in  darkness  is  supposed  to  be,  at  least  in  part,  due  to 
a  persistency  of  the  stimulus  given  to  the  plant  by  the  light;  so  that, 
as  is  well  known,  the  growth  of  the  plant  goes  on  at  its  maximum  rate 
in  the  late  afternoons,  sometimes  even  after  sunset,  and  does  not 
attain  its  minimum  until  early  morning. 


70 

Deherain  also  arranged  the  following  experiments  showing  the 
effect  of  temperature.  Some  living  leaves  of  wheat  were  kept  within 
a  glass  tube  which  lay  in  a  water  bath  at  a  uniform  temperature  of 
15°  C.  and  the  folloAving  measurements  taken : 

In  full  sunshine  the  transpiration  was  O.D39.gram  of  water  per 
hour  i^er  gram  weight  of  leaf. 

In  darkness  the  transpiration  was  0.016  gram  of  water  per  hour 
per  gram  weight  of  leaf. 

The  water  bath  was  then  reduced  to  a  temperature  of  0°  C,  and  the 
temperature  of  the  leaf  within  the  tube  must  therefore  have  been  at 
the  freezing  point.  In  this  condition  the  transpiration  in  full  sun- 
shine was  1,088  grams  of  w^ater  per  hour  per  gram  weight  of  leaf. 

Thus  leaves  in  sunshine  in  free  air  at  28°  C.  and  leaves  in  the 
air  at  15°  C,  and  again  in  the  water  bath  at  0°  C.,  give  us  the  tran- 
spiration under  these  conditions  0.882,  0.930,  1.088,  respectively.  It 
is  evident  that  this  transpiration  is  not  due  to  evaporation  alone,  else 
it  would  be  independent  of  sunshine  and  depend  wholly  on  heat ;  the 
decided  differences  here  shown  must  be  attributed  to  the  special 
excitement  of  the  cell  by  the  solar  radiation. 

Marie  Davy  gives  for  July  24  and  25,  1877,  the  following  record 
from  a  self-registering  apparatus  showing  the  diurnal  periodicity  of 
the  transpiration  from  the  leaves  of  four  plants  of  haricot  beans 
which  were  watered  daily  at  7  p.  m. : 

Diurnal  periodicity  of  transpiration. 


Hour. 

Transpi- 
ration. 

Hour. 

Transpi- 
ration. 

HO-               \l7Sr 

4 
2 
2 
4 
4 
4 
2 
4 
4 

8 

32 
76 
99 
86 
128 
153 
179 
143 

120 

R  tn  9  p  m 

5  to  6  a  m 

2  to  3  p  m 

95 

67 

10  to  11  p  m 

7  to  8  a  m 

4  to  .'i  p  -m 

44 

11  p.  m.  to  12  midnight. 

12  midniglit  to  1  a.  m 

25 

9  to  10  a.  m 

6  to  7  p.  m 

10 

4 

2to3a.  m._ 

11  a.  m.  to12  noon . . . 

12  noon  to  1  p.  m 

These  same  four  plants  showed  the  transpiration  day  by  day,  as 
given  in  the  first  column  of  the  following  table  (Marie  Davy,  1880, 
p.  239).  The  third  and  fourth  columns,  respectively,  show^  the  rela- 
tion of  this  transpiration  to  the  daily  mean  temperature  and  the  daily 
mean  radiation,  as  shown  by  the  conjugate  thermometers. 


71 


Insolation  and  transpiration  {or  kidncii  beans  at  Montsouris. 


Date,  1877. 


July  10. 
17 
18. 
19. 
20 
21 


Weight 
of  tran- 
spired 
water. 


Weight  of  tran- 
spired water 
divided  by- 


Moan 
actino- 


Grams. 
0.686 
0.422 
0.727 
0.543 
0.577 
1.127 
1.608 
1.204 


degrees. 


1.16 
1.36 
1.21 

1.56 
1.24 

1.81 
1.88 


July  24 
25 

26 
27 
28 
29 
30 
31 


Weight 
of  tran- 
spired 
water. 


Weight  of  tran- 
spired water 
divided  hy— 


Mean 
actino- 


degrees. 


Cframs. 
0.706 
1.300 
0.991 
1.255 
1.426 
1.277 
2.167 
2.710 


3.8 
7.1 
5.3 
6.7 
7.8 
5.9 
7.6 
8.4 


2.00 
2.17 
1.92 
2.46 
2.64 
2.97 
3.55 
3.15 


The  figures  in  the  above  table  are  influenced  by  the  quantity  of 
moisture  in  the  soil;  therefore  Marie  Davy  occasionally  omitted  the 
evening  watering,  and  the  transpiration  for  the  day  after  such  omis- 
sion was  smaller.  In  general,  Marie  Davy  concludes  that  the  relation 
between  transpiration  and  temperature  is  very  variable  from  day  to 
day,  while  that  between  transpiration  and  radiation  is  very  regular, 
u  regularity  that  would  very  probably  be  heightened  if  the  cloudiness 
and  the  evaporating  power  of  the  wind,  as  depending  on  its  dryness 
and  velocity,  had  been  considered.  The  belief  is  that  sunshine  excites 
the  contraction  of  the  stomata  of  the  leaves  and  thus  stimulates  tran- 
spiration; but  the  stomata  can  not  exude  water  to  a  greater  extent 
than  as  supplied  by  the  roots;  therefore  the  transpiration  is  limited 
by  the  humidity  of  the  soil  adjacent  to  the  roots.  Thus  on  the  30th 
the  radiation  averaged  45.5  actinometric  degrees,  and  the  plant  tran- 
spired 2.167  grams  of  water;  on  the  31st  the  radiation  was  64.1  and 
the  transpiration  correspondingly  increased  to  2.710  grams;  but  on 
this  day  the  reserve  moisture  in  the  soil  was  drawn  upon  very  heavily, 
and  in  the  evening  the  leaves  of  the  plant  were  flabby  and  drooping 
and  evidently  wilting  for  the  want  of  moisture. 

The  result's  by  Deherain  at  temperatures  of  15°  C.  and  0°  C.  and 
those  by  Marie  Davy  seem  to  demonstrate  satisfactorily  the  slight 
influence  of  the  temperature  of  the  air  as  such  ui:)on  transpiration. 

Daubeny  (1836),  Deherain,  and  Wiesner  have  studie<l  the  effect  of 
radiation  in  different  parts  of  the  spectrum,  and  their  work  shows 
that  the  radiations  that  are  absorbed  by  chloroi)hyl,  the  so-called 
chlorophyl-absorption  bands,  are  those  that  are  efficient  in  stimulat- 
ing transpiration;  also  that  xanthoi)hyl  acts  similarly,  but  weaker 
than  chlorophyl;  that  the  violet  and  ultraviolet  have  no  appreciable 
influence:  that  the  ultrared  rays  liavc  an  api)re<'iable  action,  but 
feebler  than  the  visible  ravs  between  the  red  and  blue,  notwithstand- 


72 

ing  that  their  heating  effect  is  usually  greater  than  those  of  the 
visible  spectrum. 

The  laws  of  growth  or  vitalit}'  are  the  laws  of  physics  and  mechan- 
ics and  chemistry  as  applied  to  living  cells.  The  changes  that  go 
on  slowly  in  the  plant  are  not  the  same  as  would  go  on  rapidly  in 
large  masses  of  the  same  chemicals  Avhen  treated  as  in  the  ordinary 
chemical  laboratory.  In  the  plant  small  masses  are  confined  within 
the  transparent  walls  of  the  cells  until  that  subtile  influence  which 
Ave  call  radiation  can  do  its  work  in  bringing  about  new  combinations 
of  the  atoms.  It  matters  not  whether  we  consider  the  radiation  as 
an  orthogonal  vibration,  as  in  light,  or  a  promiscuous  interpenetration 
of  the  molecules,  as  in  heat,  or  a  radial  vibration,  as  in  the  waves 
of  sound ;  Avhatever  view  we  take  of  it,  or  whatever  the  details  may 
be,  even  if  it  be  a  rythmic  breaking  up  and  re-formation  of  the  mole- 
cules, the  general  characteristic  of  radiation  is  an  extremely  rapid 
motion  along  the  molecules  and  atoms  of  matter.  Therefore,  by 
radiation  we  understand  energy  or  momentum  in  the  minute  atoms 
that  go  to  make  up  the  molecules  and  the  masses  that  we  deal  with ; 
this  implies  that  work  is  done  by  one  atom  upon  its  neighbor,  which 
work,  according  to  its  style,  we  call  light,  heat,  evaporation,  etc. 
Assimilation  and  transpiration  are  among  the  forms  of  work  in  the 
growth  of  the  plant  that  are  due  to  the  molecular  energy  contained 
in  sunshine,  and  it  is  essential  to  progress  in  agriculture  that  there 
be  kept  a  continuous  register  of  the  intensity  and  nature  of  the  solar 
radiations  that  reach  the  plant.  But  this  is  a  difficult  problem,  whose 
satisfactory  solution  has  not  yet  been  attained,  although  the  work 
of  Violle,  Bunsen  and  Roscoe,  Marie  Davy,  Marchand,  Langley,  Roav- 
land,  Hutchins,  and  many  others  have  marked  out  the  methods  which 
seem  most  promising. 

ANNUAL  DISTRIBUTION  OF  SUNSHINE. 

Humboldt  (1815),  in  his  chapter  on  ''Climate,"  after  comparing 
the  climates  and  fruits  of  Europe,  says: 

These  comparisons  demonstrate  how  important  is  the  -diversity  of 
the  distribution  of  heat  throughout  the  different  seasons  of  the  year 
for  the  same  mean  annual  temperature,  as  far  as  concerns  vegetation 
and  the  culture  of  the  fields  and  orchards,  and  as  well  as  regards  our 
own  well-being  as  a  consequence  of  these  conditions. 

The  lines  which  I  call  isochimenal  and  isotheral  (lines  of  equal  tem- 
perature for  winter  and  summer)  are  not  parallel  to  the  isothermal 
lines  (lines  of  equal  annual  temperature)  in  those  countries  where — 
notwithstanding  the  myrtle  grows  wild  in  its  natural  state,  and  where 
no  snow  falls  during  the  winter — the  temperature  of  summer  and  fall 
scarcely  suffices  to  bring  apples  to  full  maturity.  If  to  give  a  potable 
wine  tile  vine  shuns  the  islands  and  nearly  all  sea  coasts,  even  those 
of  the  west,  the  cause  is  not  only  in  the  moderate  heat  of  summer  upon 
the  seashore,  a  circumstance  which  is  shown  by  thermometers  exposed 


73 


/^  ^   or  THE 

[  VJNIVERSITY 


OF 


in  the  open  air  and  in  the  shade,  but  it  consists  still  more  in  the  dif- 
ference between  direct  and  ditlused  light,  between  a  clear  sky  and  one 
veiled  with  clouds,  a  ditl'erence  which  is  still  unappreciated,  although 
its  efficaciousness  may  be  proved  by  other  phenomena,  as,  for  exam- 
ple, the  union  of  a  mixture  of  chlorine  and  hydrogen. 
Humboldt  adds : 

I  have  endeavored  for  a  long  time  to  call  the  attention  of  scientists 
and  physiologists  to  this  difference;  in  other  words,  to  the  yet 
unmeasured  heat  which  direct  light  develops  locally  in  the  cell  of  the 
living  plant.     (Cosmos,  t.  I,  pp.  347-349.) 

TOTAL   QUANTITY   OF   HEAT   REaUIRED   TO   RIPEN   GRAIN. 

Boussingault  (1834),  in  his  Rural  Economy,  computes  the  total 
quantity  of  heat  required  to  ripen  grain  by  multiplying  the  mean 
daily  temperature  of  the  air  in  the  shade  in  centigrade  degrees  by  the 
duration,  in  daj^s,  of  the  process  of  vegetation.  This  product  is 
known  as  the  number  of  "  day  degrees  "  that  the  plant  has  experi- 
enced or  has  required  for  the  development  from  sowing  to  maturity. 
(See  Annual  Report  Chief  Signal  Officer  for  1881,  p.  1208.)  Bous- 
singault's  results  are  given  in  the  accompanying  table : 

Day  degrees  required  at  differeiit  latitudes. 


Plant  and  place. 


Autumn  wheat: 

Alsace 

Alais 

Kingston  . . . 
Summer  wheat: 

Alsace 

Kingston  -.. 

Cincinnati . . 

Truxillo 

Quinchuqui 
Winter  barley: 

Alsace 

Alais 

Kingston  ... 

Santa  Fe.... 

Cumbal 


Latitudes 
north. 


48  48 

44  7 

41  50 

48  48 

41  50 

9  00 

0  14 


44  7 

41  50 

4  35 

0  00 


Mean  air  Product  of 
i^i^-^  ^f      temper-      the  days 
^i^°°l   aturedur-      bythi 
mg  cul-    I  tempera- 
ture.     !      ture. 


Dura- 


the  cul 
ture, 


Days. 
137 
146 
122 

131 
106 
187^ 

loo" 

181 

122 
137 


15.0 
14.4 
17.2 

15.8 
2f).0 
15.7 
22.3 
14.0 

14.0 
13.1 
19.0 
14.7 
10.7 


Day  deg. 

2055 
2  092 
2  098 

2  069 
2  120 
2  151 
2  208 
2  230 

1  708 
1  795 
1  738 
1  793 
1  798 


The  above  table  shows  that  the  total  quantity  of  heat  required 
increases  as  the  latitude  diminishes. 


THE   STJNSHINE  AND   HEAT   REQUIRED   TO   RIPEN   GRAIN. 

Tisserand  (1875)  modifies  Boussingault's  hypothesis  that  growth 
varies  with  heat  and  time,  but  adopts  the  rule  that  the  work  done  by 
a  plant  can  be  represented  by  the  product  of  the  mean  temperature 


74 

i^y  the  number  of  hours  of  sunshine,  only  rejecting  the  useless  night- 
time, just  as  one  would  reject  the  useless  low  temperature.  In  the 
absence  of  sunshine  records  he  uses  the  number  of  hours  between 
sunrise  and  sunset,  or  the  duration  of  diffuse  sunshine,  and  obtains 
for  spring  wheat  and  barley  the  data  given  in  the  accompanying 
table,  where  the  last  cohnnn  may  be  said  to  give  "  sunshine  hour 
degrees." 

Sunshine  hour  degrees. 


Plant  and  locality. 

Latitude 
north. 

Hours  of 
possible 
sunshine. 

Sunshine 

•SK.?.    (tempera- 
shine). 

Spring  wheat: 

48    30 
.59      9 
59    47 

67  17 

68  46 

69  28 

48    30 
59      9 
59    47 
67    17 
69    28 
69    28 

1  996 

1  795 

2  187 
2  376 
2  472 
2486 

1  416 
1620 

2  035 
2  138 
2  138 
1  824 

°  C. 
15.0  j           29  900 

Christiania 

15  4              27  643 

13.0 
11.3 
10.9 
10.7 

19.0 
15.5 
11.7 

n.o 

10.7 
12.7 

28  431 

Bodo ---- 

Strand _ __ 

26  848 
26  944 
26  600 

Barley: 

Alsace                          . 

26  900 

Christiania 

25  125 

23  809 

Bodo 

23  000 

23  000 

Do 

22  876 

We  see  that  the  sunshine  hour  degrees  diminish  as  the  latitude  in- 
creases. This  diminution  ought  to  be  rather  more  rapid  in  propor- 
tion as  the  actual  state  of  the  cloudy  atmosphere  approaches  the  theo- 
retical state  of  absolute  clear  sky. 

Thus  Halsno  and  Bodo,  localities  which  have  very  nearly  the  same 
soil,  the  same  altitude,  the  same  orientation,  the  same  distance  from 
the  sea,  but  which  are  more  or  less  under  the  influence  of  the  aqueous 
vapor  coming  from  the  Gulf  Stream,  have  a  cloudiness  during  the 
evolution  of  wheat  of  5.6  and  7;  during  that  of  oats,  .5.4  and  7;  where 
0  represents  perfect  freedom  from  clouds  and  10  completely  covered. 

If  records  of  cloudiness  could  have  been  used,  the  numbers  in  the 
last  column  would  have  been  computed  like  those  in  the  following 
table : 


'sur^cio^f 

shine.        ^^ss. 


Clear  sky. 


Average 
daily 

tempera- 
ture. 


Spring  wheat:  Hours. 

Halsno i       2,187 

Bodo j       2,876 

Barley: 

Halsno !       2,0a5 

Bodo i       2,138 


Tenths.  'Percent. 
5.6  44 

7.0  30 

5.4  46 

T.O  '  30 


13.0 
11.3 


11.7 
11.0 


Hours. 
12,  .506 
7,8a5 

10.9.51 
7,a51 


THE  SUNSHINE  AND  HEAT  REQUIRED  TO  FORM  CHLOROPHYLL. 

After  considering"  the  preceding  data  Mario-Davv  (IcSSO.  p.  li-JH 
presents  the  following  as  his  views: 

It  is  the  chlorophyll  or  green  coloring  matter  in  the  cells  of  tli(> 
green  leaves  that  alone  has  the  property  of  decomposing  the  carbonic 
acid  of  the  air.  It  ntilizes  the  sunlight,  but  also  recpiires  a  certain 
temperature,  which  may  be  given  to  it  either  from  the  air  or  from  the 
sunshine  itself,  so  that  we  may  say  that  ordinarily  in  nature  the  sun- 
shine both  warms  the  chlorophyll  by  means  of  the  red  rays  and  enables 
it  to  decompose  carbonic  acid  by  means  of  the  yellow  rays.  The 
decomposing  action  of  the  chlorophyll  only  becomes  appreciable  at  a 
certain  minimum  temperature,  which  is  about  15°  C.  when  the  tem- 
perature is  rising.  It  attains  its  maximum  activity  at  about  30°  C, 
and  as  the  temperature  cools  it  retains  an  appreciable  activity  at 
about  10°  C.  These  figures  are  obtained  by  experiments  of  Cloez 
and  Gratiolet  on  water  plants  in  the  full  sunshine.  On  the  other 
hand,  Boussingault  obtains  1.5°  and  3.5°  C.  as  the  lower  limits  of 
temperature  for  the  ordinary  Graminea?,  but  these  plants  were  in  the 
sunshine,  and  if  his  temperature  observations  had  been  made  in  the 
shade  they  would  have  given  lower  figures  than  these,  so  that  un- 
doubtedly the  Graminese  can  assimilate  and  grow  when  the  tem- 
perature of  the  air  in  the  shade  is  below  freezing.  On  the  other  hand, 
Sachs  find  that  when  the  illumination  is  below  a  certain  minimum, 
which  varies  with  the  plant  and  wdth  the  temperature,  the  color  of  the 
chlorophyll  is  a  clearer  yellow^  tint,  and  for  temperatures  below  a  cer- 
tain minimum  w'hich  varies  wdth  the  plant  it  remains  colorless,  not- 
withstanding the  most  brilliant  sunshine.  Thus  in  1862  the  excep- 
tionally low^  temperature  of  the  month  of  June  was  sufficient  to 
prevent  the  development  of  new  leaves  on  the  stems  of  maize,  cucum- 
bers, and  beans,  so  that  all  these  remained  yellow  and  only  became 
green  subsequently  wdth  warmer  weather  and  better  sunshine. 

The  pale  leaves  of  a  sprouting  bean  became  gi'een  in  a  few  hours 
under  a  temperature  of  30°  to  33°  C,  but  this  happened  only  in  the 
sunlight,  for  at  the  same  temperature  in  the  darkness  they  remained 
yellow\  At  a  temperature  of  from  17°  to  20°  C.  the  greening  of  the 
leaf  went  on  much  more  slowly;  at  8°  and  10°  C.  there  was  only  a 
trace  at  the  end  of  seven  hours;  below  6°  C.  the  leaves  remained  fifteen 
days  without  greening. 

Similarly  the  pale  shoots  of  maize,  even  at  a  temperature  of  24°  to 
35°  C,  did  not  become  colored  in  the  darkness,  but  in  the  feeble  light 
of  the  interior  of  a  room  a  green  effect  was  visible  at  the  end  of  an 
hour  and  a  half,  and  at  the  end  of  seven  hours  the  leaves  were  all 
green  and  of  normal  appearance.  At  a  temperature  between  1G°  and 
17°  C.  the  first  traces  of  color  were  visible  at  the  end  of  five  hours. 


76 

But  at  temperatures  of  13°  and  li""  C.  nothing  was  seen  even  at  the 
end  of  seven  hours.  At  a  tern jDerat are  below  6°  the  leaves  remained 
nncolored  for  fifteen  daj^s  in  the  diti'use  light  of  the  room. 

Again,  the  pale  shoots  of  cabbage  placed  in  the  window,  and  there- 
fore in  full  sunshine  and  at  temperatures  of  13°  or  14°  C.,  became 
green  at  the  end  of  twentj'-four  hours;  but  under  temperatures  of 
3°  to  5°  C.  only  traces  of  green  color  were  seen  at  the  end  of  three 
days,  and  the  coloration  was  not  complete  until  at  the  end  of  seven 
days. 

Herve  Mangon,  by  employing  the  electric  light  in  place  of  sun- 
light, has  arrived  at  similar  results  for  rye.  Marie-Davy,  by  the  use 
of  a  single  gaslight,  has  obtained  similar  results  for  the  strawberry 
plant.  Similarly  De  Candolle  caused  mustard  and  other  plants  to 
become  green  by  the  light  of  four  argancl  lamps. 

Evidently  a  very  feeble  light  suffices  to  produce  the  greening,  for 
the  feeble  individual  etfects  accumulate  and  add  together ;  but  when  a 
bright  light  is  used  secondary  reactions  set  in,  transforming  and  util- 
izing the  chlorophyll  itself  .  The  light  that  determines  the  production 
of  the  chlorophyll  and  its  green  color  also  proceeds  to  destroy  the 
chlorophyll.  Thus  the  direct  light  of  the  sun  rapidly  decolors  the 
alcoholic  extract  of  chlorophyll,  while  diffuse  light  acts  more  slowly ; 
but  in  a  living  plant  the  action  of  light  is  different,  since  it  may 
become  so  intense  for  a  special  plant  that  the  destruction  of  the  chlo- 
rophyll may  go  on  faster  than  its  formation.  If  a  green  plant  is  car- 
ried into  a  dark  room  the  chlorophyll  ceases  to  form  and  a  gradual 
process  of  destruction,  or  rather  of  transformation  and  assimilation, 
goes  on  until  the  plant  becomes  pale  yellow.  This  mutability  of 
chlorophyll  makes  it  the  essential  medium  through  which  the  plant 
is  nourished. 

Draper,  Desains,  and  others  have  shown  that  the  chlorophyll  absorbs 
certain  rays  of  the  spectrum ;  that  is  to  say,  that  the  work  of  forming 
and  transforming  chlorophyll  is  accomplished  by  means  of  radiations 
that  have  a  certain  velocity  of  vibration  or  a  certain  wave  length,  and 
that  they  are  mostly  those  that  form  the  red,  orange,  yellow,  green, 
and  blue  portions  of  the  spectrmn.  Awaiting  a  more  detailed  study 
of  this  phenomenon,  we  must  at  present  adopt  the  general  rule  that 
the  variation  in  efficiency  of  each  of  these  agents  is  approximately 
proportional  to  the  variation  in  the  total  energy  of  the  solar  radia- 
tion, although  our  present  knowledge  points  to  the  conclusion  that 
a  radiant  beam  generally  contains  specific- active  wave  lengths  in 
proportions  and  intensities  that  have  no  necessary  relation  to  each 
other. 


77 

mTLUENCE  OF  ABSORBENT  MEDIA  ON  CHLOROPHYLL. 

The  action  of  sunlight  on  the  c-hk)rc)phyll  within  tlie  cell  is  not 
materially  modified  if  the  light  passes  first  through  layers  of  cells 
that  do  not  contain  chlorophyll,  such  as  those  of  the  red  colored  cab- 
bage leaf,  since  in  those  cells,  as  in  yellow  cells  and  others,  t\ui  radia- 
tioii  that  is  absorbed  is  not  to  any  extent  that  special  radiation  which 
the  chlorophyll  absorbs.  The  absorption  of  light  by  the  yellow 
cells  of  the  yellow  leaves  of  an  alder  bush  was  examined  by  T.  W. 
Engelmann  (Agr.  Sci.,  Vol.  II,  p.  139),  who  found  that  tJicse  ab- 
sorbed most  from  the  middle  of  the  spectrum  and  least  at  either  end, 
whereas  the  chlorophyll  absorption  is  complementary  to  this.  He 
also  found  that  the  green  leaves  of  the  alder  bush,  when  exposed  to 
the  light  side  by  side  with  the  yellow  leaves,  set  free  far  more  oxygen 
than  these,  so  that  it  seems  probable  that  if  the  yellow  cells  con- 
tain only  pure  xanthopyll  there  assimilating  power  would  be  zero, 

INFLUENCE  ON  THE  SUPPLY  OF  SAP. 

The  action  of  sunshine  in  producing  or  altering  the  colors  of  fruits, 
esj^ecially  the  black  Hamburg  grape,  has  been  experimentally  studied 
by  Laurent.  (Agr.  Sci.,  Vol.  IV,  p.  147.)  Bunches  of  innnature 
grapes  quite  shielded  from  the  sunlight  ripened,  colored,  and  flavored 
as  usual,  but  bunches  whose  food  supply  had  been  cut  ofl'  by  ringing 
the  base  of  the  stock  supporting  the  bunch,  and  then  also  kept  in  the 
dark,  remained  green,  small,  and  sour.  Bunches  that  had  been  sub- 
jected to  the  ringing  process,  but  which  wer^  exposed  to  the  sunlight, 
produced  berries  of  normal  size,  some  reddish  and  others  green  and 
of  an  acid  flavor.  He  concludes  that  the  coloring  matter  of  grapes 
may  be  formed  in  the  absence  of  sunshine,  provided  a  sufficient  sup- 
ply of  nourishment  be  at  hand,  but  if  this  supply  be  arrested  then  the 
color  remains  imperfect. 

CLIMATE  AND  THE  LOCATION  OF  CHLOROPHYLL  CELLS. 

Guntz  (1886)  has  studied  the  anatomical  structure  of  the  leaven  of 
cereals  and  grasses  in  their  relations  to  locality  and  climate.  This 
connection  is  infinitely  complex.  Among  other  items  brought  out  by 
him  we  note  that  the  green  assimilating  organism  consists  of  many 
cells  of  various  shapes  and  in  most  cases  fills  the  spaces  between  the 
nerves  of  the  leaves;  in  tropical  grasses  the  green  cells  occur  most 
in  the  inclosing  sheath,  but  in  the  grasses  of  the  steppes  it  lies  on 
either  side  of  the  grooves  or  ridges.  The  intercellular  gaps,  acconling 
as  they  are  larger  or  smaller,  indicate  a  moist  or  a  dry  soil  and, 
equally  so,  a  moist  or  dry  atmosphere.  The  bast  in  the  leaves  of  the 
gi-asses  serves  primarily  to  strengthen  the  whole  structure,  but  the 
bast  increases  with  the  dryness  of  the  locality,  and  its  proportional 
distribution  is  an  appropriate,  indirect  indication  of  the  climate. 


78 

THE  INFLUENCE  OF  CLOUD  AND  FOG. 

There  are  some  parasitic  plants,  says  Marie-Davy  (1881  and  1882), 
-that  require  only  moisture  and  warmth  in  order  to  vegetate.  They 
mature  and  propagate  while  entirely  cut  off  from  sunlight,  but  they 
derive  this  power  from  organic  matter  or  cells  that  have  been  pre- 
viously formed  by  the  action  of  sunshine  upon  the  plant  on  which 
^-the  parasite  itself  feeds. 

Similarly  certain  bulbous  plants  will  flower  and  mature  in  dark- 
ness, but  in  doing  so  the  bulb  itself  is  wholly  consumed  and  dies ;  the 
plant  lives  on  organic  matter  that  was  elaborated  and  stored  up  by 
its  parent  and  predecessor  in  preceding  years  Avhen  it  had  sunshine 
to  do  the  work  for  it.  If  a  new  bulb  is  to  be  formed  as  a  basis  for  the 
flowering  of  the  next  year  then  the  present  bulb  and  plant  must  be 
allowed  the  necessary  sunlight. 

Similarly  the  seeds  of  the  annuals  sprout  and  nourish  their  little 
plants  out  of  their  own  substance  while  still  beneath  the  surface  of 
the  earth,  but  when  the  shoots  reach  up  to  th^  sunshine  this  furnishes 
the  energy  needed  for  the  work  of  assimilation  and  the  plant  begins 
to  live  on  the  soil  and  the  air.  The  roots  can  only  send  up  to  the 
leaf  an  inorganic  sap  with  possibly  here  and  there  an  organic  cell 
scattered  through  it  which  has  penetrated  into  the  roots,  as  it  were, 
by  accident;  it  is  the  sunshine  that  sets  these  organic  cells  into 
activity,  causing  them  to  grow  and  to  multiply. 

If  a  plant  in  vigorous  growth  is  removed  from  sunshine  to  darkness 
it  draws  upon  its  own  reserves  and  lives  upon  itself  as  long  as  pos- 
sible. In  darkness  the  plant  transforms  the  organic  products  that 
are  at  its  disposition,  but  it  can  not  manufacture  any  new  ones.  On 
the  contrary,  it  consumes  itself  and  its  dry  weight  steadily  diminishes. 
The  experiments  of  Boussingault  on  seeds,  those  of  Sachs  on  plants 
and  seeds,  those  of  Pagnoul  on  the  beet,  and  of  Macagno  on  the  grape- 
vine all  confirm  this  general  principle.  The  observations  of  the 
latter  show  that  as  between  two  sets  of  vines,  one  exposed  to  the  sun 
and  the  other  covered  with  a  dark  cloth,  the  growth  of  the  latter,  as 
measured  by  the  amount  of  solid  and  gaseous  material,  was  not  10  per 
cent  of  the  growth  of  the  vine  in  the  sunshine.  Other  vines  under  a 
white  cloth  showed  a  growth  of  80  per  cent,  thus  apparently  proving 
that  the  differences  were  not  due  to  anything  else  except  sunshine. 

Pagnoul  experimented  upon  sugar  beets,  some  of  which  were  cov- 
ered by  glass  that  had  l)een  blackened  on  the  inside :  this  coating  of 
lampblack  is  ordinarily  said  to  absorb  heat,  but  it  would  be  more 
proper  to  say  that  it  transforms  all  the  short  waves  of  the  sunshine 
into  long  waves  so  that  the  plants  beneath  it  receive  neither  ultra- 
violet nor  visual  rays,  but  only  the  ultra-red,  or  long,  heat  weves. 
Therefore  beneath  the  black  glass  the  temperature  Avas  somewhat 
warmer  than  beneath  the  transparent  glass  and  the  latter  wanner 


than  the  free  air.  The  ivsults  of  analysis  at  the  end  of  the  oxperi- 
nients  showed  tliat  nncUn-  the  transparent  o^hiss  tlie  weight  of  the  roots 
was  the  same  as  in  the  free  air,  but  the  weight  of  the  leaf  was  much 
more,  the  weight  yf  the  sugar  much  less,  and  the  weight  of  the  nitrous 
salts  much  greater.  Under  the  black  glass  the  weight  of  the  roots 
was  4  per  cent  of  that  in  the  free  air,  and  the  weight  of  the  leaves 
was  about  25  per  cent,  the  weight  of  sugar  2  per  cent,  and  the  weight 
of  the  salts  8  per  cent,  thus  demonstrating  an  almost  complete  stop- 
page of  the  vital  processes. 

Evidently  the  action  of  these  artificial  coverings  on  the  experi- 
mental plants  is  perfectly  analogous  to  the  action  of  cloud  and  fog  in 
nature. 

It  is  commonly  said  that  on  the  seacoast  the  action  of  the  salt  brine 
blown  by  the  wind  up  over  the  land  is  to  stunt  or  prevent  vegetable 
growth,  but  the  same  effect  must  be  produced  by  the  absence  of  sun- 
light in  those  regions  where  fog  and  cloud  prevail. 

INFLUENCE    OF   SHADE   ON   DEVELOPMENT. 

According  to  Marchand  (1875,  p.  130),  the  influence  of  a  dimi- 
nution of  sunlight  on  the  development  of  the  plant  is  apparent  in  the 
relative  growth  of  plants  on  sunny  and  cloudy  days  or  in  sunny  and 
shady  places,  but  the  matter  was  brought  to  exact  measurement  by 
Hellriegel.     His  experiments  on  barley  gave  him  these  results: 

Weifjht  of  hancst  of  hurley. 


Plants  raised- 


In  the  open  air 

In  a  greenhouse  in  direct  sunshine  . . 
In  a  greenhouse  in  diffuse  light  only 


unds. 

Pounds. 

11.44 

10.10 

10.99 

11.19 

6.72 

2.86 

6.32 

3.26 

3.40 

2.59 

"We  see  here  that  plants  living  in  the  greenhouse,  receiving  sun- 
light that  has  traversed  the  glass,  have  experienced  a  considerable 
diminution  in  their  development  as  compared  with  those  in  the  free 
air  which  experienced  the  full  chemical  force  of  the  sunshine.  The 
plants  living  under  glass  and  in  the  diffuse  light  developed  only  a 
small  quantity  of  stalk  and  did  not  perfect  the  seed  at  all. 


INFLUENCE   OF   LONG   AND   SHORT   WAVES   OF   LIGHT. 

Vochting  (1887)  investigated  the  formation  of  tubers  as  influenced 
especially  by  sunlight.  Sachs  had  maintained  that  the  germination 
was  entirely  prevented,  or  at  least  went  on  very  slowly,  if  sunlight, 


80 

i.  e.,  short  waves,  had  access  to  the  tubers.  Vochting  finds  that, 
although  the  light  does  delay  the  growth  and  diminishes  the  distance 
between  the  tubers,  still  the  supply  of  water  is  the  important  factor. 
(Wollny,  X,  p.  230.) 

Sachs  (1887),  as  the  result  of  experiments  on  flie  efiect  of  ultra- 
violet radiation  upon  the  formation  of  buds,  states  that  these  rays 
exert  on  the  green  leaves  (in  addition  to  the  assimilation  produced 
by  the  yellow  and  neighboring  rays)  still  another  effect  that  consists 
in  the  development  of  particles  that  contribute  to  the  formation  of 
blossoms.  These  bud-forming  particles  move  from  the  leaves  into 
those  parts  of  the  plant  where  they  are  to  bring  about  their  own 
development  into  buds.  We  therefore  now  know  of  three  different 
portions  of  the  solar  spectrum  having  very  different  physiological 
influences :  The  yellow  and  neighboring  rays,  which  bring  about  the 
transformation  of  carbonic  acid  or  the  formation  of  starch ;  the  blue 
and  visible  violet,  that  act  as  stimulants  to  motion;  the  ultraviolet 
rays,  that  produce  in  the  gi'een  leaves  the  material  for  the  formation 
of  buds.     (Wollny,  X,  p.  230.) 

INFLUENCE    OF    DRYNESS    AND    SUNLIGHT    ON    DEVELOPMENT 
OF   TUBERS. 

In  the  climate  of  Germany  the  flowering  of  different  varieties  of 
potatoes  is  very  much  restricted.  Only  a  small  number  of  varieties 
flower  regularly  and  bear  fruit,  whereas  in  Chile  the  plant  flowers 
abundantly,  but  the  tubers  are  small;  in  other  words,  in  the  Tem- 
perate Zone  the  formation  of  tubers  is  favored  at  the  expense  of 
fertilization ;  the  energy  of  the  one  process  increases  while  the  other 
diminishes. 

Knight  and  Langenthal  have  found  that  by  detaching  the  young 
tubers  they  increase  the  blooming,  and  on  the  other  hand,  by  cutting 
off  the  flowers  the}'  increase  the  development  of  the  tubers,  thereby 
largely  increasing  the  harvest.  Wollny,  in  1886,  experimented  on 
four  plats,  each  for  many  varieties  of  potatoes.  He  found  that  cut- 
ting off  the  flowers  increased  the  crop  of  tubers  as  to  number, 
size,  and  weight,  but  that  something  depended  upon  the  time  of 
cropping  the  flowers,  which  is  best  done  a  considerable  time  before 
they  arrive  at  maturity.  It  seems  probable  that  dryness  and  sun- 
light stimulate  the  formation  of  flowers,  but  humidity  and  cloudi- 
ness, at  least  up  to  a  certain  limit,  stimulate  the  formation  of  tubers. 
This  harmonizes  with  some  recent  results  obtained  by  Sachs,  who  has 
shown  that  the  ultraviolet  rays  stimulate  the  flowering.  (Agr.  Sci., 
Vol.  II,  p.  273.) 


Chapter  V. 

THE  METHODS  OF  MEASURING  DIRECT  OR  DIFFUSE  SUNSHINE 
AS  TO  INTENSITY  OR  DURATION. 

Sunshine  may  be  measured  as  to  its  quality  or  wave  length,  its 
intensity,  or  its  duration.  The  methods  used  in  measuring  either  of ' 
these  must  be  understood  in  order  to  intelligently  compare  the  pub- 
lished observations  with  phsenological  phenomena.  The  following 
section  considers  some  of  the  methods  of  measuring  or  registering  the 
duration  or  intensity  of  sunshine,  or  the  intensity  of  the  skylight, 
at  least  in  so  far  as  these  have  been  used  in  agricultural  studies. 

THEORETICAL  RELATION  OF  DIRECT  AND  DIFFUSED  SUNSHINE. 

The  relative  intensity  of  any  radiation  may  be  measured  by  its  heat 
or  light  or  chemical  effect.  The  insolation  received  by  a  horizontal 
surface,  whether  directly  from  the  sun  or  diffusely  from  the  sky,  is 
subject  in  a  general  way  to  calculation,  but  the  irregularities  intro- 
duced by  haze  and  clouds  can  not  be  so  calculated  and  must  be  ob- 
served daily.  The  following  table  gives,  for  a  clear  blue  sky,  the 
values  obtained  by  Clausius  for  the  radiation  (S)  that  falls  upon  a 
horizontal  surface  directly  from  the  sun,  and  in  the  third  column 
the  diffuse  radiation  (C)  that  falls  from  the  whole  sky  upon  that 
same  surface;  the  total  radiation  (S-j-C)  is  the  sum  of  these  two. 
If,  however,  the  surface  is  normal  to  the  sunlight,  instead  of  hori- 
zontal, it  receives  the  quantity  in  the  fifth  column  (I)  directly  from 
the  sun,  and  (c)  which  is  less  than  the  quantity  (C)  from  the  sky, 
depending  upon  the  altitude  of  the  sun,  the  total  being,  as  before,  the 
sum  of  these  (I-|-c).  The  study  of  these  columns  shows  us  the 
maximum  and  minimum  amounts  of  sunshine  that  may  fall  upon  a 
given  leaf  surface,  since  a  leaf  will  in  general  be  in  some  position  to 
receive  the  full  sunshine  normally  to  its  surface,  Avhile  others  will  be 
horizontal,  or  vertical,  or  in  the  shade,  and  receive  only  a  part  of  the 
diffuse  light  from  the  sky. 

It  is  assumed  by  Radau,  in  his  actinometry  (1877),  as  also  by 
Marie-Davy,  that  the  bright  and  black  bulb  thermometers  in  vacuo,  or 
the  so-called  *'  conjugate  thermometers."  give  us  the  total  radiation 
(C-f  I)  as  for  the  horizontal  surface,  and  that  this  is  the  quantity  in 
which  vegetation  is  interested. 

2607—05  M 6  (81) 


82 


Relat 

vc  (luantities  of  direct  and  diffii 

■^cd  sunshine. 

Sun's  al- 
titude. 

Horizontal  surface. 

Normal  surface.           1 

Sun(S). 

Sky(C). 

Total 

(S-t-C). 

Sun  (I). 

Sky(e). 

Total    ! 
(I+c). 

10 

0.03 

0.07 

0.10 

0.19 

0.04 

0.23 

15 

.09 

.09 

.18 

.33 

.05 

.38 

M 

.15 

.11 

.26 

.43 

.06 

.49 

25 

.21 

.13 

.34 

.51 

.08 

.59 

30 

.28 

.14 

.42 

..56 

.10 

.66 

35 

.35 

.15 

..50 

.61 

.11 

.72 

40 

.41 

.16 

.57 

.64 

.12 

.76 

50 

.53 

.17 

.69 

.69 

.14 

.83 

60 

.62 

.18 

.80 

.72 

.16 

.88 

70 

.69 

.18 

.87 

.74 

.17 

.91 

hO 

.74 

.18 

.92 

.75 

.18 

.93 

90 

.75 

.19 

.94 

.75 

.19 

.94 

TOTAL  INSOLATION,  DIRECT  AND  DIFFUSED. 

The  value  of  the  intensity  of  the  direct  solar  rays  incident  nor- 
mally to  any  unit  surface,  as  determined  by  the  absolute  actinometers 
of  Pouillet,  Violle,  and  others,  is  not  so  applicable  to  the  study  of 
the  growth  of  plants  as  is  the  sum  of  the  radiation  from  the  sky  and 
other  surroundings  of  the  plant,  added  to  the  direct  solar  radiation. 

Comparative  measures  made  in  1866  by  Roscoe,  at  Manchester; 
Baker,  at  Kew ;  Wollkoff,  on  the  summit  of  Koenigstuhl,  near  Hei- 
delberg (altitude,  550  meters),  and  Thorpe,  at  Para,  have  given  the 
following  values  of  relative  intensity  of  radiation  at  certain  moments 
when  the  sun's  altitude  above  the  horizon  was  sensibly  the  same  at  all 
the  stations.     (See  Marie  Davy,  1882.) 

Relative  intensity  of  radiation  for  equal  altitudes  of  the  sun. 


r.atitudp     ^^°™        ^^'o™ 
latitude,      g^^j^  gjjy 


Manchester - 

Kew 

Koenigstuhl 

Paris 

Para 


N.53.5 
N.51.5 
N.49.4 

N.48.8 
S.00.5 


0.043 
.150 


0. 140 
.162 
.174 
.501 
.136 


S^- +     Sun/Sky 


0.183 
.312 
.437 


0.31 
0.93 
1.51 
0.44 
1.00 


At  Manchester  and  at  Paris  the  light  that  comes  from  the  sky  is 
more  than  double  that  which  comes  directly  from  the  sun.  AAHien  the 
sun  is  hidden  by  clouds,  or  even  partially  veiled,  it  is  the  radiation 
from  the  sky  that  is  of  the  most  importance  to  agriculture,  and  in 
any  case  this  radiation  is  far  from  being  negligible. 

The  Arago-Davy  actinometer  (believed  to  have  been  invented  by 
Arago  before  1844,  but  improved  by  Marie-Davy  and  used  at  the 


83 

observatory  of  Montsouris  ever  since  1873)  is  an  apparatus  that  is 
intended  to  determine  the  total  solar  plus  sky  radiation  that  is  needed 
in  agricultural  physics.  A  theory  of  the  action  of  this  instrument 
was  devised  by  Marie-Davy,  but  the  proper  method  of  calculating  its 
results  was  first  developed  with  exactness  by  Ferrel,  in  Professional 
Papers  of  the  Signal  Service,  No.  XIII  (1884),  and  subsequently  in 
his  Recent  Advances  in  Meteorology  (Annual  Report,  Chief  Signal 
Officer,  p.  373).     His  formula  will  be  given  on  page  88. 

The  Arago-Davy  actinometer  is  composed  of  two  mercurial  ther- 
mometers with  very  fine  tubes,  and  having  spherical  reservoirs  of 
equal  dimensions,  one  colorless  and  the  other  covered  with  lamp- 
black. In  the  empty  space  above  the  mercury  in  the  thermometer 
tubes  there  is  a  small  quantity  of  hydrogen  or  other  inert  gas.  The 
small  quantity  of  gas  left  in  the  tubes  of  these  thermometers  has  no 
other  object  than  to  prevent  the  mercury  from  falling  in  the  tube  by 
the  force  of  gravity  when  the  bulb  is  turned  upward  toward  the  sky. 
Each  thermometer  is  inclosed  in  a  larger  glass  tube  or  cylinder,  ter- 
minated by  a  spherical  enlargement,  in  the  center  of  which  is  placed 
the  center  of  the  bulb  of  the  thermometer.  This  tube  and  enlarge- 
ment constitute  the  inclosure,  and  it  is  exhausted  of  air  as  perfectly 
as  possible.  The  immovability  of  the  thermometer,  relative  to  the 
walls  of  its  inclosure,  is  assured  by  a  soldering  at  the  upper  extremity 
of  the  tube  and,  at  the  opposite  end  toward  the  reservoir,  by  two  rings 
of  cork  held  by  friction  between  the  interior  tube  and  exterior  cylinder. 
These  thermometers,  with  their  respective  glass  inclosures,  are  turned 
up  with  their  bulbs  toward  the  sky,  and  by  means  of  double  clamps 
fixed  parallel  to  two  metallic  rods,  arranged  in  the  form  of  a  V  and 
turned,  the  one  toward  the  east,  the  other  toward  the  west.  These 
metallic  rods  make  an  angle  Avith  each  other  of  60° — that  is  to  say,  of 
30°  with  the  vertical — and  are  fastened  to  a  support  of  wood  or  iron, 
1.20  or  1.30  meters  in  height  above  the  earth.  The  support  is  solidly 
planted  in  the  ground  in  an  open  place,  remote  from  buildings,  plants, 
or  any  other  obstacle  capable  of  intercepting  the  direct  radiation  of 
the  sun.  The  two  thermometers,  the  envelopes  of  which  are  exposed 
near  each  other,  have  necessarily  the  same  temperature  and  mark  the 
same  degree  as  long  as  they  remain  in  perfect  darkness;  but  hardly 
does  day  begin  to  break  than  the  thermometer  with  the  black  bulb 
marks  a  higher  temperature  than  that  with  a  plain  glass  bulb.  The 
difi'erence  in  temperature  of  these  two  thermometers  gives  the  ''  acti- 
nometric  degree  ''  for  the  moment  of  observation ;  that  is  to  say,  it 
serves  to  measure  the  intensity  with  which  the  radiation  strikes  the 
two  thermometers  and  is  absorbed  by  the  black  bulb;  consequently,  at 
least  approximately,  it  serves  to  measure  the  intensity  with  which  the 


84 

radiation  strikes  the  ground  and  neighboring  plants  and  accumuLates 
therein. 

After  three  years'  use  of  this  instrument,  Marie-Davy  selected  the 
observations  made  on  the  days  of  perfect  clearness  of  the  sky,  of 
which  there  were  only  nine,  since  many  days  that  would  be  called 
cloudless  showed  slight  traces  of  haze.  For  these  days  the  difference 
between  the  readings  of  the  black  bulb  and  bright  bulb  is  represented 
closely  by  the  exponential  formula 

t  —  f  =  17°  X  0.875« 
where  the  exponent  e  represents  the  thickness  of  the  layer  of  air 
through  which  the  sun's  rays  must  pass  in  order  to  reach  the  observer ; 
this  thickness,  of  course,  increases  as  the  sun  approaches  the  horizon, 
being  unity  for  the  zenith  and  10  for  an  altitude  of  2°,  as  shown  by 
the  following  table,  which  is  an  abstract  of  that  used  by  Marie-Davy 
in  his  computations : 

Thickness  of  the  hiijer  of  air  traversed  liy  the  solar  rays,  as  computed  hy  Luin- 
iert's  formula. 


Altitude 

Thick- 

Altitude 

Thick- 

of sun. 

ness,  e. 

of  sun. 

ness,  e. 

0 

12.69 

°25 

2.30 

2 

10.20 

30 

1.96 

4 

8.28 

40 

1.54 

6 

6.83 

50 

1.30 

8 

5.75 

60 

1.15 

10 

4.92 

70 

1.06 

15 

3.58 

80 

1.02 

20 

2.80 

1           90 

1.00 

As  the  formula  of  Lambert  has  been  chosen  by  Marie-Davy  for  use 
in  connection  with  his  form  of  actinometer,  we  have  therefore  given 
its  results  in  the  preceding  table ;  but  as  the  more  accurate  formula, 
as  given  by  Laplace,  has  been  applied  to  other  forms  of  actinometers, 
and  may  even  be  preferred  for  the  Arago-Davy  instrument,  I  there- 
fore give  a  table  showing  the  thickness  by  the  formula  of  Laplace  as 
used  by  VioUe  and  the  value  of  the  intensity  (I)  as  given  by  Violle. 


85 


Thichncss  of  the  layer  of  air  trarrrscd  hii  the  ilireci  solar  rai/ff  as  coiiipiitnl  lijf 
Laphiec'ft  formula,  and  the  vorrvsjHtndhin  raliir  of  I.  the  absolute  inhasit n  of 
direet  sunshine  in  calories  per  minute  /ler  stjuarc  ci-iiliiuctcr  irhieli  fall  nor- 
mally on  any  surface  through  the  purest  air.  as  i/inii  Ini  1  o///r. 


Altitude 
of  sun. 

Thickness 
(e),  La- 
place 
formula. 

Intensity- 
CD  of  di- 
rect sun- 
shine. 
Violle. 

Altitude 
of  sun. 

Thickness 
(e),  La- 
place 
formula. 

rect  sun- 
shine, 
Violle. 

0 

35.5(t 

0  359 

:50 

1.995 

2. 275 

2 

18.  iK) 

0.896 

1         :« 

1.740 

2.306 

4 

12.20 

1.293 

40 

1.555 

2.831 

6 

8.60 

1.540 

45 

1.420 

2.349 

8 

6.85 

1.730 

50 

1.305 

2.364 

10 

5.70 

1.868 

60 

i.l55 

2.383 

15 

3.81 

2.059 

70 

1.065 

2.395 

20 

2.90 

2.164 

80 

1.016 

2.401 

25 

2.425 

2.229 

90 

1 

1.000 

2.40? 

Observation  shows  that  no  two  such  Arago-Davy  actinometers 
placed  side  by  side  will  give  exactly  the  same  results;  therefore  the 
rule  has  been  adopted  of  comparing  all  instruments  with  the  stand- 
ard kept  at  INIont.souris,  and  a  standardizing  factor  is  thereby  obtained 
by  Avhich  the  observed  difference  between  the  bright  and  black  bulb 
of  any  pair  is  to  be  multiplied  in  order  to  reduce  it  to  a  common 
standard. 

In  addition  to  the  standardizing  factor  of  the  preceding  paragraph, 
Marie-Davy  has  also  introduced  the  conception  of  an  ideal  standard 
actinometer,  graduated  in  such  a  way  that  the  first  factor,  17°  in 
the  above-given  formula  as  expressed  in  centigrade  degrees,  shall 
be  represented  by  100  "  actinometric  degrees  '*  in  his  ideal  in.stru- 
ment ;  that  is  to  say,  all  the  differences  (t-t^)  observed  with  any 
actinometer,  after  being  multiplied  by  the  standardizing  factor,  have 
still  to  be  multiplied  by  the  factor  5. 88  in  order  to  convert  them  into 
ideal  actinometric  degrees.  For  convenience  both  these  factors  may 
be  replaced  by  one,  and  in  this  way  the  instrument  and  Mario-Davy's 
methods  have  been  extensively  employed  in  studying  the  relation 
between  sunshine  and  crops. 

In  such  study  Marie-Davy  and  his  pupils  take  the  "  sum  of  the 
total  number  of  actinometric  degrees  "  as  the  datum  for  comparison 
with  crop  reports,  instead  of  the  sum  of  the  temperatures  of  the  air 
observed  in  the  shade,  or  the  sum  of  the  soil  temperatures  as  used 
by  other  investigators.  If  we  divide  the  actinometric  degrees  given 
in  any  case  by  the  factor  5.88  we  shall  obtain  the  excess  of  the  black 
bulb  over  the  bright  bulb  as  originally  observed  in  centigrade 
degrees.  P^rom  this  we  can  obtain  the  true  rehitive  (|uantities  of  solar 
radiation  by  a  modification  of  the  nielhod  given  by  Ferrel  (pp.  -H-HO 


86 

of  his  above-quoted  work  of  1884,  on  the  Temperature  of  the  Atmos- 
phere and  the  Earth's  Surface). 

Until  such  a  method  lias  been  i^erfected  (see  an  article  l^y  Ferrel 
in  Am.  Jour.  Sci.,  May,  1891,  3,  Vol.  XLI,  p.  378)  we  will  for  the 
present  quote  the  actinometric  degrees  and  other  figures  as  ordinarily 
published  by  Marie-Davy  and  others;  but  the  reader  must  bear  in 
mind  that  these  results  from  the  hypothesis  assumed  by  Marie-Davy 
that  the  observed  ditference  between  the  bright  and  black  bulb  is  pro- 
portional to  and  therefore  a  proper  measure  of  the  intensity  of  the 
radiant  heat  that  falls  upon  these  thermometers;  a  hypothesis  which, 
as  Ferrel  has  shown,  is  far  from  being  true.  The  error  of  this  hypoth- 
esis is  of  such  a  nature  that  for  a  given  difference  or  a  given 
actinometric  degree  the  true  intensity  of  radiation  is  greater  at  high 
temperatures  than  at  low  temperatures.  Probably  the  recorded  acti- 
nometric degrees  therefore  give  a  rather  low  value  for  the  solar  and 
sky  radiation  during  the  hottest  portions  of  summer  days. 

The  accompanying  table,  as  published  by  Marie-Davy,  shows  the 
actinometric  degrees  calculated  for  the  clearest  of  skies  at  Paris  at 
noon  of  each  day.  They  are  computed  according  to  the  preceding 
formula,  viz,  A= actinometric  degTees=  100X0.875*";  in  which,  as 
before  said,  the  coefficient,  0.875,  represents  the  penetration  or  the 
total  heat  which  penetrates  to  the  observer,  both  from  the  sun 
and  the  surrounding  sky,  and  includes  even  that  small  part  that  is 
directly  reflected  from  the  surrounding  grassy  lawn  or  other  surface 
when  the  sun  is  in  the  zenith;  if  there  were  no  atmosphere  pres- 
ent the  total  amount  received  would  be  100.  It  will  be  less  confusing 
if  the  reader  will  consider  these  so-called  "  actinometric  degrees  "' 
as  "■  percentages  of  what  would  be  received  in  the  absence  of  the 
atmosphere." 

Columns  5,  (>,  and  7  of  our  table  give  the  mean  value  of  the  five 
actinometric  percentages  observed  on  the  clearest  days  at  6  a.  m., 
9  a.  m.,  noon,  3  p.  m.,  and  G  p.  m. ;  in  the  absence  of  actual  observa- 
tions these  means  may  be  employed  in  our  study,  provided  we  make 
a  proper  allowance  for  the  influence  of  hazy  and  cloudy  skies.  It  is, 
however,  always  desirable  that  the  actual  observation  of  the  acti- 
nometer  should  be  available,  and  witli  it  should  l)e  associated  a 
simultaneous  record  of  the  cloud  or  haze  as  given  by  the  sunshine 
recorder. 


87 


Solar  radititiun  plus  shi/  radiutioii  c.iprrsscd  iis  iictiiinnirlric  ixrcciitot/cs  dccord- 
iii)/  to  Marir-lhtrii.  calculated  for  sJclcs  as  clear  as  at  M(iiil:<(iuris  and  for 
various  latitudes. 


January  1 . . . 
January  11 . . 
January  21  . . 
February  I.. 
February  11. 
February  21. 

Mareh  1 

Mar.  h  11  .... 

March  21 

April  1 - 

April  11 

April  21 

Mayl 

May  11 

May  21 

June  1 

June  11 

June  21 

Julyl 


July  11.. 

July21 

August  1 

August  11 

August  21 

September  ]  . 
September  1  i 
September  21 

October  1 

October  11 

October  21-... 
November  1.. 
November  11. 
November  21. 
December  1 . . 
December  11  . 
December  21  . 
Januarj'  1 


Noon  observation, 
latitude— 


jMeau  of  5  observations 
I      daily,  latitude— 


42°  N.    46°  N.  !  50°N.    42°  N. 


69.9 
71.2 
72.9 

75.1 
77.0 
78.9 
80.1 


84.6 
85.2 


86.5 
86.5 
86.3 
86.0 


84.5 
83.8 
82.8 
81.7 
80.3 
78.7 
76.6 
74.7 
72.7 
71.0 
69.8 
69.4 
09.9 


65.1 
66.7 
69.0 
71.8 
74.4 
76.7 
78.4 
80.1 
81.6 
82.9 
83.8 
84.6 
85.0 
85.5 
85.8 
86.0 
86.2 
86.2 
86.2 

85.8 
85.5 
85.1 
84.5 
8:3.7 
82.8 
81.6 
80.2 
78.5 
76.4 
73.9 
71.4 
68.8 
66.5 
65.0 
64.4 
05. 1 


38.0 
39.0 
40.3 
42.0 
43.5 
45.0 
46.2 
49.6 
55.7 
60.7 
65.0 
68.4 
71.0 
73.0 
74.3 
75.3 
75.9 
76.0 
75.8 
75.3 
74.4 
73.0 
71.0 
68.4 
64.7 
60.5 
55.9 
49.4 
46.1 
44.8 
43.3 
41.3 
40.2 
38.8 
37.9 
37.6 
38. 0 


37.7 
39.9 
41.8 
4:3.6 
44.9 
48.6 
55.0 
60.6 
65.1 
68.7 
71.5 
7:14 
74.9 
75.9 
76.3 
76.6 
76.3 
75.9 
75.0 
73.5 
71.5 
68.8 
64.8 
60.2 
55.3 
48.5 
45.0 
43.4 
41.5 
39.0 
:37.5 
.35.7 
:34.5 

:34.l 

:34.6 


31.9 
:!4.2 
37.0 

41.9 
4:5.7 
47.5 
54.2 
60.2 

a-).i 

Oh.  9 
71.. s 
7:1 8 
75.3 
76.3 
76.8 
77.0 
76.8 
76.3 
75.4 
73.8 
71.9 
69.0 
64.8 
59. 9 
.54.5 
47.5 
4:3.6 
41.6 
:i9. 1 
;36.0 
:34.l) 
31.7 

;«).i 
;M.5 


THEORETICAL  FORMXTLiE  FOR  ACTINOMETER. 

In  reply  to  some  criticisms  of  Violle,  Marie-Davy   (1880,  p.  245) 
gives  the  only  statement  that  I  have  seen  of  his  theory  or  explanation, 
of  the  working  of  his  conjugate  thermometers.     It  is  about  as  fol- 
lows: Let — 

a  be  the  absorbing  power  of  the  bright  bulb. 

/  the  absorbing  power  of  the  black  bulb. 

r  a  numerical  coefficient  for  converting  degrees  of  temperature  into 
a  quantity  of  heat. 


88 

q  the  quantity  of  radiation  or  heat  falling  per  minute  on  the 
black  bulb  and  also  on  the  bright  bulb. 

a  q  the  quantity  of  radiation  absorbed  by  the  bright  bulb. 

I  q  the  quantity  of  radiation  absorbed  by  the  black  bulb. 

e  the  emissive  power  of  the  black  bulb. 

e'  the  emissive  power  of  the  bright  bulb. 

t  and  t'  the  temperatures  of  the  black  and  bright  bulbs,  respectively, 
when  they  come  to  the  stationarj^  temperature  that  indicates  equilib- 
rium between  absorption  and  emission. 

T  the  temperature  of  the  glass  envelopes  within  which  the  ther- 
mometers are  inclosed  iu  a  space  that  is  an  approximate  vacuum. 

On  the  assumption  of  the  Newtonian  law  of  radiation,  viz,  that 
the  quantity  of  heat  emitted  is  proportional  to  the  excess  of  tem- 
perature, we  have  the  following  relations : 

qz^ce    {t —T) 
aq—ee'  {f — T) 

From  these  expressions  we  can,  by  elimination  of  7",  find  the  follow- 
ing expression  for  q — that  is  to  say,  the  quantity  of  solar  radiation 
per  unit  of  time  that  is  at  that  moment  falling  on  the  two  thermome- 
ters, at  least  in  so  far  as  this  radiation  is  capable  of  being  trans- 
formed into  heat  by  absorption  into  the  bulbs  of  the  thermometers : 

Marie-Davy,  in  the  absence  of  exact  knowledge  of  these  coeiRcients 
<2,  c,  <?,  e%  prefers  to  attempt  to  determine  only  relative  measures  of 
the  intensity  of  radiation.     He  therefore  assumes  that  the  expression 

is  equal  to  5.88  units,  and  the  values  for  q  thus  obtained  he 

e  —a  e         ^  '  ^ 

calls  actinometric  degrees,  since  on  the  very  clearest  days  in  Paris 
they  accord  well  with  the  assumption  that  the  so-called  solar  constant 
of  radiation  is  100  actinometric  degrees,  and  that  the  coefficient  of 
transmission  of  sunshine  through  the  atmosphere  is  0.875, 

Ferrel  (1884),  in  his  memoir  on  the  temperature  of  the  atmosphere 
(p.  41),  has  improved  upon  Marie-Davy's  theory,  in  that  he  has 
applied  to  the  conjugate  thermometers  the  law  of  radiation,  estab- 
lished by  Dulong  and  Petit  in  1817,  which  is  applicable  to  a  much 
larger  range  of  temperatures  than  the  Newtonian  law  adopted  by 
Marie-Davy.     Ferrel's  formula  may  be  written : 

(^=4.584  k  m"  {m*-t'—l) 

where  the  notation  is  the  same  as  before,  except  that  m,  is  the  num- 
ber 1.0077,  as  determined  by  Dulong  and  Petit  and  A^  is  a  factor  that 
varies  with  the  quality  of  the  bright  bulb,  whose  absolute  value  is 


89 

usually  g:reater  than  /,  but  whoso  relative  value  may  by  preference 
be  determined  by  referring  each  pair  of  conjugate  thermometers  to 
an  adopted  standard  pair.  Ferrel's  formula  is  especially  devised 
for  thermometers  having  spherical  bulbs,  measures  made  by  it  at  high 
and  low  temperatures  give  results  that  are  comparable  with  each 
other;  for  absolute  results  the  numerical  coefficients  may  need  some 
modification,  but  as  it  stands  it  gives  the  values  of  q  approximately 
in  calories  per  minute  per  square  centimeter. 

Omitting  for  the  present  the  factor  /.'  in  FerreFs  formula,  which 
must  be  specially  applied  for  each  thermometer,  we  have  the  values 
of  q  in  calories  as  given  in  the  following  table  (see  Ferrel,  p.  37), 
which  also  presents  the  corresponding  values  given  by  the  formula  of 
Marie-Davy  in  actinometric  degrees.  In  a  critical  study  of  observa- 
tions reduced  by  these  two  methods  we  have  to  recall  that  Marie- 
Davy's  actinometric  degrees  are  really  fractions  of  a  calorie,  or  units 
of  heat  so  small  that  100  of  them  are  equivalent  to  the  absolute  radia- 
tion of  the  sun  received  at  the  outside  of  an  atmosphere  whose  coeffi- 
cient of  transmission  is  0.875;  wdiereas  Ferrel's  calories  have  been 
adopted  without  predicating  anything  as  to  the  solar  radiation  or 
atmospheric  absorption,  concerning  wdiich  his  observations  show  that 
the  solar  radiation  constant  is  between  2  and  2.25  calories  per  minute 
per  square  centimeter  and  the  atmospheric  coefficient  of  transmission 
to  be  used  with  the  conjugate  bulbs  is  0.72. 

Solar  radiation  deduced  from  oh  ser  vat  ions  loith  the  conjugate  thennoiiteters. 


t-t'. 

Marie 
Davy, 
actino- 
metric 

de- 
gree!. 

Ferrel 

calorie 

5  per  minute  per  square  centimeter  for  the  respective 
bright-bulb  temperatures. 

-10° 

-5° 

O- 

-fS" 

+10° 

+  15° 

+20° 

+25° 

+30° 

°c. 

5 

2tJ.4 

0.166 

0.172 

0.179 

0.186 

0.194 

0.201 

0.209 

0.217 

0.226 

10—. 

58.8 

.339 

.352 

.366 

.380 

.395 

.410 

.426 

.443 

.460 

15.... 

88.2 

.518 

.538 

.559 

.581 

.604 

.627 

.652 

.678 

.704 

20.-.. 

117.6 

.705 

.7:^2 

.7(51 

.791 

.822 

.854 

.887 

.922 

.958 

25.... 

147.0 

.898 

.aas 

.969 

1.007 

1.047 

1.087 

1.131 

1.175 

1.220 

30.... 

176.4 

1.099 

1.142 

1.187 

1.234 

1.282 

1.333 

i..3a5 

1.4:» 

1.495 

35.... 

205.8 

1.309 

1.360 

1.413 

1.469 

1.526 

1.585 

1.647 

1.712 

1.778 

40... 

235.2 

1.525 

1.585 

1.646 

1.711 

1.778 

1.848 

1.920 

1.995 

2.073 

45.... 

264.6 

1.750 

1.820 

1.891 

1.964 

2.042 

2.121 

2.204 

2.291 

2.380 

INTENSITY  AND  DURATION  OF  SUNSHINE  AT  MONTSOURIS. 

In  order  to  have  at  hand  data  that  will  enable  one  to  approximately 
infer  some  of  the  relations  between  the  temperature  of  the  air  and 
of  the  soil  and  of  the  solar  radiation,  one  may  consult  the  tables  for 
the  observations  at  Montsouris,  given  by  Marie-Davy  in  his  Annuaire 

for  1887. 


90 

As  those  who  can  not  make  use  of  the  actinometrie  degrees  deduced 
by  Marie-Davy  from  his  observations  of  his  conjugate  bulbs  will 
necessarily  have  to  use  either  the  simple  observations  of  clear  sky 
and  cloudy  sky,  as  given  by  the  sunshine  recorder,  or  the  equivalent 
personal  observations  of  the  clouds,  I  give  the  following  tables,  which 
show  how  nearly  parallel  these  two  phenomena  may  be.  Evidently 
in  our  study  of  the  influence  of  insolation  on  crops  in  America  from 
year  to  year  w^e  may  use  the  sunshine  recorder  or  the  ratio  between 
the  actual  and  the  maximum  possible  duration  of  sunshine  without 
much  error,  at  least  in  the  growing  season. 

Mean  of  fire  daily  actinometrie  observations  at  Montsouris,  expressed  in  Mari/'- 
Davy's  actinometrie  degrees  or  percentages  of  maximum  possible  intensity. 


Month. 


1875.      1876.      18' 


1883. 

1884. 

36.8 

34.5 

45.9 

46.3 

45.3 

43.2 

48.2 

43.4 

39.0 

36.2 

30.5 

30.8 

39.9 

39.1 

April 

May 

June -.  -.. 

July 

August 

September 

Average 


44.1  40.1 
47.7 

46.0  48.8 

47.3  52.1 

39.9  42.0 

35.7  30.9 


43.5       43.5 


36.3 
38.7 
54.5 
48.6 
43.2 
31.4 


42.1 


35.4 
41.5 

47.7 
50.6 
37.8 
30.9 

40.7 


40.6 
45.1 
41.2 
42.3 
32.7 

38.0 


38.9 
50.3 
41.2 
50.0 


33.0 
48.9 


52.0 
40.3 


39.7 
47.4 
47.0 
46.6 
34.0 
27.1 

40.3 


Mean  of  five  daily  observations  of  the  cloudiness  at  Montsouris  expressed  as  ratio 
of  the  actual  duration  of  sunshine  to  the  maximum  possible  duration. 


Month. 

1875. 

1876. 

1877. 

1878. 

1879. 

1880. 

1881. 

1882. 

1888. 

1884. 

1885. 

April. 

May 

June 

July 

August 

September 

0.66 
.64 
.60 
.63 

.62 

0.60 
.62 
.64 
.69 
.60 
.54 

0.54 
.52 
.71 
.64 
.62 
.55 

0.53 
.56 

.67 
.54 
.54 

0.43 
.55 
.59 
.55 
.61 
.67 

.08 
.54 
.66 
.56 
.53 

0.49 
.66 
.70 

.58 
.49 

0.60 
.64 
.61 
.62 
.50 
.47 

0.55 
.62 
.59 
.56 

0.52 
.62 
.56 
.57 
.52 
.54 

0.51 
.54 
.60 
.55 
.52 
.42 

Average 

.62 

.62 

.60 

.58 

.55 

.59 

.60 

.57 

.57 

.55 

.52 

RELATIVE    TOTAL    HEAT     RECEIVED    FROM    SUN    AND    SKY 
DURING  ANY  DAY,  BY  HORIZONTAL  SURFACES. 

A  more  accurate  way  of  considering  the  amount  of  insolation  at 
any  locality  is' to  compute  the  total  radiation  (expressed  by  its  equiva- 
lent heat  in  calories)  received  by  a  horizontal  surface  in  the  natural 
daytime  of  that  day  and  latitude,  taking  account  of  the  absorption  by 
the  atmosphere.  (See  Annales  Agronomique,  1878,  IV,  pp.  270-29(5, 
or  Ann.  Report  Chief  Signal  Officer  for  1881,  pp.  1200-121G.)  This 
has  been  done  by  Aymonnet  by  a  graphic  method.  He  assumes  that 
if  the  sun  were  in  the  zenith  then  the  unit  of  horizontal  earth's  sur- 
face would,  because  of  atmospheric  absorption,  receive  only  0.75  of 


91 

the  heat  that  it  would  receive  if  it  were  outside  the  atmosphere. 
Of  the  remaining  -25  per  cent  one-half  reaches  this  horizontal  unit 
by  way  of  the  diffuse  reflection  from  the  sky,  so  that  with  the  sun  in 
the  zenitli  the  unit  receives  0.875  of  the  original  solar  heat.  For  a 
point  on  the  equator  during  twelve  hours  this  would  amount  to 
O.STr>Xli^X60X()0  of  the  total  possible  if  the  sun  were  in  the  zenith. 
Using  this  as  a  basal  datum,  Aymonnet  obtains  the  relative  numbers 
given  in  the  following  table  or  the  ratio  of  the  heat  actually  received 
during  one  day  to  that  which  would  have  been  received  if  the  sun  had 
stood  for  twelve  hours  in  the  zenith.  Thus  on  June  20,  at  latitude  H0°, 
the  horizontal  unit  receives  0.347  of  that  corresponding  to  the  ideal 
sun  in  the  zenith  all  day,  while  at  the  north  pole  on  the  same  day 
the  horizontal  unit  received  during  twenty-four  hours  0.328  of  what  it 
would  had  the  sun  stood  in  the  zenith  for  twelve  hours.  In  fact  the 
amount  of  heat  received  by  horizontal  surfaces  is  nearly  uniform  for 
all  latitudes  for  the  days  June  15-July  28.  These  relative  numbers 
or  ratios  may  be  turned  into  absolute  calories  by  multiplying  them 
by  the  so-called  "  solar  constant,"  whose  value  is  probably  between 
two  and  three  calories  per  minute  per  square  centimeter. 

Relative  q)iantities  of  total  heat  received  on  specified  days  from  the  sun  and  sky 
at  different  latitudes  hy  a  unit  surface  of  horizontal  (jround  during  one 
cloudless  day,  allowing  for  the  absorption  and  diffuse  reflection  of  ordinary 
clear  air,  as  computed  hy  Aymonnet. 


Dates,  1874. 


Declin- 
nation 
of  sun, 
north. 


March  20  . 
March  2K  . 

April  7 

April  15. . 
April  35.. 

May  5 

May  15.... 


May  25 20 

June  5 ;i2 

June  15 23 

June  19  to  23 23 

July  7 22 

July  19 20 


.Iuly28 

August  7 

August  18 

August  25 

September  5  . 
September  15 
September  Zi 


Latitude— 


.279 
.274 
.273 
.368 
.267 
.272 
.274 
.279 


0.295 
.297 
.303 
.306 
.307 
.305 
.:«4 
.304 
.303 
.302 
.301 
.303 
.304 
.304 
.;«5 
.307 

.;«7 

.303 
.297 


.310 
.322 
.:« 
.337 
.342 
.346 
.347 
.342 
.337 
.331 
.322 
.310 
.301 
.284 


0. 175 
.190 
.215 
.235 
.291 
.281 
.298 
.313 
.324 


92 

RELATIVE  TOTAL  HEAT   RECEIVED   DURING  CERTAIN  MONTHS. 

By  adding  the  amount  for  each  day  of  any  month  in  the  following 
table  we  get  the  relative  numbers  for  the  total  amount  of  heat  received 
direct  from  the  sun  at  various  latitudes  during  certain  months  by  a 
unit  of  horizontal  surface  under  a  clear  sky,  and  after  absorption  by 
ordinary  clear  air,  plus  the  amount  received  from  the  diffuse  sky  light 
or  the  atmospheric  reflection,  all  expressed  in  terms  of  the  amount  that 
unit  surface  would  receive  if  the  sun  were  constantly  in  the  zenith 
(luring  twelve  hours.  The  coefficient  of  transmission  through  one 
atmosphere  for  zenithal  sun  is,  as  before,  0.75,  and  the  added  sky- 
light is  0.125,  to  accord  with  the  Arago-Davy  conjugate  thermometers, 
since  these  are  affected  by  the  sum  of  the  heat  received  by  their  sur- 
faces from  the  sun  and  from  the  atmospheric  particles  in  the  visible 
celestial  vault. 


Relative  quantities  of  total  heat  received  monthly  at  different  latitudes  in  the 
northern  hemisphere. 


Month. 

0. 

10. 

30. 

50. 

ro.    1 

1 

80. 

90. 

3.7 
10.0 
9.8 
9.2 
9.7 
10.1 
7.7 

3.7 
10.6 
10.7 
10.4 
10.7 
10.7 

7.8 

3.3 

10.1 
11.7 
11.9 
12.1 
10.9 
7.1 

2.3 
8.0 
10.5 
11.3 
11.3 
9.2 
5.2 

1 
1.1 

5.4 

9.0 
10.7 
10.3 

6.8 

2.7, 

0.6! 

3.9! 

8.6  j 
U.O  ' 
10;  1 

5.9 

1.5 

0.2 

April 

3.4 

May 

8.7 

11.1 

July 

August -- - 

September  1  to  23 

10.2 
.5.8 
0.9 

Total       - 

60.2 

64.6 

67.1 

57.8 

46.0 

41.6 

40.3 

PHOTO-CHEMICAL   INTENSITY   OF   SXINSHINE. 

Bunsen  and  Roscoe,  in  a  series  of  memoirs  published  in  the 
Philosophical  Transactions,  London,  1857,  1859,  and  1863,  entitled, 
"  Photo-chemical  researches,"  discussed  the  methods  of  measuring  the 
chemical  action  of  light  by  help  of  photographic  tints,  and  endeav- 
ored to  improve  upon  the  methods  of  Herschel,  Jordan,  Claudet,  and 
Hankel.  They  adopted  as  a  standard  unit  for  measurement  that 
intensity  of  the  light  which  in  one  second  of  time  produces  the 
standard  tint  of  blackness  upon  the  standard  paper.  Their  methods 
are  too  laborious  for  the  ordinary  meteorological  observer,  but  have 
furnished  some  important  data  as  to  the  chemical  activity  of  diffuse 
sunlight  and  of  total  daylight. 

In  his  memoir  of  1864,  Roscoe  states  that  he  and  Bunsen  had 
developed  a  method  of  determining  the  chemical  intensity  of  both 
direct  sunlight  and  diffuse  sunlight,  or  the  total  daylight,  that  is, 
based  upon  the  law  that  the  intensity  of  the  light  multiplied  by  the 
duration  of  exposure  of  chloride  of  silver  paper  of  uniform  sensi- 
tiveness gives  a  series  of  numbers  proportional  to  the  shades  of  tints, 


93 


so  that  light  of  the  intensity  50,  actin<2:  durinj^  time  t,  i)roduces  the 
same  bhK'kenin«r  eft'ect  as  light  of  intensity  /  acting  during  the  time 
50.  According  to  this  method  the  ciieniical  action  of  the  total  day- 
light was  determined  for  jNIanchester,  England,  many  times  a  day 
during  1864,  and  the  total  daily  chemical  intensity  has  been  com- 
puted for  the  year  August,  1863,  to  September,  1864.  Very  large 
changes  in  chemical  intensity  occur  when  the  sky  is  cloudless  and 
unchanged  as  far  a^  the  eye  can  perceive.  The  total  intensity  for  an 
apparently  cloudless  day  varies  from  3.3  for  December  21,  1863.  to 
110,  June  22,  1864.  This  last  number,  compared  with  the  figure  50.t) 
for  June  20,  and  26.6  for  June  28,  shows  the  enormous  variations  that 
take  place  in  the  chemical  rays  that  reach  the  observer  at  Manchester 
on  cloudless  days.  This  variation  is  undoubtedly  due  in  part  to 
smoke  and  moisture,  but  possibly  other  unknown  influences  are  also 
at  work. 

In  1867  H.  E.  Roscoe  connnunicated  to  the  Roj^al  Society  the 
results  of  work  done  by  his  method  at  Kew,  P^ngland,  in  1865,  1866, 
and  1867;  at  Heidelberg,  1862  and  1863,  and  at  Para,  Brazil,  1866. 
The  general  results  are  that  the  chemical  intensity  attains  its  max- 
imum at  noon  and  not,  like  the  temperature,  at  some  time  after  noon. 
P^verywhere  the  intensity  increases  from  hour  to  hour  with  the  alti- 
tude of  the  sun,  and  is  very  closely  proportional  to  it  even  when  the 
sky  is  partially  clouded,  but  of  course  the  rate  of  increase  varies  with 
the  season,  the  amount  of  cloud,  and  the  degree  of  atmospheric  opales- 
cence. The  total  chemical  intensity  for  each  month,  as  determined 
from  numerous  observations,  is  as  follows  for  Kew : 

Total  photochemical  intensity  of  direct  and  diffuse  light  (Roscoe). 


Month. 

1865. 

1866. 

1867. 

Month. 

1865. 

1866. 

im. 

January 

15 

13 

July 

114 

107 

February 

24 

22 

August 

89 

94 

March 

3i 

31 

September-. 

108 

70 

April 

88 

52 

October 

....\         23 

29 

May 

ns 

79 

November.. 

18 

16 

June 

92 

December 

--1    '" 

(14) 

Eoscoe  compares  these  figures  with  the  cloudiness,  and  finds  that 
the  ratio  between  cloudiness,  expressed  on  a  scale  of  10,  and  the  chem- 
ical intensity  is  as  1  to  5  in  some  months  and  as  1  to  ^  in  others.  A 
similar  irregularity  of  ratio  is  found  when  he  considers  the  absolute 
moisture  in  the  atmosphere;  whence  he  concludes  that  the  variations 
in  chemical  intensity,  as  between  the  spring  and  autumn,  are  not 
perfectly  explained  by  either  of  these  factors.  He  finds  the  high 
autumnal  and  low  vernal  intensity  fairly  well  explained  as  due  to  the 
transparency  or  opalescence  produced  by  finely  divided  solid  particles 
or  dust. 


94 


Passing  from  Kew  to  Para,  it  appears  that  the  chemical  action  of 
total  dajdight  during  the  month  of  April,  1866,  at  Para  was  6.6  times 
as  great  as  at  Kew. 

In  order  to  obtain  data  for  a  clearer  atmosphere,  Roscoe  and 
Thorpe  conducted  observations  in  1867  near  Lisbon,  Portugal,  and 
published  their  results  in  a  memoir  of  1870,  where  they  have  given 
the  relation  between  the  sun's  altitude  and  the  chemical  intensity. 
The  intensity  is  the  same  for  hours  that  are  equidistant  from  ap- 
parent noon.  The  relative  intensity  of  direct  sunlight,  reflected  sky 
light,  and  total  insolation  is  shown  for  different  altitudes  at  Lisbon 
by  the  following  table : 

Intensity  of  insolation  at  Lisbon  for  clear  skies. 


Mean  al- 
titude of 
sun. 

Number 
of  obser- 
vations. 

Observed  chemical  inten- 
sity. 

Sun. 

Sky.      ;    Total. 

9.85 
19.68 
31.23 
42.22 
53.15 
61.13 
64.23 

15 

18 
22 
22 
19 
24 
11 

0.000 

.m 

.052 
.100 
.136 
.195 
.221 

0.038 
.062 
.100 
.115 
.126 
.132 
.138 

0.038 
.085 
.152 
.215 

.327 
.359 

In  general,  the  total  intensity  is  directly  proportional  to  the  num- 
ber of  degrees  of  altitude.  For  altitudes  between  18°  and  35°  the 
intensity  on  a  plane  perpendicular  to  the  incident  rays  is  about  the 
same  as  the  intensity  of  total  sky  light  on  a  horizontal  plane.  The 
intensity  of  direct  sunlight  on  a  horizontal  plane  is  equal  to  the 
intensity  of  total  sky  light  on  a  horizontal  plane  when  the  sun's  alti- 
tude is  about  45°.  At  all  altitudes  of  the  sun  below  21°  the  chemical 
action  of  diffuse  daylight  exceeds  that  of  direct  sunlight. 

In  their  memoir  of  1871  Roscoe  and  Thorpe  determined  the  amount 
of  chemical  action  for  total  sky  light  of  a  cloudy  sky  during  totality 
of  the  solar  eclipse,  and  found  it  much  less  than  0.008,  and  therefore 
not  measurable.  They  found  the  total  chemical  action  of  the  direct 
sunlight  to  be  strictly  proportional  to  the  visible  area  of  the  portion 
of  the  solar  disk  up  to  a  certain  point  in  the  obscuration,  after  which 
the  influence  of  sky  light  is  inappreciable.  P"or  altitudes  below  50° 
at  Catania,  Sicily,  as  elsewhere,  the  amount  of  chemical  action 
effected  by  diffuse  daylight  on  a  horizontal  surface  is  greater  than 
that  exerted  by  the  direct  sunlight.  At  altitudes  less  than  10°  direct 
sunlight  is  almost  completely  robbed  of  its  chemically  active  rays. 


^♦5 

PHOTOGRAPHIC  INTENSITY  OF  SUNSHINE. 

A  photographic  method  of  determining  the  brightness  of  sunshine 
or  sky  light  is  verj'  desirable  as  supplementing  the  thermometric 
methods.  It  is  as  erroneous  to  assume  that  all  radiation  that  falls 
upon  a  black-bulb  thermometer  is  absorbed  by  it  and  converted  into 
heat  and  measured  by  the  expansion  of  the  mercury  as  it  is  to  assume 
that  all  the  radiation  that  falls  on  a  photographic  film  is  absorbed 
by  it  and  is  represented  by  the  chemical  changes  that  take  place  in  the 
film.  Equally  erroneous  Avould  it  be  to  assume  that  all  the  radiation 
that  enters  the  eye  is  represented  by  the  impression  of  brightness 
conveyed  by  the  retina  to  the  brain.  In  order  to  measure  in  absolute 
units  the  total  energy  radiated  from  the  sun,  we  need  a  proper 
summation  of  the  thermal,  visual,  and  photographic  work  done  by 
the  radiation.  If  we  wish  to  determine  only  the  intensity  of  that 
part  of  the  radiation  that  does  the  Avork  in  which  agriculture  is 
chiefly  interested  we  should  consider  only  the  heating  effects  of  the 
radiation  and  the  special  chemical  effects  manifested  in  the  action  of 
sunlight  upon  chlorophyll. 

The  action  of  the  sunlight  upon  the  chlorides  and  bromides  of 
silver,  as  in  ordinary  photographic  processes,  may  not  be  an  exact 
measure  of  its  action  upon  the  leaves  of  plants.  Some  other  chemicals 
may  be  more  appropriate  for  use  at  agricultural  experiment  stations, 
but  the  photographic  methods  perfected  by  Profs.  H.  AV.  Vogel  and 
L.  Weber  are  worthy  of  trial  as  a  first  step  in  the  right  direction. 
These  processes  give  us  the  relative  intensity  of  the  radiations  that 
belong  to  the  blue  end  of  the  spectrum,  with  only  a  small  admixture 
of  the  influence  of  green  and  yelloAv  rays. 

During  the  year  1890,  as  the  result  of  a  numerous  series  of  observa- 
tions at  Kiel,  Prof.  L.  Weber  found  that  the  reddish  light  of  Jjie 
spectrum  on  dark  winter  days  has  only  about  500  times  greater  int4M4^- 
sity  than  the  quantity  of  light  from  a  normal  candle  at  a  distance  of 
1  meter,  when  measured  by  their  relative  effects  on  a  photographic 
plate,  while  at  the  same  time  the  photographic  intensity  of  the  green 
light  of  the  spectrum  was  four  times  as  much.  On  bright  sunnner 
days  the  intensity  of  the  red  light  was  50,000  times  that  of  the  candle 
at  1  meter,  while  the  intensity  of  the  green  light  was  about  200,000, 
or  about  4  times  as  much  in  summer  as  in  winter.  The  intensity  of 
(he  blue  light  in  the  solar  spectrum  was  about  25  times  that  of  the 
red  light,  which  ratio  varied  a  little  with  the  kind  and  amount  of 
cloud.  In  all  this  photographic  work  a  very  sensitive  silver  bromide 
paper  was  used;  so  that  these  results,  strictly  speaking,  relate  only  to 
the  variations  in  the  intensity  of  those  special  rays  that  affect  this 
chemical.  But  these  variations  will  be  nearly  parallel  to  the  diurnal 
and  annual  variations  of  the  rays  that  affect  the  growth  of  plants. 


96 

Further  details  of  Weber's  results  are  given  in  the  German  periodical, 
Photographische  Mitteilungen,  edited  bv  Professor  Vogel,  at  Berlin. 
It  is  worth  while  to  call  attention  to  the  fact  that  during  the  long 
twilights  of  northern  latitudes  in  midsummer  plants  receive  an  appre- 
ciable quantity  of  the  blue  radiations  from  the  sky,  while  receiving 
little  or  nothing  of  the  red,  or  heat,  rays. 

M  ARCH  AND' S  SELF-REGISTERING  CHEMICAL  ACTINOMETER. 

A  convenient  form  of  registering  actinometer  is  that  devised  by 
Marchand  (1875),  which  he  at  first  called  '' photantitupimeter,"  but 
wdiich  name  he  afterwards  contracted  and  modified  to  '"  phantupi- 
meter.*"'  This  consists  of  a  vertical  graduated  tube,  closed  at  the 
upper  end,  into  which  there  can  escape  and  be  measured  the  carbonic 
acid  gas  given  off  by  the  decomposition  of  a  mixture  of  solutions  of 
perchloride  of  iron  and  oxalic  acid.  By  the  action  of  sunshine  on 
this  mixture,  carbonic  acid  gas  is  slowly  disengaged,  and  by  its  accumu- 
lation in  the  measuring  tube  gives  us  apparently  a  means  of  deter- 
mining the  sum  total  of  the  influences  of  the  sun  during  any  period. 
This  apparatus  was  diligently  employed  for  many  years  by  Marchand 
at  Fecamp,  near  Havre,  and  has  afforded  him  many  interesting 
results. 


COMPARISON    OF    MARCHAND' S    AND    MARIE    DAVY'S   RESULTS. 

Radau  (1877),  in  his  work  on  Light  and  Climate,  states  that  the 
results  given  by  different  methods  of  measurement  of  sunshine  appear 
to  differ  largely  among  themselves,  but  yet  there  is  a  certain  simi- 
larity in  the  figures.  The  accompanying  table  shows  the  results  of 
observations  by  Marchand's  chemical  method  and  by  Marie-Davy's 
thermometric  method,  or  conjugate  thermometers,  which  latter,  on 
account  of  its  convenience,  has  been  widely  adopted. 


Month. 

Total  daily 
chemical 
effect,  in 
cubic  cen- 
timeters, 

of  car- 
bonic  acid 
(Fecamp, 
1869-1872). 

Mean  daily 
record  of 

actinomet- 
ric  de- 
grees 
(Mont- 
souris, 

1872-1876). 

Month. 

Total  daily 
chemical 
effect,  in 
cubic  cen- 
timeters, 

of  car- 
bonic acid 
(Fecamp, 
1869-1872). 

Mean  daily 
record  of 
actin  'met- 
ric de- 
grees 
(Mont- 
souris, 
1872-1876. 

January 

1.84 
3.93 
6.44 
14.10 
19.46 
21.04 
21.41 

13.0 
15.6 
26.0 
37.5 
46.2 
48.2 
50.6 

August 

18.92 
13.65 
6.86 
2.89 
1.80 

41.2 

31.8 

March 

October 

20.1 

April 

November 

12.5 

May 

9.4 

Annual  average... 

June 

11.03 

29.3 

July 

If  the  atmosphere  were  not  so  very  different  at  these  two  localities, 
we  could  have  hoped  to  use  the  monthly  ratios  of  these  numbers  for 


97 

VIOLLE'S  CONJUGATE  BULBS. 

The  refined  methods  for  iiieasnrino;  sohir  radiation  adopted  by 
Violle  (1879)  in  his  absohite  actinonietry  can  hardly  be  utilized  in 
agricultural  investigations  oAving  to  the  labor  of  using  the  apparatus. 
But  the  continuous  register  ol)tained  by  him  by  means  of  thermo- 
electric apparatus  is  an  important  improvement  in  the  methods  avail- 
able for  comparing  climates.  On  the  other  hand,  Violle  has  sug- 
gested a  modification  of  the  conjugate  thermometers  which  he  calls 
his  •'  conjugate  bulbs,"  which  is  worthy  of  consideration,  although  far 
from  being  as  sensitive  as  Marie-Davy's  apparatus.  These  bulbs  are 
made  of  thin  copper,  one  of  them  blackened  and  the  other  gilded 
on  the  outside;  the  interiors  are  blackened,  and  the  thermometer 
bulbs  within  them  are  also  blackened.  This  apparatus  has  an  appar- 
ent advantage  over  Marie-Davy's,  in  that  the  sunlight  is  not  required 
to  pass  through  glass  before  striking  the  thermometer.  It  would 
appear  likely  that  with  smaller  bulbs  (Violle  uses  1  decimeter  in 
diameter)  and  with  more  sensitive  thermometers  Violle's  method 
might  give  better  results  and  be  worthy  of  recommendation  to  agri- 
cultural investigators.  The  results  given  by  his  apparatus  have  need 
to  be  reduced  by  some  method  based  on  the  considerations  indicated 
by  Ferrel  (189l'). 

BELLANI'S  RADIOMETER  OR  VAPORIZATION  ACTINOMETER. 

Among  the  many  devices  invented  for  the  purpose  of  obtaining, 
at  least  approximately,  the  sum  total  of  the  effect  of  sunshine  received 
during  any  day  by  a  given  plant  is  one  that  has  been  used  for  a  few 
years  at  the  Montsouris  Observatory,  and  is  a  modification  of  an 
apparatus  originally  devised  by  the  Italian  physicist,  Angelo  Bellani, 
which  is  thus  described  by  Descroix  (p.  128,  Annuaire  de  Montsouris, 
1887;  see  also  the  Annuaire  for  1888,  p.  206,  where  it  is  called  the 
lucimeter,  although  it  does  not  measure  light  properly  so  called). 

The  vaporization  actinometer  or  the  Bellani  radiometer  as  modi- 
fied at  Montsouris  consists  of  a  bulb  of  blue  glass  A  of  about  60 
mm.  in  diameter,  inclosed  within  a  larger  bulb  B  of  colorless  glass. 
The  space  between  the  two  bulbs  is  a  vacuum.  xV  is  two-thirds  filled 
with  a  volatile  liquid  and  the  space  above  it  contains  only  its  vapor, 
which  passes  through  a  curved  tube  down  into  a  large  bulb  C,  of  clear 
glass,  and  thence  down  into  the  vertical  tube  D,  which  is  graduated, 
and  where  the  condensing  licjuid  can  be  measured. 

Under  the  action  of  the  radiation  from  the  sun  and  the  slcy  the 
l>lue  bulb  A  is  warmed  more  than  the  bulb  B;  a  distillation  takes 
place  from  A  and  the  condensed  liquid  is  collected  in  the  graduated 
tube  D,  where  its  volume  is  measured.  This  c(mdensation  in  D  is  a 
source  of  heat,  while  the  vaporization  in  A  is  a  source  of  cold.  The 
heat  given  off  by  condensation  must  e<iual  that  consumed  in  evapoi-a- 
tion,  and  is  drawn  off  from  the  apparatus  by  the  action  of  the  cool 
20G7— 0.5  M 7 


98 


wind  blowing  past  C  and  the  graduated  stem  D,  which  are  shaded 
from  the  sunshine,  or  which  may  be  kept  immersed  in  melting  ice. 
although  this  is  not  done  at  Montsouris.  In  order  that  the  record  of 
liquid  condensed  in  C  and  D  may  be  proportional  to  the  heat  received 
by  A  it  is  necessary  that  the  volume  of  condensed  liquid  be  inde-' 
pendent  of  the  temperature  of  the  air  and  of  the  volume  of  liquid 
i-emaining  in  the  bulb  A,  and  be  controlled  only  by  the  excess  of 
radiant  heat  received  by  A  over  that  received  by  C  and  D. 

The  comparisons  thsit  have  been  made  at  Montsouris  between  this 
Bellani  radiometer  and  the  Marie-Davy  actinometer,  or  the  so-called 
conjugate  thermometers,  show  that  the  Bellani  apparatus  does  not 
perfectly  satisfy  the  theoretical  conditions,  but  as  it  is  extremely 
sensitive,  since  it  distills  16  or  17  centimeters  daily,  and  as  the  appa- 
ratus is  not  costly,  Descroix  has  devised  a  formula  for  reducing  its 
results  to  a  standard.  The  following  table  gives  the  results  of  actual 
observations,  showing  the  average  results  for  the  middle  portion  of 
perfectly  clear  days  "at  Montsouris,  near  Paris,  monthly  during  the 
growing  seasons  of  1885  and  1886.  The  column  N  shows  the  number 
of  clear  days;  V,  the  volume  of  alcohol  distilled  over  from  9  a.  m. 
to  3  p.  m.  on  these  days  in  the  Bellani  apparatus;  t,  the  average 
temperature  of  the  air  in  the  shade;  Tj,  the  average  temperature 
of  the  black  bulb  thermometer  in  vacuum  in  the  sunshine;  T.,  aver- 
age temperature  of  the  bright-bulb  thermometer  in  vacuum  in  the 
sunshine;  T^  —  To  is  the  average  difference  of  these  conjugate  ther- 
mometers at  midday;  R,  total  illumination  from  the  sky  at  midday, 
expressed  in  Marie-Davy's  actinometric  percentages  or  degrees. 

Comparison  of  actinometric  results  for  perfectly  clear  days  at  Montsouris.  near 
Paris,  by  the  Bellani  radiometer  and  by  the  Arago-Davy  actinometer. 


N. 

Bellani. 

Arago-Davy  at  noon. 

Month. 

V. 

t. 

T:. 

To. 

T1-T2. 

R. 

1885. 
March                                                   

6 
6 
2 

10 

3 
2 

8 
7 
9 
2 

10 
7 

11 
4 

ccm . 
9.6 
10.4 
10.2 
10.7 
11.6 
10.7 
11.0 
7.2 

11.9 
12.3 
12.9 
12.1 
12.5 
12.1 
U.7 
10.1 

5.9 
18.4 
22.6 
22.8 
24.7 
20.0 
23.4 
12.1 

1.6 
17.6 
15.6 
19.5 
23.2 
22.9 
21.0 
19.3 

°C. 

25.9 

38.5 

44.2 

45.6 

15.0 
27.5 
32.9 
33.7 

10.9 
11.0 
11.3 
11.9 
11.8 
10.7 
10.9 
8.4 

11.5 
9.9 
12.4 
10.2 
11.5 
10.5 
9.9- 
9.3 

76.9 

April                                 

70.2 

May                  

67.1 

71.5 

July                                                                                        

46.2 

34.4 

73.9 

39.9 
43.0 
29.5 

22.5 
36.7 
38.7 
42.7 
44.4 
41.8 
38.8 
35.9 

29.2 
32.1 
4.1 

11.0 
26.8 
25.9 
30.2 
32.9 
31.3 
28.9 
26.6 

73.2 

73.2 

72.0 

1886. 
March                                                     

77.2 

74.1 

Mav                                                  - 

76.6 

75.2 

July                                               

72.0 

68.6 

69.2 

October                                                

71.2 

Notwithstanding  the  simplicity  of  Bellani's  apparatus  and  the 
ingenuity  of  the  idea  embodied  therein  it  is  evident  that  it  needs  an 
important  modification,  viz,  the  evaporation  and  condensation  should 


99 

be  absolutely  independent  of  the  temperature  of  the  air  and  the  veloc- 
ity of  the  wind,  as  well  as  of  the  quantity  of  liquid  in  the  bulb  A,  and 
should  depend  wholly  on  the  heat  received  from  the  sun  and  sky.  In 
its  present  form  it  can  not  bo  recommended  as  a  simple  means  of  meas- 
uring the  daily  sum  total  of  radiation  from  the  sun  and  sky.  A  sec- 
ond and  improved  form  of  Bellani's  apparatus  has  been  brought  out 
under  the  title  "  Vaporization  lucimeter  "  (see  Marie-Davy,  Annuaire, 
1888,  p.  207),  but  further  improvements  are  necessary,  especially  the 
maintenance  of  a  uniform  constant  temperature  in  the  condensation 
bulb  and  tube,  as,  for  instance,  by  immersing  both  in  a  bath  at  melting 
point  of  ice. 

ARAGO'S  CYANOMETER  AND  DESAINS'  THERMO-ELECTRIC 
ACTINOMETER. 

Other  methods  of  observing  the  condition  of  the  sky  and  solar 
radiation  have  been  devised  by  physicists.  Thus  the  cyanometer  of 
Arago,  especially  in  the  modified  form  made  by  Dubosc,  of  Paris,  or 
the  thermo-electric  actinometer  of  Desains  (both  of  which  are  in 
occasional  use  at  Montsouris)  give  useful  indications.  The  cyanom- 
eter gives  the  blueness  of  the  sky,  which  is  largely  dependent  on  the 
number  and  size  of  the  particles  of  moisture,  while  the  actinometer 
gives  the  quantity  of  heat  that  penetrates  directly  from  the  sun 
through  this  moist  air  to  the  ground.  These  instruments  are  comple- 
mentary to  each  other,  but  can  only  give  good  results  in  the  hands  of 
those  accustomed  to  the  use  of  delicate  apparatus.  They  serve  as  checks 
upon  the  records  of  the  Arago-Davy  actinometer,  Avhich  latter  has 
been  made  by  Richard  in  such  form  as  to  keep  a  continuous  register. 
Thus  during  the  years  1879-1886  the  Arago-Davy  instruments,  both 
in  France  and  in  India,  showed  a  steady,  progressive  dimimition  in 
the  intensity  of  the  solar  radiation  received  at  the  ground,  followed, 
however,  by  a  recovery,  subsequently,  which  is  not  likely  to  have  been 
due  to  any  instrumental  peculiarity.  This  peculiar  fluctuation  may 
have  had  its  cause  either  in  the  sun  or  in  the  earth's  atmosphere." 

DURATION  OF  SUNSHINE. 

Those  who  can  not  undertake  the  labor  of  observing  the  heating  or 
chemical  effects  of  the  solar  radiation  can  easily  keep  a  photographic 
register  of  the  number  of  hours  of  sunshine,  as  in  the  apparatus 
devised  by  Jordan,  of  England,  and  modified  by  Marvin  for  use  at 
Signal  Service  stations,  or  can  keep  a  record  of  the  hours  of  full 
hot  sunshine,  as  in  the  Campbell,  or  Campbell-Stokes,  sunshine 
recorder  used  in  Canada.     The  Marvin  photographic  sunshine  reg- 

oThis  paragraph,  written  in  1801,  is  of  special  interest  in  connection  with  the 
general  interest  in  the  subject  awakened  in  1903  by  the  observations  of  Kimball, 
Dufour,  and  Abbott. 


100 

ister  has  been  established  at  20  Signal  Service  stations,  the  list  of 
which  is  given  in  our  tabular  data.  This  tabular  matter  is  omitted 
from  this  present  edition,  and  these  records  will  undoubtedly  be  so 
fully  published  as  to  be  available  to  the  student.  Such  photographic 
sunshine  records  are  complementary  to  the  ordinary  record  of  cloud- 
iness and  of  personal  observations  of  the  area  apparently  covered  by 
clouds.  But  as  the  photographic  register,  strictly  speaking,  records 
only  the  cloudy  condition  of  the  sky  in  the  immediate  location  of  the 
disc  of  the  sun,  while  personal  estimates  of  the  amount  of  cloudiness 
refer  to  the  whole  sky  (above  an  altitude  of  15°,  30°,  or  60°,  according 
to  the  various  rules  adopted  b}'  observers),  therefore  there  is  room  for 
quite  a  discrepancy  between  the  personal  and  the  photographic  record, 
and  it  is  still  a  question  as  to  which  is  more  appropriate  for  agricnl- 
tural  study." 

In  order  to  know  the  cloudiness,  sunshine,  and  rainfall  at  a  few 
stations  representative  of  the  district  in  which  cereals  are  grown  in 
America,  I  have  added  to  the  stations  in  the  United  States,  which  will 
be  published  by  the  Signal  Service,  the  following  table  for  1887 
compiled  for  Winnipeg,  Manitoba  (lat.  N.  49°  40',  long.  W.  97°  10'), 
from  the  data  published  by  Carpmael  (1890),  from  whose  report 
other  records  may  be  obtained. 

Sunshine  and  climate  of  Winnipeg. 


Average  duration  of  sunshine  per  hour  in  i)ercentage 
of  total  possible. 


°®/   jiness. 
days. 


January 0.00 

February T. 

March T. 

April 0.25 

May j  3.01 

June i  2.94 

July 1.98 

August ,  1.49 

September 1.77 

October-.. 0.25 

November T. 

December.. T. 


P.ct. 
40 
42 

50 
51 
54 
50 
54 
51 
4.S 
57 
50 


la.m.  I  a.  ni.:Ka. 


16 
3 

30  45 

20  .55 

15 


-:! 
71 
44 

4;-  I 
2.;1 


0  Elaborate  comparisons  of  these  records  were  published  from  month  to  mouth 
in  the  Monthly  Weather  Review  during  1892-1897. 


101 

Sunshine  and  elimate  of  Winnipeg — Continued. 


Month  (m:). 

Average  duration  of  sunshine  per  hour  in  percentage 
of  total  possible. 

Temperature. 

1p.m. 

2p.m. 

3  p.m. 

4  p.m. 

5  p.m. 

6  p.m. 

7  p.m. 

8  p.m. 

Maxi- 
mum. 

Mini- 
mum. 

Mean. 

63 
7n 

54 

tlti 

f: 

73 
76 
70 
75 
63 
49 
55 

60 
64 

64 
41 
69 
72 

57 
48 
44 

31 
49 
57 
.59 
47 
59 
64 
71 
70 
44 
51 
23 

0 

20 
48 
49 
49 
67 
71 
60 
38 
18 
14 

"F. 
23.2 
24.8 
43.0 
74.8 
90.6 
88.0 
93.2 
88.0 
83.8 
64.0 
58.6 
38.0 

"F. 

-42.7 

-38.7 

-36.5 

-9.0 

29.0 

33.3 

39.0 

33.3 

23.2 

-  2.8 

-31.4 

-41.7 

"F. 
-14.5 

1 
8 
35 
53 
63 
68 
58 
10 

-  8.0 

March 55 

April '        63 

May 56 

June ;. 84 

July 75 

August 70 

September 76 

October 60 

0 
13 
41 
48 
59 
30 

5 

5 

18 
29 
5 

11.7 
37.3 
57.2 
64.6 
66.5 
61.0 
53.8 

17.4 

December 54 

-  0.3 

In  the  above  table  the  records  of  sunshine  are,  of  course,  given  by 
the  self-registering  method  and  relate  to  duration  of  visibility  of  sun 
at  the  station,  Avhile  the  cloudiness  is  the  average  of  the  observer's 
estimates  of  area  of  skv  covered. 


TOTAL   POSSIBLE   DURATION   OF   SUNSHINE   BY  DECADES. 

Tables  showing  the  times  of  sunrise  and  sunset,  or  the  resulting 
length  of  the  day,  are  given  is  publications  accessible  to  American 
leaders,  as  follows:  Meech,  1855,  pages  57,  58,  calculated  especially 
for  the  year  1853;  Schott,  1870,  pages  117-119,  computed  for  an  aver- 
age year  and  for  the  actual  sunrise  and  sunset  and  for  each  degree  of 
latitude;  the  Smithsonian  Meteorological  and  Physical  Tables, 
fourth  edition,  1884,  give  a  very  convenient  table  on  pages  711-720, 
by  Prof.  W.  Libbey,  computed  with  the  declinations  for  Greenwich 
mean  noon  for  1862 ;  elaborate  general  tables  are  given  in  the  Inter- 
national Meteorological  Tables,  Paris,  1890,  but  they  are  not  so  conve- 
nient for  our  use  as  the  Smithsonian  tables  or  those  of  Schott. 

By  means  of  these  tables  of  sunrise  and  sunset  I  have  computed 
the  accompanying  table,  showing  the  sum  total  of  the  possible  sunshine 
expressed  in  hours  from  the  beginning  of  January  up  to  any  date  in 
a.  common  year  or  a  leap  year."  From  this  table  has  been  made  up 
the  column  of  maximum  sunshine  in  the  tables  of  meteorological 
results  for  1879  at  twenty  stations  in  the  United  States  as  given  in 
Section  II  for  comparison  with  th#  crops  of  that  year,  as  reported  in 
the  United  States  census  for  1880.''     In  the  absence  of  anv  other  data 


"  The  annual  sums  for  December  .SI  in  the  table  are  about  one-third  to  on*^- 
half  per  cent  smaller  than  the  figures  given  in  the  Weather  Bureau  table  of 
190.'. 

6  All  these  manuscrijtt  statistical  tables  are  omitted  in  the  present  etlitiou. 


102 

one  may  multiply  the  duration  of  sunshine  by  the  percentage  of 
observed  clearness  and  obtain  the  duration  of  sunshine  for  a  special 
station.  But  this  will  give  us  a  value  that  is  greater  or  less  than  the 
value  of  the  true  intensity  of  sunshine  according  as  the  cloudiness 
occurs  mostly  in  the  morning  and  evening  or  in  the  midday  hours. 
The  only  method  for  obtaining  a  satisfactory  value  of  the  intensity 
of  radiation  as  coming  direct  from  the  sun  or  as  reflected  from  the 
sky,  the  clouds,  and  the  earth,  is  to  maintain  a  self-registering  acti- 
nometer  or,  in  place  of  that,  frequent  daily  observations. 

In  these  tables  I  have  adopted  the  division  of  each  month  into  three 
parts,  as  done  by  Libbey  and  occasionally  used  by  meteorologists,  but 
the  system  of  pentades,  used  by  Dove,  is  often  preferable;  however, 
this  present  system  is  convenient  for  monthly  summations,  and  is  also 
used  in  the  climatic  table  of  Section  II." 

Sums  total  of  possible  duration  of  sunshine,  in  hours,  from  January  1  up  to  any 
day  of  the  year. 


January  1-10  ... 
January  11-20  .. 
January  31-31  .. 
February  1-10 . . 
February  11-20. 
February  21-28 . 

March  1-10 

March  11-20.... 
March  21-31  .... 

April  1-10 

April  11-20 

April  21-30 

May  1-10 

May  11-20 

May21-31 

June  1-10 

June  11-20 

June  21-30 

July  1-10 

July  11-20  

July  21-31 

August  1-10 

August  11-20  ... 
August  21-31  .... 
September  1-10 
September  11-20 
September  21-30 

October  1-10 

October  11-20.... 
October  21-31.... 
November  1-10.. 


Num- 
ber of  ' 
days. 


24°. 

26°. 

Hours. 

Hours. 

106.7 

105.4 

214.5 

212.0 

334.7 

331.0 

446.0 

441.4 

.559.4 

554.1 

649.9 

645.2 

767.4 

762.4 

887.2 

882.1 

1,021.7 

1,016.8 

1,146.4 

1,141.9 

1,273.3 

1,269.4 

1,402.3 

1,399.2 

1,533.3 

1,531.2 

1,666.0 

1,665.1 

1,813.6 

1,814.1 

1,948.8 

1,950.7 

2,084.5 

2,087.9 

2,220.2 

2,225.1 

2,355.4 

2,  ,361. 7 

2,489.7 

2,497.3 

2,636.0 

2,644.9 

2,767.1 

2,777.1 

2,896.3 

2,907.1 

3,036.1 

3,047.5 

3,160.8 

3,172.6 

.3,283.2 

3,295.2 

3,403.3 

3?415.2 

3,521.1 

3,532.7 

3,G36.6 

3,647.7 

3,761.2 

3,771.5 

3,872.3 

3,881.7 

Hours. 
104.0 


548.6 
640.3 
757.2 
876.8 
1,011.7 
1,137.2 
1,265.3 
1,396.0 
1,529.0 
1,664.1 
1,814.6 
1,952.7 
2,091.4 
2,2,30.1 
2,3as.2 
2,505.2 
2,654.1 
2,787.3 
2,918.1 
3,059.2 
3, 184. 7 
3,307.4 
3,427.4 
3,544.6 
3,659.1 
3,782.1 


30°. 

32°. 

34°.     i 

Hours. 

Hours. 

Hours. 

102.5 

101.0 

99.4 

206.4 

203.5 

200.4 

322.9 

318.7 

314.2 

4.31.4 

426.2 

430.6 

.542.6 

536.7 

530.2 

633.9 

627.6 

620.6 

750.5 

743.8 

736.4 

870.0 

863.3 

855.7 

1,005.0 

998.4 

991.1 

1,130.9 

1.124.7 

1,117.9 

1,259.7 

1.254.2 

1,248.1 

1,391.3 

1,386.7 

1,381.5 

1,525.4 

1,521.9 

1,517.9 

1,^61.8 

1,659.6 

1,657.0 

1,813.8 

1,813.2 

1,812.4 

1,953.4 

1,954.4 

1,9-55.3 

2,093.7 

2,096.3 

2,099.0 

2,234.0 

2,238.2 

2,242.7 

2.373.6 

2,379.4 

2,385.6 

2,512.0 

2,519.3 

2,537.1 

2,662.3 

2,671.0 

2,680.4 

2,796.6 

2,806.4 

2,817.0 

2,928.3 

2, 9;«.  0 

2,9.50.6 

3,070.2 

3,081.7 

3,094.1 

3,196.1 

3,208.0 

3,220.9 

3,319.0 

3,331.1 

3,344.2 

3,439.0 

3,4.51.0 

3,464.0 

3,555.9 

3,567.6 

3,  .580. 2 

3,669.9 

3,681.0 

3,693.0 

3,792.1 

3,802.3 

3,813.4 

3,900.3 

3,909.4 

3,919.4 

Hours. 
97.7 
197.2 
309.5 
414.9 
523.7 


1,110.9 
1,241.8 
1,376.2 
1,513.8 
1,654.3 
1,811.4 
1,956.0 
2,101.5 
2,247.0 
2,391.6 
2,534.7 
3,689.6 
2,827.5 
2,962.1 
3,106.4 
3,2:«.6 
3,a57.1 
.3,476.9 
3,592.8 
3,705.0 
3,824.5 
3,929.4 


a  Omitted. 


103 

Sum  total  i>f  possible  duration  of  ftmishine,  iti  Jtours,  from  Jautiary  I  up  to  any 
day  of  the  2/ea?'— Continued. 


November  11-20 

November  21-30 

December  1-10 

December  11-20 

December  21-31 

For  leap  year  add  to  all  num- 
bers after  February  28 

January  1— DecemberSl,  1905 


Num- 
ber of 


24° 


26». 


Hours. 
10     3,981.5 
10     4 
10  :  4 
10     4,302.2 


Hours. 

3,989.8 
.3  4,096.2 
.0  [  4,201.6 

4,306.4 


4,418.9     4,421.5 


4,436.5     4.438.1 


28». 

30°. 

Hours. 

Hours. 

3,999.3 

4,006.1 

4, 104. 3 

4, 109. 9 

4,208.3 

4,212.4 

4,311.6 

4,314.1 

4,425.1 

4,425.9 

11.5 

11.5 

4,439.9 

4,441.1 

Hours. 
4,014.0 
4,116.5 
4,217.5 
4,317.6 
4,427.7 

11.4 
4,444.6 


Hours.  Hours. 
4,022.7  4,031.4 
4,123.7  I  4,130.9 
4,223.1  I  4,228.6 
4,321.5  I  4,325.3 
4,429.7     4  431.6 


11.3 
4,445.8 


11.2 
4,448.6 


Num- 
ber of 
days. 


40°. 


44° 


46° 


January  1-10 

January  11-20  . . . 
January  21-31  . . . 
February  1-10 . . . 
February  11-20 . . 
February  21-28 . . 

March  1-10 

March  11-20 

March  21-31 

Aprill-10 

April  11-20 

April  21-30 

May  1-10 

May  11-20 

May  21-31 

June  1-10 

June  11-20 

June  21-30 

July  1-10 

July  11-20. 

July  21-31 

August  1-10 

August  11-20 

August  21-31 

September  1-10  . 
September  11-20 
September  21-30 

October  1-10 

October  11-20 

October  21-31 

November  1-10.. 
Novemljer  11-20. 
November  21-30. 
Decern V>er  1-10  .. 
December  11-20  .. 
December  21-31  . 


F(  )r  leap  year  add  to  all  num- 
bers after  February  28  . . . . 


January  1— December. SI.  1905 


Hours. 

96.8 

19.3.6 

304.2 

408.4 

516.3 

605.7 

720.7 

839.8 

975.4 

1,103.2 

1,234.9 

1,370.4 

1,509.3 

1,651.3 

1,810.3 

1,956.9 

2,104.4 

2,2.51.9 

2,398.5 

2,543.4 

2,700.1 

2,839.3 

2,975.0 

3,120.2 

3,248.0 

3,  .371. 8 

3,491.5 

3,607.1 

3,718.7 

3,837.2 

3,940.9 

4, (Ml.  4  I 

4,139.2  J 

4,2a5.0 

4,. 329. 8 

4,4.34.0 

11.2 
4,451.5 


Hours. 
94.0 
190.2 
299.2 
402.2 
509.2 
598.2 
712.8 
831.8 
967.6 

1,095.9 

1,365.0 
1,505.3 
1,618.9 
1,809.9 
1,958.4 
2,107.9 
2,257.4 
2,406.0 
2,552.7 
2,711.2 
2,851.7 
2,988.5 
3,134.7 
3,263.0 
3,387.0 
3,506.6 
3,621.8 
3,732.7 
.3,&50.2 
3,952.7 
4,051.7 
4,147.8 
4,241.8 
4,334.7 
4,436.8 

11.1 
4,454.3 


Hours. 

91.9 

186.2 

293.4 

395.1 

501.1 

589.5 

703.7 

822.6 

958.7 

1,087.5 

1,220.9 

1,3.58.7 

1,500.5 

1,645.9 

1,809.0 

1,959.7 

2,111.4 

2,263.2 

2,413.9 

2,564.6 

2,725.1 

2,867.1 

3,005.1 

3,152.3 

3,281.1 

3,405.3 

3,,52i.9 

3,639.7 

3,749.9 

3,866.3 

3,967.5 

4,064.8 

4,159.0 

4,251.0 

4,341.7 

4,441.4 

11.0 
4,457.4 


Hours. 
89.8 
182.1 


Hours. 
87.4 
177.5 


287.5 

280.8 

387.8 

379.6 

492.7 

483.3 

580.5 

570.5 

694.2 

683.7 

Hours. 
84.8 
172.6 
273.6 


Hours. 
82.0 
167.2 


813.0 
949.3 
1,078.7 
1,213.0 
1,352.0 
1,495.4 
1,642.6 
1,808.0 
1,961.0 
2, 115. 1 

2,422.3 
2,  .573. 2 
2,735.8 
2,879.4 
3,018.8 
.3,167.0 
3,296.5 
3,421.0 
.3,-540.5 
3,654.9 
3, 764. 4 
3,879.6 
3,979.3 
4,074.9 
4,167.1 
4,2.56.9 
4,345.3 
4,442.5 


1,062.0 
1,204.3 
1,344.6 

1,489.7 

1,807.0 
1,962.5 
2,119.2 
2,276.0 
2,431.5 
2,584.7 
2,7.9.6 
2,894.9 
3,0.3.5.7 
3,185.0 
3,315.1 
3,439.9 
3,5.59.3 
.3,673.3 
3,782.0 

.3,994.1 
4,087.9 
4,178.0 
4,26.5.3 
4,:i51.2 
4,44.5.7 


370.7 

'      361.1 

473.2 

462.3 

559.7 

548.1 

672.4 

660.2 

791.0 

778. 7 

927.8 

,      915.9 

1,058.6 

:  1,047.5 

1,195.0 

1,185.1 

1,.336.8 

1,328.5 

1,4«3.7 

1,477.4 

1,635.2 

1,631.3 

1,805.9 

1,805.1 

1,964.1 

1,966.3 

2,123.7 

2,129.1 

2,283.4 

2,292.0 

2,441.7 

2,453.4 

2,597.4 

2,611.9 

2,764.7 

2,782.0 

2.911.9 

2,931.3 

3,054.2 

3,075.2 

3,204.8 

3,227.2 

11.0  10.9  10.8 

4,461.5     4,465.7     4,470.8 


3,460.7 
.3,570.0 

3,801.3 
3,913.7 
4,010.2 
4,101.9 
4,189.6 
4,274.4 
4,357.6 
4,449.0 


.3,358.8 
3,484.2 
3,6ft3.4 
3.716.4 
3,823.2 
.3,934.2 
4,028.9 
4,118.3 
4,203.5 
4,285.5 
4,365.7 
4,4&3.8 

10.8 
4,476.7 


Chapter  VI. 

MOISTURE  OF  THE  SOIL. 

IN  GENERAL. 

The  soil  receives  its  water  supply  either  by  natural  rainfall  or  by 
irrigation.  The  plant  in  successive  generations  of  cultivation  adaj^ts 
itself  to  the  ordinary  supply  of  water,  but  in  order  to  perpetuate  its 
kind  it  must  have  sufficient  during  the  growing  season  to  serve  it  as 
a  medium  for  extracting  from  the  soil  and  air  the  nutritious  sub- 
stances needed  by  it  for  its  own  development.  The  water  really 
available  to  the  plant  is  principally  that  which  is  left  in  the  soil  close 
to  the  roots  after  the  surface  drainage  has  carried  off  a  large  per  cent 
of  the  original  rainfall  and  after  the  evaporation  by  the  dry  wind 
has  taken  20  per  cent  of  the  remainder  from  the  surface  soil  and  after 
a  further  large  per  cent  of  the  remainder  has  by  percolation  or 
seepage  slowly  settled  down  beyond  the  reach  of  the  roots  of  the 
plant.  Thus  it  happens  that  the  roots  rarely  have  left  for  their  use 
20  per  cent  of  the  original  rainfall,  and  this  is  the  so-called  "  useful 
remainder."  Generally  this  remainder  is  best  expressed  as  a  per- 
centage of  what  the  soil  would  hold  were  it  completely  saturated. 
Therefore  its  absolute  quantity  will  vary  with  the  character  of  dif- 
ferent soils 

EVAPORATION  FROM  THE  SURFACE  OF  FRESH  WATER. 

MONTSOURIS    DATA    FROM    DESCROIX. 

An  approximate  idea  of  the  relation  between  the  velocity  of  the 
wind,  its  temperature,  and  its  dryness,  on  the  one  hand,  and  its  power 
to  evaporate  water  on  the  other,  may  be  obtained  by  collating  the 
data  given  by  Descroix  in  his  article  on  "  The  climatology'  of  Paris," 
in  the  Montsouris  Annuaire,  1890,  page  121.  From  the  mass  of  data 
given  by  him  I  select  the  averages  taken  according  to  the  direction 
of  the  wind,  or  wind  roses,  for  the  three  summer  months  June,  July, 
and  August,  1889,  as  these  are  the  months  during  which  crops  are 
liable  to  suffer  the  most  severely  from  droughts  and  dry  winds.  I 
give  them  in  the  following  table : 


(104) 


lo; 


Suiiinicr  icinil  ruficfi  of  cruijunition  at  Mojitfioiii 


Wind. 

^I^[lT 
tempera- 
ture. 

Dally 
minima 
of  rela- 
tive hu- 
midity. 

Evapo- 
ration 
daily. 

Hini. 
6.35 
5. 71 
4.72 
4.15 
2.37 
3.54 
3.60 
3.70 
3.17 

Total 

Direction. 

Number 
of  days. 

Hourly 
velocity. 

rainfall. 

8 
8 
5 
4 

10 
20 
20 
12 
5 

Sec.  kilo. 
12.8 
14.6 
10.1 
7.2 
11.0 
15.4 
14.3 
11.2 
14.8 

°  C. 
18.24 
19.02 
20.54 
20.08 
19.71 
18.73 
17.21 
17.00 
17.76 

Per  cent. 
45.9 
46.4 
45.4 
47.8 
55.2 
51.9 
50.8 

-      51.3 
46.6 

mm. 
0.0 

From  northeast 

4.4 

0.0 

From  .soiitbfast 

0.0 

45.8 

From  southwest - 

39.3 

Zi.S 

From  Tiortliw^st 

10.4 

0.7 

92 

1 

124.4 

1 

We  see  that  the  driest  winds,  or  those  whose  relative  humidity  is 
small,  such  as  the  north  and  east  winds,  give  a  large  evaporation,  and 
that  the  velocity  and  temperature  of  the  west  winds,  which  are  a 
little  less  than  those  of  the  southwest  winds,  does  not  compensate  for 
the  dryness,  which  latter  enables  them  to  evaporate  a  little  less  than 
the  southwest  winds. 

By  multiplying  the  average  daily  evaporation  by  the  number  of 
days  we  obtain  the  total  evaporation  from  the  saturated  paper  of  the 
Piche  instrument.  This  exceeds  the  total  rainfall,  but  we  are  not  to 
infer  that  the  evaporation  from  ground  and  leaves  must  also  neces- 
sarily exceed  the  rainfall,  although  this  is  generally  true  for  the  sum- 
mer season. 

BOSTON   DATA    FROM    E.    J.    FITZGERALD. 

The  evaporation  of  the  water  from  leaves  and  from  the  ground 
depends  upon  the  temperature,  wind,  and  humidity  of  the  air.  It  is 
a  rather  complex  result ;  if  the  above-mentioned  elements  remain  con- 
stant for  any  time  at  the  surface  of  the  mass  of  water  the  evaporation 
fi-om  that  surface  will  be  closely  represented  by  the  following  formula 
which  is  due  to  Fitzgerald,  of  Boston, 

E=0.0166  (P— p)  (1+i  W), 

where  W  is  the  velocity  of  the  wind  in  miles  per  hour ;  P  the  tension 
of  vapor  in  inches  of  mercury  corresponding  to  the  temperature  of  the 
water;  p  is  the  tension  of  vapor  corresponding  to  the  dew  point  in  the 
free  air;  E  is  the  evaporation  expressed  in  inches  of  depth  of  water 
evaporated  per  hour  under  atmospheric  pressure  between  29  and  31 
inches  of  the  barometer. 

The  evaporaticm  from  leaves  and  soils  is  usually  less  than  that  from 
water  about  in  the  proportion  in  which  the  soil  approximates  its 


106 

state  of  maximum  saturation,  or  in  proportion  as  the  leaf  can  tran- 
spire moisture  through  its  cell  walls. 

Therefore  any  ^observations  of  evaporation  that  we  may  make  for 
comparative  purposes  can  give  us  only  the  relative  evaporating 
power  of  the  wind  and  not  the  absolute  evaporation  from  plants  and 
soils. 

THE    PICHE    EVAPORIMETER. 

The  simplest  apparatus  for  observing  evaporation  is  that  known 
as  the  Piche  evaporimeter.  This  consists  of  a  glass  tube  closed  at 
the  top  and  hung  in  a  free  exposure ;  the  tube  is  less  than  half  an  inch 
in  diameter  and  filled  wdth  Avater;  its  lower  open  end  is  closed  by  a 
horizontal  disk  of  bibulous  paper  about  twice  the  diameter  of  the 
tube;  the  water  evaporated  from  this  paper  is  supplied  from  within 
the  tube.  The  observer  has  simply  to  read  the  height  of  the  water 
in  the  tube  as  it  slowly  descends  hour  by  hour.  The  number  so 
read  oif  is  easily  converted  into  one  that  expresses  the  depth  of  water 
evaporated  per  hour  from  unit  surface. 

The  following  table  from  Montsouris  Annuaire,  1888,  page  254, 
shows  the  average  evaporation  thus  determined  by  an  instrument 
placed  in  the  shade,  also  the  corresponding  temperatures  and  other 
data,  as  observed  at  Montsouris  during  thirteen  years. 

Evaporation  at  Montsouris. 
[Averages  for  1873-1885.] 


Number 
of  days. 


Temper- 
ature of 
air  in 


Tension 

of  vapor 

in  air. 


Relative 

hu- 
midity. 


Hourly 
velocity 
of  wind. 


Hourly 
evapora- 
tion. 


January . . . 
February.. 

March 

April 

May 

June 

July 

August 

September 
October  . . . 
November 
December . 


3.6 
6.0 
9.1 
12.? 
16.3 
20.0 
22.0 
21.6 
17.6 
12.5 
8.0 
3.6 


mm. 
4.8 
5.4 
5.4 
6.3 
7.4 
10.1 
11.1 
11.4 
10.2 
8.0 
6.2 


Per  cent. 
80.9 
77.0 


57.3 
54.0 
58.2 
56.5 
59.4 
68.0 


77.5 

82.4 


Kilom. 
15.9 
16.1 
17.8 
17.6 
17.5 
15.3 
14.7 
15.7 
14.4 
15.4 
18.1 
15. 6 


mm. 
0.084 
.101 
.187 


.254 
.234 
.154 


THOMAS    RUSSELL  S   OBSERVATIONS. 


Prof.  Thomas  Russell,  of  the  Signal  Office,  has  published  results 
of  some  observations  on  the  effect  of  the  wind  on  the  evaporation 
from  the  disks  of  the  Piche  evaporimeter.  (See  Annual  Report 
Chief  Signal  Officer,  1888,  p.  17(5,  oi-  Monthly  Weather  Review,  1888, 


107 

p.  235.)  He  finds  that  with  the  toiuperature  of  the  air  84°  F.  and  a 
relative  humidity  50  per  cent  tlie  evaporation  varies  with  the  velocity 
of  the  wind  at  the  surface  of  the  moist  disk  as  in  the  following  para- 
graph : 

INFLUENCE   OF   THE    WIND   ON    EVAPORATION. 

At  5  miles  an  hour  the  evaporation  is  2.2  times  that  in  a  calm;  at  10 
miles,  3.8  times;  at  15  miles,  4.9  times;  at  20  miles,  5.7  times;  at  25 
miles,  6.1  times;  at  30  miles,  6.3  times. 

The  observations  of  the  Piche  instruments,  as  exposed  in  Signal 
Service  shelters  at  18  different  stations,  gave  the  results  in  the  table 
following.  (See  Monthly  Weather  Review,  September,  1888,  p.  236.) 
The  readings  on  the  scale  of  the  Piche  instrument  have  been  con- 
verted into  depths  of  water  that  would  be  evaporated  from  a  free 
surface  of  water  within  the  same  instrument  shelter  during  the 
respective  months  by  multiplying  them  by  the  constant  coefficient 
1.33,  so  that  the  evaporations  here  given  in  inches  of  depth  of  water 
correspond  entirely  to  the  ordinary  methods  of  measuring  rainfall. 

Evaporation,  in  incites,  ohserved  with  Piche  instruments  irithin  the  Signal  Slervice 
thermometer  shelters  in  1888. 


July. 


Septem- 
ber. 


Boston 

New  York 

Washington . . 

"Buffalo 

Cincinnati 

Memphis 

New  Orleans . 

Chicago 

St.  Louis 

Keeler 

Yuma 

El  Paso 

Dodge  City . . 
San  Antonio. 


Denver    

St.  Vincent - 

Helena 

Boise  City.. 


Incites. 
5.16 
4.49 
4.64 


Inches. 
5.87 
5.36 
5.27 


Inches. 
5.28 
4.14 
4.22 


6.22 
5.33 

5.59 
6.18 
11.66 
13.86 
13.91 
7.80 
2.76 
7.01 
9.42 
5.63 
4.88 
5.83 


6.93 
5.24 
9.38 
5.52 

5.79 
12.76 
13.63 


5.36 
4.57 
7.96 
6.97 
4.41 
12.69 
12.88 
11.54 
6.22 
5.36 
5.44 
8.55 
5.97 
7.80 


Inches. 
2.68 
2.88 
2.52 
3.70 
5.33 
3.86 
3.70 
5.79 
4.61 
10.95 
10.36 
10.00 
6.07 


5.94 
6.86 


"  In  October  at  Boise  City  the  evaporation  was  7.60  inches. 

Profesor  Russell  has  also  devised  the  following  very  satisfactory 
formula  connecting  the  total  daily  evaporation  in  inches  with  the 
meteorological  elements  on  which  it  depends,  viz,  the  vapor  tensions, 
pu:  for  mean  wet  bulb  and  p,i  for  mean  dew-point  temperatures,  (b) 
barometric  pressure,  b}'  means  of  which  he  has  been  able  to  compute 


108 

the  possibilities  of  evaporation  within  Signal  Service  shelters  over 
the  whole  country  for  an  average  wind  velocity. 

Daily  evaporations:  y     1.96y>,„-|-43.9(/?w — pa) 

His  results  in  this  respect  are  platted  on  chart  No.  VI  of  the 
Monthly  Weather  Review,  September,  1888,  and  show  that  the  total 
annual  depth  of  evaporation  has  its  maximum  of  over  1)0  inches  in 
southern  Arizona,  California,  and  New  Mexico,  whence  it  dimin- 
ishes to  a  minimum  of  20  inches  annually  in  the  northwest  corner  of 
the  State  of  AVashington  and  thence  eastward  to  Maine.  These  fig- 
ures, like  his  formula,  take  no  account  of  the  wind,  because  within 
the  Signal  Service  shelters  the  wind  is  reduced  to  a  velocity  far  less 
than  that  in  the  open  air.  These  figures,  therefore,  represent  the 
evaporation  in  open  air  only  when  there  is  no  wind  above  some 
small  limit — say  6  miles  per  hour  but  may  be  adapted  to  strong  winds 
by  the  use  of  the  figures  given  in  the  first  paragraph  of  this  section. 

CULTIVATION   DIMINISHES   SURFACE-SOIIi  EVAPORATION. 

The  general  effect  of  cultivation  is  to  pulverize  the  upper  soil ; 
this  protects  the  capillary  roots  from  surface  exposure,  it  breaks  up 
the  capillary  outlets  of  the  moisture  in  the  soil,  checks  the  natural 
evaporation  that  goes  on  at  the  surface,  and  thus  preserves  the  water 
within  the  soil  for  the  use  of  the  plants.  Dr.  E.  L.  Sturtevant's 
observations  show  that  the  extent  to  which  the  water  is  thus  con- 
served by  cultivation  during  the  months  from  May  to  September, 
1885,  at  Geneva,  N.  Y.,  may  be  thus  expressed:  With  a  rainfall  of 
14.42  inches  the  cultivated  soil  evaporated  1.4  inches  less  than  the 
uncultivated  naked  soil  and  2.25  inches  less  than  the  soil  covered 
with  sod.  In  other  words,  the  efficiency  of  the  soil  to  retain  useful 
water  is  increased  by  cultivation  to  an  extent  equivalent  to  10  per 
cent  of  the  rainfall.  If  the  capillary  connections  between  the  soil 
in  the  neighborhood  of  the  roots  and  the  supply  of  moisture  lower 
down  be  broken  no  supply  of  moisture  can  come  up  from  below,  but 
if  the  soil  be  well  rolled  the  compacting  will  aid  the  capillary  attrac- 
tion and  the  plants  will  secure  moisture  from  below.  Again,  when 
weeds  are  allowed  to  grow  freely  the  injury  to  the  crops  is  not  due 
to  robbing  the  soil  of  nutrition  nor  to  their  shading  the  ground,  but 
principally  to  their  robbing  the  soil  of  its  moisture.  Those  who  can 
with  impimity  allow  weeds  to  grow  must  have  soils  containing  an 
excessive  moisture,  which  they  thus  get  rid  of,  while  those  who  have 
a  comparatively  dry  soil  must  destroy  the  weeds  in  order  to  reserve 
moisture  for  the  use  of  their  crops.     (Agr.  Sci.,  Vol.  I,  p.  216.) 


109 


PERCOLATION. 

The  permeation  of  water  through  soils  of  different  qualities  has 
been  studied  by  WelitschUowsky  (AVoIhiy,  1888,  X.  p.  20:1.)  He 
maintained  a  layer  of  water  at  a  constant  height  above  the  material 
through  Avhich  it  permeated ;  therefore  the  pressure  forcing  the  water 
through  was  constant.  He  found  that  the  quantity  of  flow  increased 
at  first  rapidly,  then  slowly  for  several  days,  depending  on  the  thick- 
ness of  the  stratum  of  soil  and  the  pressure  of  the  water,  until  the 
permeation  reached  the  maximum;  then  the  rate  of  flow  diminished 
slightly  for  a  day  or  two  until  it  became  constant.  He  found  that 
the  quantity  of  water  delivered  in  a  unit  of  time  has  no  simple  rela- 
tion to  the  pressure  forcing  it  through  the  soil  or  to  the  thickness  of 
the  layer  of  soil  through  which  it  flows,  but  the  relation  is  more 
nearly  expressed  as  follows:  If  the  pressure  be  increased  by  regular 
additions  the  flow  of  water  increases  in  an  arithmetical  progression 
such  that  the  quantity  equals  (A)  plus  a  constant  factor  (D)  times 
the  pressure  (P)  less  unity;  A-f-D  (P — 1).  The  numerical  values 
of  these  terms  can  be  deduced  from  his  extensive  tables  of  experi- 
ments, of  which  the  following  table  is  an  abstract: 


Size  of 
grains. 

Maxi- 
mum 
capac- 
ity for 
water.a 

Intensity  of  flow,  in  liters,  per  minute. 

Soil. 

Layer  of  soil  50  cm.  thick. 

Layer  of  soil  100  cm. 
thick. 

Head  of  water  pressure. 

Head  of  water  pres- 
sure. 

10  cm. 

50  cm. 

100  cm. 

10  cm. 

50  cm. 

100  cm. 

Fine  sand 

mm. 
0.33 
0.33-1.0 
1.0  -2.0 
2.0  -4.0 
4.0  -7.0 

90.86 
71.46 
52.59 
19.37 
13.44 

0.00013 
0.106 
1.173 
6.747 
11.703 

0.00022 
0.179 
1.886 
9.594 
16.347 

0.00031 
0.273 
2.776 
13.137 

Average  sand 

0.096 
1.011 
6.435 
11.015 

0.126 

0.167 

Small  gravel 

8  034       10  015 

Average  gravel 

13.555   

"  The  capacity  for  water  is  expressed  as  a  percentage  of  the  weight  of  the  dry  soil. 

The  general  laws  of  the  flow  of  waters  through  soils  of  difi'erent 
natures  have  been  elaborately  investigated  by  Milton  AMiitney  in  a 
series  of  pajjers  published  in  Agricultural  Science,  Volume  IV,  to 
which  the  reader  must  refer  for  the  details. 

The  percolation  of  water  through  the  soil,  whether  it  goes  down- 
ward as  drainage  or  upward  to  be  evaporated  from  the  surface, 
depends  not  merely  upon  the  degree  of  comminution  of  the  soil  and 
its  compactness,  but  also,  among  other  things,  to  a  slight  extent,  upon 
the  barometric  pressure  of  the  atmosphere,  so  that  a  falling  barometer 
is,  according  to  E.  S. -Goff,  generally  accompanied  by  a  corresponding 
increase  in  the  rate  of  drainage  or  of  percolation  downward.  (Agr. 
Sci.,  Vol.  I,  p.  173.) 


110 


AVAILABLE   MOISTURE. 

In  his  investigations  as  to  the  relation  of  atmospheric  precipita- 
tion, esj^ecially  rainfall,  to  the  plants  and  the  soil,Wollny  shows  that 
the  percentage  of  water  in  the  layer  of  soil  containing  growing  plants 
increases  from  above  downward  as  soon  as  the  downward  movement 
of  the  rain  water  in  the  soil  ceases,  but  that  the  percentage  increases 
from  below  upward  while  the  rain  is  falling  and  so  long  as  the  water 
continues  to  be  penetrating  doAvnward.  The  frequency  of  rainfall 
is  of  even  greater  importance  than  the  quantity.  Slight  rainfalls 
that  only  wet  the  soil  to  the  depth  of  a  few  millimeters  do  but  little 
good  to  the  vegetation,  because  the  greater  part  of  the  water  is 
quickly  evaporated  back  again  into  the  atmosphere.  If  it  should 
rain  daily  2  millimeters  during  the  three  summer  months,  then,  even 
with  this  abundant  precipitation  the  plants  might  die  for  want  of 
water,  whereas  if  this  total  of  180  millimeters  were  uniformly 
divided  into  ten  or  twelve  rains  during  the  three  summer  months  it 
would  be  considered  a  remarkably  favorable  growing  season,  since 
under  these  conditions  the  earth  would  be  wet  down  to  a  considerable 
depth  and  the  water  thus  stored  up  is  protected  from  evaporation. 
Therefore,  for  equal  quantities  of  rain  its  value  for  agriculture 
increases  as  the  number  of  rainy  days  diminishes,  and  diminishes  as 
the  number  of  rainy  days  increases,  at  least  up  to  a  limit  that  varies 
with  the  character  of  the  soil. 

In  order  to  attain  precise  ideas  on  this  subject,  Haberlandt  set  out 
a  series  of  glass  tubes  full  of  dry  earth ;  each  received  at  the  begin- 
ning a  certain  quantity  of  water,  and  by  weighing  these  from  day  to 
day  he  determined  the  loss  due  to  evaporation.  These  losses  are 
given  in  the  folloAving  table,  in  percentages  of  the  original  quantity 
of  water,  which  latter  may  be  considered  as  a  rainfall  whose  depth  is 
given  at  the  top  of  the  column : 


Initial  rainfall  September ; 
Loss  by  evaporat ion 

September  21 

September  22 

September  23 

September  24- 

September  25 

September  26 

September  27 

September28 

September  29 

September  30 

October  5 

October  10 


[)  in  millimeters. 
in  percentages. 


94.75 
5.68 


Total  in  20  days J00.43 


39.51 
17.02 
18.85 
12.16 
7.29 
3.04 
1.82 


26.34 
10.22 
14.87 
14.56 


5.89 
5.58 
4.34 
2.48 
2.79 


14.78 
10.09 
13.39 
11.82 
7.30 
8.17 
3.48 


1.74 
5.55 
2.09 


9.81 

7.75 
10.33 


1.86 
1.76 
6.31 

2.89 


7.48 
9.05 
8.09 
7.05 
6.70 
3.48 
3.04 
2.61 
2.00 

2.95 


Ill 

These  experiments  give  us  some  idea  as  to  what  percentage  of  the 
rainfall  remains  in  the  soil  for  the  use  of  the  plant  in  the  case  of 
large  and  small  rains,  but  do  not  quite  answer  the  question  how  one 
and  the  same  quantity  of  rain  is  utilized  in  moistening  the  earth 
when  it  is  distributed  through  a  larger  or  smaller  number  of  rainy 
days. 

On  this  latter  question  Wollny  has  made  the  following  experi- 
ment: A  quantity  of  water  corresponding  to  a  rainfall  of  ()0  milli- 
meters was  communicated  to  an  experimental  tub,  Xo.  1,  all  at  once, 
while  in  tub  Xo.  2,  30  millimeters  were  given  the  first  time  and  the 
remaining  30  after  three  days;  in  the  third  tub  20  millimeters  were 
given  at  first  and  20  millimeters  every  other  day  thereafter,  and, 
finally,  in  the  fourth  tub,  10  millimeters  were  given  every  day,  so 
that  in  six  days  all  had  received  the  same  quantity  of  water.  These 
experiments  were  repeated  for  different  kinds  of  soil  and  the  results 
show  that  in  all  cases  the  quantity  of  water  lost  by  evaporation  is 
larger  the  more  frequently  the  water  was  communicated  or  the  greater 
the  number  of  rainy  days.  A  fine  illustration  of  the  truth  of  this 
principle  as  applied  to  practice  is  narrated  by  Haberlandt,  who  found 
that  in  1874  the  farmers  at  Postelberg  got  much  better  crops  than 
those  at  Lobositz,  which  could  only  be  attributed  to  the  fact  that 
during  that  year  Postelberg  had  received  246  millimeters  of  rain- 
fall in  forty  days,  or  an  average  of  6,  whereas  Lobositz  had  received 
309  millimeters  in  seventy-seven  days,  an  average  of  4,  so  that  the 
usefulness  of  the  gi'eater  quantity  of  rain  in  Lobositz  did  not  equal 
that  of  the  smaller  quantity  at  Postelberg. 

Wollnj^  shows  that  since  the  period  of  the  heaviest  rainfall  occurs 
throughout  central  Europe  at  the  time  of  the  largest  evaporation 
from  the  soil  we  must  conclude  that  for  the  naked  earth  the  Avetting 
of  the  soil  during  the  warmer  season  of  the  year  is  controlled  much 
more  largely  by  the  rainfall  than  by  the  evaporation  depending  on 
the  temperature.  His  observations  with  the  lysimeter  show  that  the 
precipitation  is  principally  concerned  in  the  moistening  of  the  naked 
soil  during  the  Avarmer  season,  while  the  influence  of  the  temperature 
and  the  resulting  evaporation  nearly  disappears  and  is  only  observ- 
able in  periods  that  are  deficient  in  rain.  In  most  cases  the  vegeta- 
tion is  injured  Avhen  the  atmospheric  precipitation  during  the  coldest 
season  of  the  year  is  insufficient.  The  precipitation  at  this  time  of 
the  year  is  therefore  quite  as  important  for  the  success  of  the  harvest 
as  that  which  falls  during  the  period  of  vegetation.  (WoUny's 
Forschungen,  Vol.  XIV,  pp.  138-101.) 

A.  Seignette  has  shown  that  the  law  of  levels  propounded  by 
Royer  is  confirmed.  This  law  states  that  for  given  plants  and  for 
other  uniform  conditions  the  reserve  nutriment  in  the  earth  is  always 
found  at  a  constant  distance  below^  the  surface;    thus  the  bulbs  of 


112 

a  plant  under  given  conditions  are  found  at  a  given  level,  and  if  we 
change  these  conditions  as  to  moisture,  temperature,  etc.,  we  shall 
change  the  distance  from  the  surface  down  to  this  level.  (Wollny's 
Forschungen,  Vol.  XIV,  p.  132.) 

TRANSPIRATION. 

The  quantity  of  water  transpired  by  trees  and  plants  depends  upon 
the  amount  of  water  at  their  disposal,  as  well  as  on  the  temperature 
and  dryness  of  the  air,  the  velocity  of  the  wind,  the  intensity  of 
sunlight,  the  stage  of  development  of  the  plant,  the  amount  of  its 
foliage,  and  the  nature  of  its  leaf.  The  following  are  some  of  the 
results  of  measurements  at  European  experiment  stations.  (See 
Fernow,  Report,  1889,  p.  314.) 

F.  B.  Hoehner  found  that  the  transpiration  per  day  per  100  grams 
of  dry  weight  of  leaves  is  for  conifers  4.778  to  4.990  grams,  but  for 
deciduous  trees  about  ten  times  as  much,  44.472  to  49.553.  During 
the  whole  period  of  vegetation  a  unit  weight  of  dry  leaves  corre- 
sponded to  a  total  weight  of  evaporated  water,  as  shown  by  the  fol- 
lowing table,  for  three  diflferent  years. 

Transpiration  of  tratcr  corresponding  to  c/rontJi  of  unit  weight  of  dry  leaves. 


Plant. 

1878. 

1879. 

1880. 

Plant. 

1878. 

1879. 

1880. 

Birch  and  linden 

650 
550 
475 
425 

1,000 
700 
600 
5.50 

90 
101 
91 
70 

Oaks 

250 
60 
35 
35 

400 
150 
100 
75 

59 

Ash 

Spruce  and  Scotch  pine. 
Fir 

13 

Beech 

9 

Maple 

Black  pine 

7 

The  variability  of  transpiration  is  shown  by  the  action  of  a  birch 
in  the  open  air,  which  transpired  on  a  hot  summer  day  from  700  to 
900  pounds,  while  on  other  days  it  probably  transpired  not  more 
than  18  to  20  pounds.  A  beech  about  60  years  old  had  35,000  leaves, 
whose  total  dry  weight  was  9.86  pounds;  hence  its  transpiration,  at 
the  rate  of  400  j^ounds  of  water  per  pound  of  leaves,  would  be  22 
pounds  daily.  An  acre  containing  500  trees  would,  during  the  total 
period  of  vegetation,  transpire  nearly  2,000,000  pounds  of  water,  or 
about  50  pounds  to  the  square  foot. 

A  younger  beech,  thirty-fi^'e  years  old,  with  3,000  leaves  and  a  dry 
weight  of  0.79  pounds,  would,  under  the  same  conditions,  transpire 
470  pounds  per  pound  or  2|  jiounds  per  day  from  June  to  November. 
An  acre  containing  1,600  such  trees  would  transpire  about  600,000 
pounds  per  acre  or  15  pounds  to  the  square  foot  from  June  to 
November. 

Of  the  entire  mass  of  wood  and  foliage  on  an  acre  of  forest  from  56 
to  60  per  cent  of  the  weight  is  water  and  44  to  40  per  cent  dry  sub- 


113 

stance.     In  agricultural  crops  the  amounts  of  water  are  still  larger, 
sometimes  reaching  95  per  cent  of  the  whole  weight. 

The  amounts  transpired  by  cereals,  grasses,  weeds,  etc.,  are  consid- 
erably larger  than  the  preceding,  as  shown  by  the  following  table 
compiled  from  AVollny's  results,: 


Plant.  . 

Year. 

Begin- 
ning of 
vegeta- 
tion. 

End  of 
vegeta- 
tion. 

Water  consump- 
lion  per  acre. 

Pounds. 

Inches. 

1879 

Apr.  20 

Aug.    3 
....do.-. 

2,590,000 
2,720,000 
3,140,000 
3,070,000 
3,000,000 
3,420,000 

3, 140,  aw 

4,110,000 

10 

1879 

---.do.  . 

11 

Peas                                                                                     187P 

do 

do 

12 

Red  clover 

1879 

do 

Oct.     1 
Aug.  14 
Sept.  14 
Sept.  10 
Oct.     1 

12 

Summer  rye 

Oats - 

Beans 

iiil 

5     0     O     O 

12 

14 
12 
16 

The  following  table  is  given  by  Risler  (1873)  in  his  "  Note  on  the 
diminution  of  the  volume  of  water  courses,"  and  shows  the  mean  daily 
consumption  of  Avater  by  plants,  expressed  in  millimeters  of  depth 
of  water  over  the  area  of  the  field : 


Plant. 

Daily  con- 
sumption of 
water. 

Plant. 

Daily  con- 
sumption of 
water. 

mm. 
3.4-. ..7.0 
3.1. ...7.3 
2.9.. ..4.9 

3.0+ 

2.8--. -4.0 
2.7.. -.2.8 

Clover     

mm. 

2.9 

Rye 

2.3 

Oats 

Vine         

0.9....1.3 

Beans 

Potatoes 

0.7    .1.4 

Maize 

0.5....1.1 

Wheat 

Oak  forest 

0.5... .0.8 

These  numbers  have  been  deduced  from  the  results  of  many  years  of 
experiments  in  the  laboratory  and  from  observations  made  in  a 
drained  field  under  conditions  favorable  to  this  kind  of  research. 
The  crops  have  necessarily  varied  from  one  year  to  another,  but 
unfortunately  I  am  not  acquainted  Avith  these  details. 

The  transpiration  of  the  plant  is  only  a  means  to  an  end.  (See 
Marie-Davy,  1875,  p.  209.)  Its  object  is  the  introduction  into  the 
vegetable  organism  of  the  mineral  elements  necessary  for  the  develop- 
ment of  its  tissues  and  that  of  the  other  principles  united  there. 
The  experiments  of  Woodward  and  those  of  Lawes  have  already 
shown  us  that  the  same  quantity  of  water  is  not  always  necessary 
in  order  to  furnish  the  same  amount  of  mineral  substance  and  to 
produce  in  the  plant  all  the  elaboration  and  movements  of  organic 
products  which  should  be  produced  there. 

It  appears  evident  that  in  soils  more  or  less  fertile  and  which  con- 
2667—0.5  M 8 


114 

tain  in  unequal  quantities  soluble  and  nourishing  principles  the 
water  absorbed  by  the  roots  may  be  more  or  less  charged  with  these 
elements.  We  can  understand,  then,  that  the  quantity  of  water 
necessary  to  enable  a  plant  to  furnish  a  given  result  is  not  the  same 
for  all  soils,  and  that  the  richest  soils  may  produce  a  greater  result 
with  a  proportionably  smaller  consumption  of  water.  By  increasing 
the  richness  of  the  soil  in  soluble  substances  that  can  be  assimilated, 
Ave  should  succeed  in  economically  reducing  the  quantity  of  Avater 
consumed  by  the  crops.  In  any  case  we  might  at  the  same  time  ask 
ourselves  if  all  the  water  absorbed  by  the  roots  and  introduced  into 
the  plant  is  utilized  by  it  and  at  what  limit  the  richness  of  the  water 
should  be  arrested  so  as  to  be  really  profitable  to  the  plant.  In  this 
connection  Marie-Davy  cites  the  following  fact,  mentioned  by  Perret 
in  the  Journal  of  Practical  Agriculture  for  1873 : 

In  Perret's  experiments  a  meadow  having  been  covered  with  a  suffi- 
cient quantity  of  nitrate  of  soda  for  a  nitrogenous  manuring  of  four 
years,  the  grass  was  magnificent  in  the  spring.  This  grass  was  given 
green  to  the  horses,  who  before  long  began  to  show  strong  diuretic 
symi^toms  accompanied  by  raging  thirst.  These  animals  seemed  to 
be  completely  under  the  influence  of  the  administration  of  a  strong 
dose  of  nitrate.  The  following  year  there  was  a  complete  cessation 
of  the  beneficial  effects  of  the  nitrate  on  the  meadow,  which  showed 
conclusively  that  the  plants  of  the  first  year  contained  nitrate  in  a 
natural  state  and  not  decomposed  by  the  assimilation. 

When  nutritive  substances  are  given  to  plants  in  abundance  they 
can  absorb  a  quantity  of  these  elements  besides  what  is  necessary  for 
their  nourishment.  This  is  particularly  true  when  in  the  series  of 
minerals  which  compose  a  normal  nourishment,  one  of  these  sub- 
stances is  in  excess  of  the  others.  Besides,  if  we  compare  the  chemical 
composition  of  a  crop  cut  green  with  that  of  a  similar  crop  after 
arriving  at  maturity,  we  find  that  in  the  latter  there  is  a  diminution 
in  Aveight  of  several  of  the  substances  present  in  the  former.  It 
would,  therefore,  have  been  interesting  to  know  if  the  trouble  men- 
tioned by  Perret  was  continued  with  the  same  intensity  in  the  dry  hay. 

RELATION  OF  PLANTS  TO  MOISTURE  OF  SOIL. 

E.  WoUny  (1887,  Vol.  X,  p.  320)  gives  some  results  as  to  the  influ- 
ence of  plants  and  shade  on  the  moisture  of  the  soil,  being  a  modifica- 
tion of  a  memoir  published  by  him  in  1877.  His  conclusions  are  as 
follows : 

(1)  The  water  contained  in  the  soil  under  a  covering  of  living 
plants  is,  during  the  growing  season,  always  less  than  in  a  similar 
layer  of  fallow,  naked  soil. 


115 

(2)  Tlio  caiiso  of  tho  dning  iii)  of  the  soil  by  the  plants  is  to  be 
foMiul  in  the  very  considerable  transpiration  of  aqueous  vapor  by 
their  leaves. 

(8)  The  plants  deprive  the  soil  of  water  in  proportion  as  they 
stand  eloser  together  and  have  developed  their  tops  more  luxuriantly. 
V  (4)  The  influence  of  the  vegetation  on  the  moisture  of  the  soil 
extends  to  the  deeper  layers  of  soil. 

^  (5)  The  moisture  of  the  soil  under  a  layer  of  inert  objects,  such 
as  dead  plants,  manure,  straw,  pieces  of  wood,  windfalls,  etc.,  is 
always  greater  than  that  of  the  uncovered  soil. 

(6)  The  retention  of  the  moisture  in  the  soil  under  a  cover  of  dead 
matter  is  a  consequence  of  the  protection  a  Horded  l)y  the  latter  against 
the  influences  that  favor  evaporation. 

(7)  The  quantity  of  moisture  in  the  soil  is,  wnthin  certain  limits 
and  to  a  depth  of  about  5  centimeters,  or  2  inches,  greater  in  propor- 
tion as  the  covering  of  dead  matter  is  thicker, 

\  (8)  The  soil  shaded  by  living  plants  is,  under  otherwise  similar 
conditions,  driest  during  the  growing  period,  but  that  covered  by 
dead  objects  is  the  moistest,  while  that  which  is  not  cultivated,  not 
covered  with  plants  and  naked,  is  midway  between  the  two  previous 
in  reference  to  its  relations  to  moisture. 

Wollny  has  also  studied  the  influence  of  plants  and  shade  upon  the 
drainage  of  water  from  the  soil.     His  conclusions  are : 

v(l)  A  notably  smaller  quantity  of  water  drains  through  the  soil 
supporting  living  plants  from  the  same  quantity  of  rainfall  than 
through  a  naked  soil  during  the  growing  season. 

1/(2)  The  quantity  of  drainage  in  cultivated  fields  is  less  in  pro- 
portion as  the  plants  stand  more  closely  together  and  in  proportion 
as  they  have  developed  themselves  more  luxuriantly. 
^  (3)  The  quantity  of  drain  water  from  a  soil  covered  by  inert 
objects  is  increased  in  comparison  with  that  from  fallow  land  in 
proportion  as  the  covering  layer  is  thicker,  up  to  a  certain  limit,  up 
to  about  5  centimeters,  beyond  which  a  further  increase  in  the  thick- 
ness of  the  covering  steadily  diminishes  the  quantity  of  drainage 
water. 

^  (4)  For  the  same  quantity  of  rain  and  under  otherwise  similar 
circumstances,  the  soil  covered  with  dead  leaves  and  similar  objects 
furnishes  the  greatest  quantity  of  drainage  water  up  to  a  covering 
of  about  .5  centimeters  thickness;  the  naked,  fallow  land  furnishes 
the  next  smaller  quantity  of  water;  the  soil  covered  with  livnig  plants 
furnishes  the  least  quantity  of  drain  water. 


llf> 

RELATION   OF   "WATER   TO   CROPS. 

E.  A\V)llny  has  studied  the  rehitioii  of  the  irrigation  and  rainfall  to 
the  development  and  productive  poAver  of  plants  in  cultivated  fields, 
and  the  following  sununarv  is  essentially  as  given  by  him  in  Volume 
X  of  his  Forschungen  for  1888,  page  153. 

An  early  investigation  of  this  subject  was  made  by  Ilionkotf,  who 
filled  five  large  tubs  with  soil  and  sowed  buckwheat  in  each  on  the 
loth  of  May;  each  tub  was  then  watered  regularly  with  a  definite 
quantity  of  water,  the  total  quantity  used  being  given  in  the  second 
column  of  the  table  following.  The  relative  quantities  of  buckwheat 
harvested  at  the  end  of  the  season  are  given  in  the  third  column  and 
the  straAv  is  given  in  the  fourth  column.  The  weight  of  the  buck- 
wheat originally  sown  in  each  tub  was  the  same,  viz,  0.154  gram. 


Total 
water 

ap- 
plied. 


Weight  of  green  har- 
vest. 


Grain.!  Straw, 


Sum 
total. 


Weight  of  dry  „ 
harvest.         Num- 
ber 
of  ker- 
I    nels 
Grain.  Straw.  I    har- 
i  vested. 


Ratio 

of 

straw 

and 

kernels 

to  the 

seed. 


2 

3 
4 


Liters 
25.00 
12.50 
6.25 
3.12 
1.56 


6.15 
1.95 
.58 
.10 


Grams. 
26.10 
58.85 
23.03 
9.42 
2.20 


Grams, 
27.99 
65.00 
24.98 
10.00 
2.30 


Grams.  Grams. 


1.68 
5.47 
1.73 
.52 
.09 


4.52 
8.47 
4.55 
1.41 
.30 


These  figures  show  plainly  that  the  plants  in  tub  No.  2  were  most 
favorably  situated.  Probably  No.  1  had  too  much  water  and  Nos.  3, 
4,  and  5  too  little. 

Haberlandt,  in  18G(),  experimented  on  the  quantity  of  water  needed 
in  the  growth  of  plants  in  three  plats  of  14.41  square  meters  each; 
of  these  No.  1  received  no  artificial  watering;  No.  2  was  watered  once 
a  w^eek,  except  in  great  droughts  tAvice  a  week;  No.  3  received  a 
double  quantity  once  a  week.  These  quantities  corresponded  to  a 
rainfall  of  6.46  millimeters  for  No.  2  and  13.92  millimeters  for  No.  3. 
The  total  quantities  for  the  season  Avere  96.96  and  193.92  millimeters. 
The  natural  rainfall  Avas  as  follows: 


K^y^  Rainfall. 


March 17  i 

April 15  ! 

May 11  I 

June - 13  I 

July. _. 17  i 

Total 73  I 


mm. 
40.98 
35.38 
52.20 
46.03 
34.40 


208.99 


117 

The  miinhor  of  rainy  days  was  lar«2:e,  but  the  rainfall  was  small, 
and  the  plants  in  bod  No.  1  sutiVrod  for  want  of  water.  The  relative 
harvests  for  the  ditferent  beds  and  crops  were  as  follows: 


Plant  and  \ied. 

Harvest  (rela- 
tive numbers). 

Plant  and  bed 

1  Harvest  (rela- 
tive numbers). 

Grain. 

Straw. 

Grain. 

Straw. 

Wheat: 

1. 

2 

100 
132 
172 

100 
136 
161 

100 
129 
164 

100 
124 
219 

Barley: 

1 

2.. 

3 

Kfl 

10!) 

100 
105 
123 

100 
116 

3 

Rye: 
1... 

Oats: 

1 

2 

100 

133 

2 

3 

3 

1        182 

126 

Beds  Nos.  1  and  2  showed  about  the  same  rate  of  growth.  No.  ?> 
showed  a  retardation.  The  barley  and  the  rye  were  harvested  from 
this  bed  four  days  later  than  from  the  other  two.  The  quantity  of 
harvest  increased  with  the  quantity  of  water,  and  the  harvest  of 
grain,  except  in  the  case  of  the  wheat,  was  more  increased  by  water- 
ing than  w^as  the  harvest  of  straw ;  the  quality  of  the  grain  show^ed 
only  slight  differences. 

Hellriegel  experimented  (1867-1883)  on  the  influence  of  w^ater 
upon  the  crops.  He  filled  a  number  of  vessels  with  quartz  sand  and 
maintained  the  earth  at  a  different  state  of  dryness.  The  exjDeri- 
ments  were  repeated  for  several  years  on  wheat,  rye,  and  oats,  the 
general  results  being  that  wdien  the  ground  contained  from  GO  to  80 
per  cent  of  its  full  capacity  of  water  the  harvest  was  larger  than 
when  the  ground  was  drier  and  about  in  the  following  proportions: 


Tub. 

Mois- 
ture. 

Wheat  crop. 

Bye  crop. 

Oat  crop. 

.Straw. 

Grain. 

Straw. 

Grain. 

Straw.  Grain. 

Per  ct. 

1 

80-60 

22 

11.0 

16 

10 

16           12 

2 

60-40 

21 

10.0 

15 

10 

14            11 

3 

40-20 

15 

8.0 

12 

8 

13             8 

4 

20-10 

7 

2.8 

12 

4 

4             2 

Hellriegel  also  varied  the  experiment  by  giving  the  tubs  daily, 
each  evening,  as  much  water  as  they  had  lost  during  the  day,  thus 


118 


maintaining  a   very   constant   state  of  moisture   in  each, 
following  results: 


with   the 


Tub. 

Con- 
stant 
mois- 
ture. 

Harvest. 

Tub. 

Con- 
stant 
mois- 
ture. 

Harvest. 

Straw. 

Grain. 

Straw. 

Grain. 

1 
2 

4 

P.  ct. 
80 
60 
40 
30 

11.0 
12.8 
11.2 
8.3 

8.8 
9.9 
10.5 

8.8 

5 
6 

7 

P.ct. 

20 
10 
5 

6.9 
3.0 
0.1 

3.3 

The  general  result,  therefore,  was  that  the  largest  harvest  is  given 
by  soil  containing  40  per  cent  of  its  maximum  capacity  for  water. 
The  general  appearance  of  the  plants  showed  that  those  having  too 
little  water  had  a  less  intensive  life  and  were  suffering  from  lack  of 
nourishment  rather  than  from  the  want  of  pure  water  itself. 

Fittbogen  (1873)  conducted  a  series  of  experiments  on  twenty 
tubs  in  groups  of  four.  The  relative  weights  of  his  harvests  of  oats 
were  as  follows : 


Tub. 

Mois- 
ture. 

Harvest. 

Tub. 

Mois- 
ture. 

Harvest. 

Straw. 

Grain. 

Straw. 

Grain. 

1 
2 
3 

P.ct. 

80-60 
6(V40 
40-30 

7.7 
6-9 

6.0 
5.3 
6.1 

4 
5 

P.ct. 
30-20 
20-10 

3.7 
0.9 

4.0 
0.6 

These  figures  show  that  for  moistures  varying  between  30  and  80 
per  cent  there  was  very  little  difference  in  the'  harvest,  Avhile  for 
drier  soils  the  harvest  was  decidedly  diminished;  but  it  is  notable 
that  for  the  driest  soil  (No.  5)  the  grain  ripened  earliest  of  all. 

Haberlandt,  in  1875,  reports  the  results  of  experiments  on  three 
tubs  sown  with  summer  wheat.  The  quantity  of  water  allowed  to 
tub  No.  1  was  just  sufficient  to  keep  the  wheat  alive;  the  other  quanti- 
ties, with  the  harvest,  are  given  in  the  following  table: 


Tub. 

Quantity 
water. 

Num- 
ber wa- 
ter- 
ings. 

Equiv- 
alent 
rain- 
fall. 

Harvest. 

Grain. 

Straw. 

1 
2 
3 

cc. 

6,200 
14,400 
24,800 

31 
36 
31 

mm. 
24.4 
56.6 
97.5 

21.8 
29.4 
41.6 

6.6 
16.4 
31.6 

Whence  it  would  seem  that  the  limit  of  useful  water  had  not  yet 
been  reached. 


119 

Birnor  (1881)  oxporimoiittHl  on  the  amount  of  water  needed  by 
potatoes.  Four  series  of  experiments  were  made,  eaeh  inchidin<;  five 
tubs  having:  dirt'erent  amounts  of  water,  as  shown  in  the  foUowing 
table,  which  mves  the  average  of  the  four  series: 


Tub. 

Mois- 

Harvest 

weight  of 

tubei-s. 

ture. 

Per 
plant. 

Aver- 
age per 
tuber. 

1 
2 
3 
4 
5 

P.ct. 
80-60 
6^40 
40-30 
30-20 
20-10 

Orarux. 
80d 

413 
313 
214 

(Jrams. 
42 
46 
42 
34 
23 

These  figures  show  a  steady  increase  in  the  amount  of  harvest  with 
increasing  moisture. 

The  student  will  notice  that  in  these  experiments  where  the  plants 
are  kept  in  tubs  under  protection  from  natural  rains  the  watering  and 
growth  go  on  under  continued  sunshine.  The  experiments  therefore 
correspond  with  the  case  of  irrigation  in  a  dry,  sunny  climate,  and  it 
is  not  to  be  understood  that  the  same  amount  of  water  deposited 
naturally  by  clouds,  with  attendant  long-continued  obstruction  of 
sunlight  and  heat  by  the  clouds,  would  have  produced  the  same  large 
crops. 

R.  Heinrich  (ISTG)  experimented  at  Mecklenburg  on  the  influence 
of  water  on  grasses  and  clover.  Ten  sets  of  tubs  filled  with  sterile 
i^^and  were  sown  with  grasses  and  clover  and  watered  daily,  with 
results  as  shown  in  the  following  table : 


Tub. 

Weight 
of  daily 
water. 

Equiv- 
alent 
daily 

rainfall. 

Harvest 
weight 

of  fresh- 
cut 
grass. 

Tub. 

Weight 
of  daily 
water. 

Equiv- 
alent 
daily 

rainfall. 

Harvest 
weight 

of  fresh- 
cut 
grass. 

(hams. 

mm. 

Grama. 

frrams. 

mm. 

fh-ams. 

1 

100 

1 

35 

6 

600 

6 

138 

2 

200 

2 

44 

r 

TOO 

7 

148 

3 

300 

3 

57 

8 

800 

8 

161 

4 

400 

4 

84 

9 

900 

9 

156 

5 

500 

5 

110 

10 

1,000 

10 

no 

This  shows  that  the  harvest  increased  steadily  up  to  8  millimeters 
of  rainfall  daily,  but  for  9  or  10  millimeters  per  day  the  increase  in 
harvest  was  so  slight  that  we  may  consider  9  millimeters,  with  an 
average  harvest  of  162  grams,  as  the  best  that  could  be  obtained  under 
the  temperature  and  sunshine  prevailing  that  year  at  Mecklenbui-g. 
Doubtless  a  differwit  quantity  of  water  would  be  required  in  order  to 
obtain  the  maximum  harvest  in  other  climates. 


120 

E.  Wollny  (1882-83)  made  seven  series  of  experiments,  in  each 
of  which  five  or  six  tubs  received  daily  different  quantities  of  water, 
except  only  that  in  the  driest  tubs  extra  water  Avas  given  for  the 
first  few  days  in  order  to  insure  the  sprouting  of  the  seeds,  and 
except,  further,  that  in  the  experiments  of  1882  the  water  was  given 
every  second  or  third  day  instead  of  daily,  w'hereby  was  brought  about 
the  rather  large  variations  in  the  moisture  of  the  earth.  The  tubs 
were  shielded  from  natural  rain,  were  of  the  same  size,  and  had  the 
same  Aveight  of  earth  and  aliment.  Nothing  is  said  as  to  whether 
special  manure  or  fertilizer  Avas  used,  but  only  that  all  w^ere  treated 
perfectly  alike  except  as  to  water ;  the  effect  of  manuring  Avas  shown 
only  in  the  case  of  Nos.  6  and  7  in  that  No.  6  w^as-  treated  like  the 
previous  ones,  Avhile  No.  7  received  a  supply  of  mixed  Peruvian  guano, 
superphosphate,  and  sulphate  of  lime,  gypsum,  or  plaster  equivalent 
to  526  kilograms  per  hectare.  Exact  measurements  were  made 
upon  six  plants  in  each  tub  in  order  to  judge  of  the  relatiA^e  harA^ests. 
An  abstract  of  Wollny's  measures  is  given  in  the  following  tables : 

EXPERIMENT  OF  1882. 


Tub. 

Mois- 
ture. 

Grain  harvest  dried  in 
air. 

Mixed 
grain. 

Sum- 
mer 
rye. 

Beans. 

Sum- 
mer 
rape 
seed. 

1 
2 
3 
4 
.5 

100-80 
80-60 
60-40 
40-20 
20-10 

4.3 
5.7 
5.1 
3.9 
0.4 

9.2 
11.1 
U.6 
3.3 
0.5 

2.4 
4.4 
4.9 
2.0 
0.25 

11.0 
13.9 
12.  r 
9.4 

1.8 

EXPERIMENT  OP  1883. 


Tub. 

Mois- 
ture. 

Grain  harvest  dried. 

Horse 
bean.a 

Summer  rape  seed. 

Not 
warmed. 

Warmed. 

1 

100 

7.4 

0.2 

0.3 

2 

80 

21.9 

3.3 

3.9 

3 

60 

14.0 

4.2 

4.3 

4 

40 

10.6 

4.6 

6.9 

5 

20 

3.5 

2.5 

2.7 

6 

10 

1.3 

0.8 

1.4 

"A  variety  of  English  or  Windsor  beans    (Faba  vulgaris)    raised  in  Europe  for  feeding 


He  concludes  that,  in  general,  the  quantity  of  harvest  is  influenced 
to  an  extraordinary  degree  by  the  quantity  of  available  water  and 
much  more  than  by  any  other  factor  of  A-egetation.     In  general  the 


121 

harvest  increases  with  increasin<i:  water  supply  up  to  a  definite  limit, 
beyond  which  the  hai-vest  diminishes  steadily  for  any  further  increase 
in  the  water  sup{)ly,  until  when  the  earth  is  completely  saturated  with 
water  the  harvest  in  some  cases  becomes  almost  nil.  The  most, 
advantageous  percentage  of  moisture  in  the  soil  varies  foi"  the  differ- 
ent plants,  depending  on  their  own  method  of  using  the  water,  on  the 
evaporation  from  their  leaves,  and  on  the  number  of  j^lants  to  the 
unit  of  area  of  the  field,  namely,  their  closeness  to  each  other. 

In  reference  to  the  needs  of  practical  agriculture  it  would  be 
improper  to  consider  in  such  experiments  as  these  only  the  water 
that  has  been  used,  since  the  number  of  plants  to  the  miit  area  is  of 
equal  if  not  greater  importance.  It  would  therefore  be  improper 
to  reason  from  these  experiments  up  to  the  needs  of  another  field  or 
tub  having  a  greater  or  less  plant  density.  Again,  as  also  shown  by 
AVollny,  more  water  is  used  in  proportion  as  more  nutriment  is  avail- 
able in  the  ground,  because  the  development  of  the  organs  of  tran- 
spiration or  the  leaves  is  thereby  increased.  Therefore,  in  general, 
the  quantity  of  water  required  to  attain  the  maximum  crop  will 
increase  with  the  richness  of  the  soil  and  the  closeness  of  the  plants  as 
well  as  the  dryness  and  velocity  of  the  wind.  For  different  crops, 
moreover,  the  absolute  quantity  of  water  wall  depend  upon  the  dura- 
tion of  the  whole  process  of  vegetation,  from  germination  to  harvest, 
(See  Wollny,  1881,  IV,  p.  109.) 

The  character  of  the  plant  affects  the  quantity  of  necessary  water, 
not  only  by  the  duration  of  the  process,  but  by  the  relative  quantity 
of  auxiliary  organs  that  the  plant  develops  in  order  to  produce  the 
ripened  seed,  which  we  call  the  harvest.  The  ratio  of  the  grain  to  the 
straw  and  chaff  when  the  maximum  crop  of  grain  is  produced  in 
each  of  Wollny's  seven  cases  is  shown  in  the  following  table : 

Ma.rirniuti  liarrrst  (IrlciJ  in  air. 


Grain. 

Straw 
chaflf. 

Ratio. 

5.7 

n.6 

4.9 
21.9 
4.6 
6.9 

12.0 
15.4 
7.6 
31.6 
15.4 
17.1 

P.ct. 
48 

n.  Peas 

75 

65 

69 

V.  Onlza  hfian  ■withnnt.  manurp! 

30 

-40 

These  percentages  show  the  success  with  which  the  plant  labors 
to  perpetuate  its  species  with  the  least  possible  waste  of  molecular 
energy  on  extraneous  matters. 


122 

Hellriegel's  experiments  gave  80  to  60  and  sometimes  40  per  cent, 
Fittbogen's  gave  40  to  30  per  cent,  Wollny's  gave  80  to  60  per  cent 
of  moisture  for  the  maximum  harvest.  These  differences  undoubt- 
edly arose,  at  least  in  part,  from  differences  in  richness  of  the  soil, 
the  closeness  of  the  plants,  and  differences  in  the  sunshine  and  wind. 
These  results  are  therefore  in  general  only  relative,  and  justify  us 
in  saying  that  the  best  crops  are  obtainable  when  the  earth  contains 
from  40  to  80  per  cent  of  its  maximum  capacity  for  water  and  that 
the  percentage  is  higher  in  proportion  as  the  soil  is  richer;  as  the 
plants  are  closer;  as  the  leaves  of  the  plants  are  broader;  as  the 
sunshine,  the  dryness  of  the  air,  and  the  velocity  of  the  wind  are 
greater ;  and  as  the  barometric  pressure  is  less,  since  all  these  increase 
the  useful  evaporation  from  the  leaves  and  the  wasteful  evaporation 
from  the  soil. 

The  growth  of  the  auxiliary  organs  was  shown  by  Fittbogen,  who 
gives  the  weight  of  the  organic  matter  as  determined  by  burning  the 
Avell-washed  roots,  and  is  also  shown  by  Haberlandt  by  the  weights 
oi  the  roots  and  stubble.  Their  measures  are  given  in  the  following 
tables : 

FITTBOGEN'S  EXPERIMENTS. 


Moisture 
in  the 
soil. 

Organic 
matter 
lost  by 
burn- 
ing. 

Per  cent. 

iitg. 

80-60 

470 

60-40 

429 

4<V30 

440 

m-)iO 

359 

20-10 

109 

HABERLANDT'S  EXPERIMENTS. 


Water. 

Weight 
of  roots 

and 
stubble. 

cc. 

Gram. 

24,800 

5.35 

14,400 

3.2 

6,200 

2.9 

123 

Again,  the  variation  in  the  stock  independent  of  the  grain  is  shown 
by  the  measurements  of  the  dimensions  of  the  heads  and  stocks  as 
given  in  the  folk)wing  tabh^s : 

OATS    (FITTBOr.KN'S   RXPEKIMENTS). 


Mois- 
ture. 

Number  1  Length 
ofshoots.1  of  heads. 

Diame- 
ter of 
heads. 

Per  cent. 
80-60 
60-40 
4(»-30 
30-20 
20-10 

8 
3 
4 
2 
4 

mm 
555 
442 
450 
250 
136 

mm. 
3.9 
4.1 
3.6 
3.3 
1.4 

SUMMER   WHEAT  ( HABERLANDTS   EXPERIMENTS). 


Water. 

Number  of  stalks. 

Height  of  stalks 
bearing  heads. 

Bearing 
heads. 

Not 
bearing 
heads. 

Shortest. 

Longest. 

cm. 

cm. 

24,800 

18 

12 

70 

95 

14,400 

12 

13 

30 

65 

6,200 

5 

16 

20 

*"> 

Similar  experiments  by  Sorauer  (1873)  give  results  analogous  to 
the  preceding.  He  measured  the  greatest  length  and  width  of  the 
leaves,  at  several  stages  of  their  growth,  of  barley  plants  in  tubs  of 
dilferent  moistures,  with  the  average  results  for  all  stages  of  growth, 
showing  that  the  leaves  were  longer  and  broader  the  more  watei-  was 
furnished,  while  the  available  nutrition  remained  the  same. 


BARLEY    (SORAI^ERS    KXl'EItl  MEXTS). 


Mois- 
ture. 

Length 
ofl4f. 

Width 
of  leaf. 

Percent. 

mm. 

mm. 

m 

182.2 

9.4 

40 

166.3 

9.1 

20 

138.7 

6.8 

10 

93.7 

5.6 

These  and  similar  observations  show  that  the  assimilating  organism 
of  the  plant  (viz,  its  leaves),  as  also  its  organism  for  absorl)ing  nutri- 
tion (viz,  its  roots),  both  alike  increase  with  the  increase  in  avail- 
able moisture  near  the  roots  in  the  earth,  at  least  within  the  limits 
existing  in  these  experiments,  and  to  the  same  extent  is  the  develop- 
ment of  the  plant   favorable   to   the   increase  of   its  productivity. 


124 

Under  such  circuinstances  it  is  not  surprising  that  the  development 
of  the  crop  of  grain  keeps  pace  with  the  increase  of  the  available 
water,  at  least  up  to  the  point  where  the  quantity  of  water  is  suffi- 
cient to  give  a  maximum  crop. 

The  supply  of  water  has  an  influence  not  merely  on  the  quantity 
of  the  crop,  but  also  on  the  rapidity  of  the  development  of  the  plant. 
Wollny  (1881)  shows  that  in  general  the  grain  ripens  sooner  as  the 
quantity  of  water  diminishes.  This  is  well  seen  in  the  following  series 
of  experiments  (Table  62)  on  the  time  of  ripening  of  grain  in  fields 
that  are  sown  more  or  less  thickly.  The  thickly  sown  fields  correspond, 
of  course,  to  a  less  quantity  of  water  available  for  each  plant. 

WINTER  RYE    ( WOLLNY,   1875-76). 


Number 

Number 

of 

of  plants 

square 

Date  of 

to  the 

centi- 

ripening 

square 

meters 

(1876). 

meter. 

to  each 
plant. 

625 

16 

July  18 

400 

25 

July  21 

229 

44 

July  28 

100 

100 

July  30 

25 

400 

Aug.    8 

PEAS    (WOLLNY.   1877). 


Number 

1 

Number 

of 

of  plants 

square 

Date  of 

to  the 

centi- 

ripening 

square 

meters 

(1877).      , 

meter. 

to  each 
plant. 

357 

28 

Aug.  15 

157 

64 

Aug.  17 

89 

118 

Aug.  19 

85 

117 

Aug.  26 

40 

254 

Aug.  28 

29 

346 

Sept.  5 

Similar  experiments  were  made  by  Wollny  on  the  Ramersdorfer 
variety  of  potatoes.  A  plat  containing  1  phmt  to  4,435  square  centi- 
meters ripened  by  the  end  of  September  (1875),  but  a  plat  containing 
1  plant  to  812  square  centimeters  ripened  the  1st  of  August,  and 
other  plats  containing  1  plant  to  2,500,  1,600,  1,109  square  centimeters, 
respectively,  ripened  at  dates  proportional  to  the  area  occupied 
by  each  plant.  As  each  plat  received  the  same  amount  of  sunshine 
and  of  water,  the  dates  of  ripening  must  have  been  hastened  in  pro- 
portion as  the  number  of  plants  in  each  plat  were  increased. 


125 


Similar  experiments  on  maize  showed  a  similar  acceleration  of  the 
date  of  ripening,  as  given  in  the  following  table,  which  also  shows 
in  the  last  cohnnn  what  proportion  of  the  maize  was  unripe  in  the 
sparsely  jilanted  plats  when  that  which  was  closely  planted  was 
already  fully  ripe. 

MAIZE    (WOLLNY,   1875). 


Number 

of  plants 

to  the 

square 

meter. 

Number 
of  square 
centi- 
meters 
to  each 
plant. 

Order 

of 

ripening. 

Percent- 
age of 
unripe 
ears. 

85 

16 
9 
6 
4 

400 

625 

1,109 

1,600 

2,500 

1 

3 
4 
5 

3.7 
0.0 
26.7 
34.8 
56.2 

A  striking  illustration  of  the  effect  of  scant  water  supply  is  given 
in  the  case  of  four  plats  of  flax,  which  were  sown  at  the  rate  of 
50,  100,  150,  and  200  grams  of  seed  per  4  square  meters  of  ground. 
During  the  drought  of  1875  the  plants  sown  most  closely  all  died 
early  in  July,  whereas  those  sown  most  sparsely  withstood  the  drought 
very  well ;  of  the  plants  sown  with  intermediate  densities  the  number 
that  died  was  proportional  to  the  density.  In  general,  if  all  other 
conditions  are  the  same,  plants  ripen  sooner  and  have  a  shorter  dura- 
tion of  vegetation  in  proportion  as  the  soil  is  drier,  or  in  proportion 
as  there  are  more  plants  to  the  unit  area. 

Evidently  the  plants  whose  roots  extend  the  farthest  in  search  of 
water  will  outlast  the  species  or  varieties  whose  roots  are  of  smaller 
dimensions. 

RAINFALL  AND  SUGAR  BEETS. 

Briem  (1887)  has  investigated  the  effect  of  rainfall  on  the  harvest 
of  sugar  beets.  His  observations  were  made  at  the  experiment  station 
"  Grobers."  A  long  drought  during  August  and  September  was  fol- 
lowed by  a  rainy  period  of  many  weeks.  During  the  latter  the  beets 
increased  in  weight  on  an  average  for  each  beet  from  388  to  450 
grams;  the  presence  of  sugar  was  shown  by  the  ordinary  polariza- 
tion test,  both  before  and  during  the  rainy  period.  The  following 
table  gives  the  results  of  the  analyses,  each  figure  being  the  average 
of  16  readings  on  samples  taken  from  100  beets.  These  samples  show 
that  immediately  after  the  first  rainfall,  on  September  21,  the  per- 
centage of  sugar  per  beet  diminished  somewhat,  but  that  toward  the 


126 

end  of  the  rainy  period,  when  the  rainfalls  became  less  frequent,  the 
percentage  rose  to  nearly  its  former  value.  On  the  other  hand  there 
was  a  regular  diminution  of  the  other  elements  that  were  not  sugar, 
and  consequently  an  improvement  in  the  percentage  of  purity.  There- 
fore a  permanent  injurious  influence  of  the  heavy  rainfall  on  the 
quality  of  the  beet  was  not  proven. 


Num- 
ber 
i-ainy 
days. 

Percentage 
of— 

Quo- 
tient. 

Per- 
cent- 

Date  of  measures. 

Sugar. 

Not 
sugar. 

of  not 

inloo 

of 
sugar. 

0 
6 
9 

13.13 
12.35 
12.56 
13.04 

3.15 
2.84 
2.81 

80.0 
79.6 
81.5 
82.3 

24.9 

September  27  (after  rain) 

25.4 

22.5 

October  20  (after  rain) 

21.4 

Grassmann  (1887)  also  confirms  the  results  of  Girard  to  the  effect 
that  the  sugar  once  formed  in  the  beet  remains  there,  no  matter  what 
the  further  growth  may  be.  There  the  diminution  of  the  percentage 
of  sugar  after  a  rainfall  is  only  relative  in  that  the  sugar  is  dissolved 
in  more  sap,  and  this  is  distributed  throughout  a  greater  mass  of  beet ; 
the  sugar,  and  with  it  the  percentage  of  purity,  sinks  only  very  lit- 
tle after  the  first  rainy  day,  but  on  the  second  sinks  more  considera- 
bly and  then  slowly  rises  from  the  third  to  the  fifth  day.  (See 
Wollny,  X,  p.  300.) 


Now  that  the  previous  studies  have  shown  the  importance  in  agri- 
culture of  the  quantity  of  available  water  the  question  still  remains 
whether  the  results  of  these  experiments  are  directly  applicable  to 
determining  the  influence  of  rainfall  on  vegetation  under  the  natural 
climatic  conditions.  We  could  in  advance  answer  this  question  in 
the  negative,  inasmuch  as  the  precipitation  is  never  so  uniform  as"the 
water  artificially  supplied  in  these  experiments,  as  also  because  the 
utilization  of  the  natural  rainfall  by  the  earth  varies  with  the  physi- 
cal properties  of  the  latter;  but  by  a  closer  consideration  one  is  led  to 
the  conclusion  that  in  spite  of  the  departure  from  natural  conditions 
still  the  results  of  these  experiments  do  allow  us  to  draw  many  con- 
clusions as  to  the  influence  of  rainfall  on  the  growth  of  cultivated 
useful  plants,  especially  when  we  leave  out  of  consideration  the  effect 
of  the  water  at  different  epochs  of  vegetation  and  the  peculiarities  of 
the  capacity  of  the  soil  for  water,  and  at  first  study  only  the  average 
character  of  the  climate  as  depending  on  the  amount  of  precipitation 
and  consider  the  weather  during  the  growing  season. 


127 

In  this  case  it  would  scarcely  be  denied  that  a  relatively  dry  or 
moist  climate  or  any  similar  modification  of  the  weather  should  exert 
an  influence  on  the  vegetation  similar  to  that  exerted  by  the  soils  of 
different  moistures  in  the  above-described  experiments.  We  must 
the  more  readily  agree  to  this  conclusion  since,  independently  of  the 
fact  that  water  belongs  to  the  most  important,  indispensable,  factor  of 
vegetation,  it  is  also  true  that  the  observations  on  the  growth  of  plants 
made  in  climates  having  different  degrees  of  moisture  agree  closely 
with  the  views  above  explained.  It  is  already  well  known  in  agri- 
culture that  in  a  dry  climate  the  harvests  are  only  scanty  and  to  an 
extraordinary  degree  dependent  on  the  rainfall,  and,  furthermore,  it 
is  well  known  how  favorably  the  general  condition  of  the  plants  is 
affected  by  a  moderately  moist  climate,  and  how,  on  the  other  hand, 
the  crops  of  cultivated  lands  are  diminished  by  extremely  large  quan- 
tities of  rain,  when  in  consequence  of  a  large  capacity  of  the  soil  for 
water,  a  large  quantity  of  water  accumulates  in  it  either  temporarily 
or  for  long  periods  of  time.  Furthermore,  it  is  well  known  that  the 
stalk  of  the  plants  and  the  formation  of  straw  are  greater  in  pro- 
portion as  the  climate  is  moister;  that  the  various  kinds  of  cereals  in 
dry  regions  produce  a  glassy,  glutinous  grain,  but  in  moist  lands  a 
mealy  seed,  poor  in  nitrogenous  compounds.  All  these  phenomena, 
observed  on  a  large  scale  in  the  life  of  the  useful  plants,  make  them- 
selves felt  also  in  a  similar  way  in  the  experiments  above  quoted,  and 
therefore  the  results  of  the  latter  can  with  perfect  justice  be  quoted 
in  deciding  upon  the  questions  lying  at  the  base  of  our  work.  But 
these  present  conclusions  hold  good  only  for  the  total  rainfall  during 
the  growing  season,  and  it  will  be  further  necessary  to  fix  in  a  similar 
way,  by  experiments,  the  influence  of  precipitation  during  the  indi- 
vidual stages  of  growth  of  the  plants,  as  also  the  relation  of  the  soil 
to  the  water,  so  as  to'  determine  the  influence  of  the  ordinary  natural 
climatic  conditions. 


Chapter  VII. 

MISCELLANEOUS  RELATIONS. 

RAPID  THAWS. 

The  following  extracts  from  a  report  for  1889  of  the  department  of 
the  interior  of  the  Canadian  government  shows  the  influence  of  the 
change  from  warm  to  cold  weather  not  only  on  forest  trees  but  on 
other  plants : 

Considerable  attention  has  been  paid  to  this  subject  during  the  past 
year,  and  there  has  been  urged  on  the  department  of  agriculture  the 
desirability  of  the  establishment  at  some  point  in  the  southwestern 
portion  of  the  Northwest  Territories  of  a  farm  or  garden  for  con- 
ducting experiments  on  this  line.  Failure  in  tree  culture  so  far  as 
tried  seems  to  be  owing  not  to  the  severity  of  the  winters,  nor  to  the 
droughts  of  the  summers,  but  to  the  winds.  Those  in  the  winter 
known  as  ""  chinooks,"'  which  cause  the  sap  to  rise  and  the  buds  to 
swell,  being  followed  by  a  lowering  of  the  temperature  (in  some  cases 
very  rapid),  prove  destructive;  and  during  the  summer  there  are 
often  high,  dry,  hot  winds  which  blow  continuously  for  several  hours 
and  which  seem  to  dry  up  the  young  trees.  By  planting  in  close 
clumps  the  native  trees  which  will  grow  (cottonwoods  and  others), 
and  among  them  those  ornamental  trees  which  are  so  much  to  be 
desired,  these  difficulties  will  probably  be  overcome,  and  in  time  it  will 
be  found  what  ones  are  best  suited  to  the  district. 

The  great  difficulty  which  at  present  impedes  the  cultivation  of 
large  plantations  of  forest  trees  in  Manitoba  and  the  northwest  is 
climatic.  In  early  spring,  delightfully  soft,  balmy  days,  something 
like  the  maple-sugar  Aveather  in  Ontario  and  Quebec,  awaken  the 
young  trees  to  life  and  cause  the  sap  to  run;  but  then  suddenly  a 
terrific  blizzard  from  the  north  and  northwest  comes  down  and 
freezes  up  the  sap  and  destroys  the  trees.  Professor  Saunders  is 
now  engaged  in  experiments  with  a  view  to  overcoming  this  climatic 
obstacle.  I  have  thought  that  by  planting  the  young  trees  very 
closely  together,  or  by  sheltering  them  during  their  earlier  seasons, 
as  is  done  in  the  case  of  the  seedlings  at  the  model  farm  at  Ottawa, 
this  trouble  might  be  gradually  lessened;  or,  willows  or  cottonwood 
might  be  planted  with  the  young  trees  as  a  shelter-belt  protection  for 
them  against  these  early  spring  frosts  and  sudden  and  extreme 
changes  of  temperature.  As  yet,  of  course,  we  have  no  practical 
experience  in  the  northwest  on  the  subject,  and  can  only  base  any 
action  we  may  take  upon  knowledge  obtained  from  what  has  been 

(128) 


129 

done  in  other  countries  with  the  same  eharaeteristics  both  of  soil  and 
elimate.  (See  American  Meteorological  Journal,  1891,  Vol.  VII,  p. 
41.) 

WIND. 

The  effect  of  the  wind  on  vegetatit>n  is  quite  various.  Among  other 
influences,  we  note  the  following: 

(«)  It  is  considered  that  the  mechanical  action  of  the  motion  of  the 
stems  and  trunks  and  stalks  is  to  strengthen  them  and  to  stimulate 
the  growth  of  the  roots. 

(b)  The  winds  distribute  the  pollen  and  the  seed  and  thus  assist, 
or  even  entirely  control,  the  preservation  of  the  plant  and  its  geo- 
graphical distribution. 

(/■)  The  wind  renews  the  air,  so  that  a  superabundance  of  the 
necessary  gases  is  then  assured. 

{(I)  During  cool,  clear  nights  a  wind,  by  renewing  the  supply  of 
heat,  prevents  the  fonnation  of  frosts  by  radiation. 

{e)  On  dry,  cold,  frosty  nights  the  wind,  by  its  dryness,  evaporates 
any  frost  that  may  be  formed  upon  the  plant,  but  does  not  prevent 
the  freezing  of  the  plant  as  a  whole. 

(/)  By  bringing  moisture,  fog,  and  clouds  from  the  lakes  and 
ocean  up  over  the  fields  and  forests  the  Avind  prevents  frosts  and 
favors  the  growth  of  delicate  plants  on  the  leeward  side  of  large 
masses  of  water. 

(ff)  Gasparin  states  that  when  a  cold,  dry  north  wind  suddenly 
l)lows  over  plants  in  active  groAvth  they  become  stunted,  and  it  is 
said  that  the  plants  have  taken  cold.  A  similar  phenomenon  occurs 
in  the  valleys  of  California. 

Gasparin's  description  is  as  follows  (Cours  d'Agriculture,  2d  ed., 
1852,  p.  202)  : 

In  the  valley  of  the  Khone  the  north  wind  produces  a  lowering  of 
the  normal  temperature  of  about  7° ;  all  the  vegetation  is  more  or  less 
involved  if  after  several  days  of  calm,  clear  weather,  during  which 
the  heat  has  increased,  such  lowering  of  temperature  is  experienced. 
P^ven  if  there  has  been  no  frost  and  the  plants  have  preserved  their 
vitality  unimpaired,  it  produces  a  singular  effect  on  them ;  their  growth 
stops  and  they  remain  stunted.  Our  agriculturists  describe  this  con- 
dition by  saying  that  the  plants  have  ''taken  cold."  The  leaf  buds 
which  put  out  later  resume  their  growth,  but  the  leaves  and  branches' 
experiencing  this  cessation  of  growth  never  entirely  recover  from  it. 
This  accident  is  especially  injurious  to  natural  and  artificial  meadows 
and  to  the  leaves  of  the  mulberry  tree.  As  regards  the  meadows, 
the  best  thing  to  do  is  to  hasten  the  mowing  of  the  grass,  in  order  to 
gain  time  for  the  succeeding  crops  to  prosper,  and  for  the  nniUierrv 
trees  it  is  advisable  to  await  the  development  of  new  buds. 

The  more  rapid  these  dry  winds  are  the  more  tliey  hasten  the  drying 
up  of  the  soil.  After  they  have  prevailed  for  several  days  the  earth 
2667—05  M 9 


becomes  hard,  and  this  condition  prolonged  until  spring  contributes 
much  to  injure  the  growth  of  the  plants.  The  wheat  remains  low  and 
does  not  head ;  the  meadows  yield  but  little  grass,  if  a  spell  of  warm 
weather  does  not  soon  follow  so  that  they  may  be  irrigated,  for  if  the 
Avind  is  dry  and  cold  at  the  same  time  watering  will  do  them  little 
good. 

{h)  Damp  warm  winds  are  generally  favorable  to  plants  and  par- 
ticularly so  to  various  kinds  of  fodder.  Xevertheless,  we  observe  that 
under  their  action  the  fertilizing  proceeds  badly,  growth  is  imper- 
fect, and  the  maturing  is  retarded. 

(/)  AVarm  dry  winds  produce  very  rapid  evaporation,  and  their 
effect  is  still  more  marked  if,  like  the  simoon  of  Arabia,  they  carry 
with  them  sand  heated  by  the  powerful  southern  sun. 

(j)  Hot  dry  winds  occur,  notably  along  the  whole  eastern  slope  of 
the  Rocky  Mountain  Divide,  Avhich  by  their  rapid  evaporation  use  up 
all  the  moisture  in  the  plant  and  in  the  soil,  causing  the  plant  to 
entirely  wilt  away. 

THE  ORGANIC  DUST  OF  THE  ATMOSPHERE.  * 

IN    GENERAL. 

The  dust  contained  in  the  atmosphere,  in  so  far  as  it  consists  of 
organic  debris,  has  a  slight  influence  on  agriculture,  but  in  so  far  as 
it  consists  of  living  germs  seeking  places  to  rest  and  grow  it  is  a 
matter  of  vital  importance.  Undoubtedly  most  of  the  plant  diseases 
are  spread  in  all  directions  by  the  winds  that  carry  the  spores  of 
fungi  even  more  widely  than  they  do  the  seeds  of  the  weeds.  But  the 
examination  of  this  dust,  either  by  the  microscope  or  by  cultivation 
in  various  appropriate  moist  media,  as  al'-o  the  study  of  the  injuries 
or  the  good  done  by  the  microbes,  bacteria,  bacilli,  micrococci,  fungi, 
and  other  organisms,  belongs  to  vegetable  pathology  rather  than  to 
the  relations  betAveen  climates  and  crops  and  is  a  subject  so  large  that 
we  must  refrain  from  even  attempting  to  quote  the  titles  of  recent 
treatises  on  the  subject  by  Pasteur,  ^liquel.  Van  Tieghem,  Koch,  Kohn, 
and  many  other  prominent  authors  in  Europe  and  America.  Syste- 
matic daily  examination  by  the  culture  method  of  the  dust  deposited 
from  the  air  had  been  established  at  Montsouris  under  Marie-Davy, 
and  at  Philadelphia  under  Dr.  J.  S.  Billings,  and  will  undoubtedly 
do  much  to  explain  the  dependence  of  crop  diseases  upon  wdnd, 
moisture,  and  temperature. 

WIND    AND    FORESTS    AND    GERMS. 

The  influence  of  the  forests  on  the  transportation  of  the  micro- 
organisms by  the  wind  has  been  studied  by  A.  Serafini  and  J.  Arata 


131 

by  countins:  (ho  colloctions  of  oroanisius  that  arc  c'aii<iht  and  dcvd- 
oped  oil  appropriate  i>lass  phites  prepared  aoeordiiig  to  tlie  iiietliods 
of  Miqiiel  at  Moiitsouris.  Their  observations  show  that  in  JM)  cases 
out  of  40  the  catch  of  trorins  within  the  forest  is  less  than  the  catch 
outside  the  forest,  the  average  ratio  being  as  3  to  1.  so  that  the  forests 
act  as  a  strainer  upon  the  organisms  carried  by  the  wind.  WoUny 
suggests  that  the  result  Avould  be  even  still  more  decided  if  the  wind 
were  stronger  and  the  forests  more  extensive.  (Wollny,  Forschun- 
gen,  1891,  XIV,  p.  176.) 

ATMOSPHERIC   ELECTRICITY. 

IN    GENERAL. 

The  relations  of  atmospheric  electricity  to  vegetation  and  crops 
are  too  little  understood  to  justify  any  attempt  to  present  this  sub- 
ject. In  fact,  it  does  not  seem  clear  that  any  appreciable  influence 
is  exerted  by  this  atmospheric  or  geophysical  element  upon  the 
development  of  plants.  In  natural  conditions  evaporation  is  un- 
doubtedly facilitated  by  the  dissipation  of  an  electric  charge,  but 
we  do  not  know  that  transpiration  is  at  all  affected  by  it,  and  have 
no  reason  to  think  that  assimilation  is  affected  by  it.  The  passage 
of  an  electric  current  through  the  earth  in  proximity  to  the  roots 
may  affect  the  decomposition  of  the  soil  and  setting  free  of  nutritious 
substances  or  may  affect  the  temperature  of  the  soil.  A  fcAv  experi- 
ments have  been  made  to  show  that  artificial  earth  currents  stimulate 
the  growth  of  the  plant,  but. nothing  has  yet  been  found  to  show  that 
under  natural  conditions  electric  currents  have  any  appreciable 
influence.  Nevertheless,  observations  are  made  regularly  at  some 
stations,  such  as  Kew,  JNIontsouris,  Potsdam,  and  at  a  few  agricul- 
tural experiment  stations. 

An  excellent  series  was  maintained  for  many  years  by  AVisliczenus 
at  St.  Louis,  Mo.,  a  summary  of  Avhich  is  published  in  the  transac- 
tions of  the  Academy  of  Science  at  St.  Louis  and  also  at  page  65, 
Report  of  the  Chief  Signal  Officer  for  1871.  The  following  table 
gives  the  monthly  means  for  Montsouris  and  for  St.  Louis.  The 
record  for  Montsouris  expresses  the  potential  in  units  of  1  Daniell 
cell,  which  is  approximately  1  volt  at  a  point  2  meters  above  the 
soil  and  1  meter  from  a  Avail,  for  the  calm  days  of  the  years  1880  to 
1887.     The  record  for  St.  Louis  gives  the  electric  intensity  on  a  scale 


182 


of  arbitrary  degrees  for  a  point  at  the 
for  all  days  in  the  years  1861-1870 : 


top  of  a  house  in  that  city 


Month. 

Electric 

potential, 

Mont- 

souris. 

Electric 
intensity, 
St.  Louis, 

Month. 

Electric  '  Electric 
potential,  intensity, 
Mont-     St.  Louis, 
souris.          Mo. 

January 

February 

March 

April 

80 
68 
49 
41 
39 

n.o 

9.9 
7.4 
5.6 
4.0 

2.4 

July 

36                 2  1 

50  '               2. 8 

September. 

October 

November 

December 

59                  2.3 
a5                5.8 

May 

73                 8.0 

80                  8.3 

These  observations  agree  with  those  throughout  the  world  in  show- 
ing that  the  intensity  is  least  in  the  summer  seasons  and  greatest 
in  the  winter  seasons  of  the  respective  hemispheres.  There  is  also  a 
corresponding  slight  diurnal  variation,  in  accordance  with  which 
the  intensity  at  a  given  point  is  least  at  3  p.  m.  local  mean  time. 


Chapter  VIII. 

RELATION  OF  PLANTS  TO  ATMOSPHERIC  NITROGEN. 

IN  GENERAL. 

If  the  atmosphere  varied  largely  in  its  chemical  constituents,  this 
Avould  doubtless  have  an  appreciable  influence  on  vegetation.  Labo- 
rious studies  at  Montsouris  and  elsewhere  have  shown  that  there  is 
a  measurable  variation  in  the  quantity  of  ozone,  so  called,  of  ammonia, 
and  of  carbonic  acid  gas,  and  Morley,  at  Cleveland,  has  shown  an 
appreciable,  but  very  slight,  systematic  variation  in  the  proportions 
of  nitrogen  and  oxygen.  But  all  these  variations  are  so  small  as 
comj^ared  Avith  the  variations  in  the  quantity  of  air  brought  to  the 
jDlants  by  the  wind,  that  their  influence  on  vegetation,  if  any,  can 
not  be  separated  from  that  of  the  wind,  and  is  probably  entirely 
inappreciable  as  compared  with  other  influences. 

On  the  other  hand,  the  general  fact  that  plants  must  have  nitrogen 
in  order  to  produce  albuminous  and  other  nitrogenous  compounds 
has  long  been  apparent.  The  question  how  to  furnish  this  nitrogen 
to  the  plants  in  such  a  chemical  form  that  it  can  be  readily  assim- 
ilated by  the  cells  has  undoubtedly  been,  consciously  or  unconsciously, 
the  problem  of  the  agriculturist  for  many  ages.  Without  nitrogen, 
which  is  usually  supposed  to  be  furnished  by  fertilizers,  manures, 
rich  soils,  or  the  alluvial  deposits  of  the  rivers,  no  nutritious  seeds 
are  formed,  and  the  more  molecules  of  nitrogen  that  we  can  force  the 
plant  to  take  up  into  its  tissues  the  more  and  better  seed  we  may 
expect  to  obtain  in  the  harvest. 

THE  AMOUNT  OF  NITROGEN  BROUGHT  DOWN  BY  THE    RAIN  TO 
THE  SOIL. 

According  to  Marie-Davy,  nitrogeii  is  added  to  the  soil  by  the  nat- 
ural meteorological  process  of  rainfall.  Nitrogen  can  exist  in  water 
either  as  a  dissolved  salt  of  ammonia  or  as  pure  annnonia,  or  in  the 
state  of  a  nitrate  or  a  nitrite  of  soda  or  other  alkali,  or  as  com- 
pounded with  carbon,  hydrogen,  and  oxygen,  as  in  the  case  of  organic 
bodies  floating  in  the  water.  The  nitrogen  brought  down  by  the  rain 
water  is  washed  out  of  the  atmosphere  where  it  had  existed  in  some 
one  of  these  forms,  and,  although  the  percentage  is  small,  yet  the  abso- 

(13.3) 


134 

lute  quantity  has  an  appreciable  value  as  a  fertilizer.  The  methods 
of  determining  the  quantities  of  nitrogen  need  not  here  be  given,  but 
the  following  results  of  observations  in  Europe  give  at  least  an 
approximate  idea  of  the  probable  effect  of  rains  in  the  United  States. 
(See  Annuaire  de  Montsouris,  1889,  p.  254.)  Similar  data  for  our 
own  territory  have  not  been  measured,  so  far  as  I  can  find. 

Quantity  of  nitrogenous  compounds  in  the  rainfall  of  1S88  at  Montsouris. 


Total 
rain- 
fall. 


hev  of       contains  receives- 


ramy  ] 

days,  j    Am-     Nitric}   Am-     Nitric 
monia.    acid.   I  monia.    acid. 


January 

February 

March 

April  ..._ 

May 

•June 

July.. 

August 

September  ... 

October  

November 

December 

Total  ... 

Average 


55.5 
19.8 
79.6 
76.0 
47.5 
23.0 
19.4 
48.3 
31.6 


548.3 
45.7 


16} 

22| 

nl 

.:! 

17  1 
10 


mg. 
5.15 
2.19 
1.51 
1.50 
0.80 
1.10 
0.56 
0.88 
2.33 

2.21 
3.62 


mg. 
0.84 
1.00 
0.61 
0.78 
0.82 
1.02 
1.36 
1.10 
0.87 
0.68 
0.85 
0.50 


mg. 

110.7 
84.1 

132.4 
84.2 
15.8 
87.9 
44.0 
41.7 
53.6 
51.4 

106.7 

114.3 


18.1 
38.5 
53.3 
43.2 
16.2 
81.2 

las.e 

52.5 
20.1 
13.2 
41.2 
15.9 


497.0 
41.4 


Quantity  of  nitrogenous  compounds  in  the  rainfall  during  successive  years  at 
Montsouris. 


Seasons  (warm  or  cold). 

1  square  meter 
receives— 

Seasons  (warm  or  cold). 

1  square  meter 
receives— 

Ammo- 
nia. 

Nitric 
acid. 

Ammo- 
nia. 

Nitric 
acid. 

1875  (Sept.)-1876  (Feb.) 

1876  (Mar.)  1876  (Aug.; 

mg. 
_   574.9 
499.9 
387.6 
542.1 
423.7 
725.7 
462.1 
325.3 
230.5 
310.6 
503.4 
348.1 
415.2 
701.5 
901.7 

mg. 

210.3 
135.5 
93.6 
50.3 
169.1 
285.4 
336.4 
299.8 
264.7 
181.1 
83.4 
207.4 
279.0 

1883  (Mar  )  1883  (Aug  ) 

mg. 

431.6 

481.3 

.544.0 

.518.5 

499.5 

569.9 

589.6 

376.2 

728.2 

693.9 

406.0 

mg. 
106.4 

1883  (Sept.)-1884  (Feb.)  J 

1884  (Mar.)-1884  (Aug.) 

1884  (Sept.)-1885  (Feb.) 

228.5 

1876  (Sept  )  1877  (Feb  ) 

91.9 

1877  (Mar.) -1877  (Aug.) 

152.7 
152.7 

1878  (Mar  )-1878  (Aug  ) 

1885  (Sept  )  1886  (Feb  ) 

137.4 

1878  (Sept  )  1879  (Feb.) 

^2.8 
158.9 

1879  (Mar  )  1879  (Aug  ) 

1886  (Sept  )  1887  (Feb  ) 

219.6 

1880  (Mar  )  1880  (Aug  ) 

1887  (Sept  )  1888  (Feb  ) 

180.1 

1880  (Sept.)-1881  (Feb.) 

1888  (Mar.)-1888  (Aug.) .. 

Average,  cold  .seasons .... 
Average,  warm  seasons  _  _ 

350.0 

18.S1  (Mar.)-1881  (Aug.) 

503.0 
511. 7 

191.2 
191.9 

1881  (Sept.)-1882  (Feb.) 

1882  (Mar.)-1882  (Aug.) 

1882  (Sept. )-1883  (Feb.) 

135 

It  is  evident  that  there  is  no  nppreeiahle  differenee  between  the 
warm  and  eokl  seasons.  A  sli<>ht  addition  is  to  be  made  to  the 
above  table,  in  order  to  inehule  the  quantities  of  nitrogen  contained 
in  the  water  of  fogs  and  dew.  The  quantities  under  the  eohnnn 
"  Nitric  acid  "'  inchides  such  nitrites  as  become  converted  into  nitrates 
in  the  hiboratorv  analysis.  The  great  variations  in  the  successive 
seasons  depend  ujjon  the  variations  in  rainfall  (juite  as  nnich  as  upon 
the  variations  in  the  quantity  of  nitrogen  j^er  liter,  or  the  variations 
in  the  atmospheric  constituents. 

The  variations  in  the  (luantity  of  nitrogen  brought  to  the  soil  by 
the  rainfall  in  ditt'erent  parts  of  the  world  is  shown  in  the  following- 
table,  as  quoted  by  Marie-Davy  from  the  memoir  of  Messrs.  LaAves, 
Gilbert,  and  Warington,  on  the  composition  of  the  rainfall  at  T\oth- 
amsted.  This  table  shows  that  the  richness  of  the  rain  in  nitrogenous 
compounds  varies  geographically  quite  as  much  as  the  quantity  of 
rain  does,  so  that  in  general  the  ground  in  (iermany,  Italy,  and 
France  receives  decidedly  more  nitrogen  })er  acre  than  does  the 
ground  in  England.  A  further  study  of  the  subject  also  shows  that 
the  rain  caught  in  cities  contains  vastly  more  nitrogen,  especially 
ammonia,  than  that  caught  in  the  open  country. 


Quaniity  of  iiitrofjrii  (uiminllii  hroiinht  to  tlic  xo//  by  rain. 


Date. 

Total  nitro- 
gen- 

Station. 

'    Total  nitro- 
!          gen- 

Station. 

Per 
hec- 
tare. 

Per 
acre. 

Date,       p^,. 

hec- 

j  tare. 

Per 
acre. 

Kuschen 

1864-65 

ism-m 

1864-&5 

isa-s-^ 

18&5 
1864-65 
1865-66 
1866-67 

Kilos. 
2.08 
2.80 
6.15 
7.63 
7.46 
16.90 

Lbs. 
1.86 
2.50 
5.49 
6.81 
6.66 
•15.09 

Proskau 

1  Kilos.      Lb.1. 
18(J4-f!5       23.42        20.91 

Do 

1870         14.91;         13.36 

Insterburg -.. 

Do 

Do 

1871           11.08           9.89 

Do 

1872          14.01         12.51 

Dahino 

Vallombrosa 

1872          11.63      .  10.38 

ia5:}-54        6. 24          5. 9(5 

Do 

11.63     mm 

18.41       16.44 

Do 

Do 

1855           7.29          6.58 

Do 

1856           8.&5          8.00 

Ida-Marienhiitte 

1865-70 

n.i2 

9.92 

Montsouris 

1876-88       14.04 

12.53 

•  The  appreciable  quantities  of  nitrogen  shown  in  the  above  table 
must  be  diminished  in  agricultural  computations  in  i)roportion  as 
the  rainfall  carries  it  off  into  the  rivers,  since  only  that  which  remains 
in  the  soil  can  be  supposed  to  have  an  appreciable  influence  on  the 
growth  of  crops. 

The  quantity  of  nitrates  in  rain  Avater  may  be  expected  to  vary 
with  the  character  of  the  climate  and^may  be  greatest  in  those  regions 
where  lightning  is  most  frequent.  Observations  on  this  subject  were 
made  by  A.  Muntz  and  V.  Marcano  (Agr.  Sci.,  Vol.  Ill,  p.  2^3),  who 
showed  that  at  Caracas,  Venezuela,  where  thunder  storms  are  frc- 


136 

quent  and  violent,  there  is  a  very  large  amount  of  nitric  acid,  either 
free  or  combined,  in  the  rain  water.  The  relative  values  in  different 
climates  are  as  follows : 


The  island  of  Reunion. 

Caracas 

Rothamsted  ._ -- 

Liebf  rauenberg 


Weight  of 
nitrogen 

per  meter 
rainfall 
per  hec- 
tare. 

Kilos. 
6.93 


NITROGEN  DIRECTLY  ABSORBED  BY  THE  SOIL. 

Schloesing  has  shown  that  the  atmospheric  ammonia  has  its  in- 
fluence upon  the  plant  greatly  multiplied  by  the  direct  absorption 
of  this  ammonia  from  the  air  into  the  soil.  The  absorption  is  greatest 
when  the  difference  between  the  tension  of  the  ammonia  in  the  soil 
and  that  in  the  atmosphere  is  at  a  maximum ;  it  is  therefore  greatest 
when  the  soil  is  moist  and  when  nitrification  converts  the  ammonia 
into  nitrates  as  fast  as  it  is  absorbed.  'Wlien  the  earth  is  dry  nitrifi- 
cation is  suspended,  and  the  ammonia  accumulates  in  the  soil  up  to 
a  certain  point,  beyond  which  the  rate  of  absorption  gradually 
diminishes.     (Agr.  Sci.,  Vol.  IV,  p.  292.) 

FIXATION  OF  NITROGEN  BY  PLANTS. 

Experiments  as  to  the  source  whence  the  grains  (Graminea^)  and 
the  beans  and  peas  (Leguminosa^)  derive  their  nitrogen  have  been 
made  both  in  Germany  and  France  by  independent  methods.  Thus 
Hellriegel  and  Wilfarth  from  18S3  to  1887  experimented  upon  sam- 
ples of  these  plants,  each  of  which  was  placed  in  a  pot  of  sterilized 
quartz  sand  to  which  was  added  a  nutrient  solution,  and  the  plants 
were  watered  with  distilled  water  so  as  to  keep  the  conditions  favor- 
able to  growth.  The  results  were  that  oats  and  barley  behaved  alike ; 
when  they  are  not  furnished  with  nitrates  there  is  no  developmei\t 
beyond  the  reserve  in  the  seed,  and  when  they  are  fed  with  nitrates 
the  harvest  of  dry  matter  is  directly  proportioned  to  the  quantity  of 
nitrate.  For  every  milligram  of  nitrogen  the  increase  of  dry  matter 
is  93  milligrams  for  barley  and  96  for  oats,  respectively.  Steriliza- 
tion of  the  soil  and  of  the  pots  on  the  one  hand,  and  the  addition  of 
the  microbes  contained  in  the  washings  of  cultivated  soil  on  the  other 
hand,  cause  no  variation  in  the  above  results. 

Peas  behave  quite  differently  from  the  preceding.  Some  plants 
languish  if  they  have  no  nitrates,  but  others  suddenly  acquire  new 


137 

life  and  yield  a  crop  comparable  with  that  obtained  with  a  eood  sup- 
ply of  nitrate.  The  amount  of  nitro<»en  in  the  crop  is  sometimes  a 
very  large  gain  over  that  contained  in  the  soil ;  this  latter  also  occurs 
when  the  air  is  deprived  of  all  ammonia,  etc.,  and  the  nitrogen  must  be 
obtained  from  the  free  nitrogen  of  the  atmosphere.  But  when  the 
soil  is  sterilized  by  heat  and  the  pots  and  seeds  are  sterilized  as  to 
their  surfaces  by  washing  with  very  dilute  mercuric  chloride,  then  peas 
behave  like  oats  and  barley;  there  is  no  gain  of  nitrogen  from  the  air, 
the  crops  are  proportional  to  the  quantity  of  nitrate  in  the  soil,  and 
no  tubercles  are  formed  on  the  roots. 

In  all  cases  where  the  peas  had  gained  nitrogen  when  planted  in 
unsterilized  soil,  tubercles  are  formed  on  the  roots,  and,  on  the  other 
hand,  when  they  are  planted  in  sterilized  soil  no  tubercles  are  formed 
unless  we  add  to  the  soil  the  washings  of  a  small  quantity  of  arable 
soil,  in  which  case  tubercles  are  generally  formed.  Such  washings 
may  themselves  be  sterilized  by  boiling  or  possibly  by  lower  tempera- 
tures. 

The  authors  infer  that  the  assimilation  of.  nitrogen  from  the  air 
by  peas,  lupines,  and  other  leguminous  plants  is  not  within  the  power 
of  the  plant  as  such;  nor  can  it  take  place  when  the  plant  grows 
within  a  sterilized  medium,  but  is  connected  with  the  presence  of  mi- 
crobes and  with  the  development  of  tubercles  on  the  roots.  (Agr. 
Sci.,  Vol.  Ill,  p.  215.) 

The  fixation  of  nitrogen  by  Leguminosao  has  been  studied  b}'  E. 
Breal,  who  succeeded  in  inoculating  Spanish  beans  with  bacteria  from 
tubercles  on  the  roots  of  Cystisa.  At  first  the  growth  was  vigorous, 
then  the  plant  languished,  but  eventually  recovered,  flourished,  and 
matured.  Again,  lucerne,  growing  in  a  pot  in  sandy  soil,  was  inocu- 
lated by  laying  a  fragment  of  tuberculous  root  of  lucerne  on  the  soil 
and  watering  the  plant  with  drainage  water.  In  both  these  cases  not 
only  did  the  plants  gain  in  nitrogen,  but  the  soils  also,  so  that  this 
experiment  confirms  the  ordinary  experience  as  to  the  behavior  of 
the  Leguminosa^  as  soil  improvers.     (Agr.  Sci.,  Vol.  IV,  p.  75).) 

Lawes  and  Gilbert,  in  a  memoir  published  in  the  Philosophical 
Transactions  of  the  Royal  Society  of  London  for  1889,  state  their 
conclusions  as  to  the  sources  of  the  nitrogen  in  the  plant  as  follows: 

In  our  earlier  papers  we  had  concluded  that,  excepting  the  small 
amount  of  combined  nitrogen  coming  down  in  rain  and  the  minor 
aqueous  deposits  from  the  atmosphere,  the  nitrogen  source  of  crops 
was  the  stores  within  the  soil  and  subsoil,  whether  from  previous 
accumulations  or  from  recent  manuring.  *  *  *  With  the  Grami- 
neae  it  was  concluded  that  most,  if  not  all,  of  their  nitrogen  was 
taken  up  as  nitric  acid.  In  leguminous  crops,  in  some  cases,  the  whole 
is  taken  up  as  nitric  acid,  but  in  other  cases  the  source  seemed  to  be 
inadequate.  *  *  *  It  is  admitted  that  existing  evidence  is  insuf- 
ficient to  explain  the  source  of  all  the  nitrogen  of  the  Leguminosa?. 


138 

Frank  had  observed  that  the  feeding  roots  of  certain  trees  were 
covered  with  a  fungus,  the  threads  of  which  forced  themselves  be- 
tween the  epidermal  cells  into  the  root  itself,  which  in  such  cases  had 
no  hairs,  but  similar  bodies  were  found  external  to  the  fungus  mantle, 
which  prolonged  into  threads  among  the  particles  of  soil.  Frank 
concluded  that  the  cldorophyllous  tree  acquires  its  nutriment  from 
the  soil  through  the  agency  of  the  fungus.  Such  a  mode  of  accumu- 
lation by  these  green-leaved  plants  plainly  allies  them  very  closely 
to  fungi  themselves:  but  inasmuch  as  in  the  cases  observed  by  Frank 
the  action  of  the  fungi  was  most  marked  in  the  surface  layers  of  soil 
rich  in  humus,  and  since  this  development  has  not  been  observed  on 
the  roots  of  any  herbaceous  j^lants,  therefore  the  facts  hitherto 
recorded  do  not  aid  us  in  explaining  how  the  deep  and  strong  rooted 
Leguminosjp  acquire  nitrogen  from  the  raw  clay  subsoils  of  Roth- 
amsted. 

In  continuation  of  their  investigations,  Lawes  and  Gilbert  have 
published  a  subsequent  paper  stating  that  in  1888  they  began  experi- 
ments in  the  same  line  as  those  of  Hellriegel.  Peas,  red  clover, 
vetches,  blue  and  yellow  lupins,  and  lucerne  were  sown  in  pots,  of 
which  there  were  four  to  each  series.  No.  1  contained  sterilized 
coarse  white  sand;  Xos.  '2  and  3  contained  the  same  sand,  to  which 
a  soil  extract  was  added;  Xo.  4  contained  garden  soil  or  special 
lupin  soil.  Their  general  results  were  that  the  fixation  of  free  nitro- 
gen only  occurred  under  the  influence  of  microbes  in  the  soils  that 
had  been  seeded  with  soil  organisms  by  adding  soil  extract  to  the 
sand  in  the  pots.  They  find  that  the  Rothamsted  experiments  indi- 
cate that  with  a  soil  that  is  rich  in  nitrates  there  are  far  fewer  nodules 
on  the  roots  of  the  plants  than  were  formed  in  the  pots  of  sand  con- 
taining but  little  nitrates  but  seeded  with  soil  organisms.  The 
authors  suggest  (1)  that  somehow  or  other  the  plant  is  enabled  under 
the  condition  of  symbiotic  life  to  fix  free  nitrogen  of  the  atmosphere 
by  its  leaves,  a  supposition  in  favor  of  which  there  seems  to  be  no 
evidence  whatever;  (2)  that  the  parasite  microbe  utilizes  and  fixes 
free  nitrogen  and  that  the  nitrogenous  compounds  formed  by  it  are 
then  taken  up  by  the  plant  host.  On  this  latter  supposition  the 
large  gain  of  nitrogen,  as  made  by  the  leguminous  plant,  when  grow- 
ing in  a  soil  that  is  free  from  nitrogen  but  properh^  infected  by 
microbes,  becomes  intelligible.     (Agr.  Sci.,  Vol.  IV,  p.  201.) 

As  to  the  relations  between  plants  and  atmospheric  ammonia,  almost 
all  agree  that  the  plant  derives  ammonia  from  the  atmosphere  through 
the  medium  of  the  soil  only.  Berthelot  finds  that  vegetable  soils 
usually  have  sufficient  ammonia  to  enable  them  to  evolve  it  into  tlie 
atmosphere,  but  under  certain  conditions  they  can  absorb  this  gas 
from  the  atmosphere.     (Agr.  Sci.,  Vol.  IV,  p.  295.) 


139 

Berlhelot  shows  that  veo^etable  soils  continually  absorb  nitrogen 
from  the  air,  aiul  very  much  more  than  exists  in  the  air  as  ammonia 
or  nitrooenous  compounds,  so  that  it  must  be  taken  directly  from 
the  free  nitrogen  and  this,  too,  although  the  soil  contains  no  growing 
vegetables.  (Agr.  Sci.,  Vol.  I,  p.  120.)  Apparently  this  absorption 
is  the  work  of  the  microbes  preparing  the  soil  for  future  i)lant  growth, 
and  much  of  the  irregularity  in  our  crop  reports  depends  not  u|)on 
the  climate  or  the  fertilizer,  but  upon  the  activity  of  this  form  of  life. 

Berthelot  (1887)  shows  that  the  fixation  of  gaseous  nitrogen  of  the 
atmosphere  by  the  soil  takes  place  continualh"  even  when  no  vegeta- 
tion is  presented  and  that  it  is  greater  in  soil  exposed  to  rain  than  in 
soil  protected  from  the  rain,  this  being  undoubtedly  due  to  the  fact 
that  in  the  exposed  soil  the  minute  forms  of  life  by  means  of  which 
nitrogenous  compounds  are  formed  can  operate  more  intensely  because 
of  the  greater  quantity  of  air  dissolved  in  and  carried  down  to  them 
by  the  rain.     (See  AVollny,  X,  p.  205.) 

A  parallel  investigation  by  Heraeus  shows  that  probably  tht^  bac- 
teria may  be  divided  into  two  classes — those  which  oxidize  and  those 
which  reduce  the  oxides,  and  that  in  general  where  an  abundance  of 
nutj'ition  exists,  as  in  rich  soils,  the  reducing  bacteria  are  in  excess, 
and  that,  on  the  contrary,  where  these  do  not  find  a  sufficiently  favor- 
able soil  there  the  oxidizing  bacteria  have  the  upper  hand. 

Salkowsky  (188-7),  as  the  result  of  his  ow^i  experinients,  considers 
it  indubitably  established  that  processess  of  oxidation  in  water  can 
onl}'  be  due  to  the  vital  activity  of  bacteria,  and  that  this  is  equally 
true  of  water  permeating  the  soil,  and  therefore  of  the  oxidation 
l)rocesses  in  the  soil  itself. 

Warington  (1887),  having  shown  that  the  process  of  nitrification 
goes  on  by  means  of  organisms  that  are  rather  uniformly  distributed 
at  the  surface,  and  that  they  are  less  frequent  at  depths  of  9  and  18 
inches,  depending  on  the  porosity  of  the  soil,  and  that  none  could  be 
found  at  depths  of  from  2  to  8  feet,  has  now  revised  these  early 
(•xi)eriments  and  finds  a  few  nitrifying  bacteria  at  depths  at  from  5 
to  0  English  feet,  but  that  in  general  they  are  less  numerous  and 
have  a  feebler  activity  the  deeper  they  are  in  the  earth.  Under 
natural  conditions  nitrification  occurs  principally  in  the  highest  layer 
of  soil,  because  the  conditions  of  this  process — viz,  accessibility  of  the 
ir  and  quantity  of  nitrogenous  compounds — are  more  favorable  here 
than  in  the  loAver  strata.     (See  AVollny,  X,  p.  211.) 

As  our  views  as  to  the  relation  of  the  nitrogen  of  the  atmosphere  to 
vegetation  have  been  entirely  remodeled  within  the  past  livo  years, 
the  following  summary  by  Maquenne  (1891)  has  been  selected  as 
showing  the  slow  progress  of  our  Ivuowledge  up  to  the  brilliant  suc- 
cess of  Hellrieffel  and  Wilfarth. 


140 

Of  all  the  characteristic  functions  of  life  nutrition  is  certainly 
the  most  important.  It  is  by  means  of  it  and  with  the  assistance  of 
certain  inanimate  products  which  we  call  food  that  man  in  the  first 
stages  of  his  existence  succeeds  in  increasmg  his  size  to  a  limit  Avhich 
depends  upon  his  nature  and  later  on  succeeds  in  constantly  repair- 
ing the  loss  of  material  Avhich  he  suft'ers  in  his  contact  with  the  out- 
side world. 

•  Nutrition  has  everywhere  the  same  object,  but  it  may  be  accom- 
plished in  two  entirely  diiferent  ways.  In  the  animal,  considered 
as  essentially  a  producer  of  power,  nutrition  is  nothing  more  than 
a  transforniation  of  forces  similar  to  that  which  we  realize  arti- 
ficially in  our  steam  engines.  Nourishment  must  therefore  contain 
within  itself  the  motive  power  to  be  used  by  the  organism  which 
absorbs  it.  In  other  words,  it  should  be  so  composed  as  to  be  capa- 
ble of  furnishing  heat  by  transforming  itself  into  more  simple  ele- 
ments. I  speak  here  of  the  organic  matter  which  forms,  indeed,  the 
basis  of  nourishment  in  the  entire  animal  kingdom. 

With  the  plant,  on  the  contrary,  which  is  constantly  absorbing 
energy  instead  of  producing  it,  the  nutriment  is  no  longer  subject 
to  any  conditions,  and  thanks  to  the  living  force  of  the  solar  rays, 
which  the  plant  stores  up  in  its  chlorophyllian  tissues,  it  succeeds  in 
nourishing  itself  on  true  products  of  combustion — such  as  water, 
carbonic  acid,  and  nitric  acid.  In  other  words,  on  substances  which 
have  reached  their  maximum  stability  and  which  by  a  concentration 
of  force  it  converts  to  the  condition  of  organic  matter. 

It  is  thus  that  the  vegetable  kingdom  has  acquired  that  wonderful 
power  of  combination  which  the  methods  of  our  lalDoratories  so 
rarely  attain.  It  is  thus  above  all  that  it  is  able  to  continually  re- 
produce the  combustible  matter  which  the  animal  kingdom  has  con- 
sumed, and  that  it  enables  a  limited  quantity  of  matter  to  suffice  for 
the  support  of  an  indefinite  number  of  generations  belonging  by 
turns  to  the  two  kingdoms. 

By  its  synthetical  nature  vegetable  nutrition  must  necessarily  pre- 
cede aninial  nutrition.  It  is  as  indispensable  to  this  latter  as  the 
light  of  the  sun  is  absolutely  necessarj-  to  the  development  of  plants; 
and  this  is  not,  as  we  may  well  believe,  the  least  interesting  aspect 
of  its  study,  for  it  is  probable  that  when  we  become  well  acquainted 
with  every  detail  of  the  changes  which  contribute  to  the  organizatu)n 
of  mineral  matter  in  the  vegetable  tissues  we  shall  then  be  able,  by 
making  use  of  suitable  agricultural  methods,  to  assist  the  nutrition 
of  plants  artificially  and  at  the  same  time  to  improve  our  own  food, 
which  is  the  object  "of  all  progress  in  agriculture. 

We  must  also  in  this  connection  call  attention  to  the  present  almost 
universal  use  of  chemical  fertilizers.  This  is  certainly  not  the  only 
improvement  which  we  have  a  right  to  expect  from  scientific  re- 
searches, and  we  shall  now  see  that  recent  researches  relating  to  the 
assimilation  of  liberated  nitrates  by  plants  are  of  a  nature  to  make  us 
look  for  others  and  perhaps  equally  important  steps  of  progress. 

Analysis  shows  that  besides  some  mineral  substances  whose  role  is 
still  very  obscure,  the  cellular  juice  of  all  A^egetables  is  formed  of 
carbon  and  nitrogen  combined  w^ith  the  elements  of  water — that  is  to 
say,  with  hydrogen  and  oxygen.  These  latter  are  evidently  provided 
by  the  water  which  impregnates  the  earth,  and  as  there  is  almost 
always  a  sufficient  quantity  of  this,  we  need  not  occupy  ourselves  with 
it  here. 


141 

Carbon,  as  wo  know,  is  taken  by  tho  plants  from  the  carbonic-acid 
gas  of  the  air,  at  least  for  the  most  part.  Carbonic  acid,  like  watvr, 
exists  everywhere,  and  if  I  remind  you  that  we  have  succcetlcd  in 
transformino-  it  into  some  of  the  sufjars  which  exist  so  ijeneraiiy  in 
the  vegetable  tissues,  you  will  agree  with  me  in  saying  that  the  great 
phenomenon  of  the  assimilation  of  carbon  by  plants  is  at  present 
understood  only  in  its  smallest  details. 

The  mechanism  of  the  assimilation  of  nitrogen  is  far  from  being 
as  well  understood  even  as  that  of  carbon.  We  as  yet  know  nothing 
of  the  chemical  changes  which  cause  this  element  to  pass  from  a  gas- 
eous state  to  that  of  albuminous  food:  but  its  diU'erent  modes  of  ])ene- 
trating  into  the  plant  are  welf  known  to  us,  and  we  can  affirm  to-day 
that  the  atmosphere  contributes  as  much  as  the  soil  to  that  portion  of 
vegetable  nutrition. 

This  fact,  of  which  we  shall  shortly  give  the  demonstration,  was 
almost  evident,  a  priori.  In  fact  the  soil  contains  onlv  very  small 
proportions  of  nitrogen.  The  store  which  it  offers  to" us  (scarcely 
10.000  kilograms  per  hectare)  is  insignificant  in  comparison  with  the 
innnensity  of  time;  but  in  comparison  with  it  the  atmosphere  con- 
tains an  enormous  quantity,  about  three-fourths  of  its  entire  volume; 
hence  the  idea  of  a  continual  circulation  of  nitrogen  betAveen  its  com- 
))ounds  and  the  air — in  other  words,  between  the  air,  the  earth,  and 
the  living  organisms — forced  itself  upon  us,  in  the  same  way  as  the 
circulation  of  water  between  the  ocean  and  all  points  of  the  earth 
obtrudes  itself. 

It  is  therefore  the  more  remarkable  that  this  conception  of  the 
subject  has  only  quite  recently  been  brought  to  light.  Enunciated  as 
a  principle  more  than  thirty  years  ago,  it  has  only  been  taken  into 
serious  consideration  in  these  latter  years,  after  a  series  of  researches 
which  we  are  now  going  to  pass  in  review. 

But  I  should  like  first  to  establish,  by  experience  alone,  outside  of 
all  speculative  ideas,  the  fact  that  the  intervention  of  atmospheric 
nitrogen  in  the  phenomena  of  vegetation  is  an  absolute  necessity.  It 
Avill  suffice  for  that  pur^Dose  that  I  show  a  parallel,  a  sort  of  balance 
between  the  sources  of  gain  and  the  sources  of  loss  to  the  soil  in  nitrog- 
enous compounds;  it  is  clear  that  if  this  comparison  shows  us  a  diff'er- 
ence  in  favor  of  the  enriching  of  the  soil  then  we  need  have  no  fear  of 
seeing  our  soil  become  one  day  sterile ;  if,  on  the  contrary,  the  losses 
are  in  excess  of  the  gains  from  the  exterior  then  we  knoAv  that  it  must 
be  receiving  from  the  atmosphere  the  quantity  of  gaseous  nitrogen 
(>(jual  to  the  difference.  It  is  very  easy  to  bring  together  the  data  for 
this  great  problem. 

The  most  important  cause  of  the  decrease  of  nitrogen  in  the  soil 
is  unquestionably  the  crop  taken  from  it  each  year;  .the  amount  of  this 
loss  is,  however,  very  variable;  a  crop  of  cereals — of  wheat,  for  ex- 
ample— takes  from  the  soil  about  50  kilograms  of  nitrogen  per  he(;- 
tare;  roots,  beets,  or  others  generally  contain  more;  finally,  certain 
liinds  of  vegetation,  such  as  clover  or  lucern  grass,  take  as  much  as 
100  to  '200  kilograms,  and  even  more  nitrogen  i)er  hectare  annually. 

Judging  by  these  figures,  we  nuist  conclude  that  by  an  average 
rotation  of  crops,  where  root  vegetables,  leguminous  plants,  and 
cereals  are  made  to  alternate  one  with  the  other,  the  earth  loses  every 
year  by  the  fact  of  cultivation  alone  a  mininnnn  of  from  GO  to  TO 
kilograms  of  nitrogen  in  combination  with  other  substances. 


142 

On  the  other  hand,  the  soil  is  the  seat  of  never-ceasing  oxidations, 
caused  by  the  free  circuhition  of  air  within  it ;  one  of  these  phenomena 
of  oxidation  is  that  which  acts  upon  the  conibustibk^  nitrog-enous 
substances  hekl  in  reserve  by  the  soil;  under  the  sinuiltaneous  action 
of  a  free  atmospheric  oxygen  and  of  a  special  kind  of  microbe,  "  the 
nitric  ferment,"  discovered  by  Messrs.  Schloesing  and  Miintz  and 
described  later  by  Winogradski,  these  substances  are  rapidly  trans- 
formed into  nitrate  of  calcium,  or  lime,  which,  by  a  happ}^  combina- 
tion of  circumstances,  is  the  favorite  nutrition  of  most  plants;  this 
nitrate  of  calcium  is  extremely  soluble  and  does  not  possess  any 
affinity  for  the  elements  of  the  soil,  like  that  existing  between  these 
b:ame  elements  and  annnonia.  or.  again,  between  them  and  the  salts 
of  potassium,  Avhence  it  comes  to  pass  that  every  infiltration  of  water 
takes  this  nitrate  along  with  it,  even  to  the  de]:)ths  of  the  loAver  soil, 
and  from  thence  into  the  brooks,  rivers,  and  thence  into  the  ocean. 
In  autumn,  vdien  the  rains  are  abundant  and  when  the  denuded  earth 
evaporates  only  a  small  quantity  of  the  water  which  it  receives,  a 
veritable  cleansing  takes  place  systematically,  and  all  the  nitrates  are 
carried  far  away  as  fast  as  they  are  produced. 

The  loss  from  this  cause  is  enormous.  In  experiments  nuide  by 
Messrs.  Lawes  and  Gilbert,  at  Rothamsted,  for  a  great  many  years 
past  these  learned  English  agronomists  have  discovered  that  one 
hectare  of  soil  planted  in  wheat  loses  in  this  way  50  kilograms  of 
nitrogen — that  is  to  say,  as  nnich  as  the  wheat  itself  contains,  or, 
again,  a  quantity  equal  to  a  manuring  of  300  kilograms  of  nitrate  of 
soda. 

These  figures  are  far  from  being  exaggerated,  and  other  observers, 
among  whom  I  will  mention  Deherain,  have  obtained  similar  and 
sometimes  even  higher  results  than  those  of  LaAves  and  Gilbert. 

But  this  is  not  all.  Boussingault  found  that  rich  soils  continually 
give  out  ammonia  in  the  gaseous  state.  These  are  the  circumstances 
under  which  he  discovered  it :  Having  conceived  the  idea  of  analyz- 
ing a  sample  of  snow  which  had  remained  for  thirty-six  hours  in  a 
garden  bed,  Boussingault  found  in  it  10  milligrams  of  nitric  ammonia 
per  kilogram,  while  the  same  snow  taken  from  a  terrace  very  near  there 
contained  scarcely  2  milligrams.  The  difference  of  8  milligrams  was 
evidently  due  to  the  emanations  from  the  earth.  If  we  allow  that 
this  snoAV  had  a  uniform  deyith  of  10  centimeters  and  a  mean  density 
of  0.25  we  shall  find  on  a  hectare  a  total  weight  of  250  tons,  containing 
2  kilograms  of  annnoniacal  nitrogen  which  was  given  out  from  the 
soil  during  the  short  time  that  the  snow  lay  on  the  ground. 

By  what  coefficient  must  we  multiply  this  figure  in  order  to  cal- 
culate the  amount  of  annual  loss  which  takes  place  upon  an  ordinary 
piece  of  arable  land  ?  AVe  do  not  knoAv  at  all,  but  we  can  affirm  that 
the  result  of  such  a  calculation  would  give  more  than  10  kilograms 
annually  per  hectare. 

According  to  Schloesing,  certain  soils  emit  nitrogen  in  its  free, 
uncombined  state.  This  is  particularly  perceptible  in  soils  which 
are  badly  ventilated  and  Avhich  contain  a  great  deal  of  organic  mat- 
ter. The  nitrogen  then  results  from  the  decomposition  of  the  nitrates 
existing  in  the  soil,  which  decomposition  is  attributable,  as  Deherain 
and  I  have  shown,  to  the  development  of  certain  anserobic  micro- 
orsranisms. 


143 

If  wo  leave  out  of  the  calculation  this  last  cause  of  loss,  which  it  is 
impossible  to  estimate  and  which  is  doubtless  of  little  imi)()i-tance 
under  ordinary  circumstances,  we  shall  find  that  a  piece  of  arable, 
land  of  avera<ie  (piality  loses,  by  exhaustion  from  the  crops,  the  infil- 
tration of  rain  water  and  the  anunonia  which  it  disen<»;a<jes,  an 
amount  of  nitrogen  e(iual  to  a  minimum  of  120  kilograms  j)ei-  hectare 
anmuilly.  Therefore,  as  its  soil  contains  scarcely  10,000  kilograms, 
its  exhaustion  would  be  complete  in  less  than  a  century  if  these  losses 
were  not  compensated  by  gains  of  about  the  same  extent.  Let  us 
now  examine  into  these  causes  of  gain. 

The  soil  receives  nitrogen  principally  by  the  fertilizers  given  to  it. 
Their  proportion  and  richness  are  very  variable;  but  experienc(^ 
shows  that  in  general  they  do  not  suffice  to  supply  the  loss  occasioned 
by  cultivation  alone.  The  difference  which  is  found  between  the 
quantity  of  the  nitrogen  contained  in  the  crop  and  that  contained  in 
the  fertilizers  is  sometimes  very  great.  Boussingault,  to  whom  we 
are  indebted  for  very  precise  researches  on  this  subject,  mentions  a 
field  where  lucerne  grass  and  wheat  were  cultivated,  which  having 
originally  received  "225  kilograms  of  nitrogen  in  the  form  of  manure, 
furnished  in  a  space  of  six  years  44,000  kilograms  of  dry  hay  and 
•VooO  kilograms  of  wheat,  straw,  and  grain,  containing  altogether 
1,078  kilograms  of  nitrogen.  The  total  excess,  854  kilograms,  amounts 
in  this  case  to  a  little  more  than  140  kilogi'ams  per  hectare  annually. 

In  general,  this  diflerence  is  less,  but,  I  repeat,  it  is  always  in  the 
same  direction  and  may  be  estimated  on  an  average  at  80  or  40  kilo- 
grams annually;  it  remains  then  for  us  to  provide  for  this  excess, 
increased  as  it  is  by  the  losses  caused  by  drainage  of  nearly  100  kilo- 
grams per  hectare  annually. 

The  most  diverse  and  sometimes  the  most  improbable  reasons  have 
been  brought  forward  to  account  for  this  fact.  It  has  even  been  sug- 
gested that  the  atmospheric  dust  acted  as  a  natural  fertilizing  agent ; 
but  let  us  go  on  to  more  serious  hyijotheses.  It  has  l)een  thought  that 
the  rain  water  in  taking  from  the  air  its  soluble  compounds  might  fur- 
nish a  certain  proportion  of  ammonia  or  nitric  acid  to  the  soil. 
Analysis  has  shown  that  this  proportion  is  extremely  small ;  water 
caught  in  a  rain  gauge  contains,  indeed,  only  a  mere  trace  of  nitri(; 
substances,  scarcely  2  grams  of  ammonia  and  less  than  1  gram  of 
nitric  acid  per  cul)ic  meter,  which  corresponds  to  a  nuixinnnn  of  5  to 
8  kilograms  of  nitrogen  a  year  per  hectare.  This  quantity  would, 
then,  be  barely  sufficient  to  compensate  for  the  losses  due  to  the  gase- 
ous annnoniacal  emanations  from  the  earth. 

On  the  other  hand.  Schloesing  admits  that  the  earth,  and  the  plants 
by  means  of  their  foliage,  directly  attract  the  ammonia  existing  iM 
the  air.  This  annncmia,  according  to  the  learned  agronomist,  is  con- 
stantly emitted  by  the  sea  water,  w4iicli  thus  restores  to  us  under 
another  form  the  nitrogen  which  is  constantly  being  brought  to  it 
by  the  drainage  water. 

It  is  certain  that  humid  soil  can  attract  the  annnoniacal  vapors, 
but  it  is  also  certain,  as  proved  by  the  experiments  of  Boussingault, 
that  such  soil  can  also  emit  them:  there  is,  therefore,  a  tendency  to 
establish,  in  this  resj)ect,  an  equilil^rium  betAveen  the  soil  and  the 
atmosphere,  the  result  of  which  is  probably  not  far  from  a  perfect 
compensation. 

If,  then,  it  is  true  that  the  leaves  of  plants  can  assimilate  gaseous 


144 

ammonia,  we  know  that  the  average  air  contains  extremely  few 
nitric  compounds.  According  to  the  analyses  made  first  by  G.  Ville 
and  later  by  Schloesing,  the  atmosphere  contains  at  most  from  25  to  80 
grams  of  ammonia  per  cubic  kilometer.  It  would,  therefore,  be 
necessary,  in  order  to  provide  for  the  loss  which  we  have  just  spoken 
of.  that  the  soil  and  its  plants  should  absorb  in  the  space  of  a  year  all 
the  ammonia  contained  in  a  column  of  air  having  the  surface  of  the 
field  for  its  base  and  a  height  of  400  kilometers  under  a  constant  pres- 
sure equal  to  the  barometric  height  at  sea  level.  Thi*s  is  about  50 
times  the  quantity  required  for  the  carbonaceous  nutrition  of  a  crop 
weighing  when  dry  5.000  kilograms. 

Such  an  hypothesis  is  inadmissible;  besides,  if  it  were  correct  we 
should  not  be  able  to  understand  why  a  crop  of  graminea?  cultivated 
in  a  sterile  soil,  aided  only  by  a  small  quantity  of  fertilizer,  never 
contains  more  nitrogen  than  was  contained  in  the  seed  and  in  the 
manure  given  to  it. 

The  above-mentioned  deficiency,  then,  always  remains,  whichever 
way  we  look  at  it.  Let  us  see  if  it  is  real  or  if  the  soil  receives  any 
compensation. 

Since  the  application  of  chemical  analysis  to  agricultural  re- 
searches no  decrease  in  the  average  fertility  of  our  arable  lands  has 
been  discovered:  on  the  contrary,  many  have  become  richer  in  con- 
sequence in  the  improvements  in  the  methods  of  cultivation  and, 
above  all,  in  the  regidar  use  of  fertilizers.  They  have  therefore 
become  more  productive,  and  the  average  yield  of  wheat  in  France, 
which,  at  the  beginning  of  this  century,  was  only  at  the  rate  of  11 
hectoliters  to  the  hectare,  has  gradually  risen  to  15  and  10  hectoliters. 

This  fact  alone  is  in  direct  opposition  to  the  hypothesis  of  a 
gradual  impoverishment  of  the  soil.  Here  are  other  objections  more 
striking  still : 

The  forests,  the  meadows  high  up  on  the  mountains,  which  are 
never  manured,  have  from  the  remotest  ages  furnished,  in  the  form 
of  wood.  milk,  cheese,  wool,  or  viands,  quantities  of  nitrogen  inferior, 
no  doubt,  to  what  it  would  be  under  a  more  intense  cultivation,  but 
constant  and  without  the  soil  which  produces  them  showing  the  least 
sign  of  exhaustion. 

This  virgin  soil  is  even  more  fertile  than  our  best  arable  lands. 
In  Auvergne  Truchot  saw  meadow  lands  containing  !)  grams  of 
combined  nitrogen  per  kilogram:  Joulie  mentions  some  which 
contain  1.5  grams,  and  1.8  grams  per  100  of  nitrogen,  while  land  of 
good  quality  on  which  cereals  were  cultivated  3'ielded  ordinarily 
ten  times  less.  Finally,  and  it  is  with  this  that  we  terminate  this 
part  of  our  subject,  certain  plants,  among  which  we  must  place  in 
the  first  rank  grasses  of  natural  or  artificial  meadoAvs.  cause  a 
progressive  enriching  of  the  soil  even  in  the  absence  of  every  species 
of  fertilizer,  and  notwithstanding  that  they  contain  more  nitrogen 
than  other  crops,  said  to  be  exhausting,  such  as  the  root  plants  and 
cereals. 

Practical  agriculture  has  long  since  demonstrated  this  fact  in 
regard  to  leguminous  plants:  all  farmers  know  that  wheat  planted 
after  a  crop  of  clover  or  of  lucerne  grass  yields  a  much  better  harvest 
than  it  would  have  done  under  the  most  copious  fertilizing,  and  it 
is  for  this  reason  they  speak  of  the  leguminous  plants  as  ameliorators 
or  natural  fertilizers  of  the  soil. 


145 

The  action  of  natural  meadows  in  enrichino:  arable  soils  is  of  the 
same  nature;  here  follow  some  curious  results  on  this  subject  which 
I  have  borrowed  from  the  works  of  Messrs.  Lawes  and  Gilbert  and 
those  of  Deherain. 

In  1856  Messrs.  Lawes  and  Gilbert  transformed  into  meadow 
lands  a  portion  of  the  domain  of  Rothamsted,  which  for  a  long 
series  of  years  had  been  used  only  for  raising  grains.  The  soil  con- 
tained then  1.52  grams  per  1,000  of  nitrogen;  it  was  manured  regu- 
larly and  in  what  would  be  called  excessive  doses  in  such  a  way  that 
the  nitrogen  of  the  fertilizers  always  exceeded  that  of  the  crop  by 
about  15  kilograms  every  year. 

It  is  evident  that  they  could  not  pretend  with  this  small  surplus  to 
compensate  entirely  for  the  losses  caused  by  the  drainage ;  neverthe- 
Ici^s  the  soil,  instead  of  becoming  impoverished,  was  constantly 
enriched,  and  at  the  end  of  the  year  1888  its  proportion  of  nitrogen 
was  2.35  grams  per  1,000 — that  is  to  say,  0.83  gram  more  than  at  the 
beginning.  This  ditference  corresponds  to  a  total  of  1,813  kilograms 
to  the  hectare  for  the  entire  time  that  the  experiment  lasted — that  is 
to  say,  an  annual  gain  of  50  kilograms  per  hectare. 

The  phenomenon  is  moreover  progressive,  and  nothing  in  its  rate 
gives  any  reason  for  supposing  that  it  is  approaching  its  limit. 

At  the  experiment  field  of  Grignon,  my  learned  instructor,  Dehe- 
rain, observed  similar  facts.  From  1875  to  1879  he  raised  beets  and 
maize'  for  fodder  upon  a  piece  of  land  freshly  cleared  of  lucerne 
grass  and  containing  a  proportion  of  2.05  per  1,000  of  nitrogen.  In 
spite  of  the  fertilizers  given  to  it  during  that  time,  the  land  became 
rapidly  impoverished,  no  doubt  from  excessive  nitrification,  and  in 
1879  its  fertility  had  declined  to  1.50  grams — that  is  to  say,  to  about 
three-quarters  of  its  former  value. 

The  maize  was  then  replaced  by  French  grass  [sainfoin]  from  1879 
to  1883,  then  with  a  meadow  of  Graminew  from  1884  to  1888, 
inclusive,  this  time,  however,  without  giving  it  any  kind  of  fer- 
tilizer. The  soil  then  began  gradually  to  increase  in  fertility  and  has 
now  returned  to  its  former  state  of  richness. 

Another  experiment  very  similar  to  the  preceding,  but  in  which 
they  had  not  manured  the  soil  since  1875,  gave  nearly  identical 
results. 

If  we  admit  that  at  Grignon  the  soil  of  a  hectare  weighs  on  an 
average  4,000  tons,  we  see  that  in  ten  years,  from  1879  to  1888,  the 
soil  gained  under  the  influence  of  the  prairie  grass  alone  1,920  kilo- 
grams of  nitrogen,  to  which  we  must  add  1,210  kik)granis  taken  away 
by  the  crops,  or  a  total  of  3,130  kilograms,  or  more  than  300  kilograms 
a  year  per  hectare. 

Here  again  the  limit  is  far  from  being  attained,  and  it  can  be 
easily  untlerstood  that  soils  subjected  to  this  treatment  would  in  time 
come  to  contain  10  grams  per  1,000,  or  a  hundredth  or  more  of  nitro- 
gen, like  the  meadows  mentioned  by  Messrs.  Truchot  and  Joulie. 

It  is  clear  that  this  natural  phenomenon  can  not  be  owing  to  the 
contributions  of  nitric  comi)oun(ls  brought  by  the  rain  water  or  by 
the  atmosphere,  for,  even  l)y  attributing  to  these  sources  a  power 
much  beyond  that  which  we  have  i-ecognized  as  belonging  to  them, 
all  plants  should  then  behave  in  the  same  manner;  whereas  we  liav'e 
seen  that  we  must  distinguisli  between  the  cereals  Avhich  impoverish 
the  soil  continually  and  tlie  leguminous  plants  which  always  enrich  it. 
2607—05  M 10 


146 

Lawes  and  Gilbert  have  thought  to  find  an  explanation  of  the 
ameliorating  influence  of  leguminous  plants  on  the  soil  in  the  fact 
that  plants  of  that  kind  generally  have  very  long  roots  and  are  there- 
fore able  to  go  much  deeper  in  search  of  their  nourishment  than  the 
depth  at  which  the  roots  of  the  Graminea^  are  developed;  the  enrich- 
ing of  the  earth  would  therefore  be  due  to  the  organic  debris  that  culti- 
vation leaves  there  after  the  harvest,  the  nitrogen  in  Avhich  had  been 
taken  from  the  subsoil.  The  defect  of  this  view  is  that  the  fertility 
of  the  soil  decreases  rapidly  as  the  depth  increases,  and  in  the 
majority  of  cases  the  subsoil  contains  only  such  very  insignificant 
quantities  of  nitrogen  that  it  is  impossible  to  conceive  "that  any  plant 
could  be  nourished  by  it,  particularly  a  leguminous  plant  which  con- 
tains in  its  tissues  five  or  six  times  more  nitrogen  than  does  a 
Gramineee. 

In  a  word,  the  most  simple  observations  of  j^ractical  agriculture 
show  us  that  the  amount  of  nitrogenous  substances  furnished  by 
nature  would  not  suffice  for  the  requirements  of  vegetation;  it  is 
therefore  indispensable  that  gaseous  nitrogen  should  interpose  di- 
recth',  and  that,  too,  to  an  important  extent,  at  least  for  the  cultiva- 
tion of  leguminous  plants. 

Mr.  G.  Ville  proved  this  experimentally  as  early  as  1849,  and  he 
has  not  ceased  repeating  it  since  then,  in  spite  of  the  systematic 
opposition  of  most  physiologists  and  agronomists. 

The  primitive  experiment  of  ^Ir.  G.  Yille  has  now  become,  by 
recent  labors  in  connection  with  it,  an  established  fact.  Allow^  me, 
then,  to  describe  it  briefly,  dwelling  principally  upon  its  results. 

In  a  sterile  soil,  containing  at  least  1  kilogram  of  calcined  sand, 
various  leguminous  plants,  such  as  peas,  beans,  lupins,  and  others, 
w^ere  sown ;  then  were  added  some  nutritive  substances,  either  mineral 
substances  alone  or  a  mixture  of  mineral  fertilizers  with  a  small 
quantity  of  nitrate  of  soda,  the  object  of  which  was  to  aid  the  young 
plant  to  pass  safely  over  the  critical  period  of  its  growth,  or,  in 
other  words,  the  time  when,  having  exhausted  the  alimentary  re- 
serves provided  for  it  by  its  cotyledons,  it  must  henceforth  nourish 
itself  with  substances  entirely  inorganic. 

The  jDlants  were  watered  with  puvi}  water  free  from  annnonia; 
every  i^recaution  Avas  taken  to  assure  the  aeration  of  the  soil;  finally 
the  plants  Avere  kept  in  as  pure  an  atmosphere  as  possible,  either  in 
a  glass  cage,  where  from  time  to  time  carbonic-acid  gas  was  intro- 
duced, or,  what  is  preferable  in  the  open  air,  far  from  the  laboratory, 
and,  in  general,  far  from  everything  which  could  contribute  to  the 
disengagement  of  ammonia. 

Under  these  conditions,  and  particularly  when  the  soil  received  no 
nitrogenous  fertilizer,  the  plant  remained  puny  at  first,  suffering  from 
wdiat  the  German  physiologists  have  called  "nitrogen  famine."  Some 
plants  even  do  not  survive  this  })ainful  stage  of  their  existence, 
but  die  without  having  sensibly  increased  their  dry  weight;  others, 
more  vigorous,  yield  a  mediocre  crop;  finally  some,  by  the  side  of 
other  dying  stalks,  become  suddenly  very  flourishing.  Upon  the  first 
stalk,  which  up  to  that  time  has  been  lank  and  without  strength,  a 
new  stalk  seems  in  some  way  to  graft  itself — stronger,  stiff,  turges- 
cent — which  soon  becomes  covered  with  broad,  well-developed  leaves 
of  a  green  that  are  entirely  different  from  the  yellowish  tint  of  the 


147 

first  leaves,  and  this  plant  is  soon  as  full  i»f  flowers  and  fruit  as  if 
its  entire  fjrowtli  had  taken  place  in  a  soil  of  excellent  (|uality.  The 
crop  is  then  Aery  f>;ood.  It  contains  a  large  quantity  of  nitrog-en, 
which  evidently  could  only  come  to  it  from  the  atmosphere. 

This  recrudescence  of  vegetation  shows  itself  at  a  time  when  the 
weight  of  the  plant  is  eight  or  ten  times  that  of  the  seed,  and  similar 
contrasts  are  often  observed  in  two  stalks  grown  in  the  same  pot, 
which  are,  therefore,  consequently  in  the  same  soil,  under  the  same 
conditions,  the  seeds  being  as  similar  as  possible. 

In  a  Avord,  the  experiments  of  Yille  teach  us  tAvo  unforeseen  and 
equally  remarkable  facts.  The  first  and  most  important  is  that  a 
leguminous  plant  can  live  and  prosper  in  a  soil  entirely  destitute  of 
all  nitrogenous  compounds,  thus  necessitating  the  direct  assistance  of 
the  atmosphere :  the  second  is  that  all  seeds  of  the  same  kind  are 
far  from  behaving  in  the  same  manner,  whence  it  results  that  the 
course  of  the  experiment  is  eminently  uncertain. 

AVith  i^lants  of  the  family  of  the  Graminepe  nothing  similar  takes 
place.  The  results  are  absolutely  invariable;  the  crop  is  zero  if 
the  soil  does  not  contain  nitrogenous  substances.  It  increases  regu- 
larly Avith  the  quantity  of  fertilizer,  and  each  seed  produces  about 
the  same  Aveight  of  dry  material. 

The  irregularity  of  the  results  givtm  by  the  leguminosse  under  the 
same  conditions  shoAvs  that  there  could  be  in  this  case  no  question 
as  to  the  accidental  gains  of  nitrogen,  attributable  to  ammonia  or 
to  atmospheric  dusts,  or  to  the  Avater  used  in  Avatering;  the  fact  had 
been  disco A'ered,  but  its  true  cause  had  escaped  the  disco A'erer. 

(t.  Yille,  conA'inced  of  the  correctness  of  the  positi\"e  results  ob- 
tained by  him,  Avas  certainly  right  in  concluding  from  them  that  cer- 
tain kinds  of  plants  attract  carbonic-acid  gas,  but  he  Avas  not  master 
of  his  experiment.  Other  obserA'ers  also  tried  to  repeat  it  after  him, 
but  did  not  succeed.  Boussingault,  in  particular,  having  placed  his 
plants  in  spaces  that  Avere  too  restricted  to  alloAv  of  the  free  develop- 
ment of  their  roots,  only  obtained  stunted  plants  Aveighing  scarcely 
four  or  fiAe  times  as  nnich  as  the  seed  and  containing  no  more  nitro- 
gen than  the  latter,  because  they  had  never  attained  the  second  stage 
of  their  groAvth. 

In  consecjuence  Boussingault,  Avho,  hoAvcA'cr,  had  scAcral  years  be- 
fore obtained  results  similar  to  those  of  Ville,  thought  himself  justi- 
fied in  laying  doAvn  as  a  principle  that  A'egetables,  no  matter  to  Avhat 
variety  thev  l)elong.  are  ahvays  incapable  of  taking  cA'en  the  smallest 
quantity  of  nitrogen  from  the  air. 

I  shall  not  dAvell  upon  this  discussion,  Avhich  has  remained  cele- 
brated and  Avhicli  is  very  much  to  be  regretted,  inasnmch  as  the  re- 
sult of  it  Avas  that  by  deterring  those  students  Avho  Avould  have  liked 
to  pursue  the  study  of  the  question  further  its  definitive  solution  Avas 
retarded  for  thirty  years.  I  only  Avish  here  to  confine  myself  to  a 
single  point  in  it,  Avhich  is  that  the  fixing  of  free  nitroo^en  by  plants 
Avas  obserA-ed  already  in  1850,  Avith  all  the  characteristics  of  irregu- 
larity belonging  to  it  and  as  they  have  been  again  described  in 
recent  physiological  researches  of  German  physiologists. 

I  noAv  come  to  the  recent  Avorlcs,  and  I  shall  commence  by  those  of 
Berthelot,  in  Avhich  Ave  shall  l)e  confronted  by  an  entirely  ncAV  idea — 
that  of  the  interrelation  of  microscopic  life  and  the  phenomena  of 
vegetable  nutrition. 


148 

The  first  experiments  of  Berthelot  date  from  1885.  Tlieir  object 
was  the  fixation  of  nitrogen  by  denuded  soils,  leaving  out,  conse- 
quently, all  idea  of  vegetation.  The  soils  used  for  the  purpose  were 
chosen  from  among  the  poorest  in  nitrogen.  They  were  sandy  clays 
taken  from  INIeudon  or  from  Sevres,  below  the  level  of  the  quarries, 
or,  again,  porcelain  earths,  crude  kaolins  not  yet  crushed  in  the  mills. 

These  soils,  four  in  number,  were  submitted  to  five  series  of  ex- 
periments. They  were  left  to  themselves  in  glazed  pots,  either 
within  a  Avell-closed  room  or  in  the  open  air  in  a  meadow,  either 
without  shelter  or  under  a  little  glass  roof,  merely  to  protect  them 
from  vertical  rains,  or  on  the  top  of  a  tower  29  meters  above  the 
ground  and  without  anv  shelter,  or  finally,  in  corked  flasks,  so  as  to 
exclude  all  possibility  of  absorption  of  ammoniacal  or  nitric  vapors. 
In  the  fifth  series  of  experiments  the  same  soils  had  first  been  ex- 
posed to  a  temperature  of  100°,  so  as  to  destroy  from  the  first  all  the 
organic  germs  that  they  might  contain.  The  quantity  of  nitrogen,  de- 
termined with  great  precision  in  each  of  the  samples  at  the  very 
beginning  of  the  experiment,  was  again  analyzed  after  tAvo  months, 
and  again  after  renuiining  five  months  under  the  conditions  indi- 
cated above,  allowance  being  made  for  exterior  additions  attribut- 
able to  air  and  to  the  rains  when  the  pots  were  not  sheltered. 

The  results  obtained  did  not  leave  the  slightest  doubt.  In  every 
case  in  which  the  earth  had  been  left  in  its  normal  state  it  had  be- 
come enriched,  and  sometimes  to  a  very  great  extent  more  than 
doubling  the  quantity  of  the  initial  nitrogen ;  when,  on  the  contrary, 
the  soil  had  been  sterilized  by  heat,  it  became  constantly  more 
impoverished.  In  a  word,  then,  poor  clayey  soils  are  able  to  absorb 
atmospheric  nitrogen  directly.  This  absorption  is  not  accompanied 
by  any  increase  in  the  previous  proportions  of  ammonia  or  of  nitric 
acid ;  it  is,  then,  due  to  the  formation  of  com]ilex  organic  substances. 
Finally,  it  is  the  work  of  a  micro-organism,  since  it  ceases  to  be  pro- 
duced as  soon  as  the  soil  has  been  sterilized. 

To  what  sum  per  hectare  does  such  a  fertilization  correspond? 
Berthelot  estimates  at  20  or  30  kilograms  for  a  thickness  of  one 
decimeter  of  soil.  Hence  for  a  thickness  of  0.35  meter  it  would 
suffice  to  compensate  for  the  losses  inherent  to  drainage  and  cultiva- 
tion ;  but  before  going  further  it  is  well  to  remark  that  the  experi- 
ments which  we  have  just  described  relate  to  particidarly  poor  soils, 
which  are  therefore  of  a  nature  to  enrich  themselves.  In  truly 
arable  soils,  averaging  from  1  to  2  grams  of  nitrogen  per  kilogram, 
Berthelot  has  also  observed  a  perceptible  fixing  of  niti'ogen,  which, 
hoAvever,  is  relatively  less  than  in  sandy  clays,  and  it  is  probable 
that  this  phenomencm  Avould  cease  to  be  apparent  after  a  certain 
limit,  Avhich,  doubtless,  is  not  very  high. 

The  conditions  which,  according  to  Berthelot,  apear  the  most 
favorable  to  the  fixing  of  nitrogen  by  the  naked  soil  are : 

1.  The  presence  of  a  quantity  of  water  comprised  betAveen  3  and  15 
per  cent  of  total  saturation ; 

2.  A  sufficient  porosity  to  assure  the  free  jienetration  of  air 
throughout  the  wliole  mass  of  earth: 

3.  A  temperature  of  betAveen  10°  and  40°^  C. 

Th?se  conditions  define  the  microbe  AA'hich  secretes  or  fixes  the 
nitrogen  as  an  aerobic  organism  (i.  e.,  one  that  feeds  on  the  atmos- 
phere or  is  aerobiotic) . 


149 

Exro])t  un(l(>r  (lio  conditions  jjiwiously  i)ointo(l  out,  tho  phenome- 
non is  no  longer  seen,  and,  in  general,  it  is  limited  by  the  inverse 
action — that  is  to  say,  by  a  continual  dissipation  of  nitrogen  or 
ammonia  into  the  gaseous  state. 

AMiatever  may  fix  this  limit,  the  fact  observed  by  Berthelot  is  of 
the  first  imi)ortance.  It  is  the  first  time,  in  fact,  that  we  see  the 
fixation  of  nitrogen  in  naked  soils  clearly  stated ;  especially  is  it  the 
first  time  that  we  see  a  cause  exi)erimentally  defined  and  demonsti-ated 
without  any  reasonable  doubt  stand  forth  in  the  midst  of  such  com- 
plex phenomena.  This  cause,  as  we  have  seen,  is  no  other  than  the 
development  of  inferior  organisms"  whose  nature  it  remains  for  us 
to  define  more  precisely. 

This  was  an  entirely  new  idea  and  one  which  could  not  fail  to  pro- 
duce its  fruits.  We  shall  therefore  see  researches  rapidly  multiply 
and  lead  their  authors  to  more  and  more  definite  conclusions. 

A.  Gantier  and  Drouin  verified  first,  in  artificial  soils,  the  principal 
results  stated  by  Berthelot ;  they  employed  a  mixture  of  siliceous 
sand,  pure  limestone,  kaolin,  and  neutral  phosphate  of  potash,  to 
which  they  added,  in  particular  cases,  humus,  humic  acid  or  humates, 
or  oxide  of  iron.  This  mixture,  with  the  addition  of  a  little  nitrate 
of  potassium,  seems  to  be  very  favorable  to  the  development  of 
leguminous  plants. 

Under  these  conditions  Gautier  and  Drouin  recognized  that  the 
fixation  of  nitrogen  always  takes  place  in  mixtures  wdiich  have 
received  organic  matter;  in  its  absence,  on  the  contrary,  there  is 
always  a  loss.  Organic  matter  appears,  then,  to  be  an  important 
factor  in  this  great  natural  phenomenon.  It  acts,  doubtless,  by  ]3ro- 
moting  the  nutrition  of  the  microbe  wdiich  fixes  the  nitrogen. 

I  will  now  indicate  other  e.xperiments,  repeated  by  Ville  and 
Boussingault,  in  which  we  shall  see  the  effect  of  the  intervention  of 
vegetation. 

Berthelot  first  undertook  a  series  of  cultivations  of  leguminous 
plants  in  large  pots  which  were  left  in  the  open  air,  either  with  or 
without  shelter,  or  kept  under  a  glass  cover,  care  being  taken  to  supply 
the  plants  with  the  carbonic  acid  necessary  to  their  growth. 

The  soil,  the  seeds,  the  gathered  plants,  the  drainage  water  and 
rain  water  were  all  analyzed  with  the  greatest  care  in  order  that  an 
exact  comparison  might  be  established  between  the  initial  and  the 
final  nitrogen. 

Under  the  glass  cover  the  fixation  of  nitrogen  was  very  weak, 
because  the  plant,  under  these  circumstances,  did  not  reach  its  normal 
development,  but  in  the  open  air  the  quantity  of  niti-ogen  fixed  was, 
in  every  case,  superior  to  that  fixed  l)v  the  soil  alone. 

For  example,  the  tare  tripled  this  quantity:  the  cro]D  furnished 
by  a  mixture  of  kidney-vetch  and  Medu-xKjo  lupulina  contained  ten 
times  more  nitrogen  than  was  contained  in  the  seed  bed ;  a  crop  of 
lucerne  grass  contained  sixteen  times  more,  and  this  excess  of  nitro- 
gen was  always  found  more  abundantly  in  the  roots  than  in  the  leafy 
parts  of  the  plant. 

The  soil  enriched  itself,  but  in  a  less  degree  than  plant  and  soil 
together;  therefore  active  vegetation  promotes  in  an  enormous  degree 

oAerobies :  Micro-organisms  which  live  in  contact  witli  the  air  and  require 
oxygen  for  their  growth.  Anaerol)ios :  Micro-organisms  which  do  not  rccjuire 
oxygen,  but  are  killed  by  it. 


150 

the  assimilation  of  free  nitrogen  by  the  earth,  a  fact  which  is  in 
conformit}^  with  all  observations  made  in  extensive  farminc;  opera- 
tions. The  distribution  of  this  nitrogen  in  the  plant  shows  that  it 
enters  through  the  roots,  doubtless  in  consequence  of  microbic  inter- 
vention. Finally,  if  we  sum  up  the  excess  of  nitrogen  thus  found  in 
the  crop  and  in  the  soil,  together  with  the  drainage  water,  we  should 
find,  according  to  Berthelot,  300,  500,  and  even  700  kilograms  per 
hectare,  a  part  of  which  evidently  remains  in  the  ground  as  roots,  if 
we  are  contented  to  gather  only  the  portion  of  the  crop  which  is  above 
ground,  as  is  generally  done  in  practical  agriculture. 

Thus  it  is  that  there  results  the  progressive  enriching  of  arable 
soils  under  the  ameliorating  or  improving  action  of  leguminous 
plants;  thus  also  results  the  possibility  of  continuous  cultivation  of 
certain  crops,  such  as  meadow  grass  or  forest  trees,  without  fertilizers 
and  without  the  earth  becoming  impoverished. 

Joulie  arrives  at  very  similar  conclusions  from  experiments  of  the 
same  kind.  The  cultivation  of  buckwheat  and  of  hay  on  a  piece  of  land 
in  the  department  of  Dombes  showed  in  two  years  a  fixation  of  nitro- 
gen equal  to  more  than  1,000  kilograms  per  hectare.  The  mean  of 
twelve  experiments,  one  only  of  which  showed  a  loss  of  0.013G  gram 
per  1.5  kilograms  of  soil,  showed  a  fixation  of  about  500  kilograms  of 
nitrogen  per  hectare  in  a  space  of  two  years. 

A  little  later  Messrs.  Gautier  and  Drouin  also  found,  under  the 
influence  of  the  cultivation  of  common  beans,  an  enrichment  of  their 
artificial  soils  which,  as  they  estimated,  corresponded  to  185  kilo- 
grams per  hectare  for  a  single  crop  only. 

Finally  Pagnoul.  after  having  recognized  that  the  soil  alone  is 
callable  of  directly  fixing  the  nitrogen  of  the  air,  found  like  the  pre- 
ceding authorities  that  the  enrichment  of  the  soil  took  place  to  a  con- 
siderable extent  even  with  a  simple  crop  of  grass  or  clover.  For  the 
latter  he  found  fixations  amounting  to  500  and  900  kilograms  of 
nitrogen  per  hectare. 

We  see  that  all  these  results  are  in  absolute  accord  with  each  other, 
and,  what  is  worthy  of  remark,  they  are  of  the  same  order  of  magni- 
tude in  experiments  made  by  several  difi'erent  persons.  Nothing  is 
wanting  to  them  but  the  direct  control  to  be  obtained  by  a  cliange  in 
the  composition  of  the  gases  in  which  the  plants  grow. 

From  this  point  of  view  the  experiment  is  particularly  difficult  to 
carry  out.  The  plants  must  be  kept  constantly  in  closed  vases  in  a 
confined  atmosphere,  consequently  in  the  presence  of  vapor  of  water 
at  its  maximum  intensity,  which  seems  to  be  an  eminently  unfavorable 
condition ;  besides,  it  is  necessary  to  be  able  to  measure  the  volumes 
of  the  gas  contained  in  the  apparatus,  to  analyze  them  with  scrupu- 
lous exactitude,  and,  finally,  to  promote  the  chylophyllic  nutrition  by 
regular  additions  of  carbonic  acid  without  allowing  the  proportion  of 
oxygen  to  vary  too  greatly.  Schloesing,  jr.,  and  Laurent  have  tri- 
un'iphantly  overcome  all  these  difficulties.  In  a  memt)ir  published  in 
ISDO  these  clever  experimentalists  state  that  in  the  space  of  three 
months  three  seeds  of  dwarf  peas  soAvn  in  a  soil  destitute  of  nitrogen, 
but  prepared  in  such  a  manner  that  the  absorption  of  nitrogen 
could  easily  take  place,  absorbed  from  20  to  29  cubic  centimeters  of 
nitrogen,  weighing  32.5  milligrams  and  30.5  milligrams,  respectively. 
This  nitrogen,  measured  volumetrically,  was  found  again  (with  all 
the  precision  recpiisite  in  so  delicate  a  research)   partly  in  the  soil. 


151 

which  was  oiirichod  on  an  average  to  12  luilliuranis,  partly  in  the 
phmts,  which  had  gained  20  to  30  milligrams,  although,  owing  to  the 
narrow  space  in  which  they  were  confined,  they  were  not  able  to 
attain  their  full  development. 

This  last  proof  appears  to  have  finally  closed  the  discussion  for- 
merly inaugurated  by  Boussingault  and  which  had  not  been  com- 
pletely closed  by  the  analytic  results  e.\})lained  above. 

Thus  a  few  years  have  sufiiced  to  definitely  decide  this  theory  of  a 
direct  assimilation  of  nitrogen  by  plants,  first  enunciated  by  Ville. 

What,  now,  is  the  mechanism  or  modus  operandi  of  this  assimila- 
tion? We  have  just  seen  how  Berthelot  was  led,  by  certain  i)eculiar- 
ities  of  his  experiments,  and,  above  all,  by  the  complete  cessation  of 
all  fixation  of  nitrogen  in  soils  that  had  been  subjected  to  a  tempera- 
ture of  100°,  to  admit  that  nitrogen  is  assimilated  directly  by  certain 
inferior  organisms  Avhich  force  it  into  organic  combination;  but  we 
have  also  seen  that  the  fixation  of  niti-ogen  by  naked  soils  is  always 
weak  and  generally  insufficient  for  the  necessities  of  a  normal  vege- 
tation. 

It  is  true  that  when  the  aid  of  a  leguminous  plant  is  invoked  the 
fixation  becomes  more  active  and  may  become  powerful  enough  to 
compensate  alone  for  all  the  known  causes  of  loss;  but  how,  then, 
are  we  to  account  for  the  difterence  in  this  respect  found  between  the 
Leguminosa:*  and  the  Graminea??  Shall  we  be  forced  to  admit  that 
the  Leguminosa?  are  able,  by  themselves,  to  assimilate  gaseous  nitro- 
gen, by  a  power  possessed  by  them  which  is  wanting  in  the  other 
species  ? 

Berthelot  has  concluded,  from  his  researches  upon  this  subject,  that 
in  the  development  of  leguminous  plants  there  comes  into  play  some 
micro-organism  which  facilitates  the  fixation  of  nitrogen  upon  the 
root  of  the  plant,  or  rather  upon  the  mass  formed  by  the  root  and 
the  soil,  intimately  connected  one  to  the  other;  but  this  idea  could 
not  be  definitely  adopted  unless  the  existence  of  such  a  microbe  were 
proved  by  experiments.  This  result  is  fully  demonstrated  by  a 
series  of  very  remarkable  experiments  made  by  Hellriegel,  Wilfarth, 
Frank,  Prazmoff'ski,  and  others  in  (Jermany,  and  which  have  been 
most  successfully  verified  l)v  Breal,  Schloesing,  jr.,  and  Laurent  in 
France,  and,  finally,  by  LaAves  and  (Gilbert  in  England. 

Before  proceeding  to  explain  these  researches  I  nuist  call  attention 
to  a  well-established  fact  which  had  been  well  known  for  a  great 
many  years,  although  no  one  before  Hellriegel  and  Wilfarth  ever 
thought  of  seeing  in  it  anything  more  than  a  phenomenon  of  nature. 

^^lien  we  examine  the  roots  of  a  leguminous  plant  grown  in  good 
soil  we  always  see  ii'regularly  disposed  on  them  tuberculous  enlarge- 
ments, a  kind  of  nodosity  |  node,  nodule,  knot,  or  knob]  formed  of  a 
special  tissue  and  appai'ently  quite  accidental.  Examined  with  a 
microscope  the  interior  of  the^e  excrescences  ai)pears  to  be  filled  with 
corpuscles  of  varying  forms,  always  animated  with  the  ''  Brownian  ■' 
movement,  although  they  have  sometimes  a  movement  of  their  own. 
These  assume  various  shapes:  sometimes  they  are  like  simple  rods 
similar  in  form  to  certain  bacteria;  sometimes  they  have  the 
appearance  of  vegetal)le  cornlloids  and  take  the  branched  T  or  Y 
form  more  or  less  ramified. 

Botanists  have  for  a  long  time  discussed  the  nature  of  these  excres- 
cences, but  at  present  it  seems  to  be  generally  admitted  that,  mor])ho- 


152 

logically  considered,  they  constitute  roots  modified  by  the  penetration 
of  an  exterior  organism.  Under  no  circumstances  have  we  a  right  to 
consider  them  as  a  natural  production  of  the  plant,  because,  as  Praz- 
moffski  has  shown,  plants  that  are  kept  protected  from  all  causes  of 
contamination  are  always  free  from  them;  while,  on  the  contrary, 
their  roots  become  covered  with  a  multitude  of  nodosities  when 
plunged  into  a  liquid  where  a  tubercle  has  been  crushed  or  when  they 
are  replanted  in  any  sort  of  soil  that  is  watered  with  a  similar  liquid. 

The  artificial  infection  of  the  roots  of  leguminous  plants,  as  enun- 
ciated a  dozen  years  ago  by  Prillieux,  has  been  verified  by  Hellriegel 
and  Wilfarth,  Prazmolfski,  Laurent,  and  Break  This  latter  investi- 
gator has  even  discovered  that  we  may  certainly  assure  the  formation 
of  a  tubercle  by  pricking  the  root  of  a  leguminous  plant  with  a  needle 
which  had  been  previously  inserted  into  a  tubercle  growing  on 
another  root. 

There  remains  no  doubt  of  this  fact:  The  nodules  of  the  Legumi- 
nos£e  have  a  microbian  origin.  The  organism  which  causes  them 
has  received  the  name  Bacillus  radicicolu;  Laurent  places  it  beside 
the  Pasteuria  ramosa,  between  bacteria  proper  and  the  lower  fungi. 
Essentially  aerobic  in  its  nature,  it  resists  all  freezing  and  drying; 
but  a  temperature  of  70°  C.  is  sufficient  to  destroy  it.  It  has  been 
successfully  cultivated  in  bouillons  made  of  peas,  or  of  beans,  sup- 
plemented with  gelatine  and  asparagine,  or  even  in  a  solution  of 
phosphate  of  potash  and  of  sulphate  of  magnesia,  to  which  is  added  a 
little  sugar,  but  without  any  nitrogenous  substance  whatever.  This 
organism  grows  in  such  liquids,  preserving  its  habitual  ramified 
forms,  but  without  producing  any  true  spores. 

As  to  the  tul^ercles  themselves,  they  have  until  lately  been  consid- 
ered as  morbid  productions,  useless  to  the  plant.  Some  authors  have 
sought  to  see  in  them  organs  either  of  reserve  or  organs  for  the  trans- 
formation of  the  albuminous  substances  necessary  for  the  nutrition 
of  the  plant ;  others — and  this  is  the  general  opinion  at  the  present 
time — look  upon  them  as  the  result  of  a  symbiosis — that  is  to  say,  of 
an  extremely  intimate  association  between  the  root  of  the  plant  and 
the  microbe  living  with  it.  entirely  difJ'erent,  however,  from  the  action 
of  the  ordinary  parasite. 

Hellriegel  and  Wilfarth  were  the  first  to  discover  a  connection 
between  the  development  of  bacteroidal  nodosities  and  the  assimila- 
tion of  gaseous  nitrogen  by  the  Leguminosse.  After  having  observed 
that  in  a  culture  of  peas  the  most  vigorous  plants  were  alwa3's  those 
that  possessed  the  greatest  number  of  tubercles,  these  investigators 
carried  out  many  series  of  systematic  experiments  in  glass  jars  con- 
taining 4  kilograms  of  quartz  sand,  to  which  they  added  certain  of 
the  principal  minerals  necessary  to  vegetation,  such  as  phosphoric 
acid,  sulphuric  acid,  chlorine,  potassium,  etc.,  and  in  certain  cases  a 
small  quantity  of  nitrogen  in  the  form  of  nitrates. 

In  these  jars,  which  were  exposed  to  the  open  air,  they  sowed  bar- 
ley, oats,  and  peas.  The  results  were  exactly  the  same  as  those 
formerly  obtained  by  Ville  and  Boussingault. 

In  soils  destitute  of  nitrogen  the  crop  of  cereals  (barley  and  oats) 
is  nearly  nil,  but  it  increases  in  api)roximate  ])ro])ortion  to  the  dose 
of  nitrate  added,  so  that  for  each  added  milligram  of  nitrogen  there 
is  an  increase  of  crop  equal,  on  an  aver;).ge,  to  95  milligrams  of  vege- 


153 

table  matter,  Tims  Ave  see  that  all  tlu^  ex])eriineiits  ao:roo  with  each 
other. 

Ill  the  case  of  peas  the  results  aic  entirely  different,  for  we  see, 
as  in  Ville's  former  experiments,  that  hy  the  side  of  a  plant  weiohinc; 
less  than  a  gram  there  will  be  another  i)lant  weii>hin<>-  10  or  I.")  or  20 
grams,  and  even  more,  without  its  being  })ossible  to  attribute  the 
difference  to  any  apparent  influence  coming  from  the  outside.  There 
is  a  regime  of  absolute  irregularity,  and  an  examination  of  the  roots 
shows  that  the  irreguhyity  is  proportional  to  the  presence  or  absence 
of  tubercles  on  the  roots,  whence  arises  the  connection  above  men- 
tioned. 

It  now  only  remains  for  us  to  distinguish  between  cause  and  effect. 
Is  this  appearance  of  these  nodosities  in  itself  merely  a  consecpience  of 
the  greater  vigor  of  the  plants,  or  ought  we,  on  the  contrary,  to  see 
in  these  very  tubercles  the  origin  and  cause  of  that  greater  vigor  ?  The 
following  exiDeriment  will  show  us  which  of  these  two  hypotheses  is 
correct : 

When  to  the  same  soil  of  sterile  sand  which  served  for  the  preced- 
ing experiments  only  5  grams  of  good  arable  soil  dissolved  in  25 
cubic  centimeters  of  water  was  added,  the  peas  grew  in  a  natural 
manner  and  produced,  on  the  average,  from  15  to  20  grains  of  dried 
crop.  Each  stalk  contained,  on  an  average,  150  milligrams  of  nitro- 
gen, although  there  were  scarcely  10  contained  in  the  soil.  In  every 
case  there  was  a  fixation  of  nitrogen  in  the  gaseous  state  amounting  to 
nearly  half  a  gram. 

Under  the  same  conditions  a  seed  of  lupin  produced. a  crop  of  from 
42  to  45  grams,  containing  more  than  1  gram  of  nitrogen. 

French  grass  (sainfoin)  produced  the  same  results,  and  in  all  cases 
we  see  that  the  roots  of  these  different  plants  are  abundantly  pro- 
vided with  tubercles;  but  if  the  artificial  soils  and  the  solutions  of 
earth  employed  in  these  experiments  have  been  sterilized  by  the  action 
of  heat  the  plants  remain  invariably  i)uny  and  produce  less  than  5 
grams  of  dried  material  per  stalk.  In  this  case  the  tubercles  are 
always  wanting. 

Under  cover,  in  pure  air  to  which  a  little  carbonic-acid  gas  has 
been  added,  the  results  are  a  little  less  favorable  than  in  the  open  air, 
but  they  still  show  an  important  fixation  of  nitrogen  in  the  case  of 
Leguminosffi  infected  with  bacteria. 

These  principles,  then,  represent  the  determining  cause  of  the 
phenomenon,  and  the  systematic  addition  to  the  soil  of  a])propriatc 
germs  will  enable  us  hereafter  to  reproduce  at  will  the  experiment  of 
Ville,  which  was  formerly  attended  with  sudi  uncertain  results. 

In  the  Museum  of  Natural  History,  Breal  has  obtained  results  sim- 
ilar to  those  of  Ilellriegel  and  Wilfarth.  In  one  of  his  experiments 
a  pea  containing  9  milligrams  of  nitrogen,  in  a  soil  of  poor  gravel, 
but  into  which  bacteria  had  l)een  sown,  produced  a  plant  weighing 
103  grams  in  a  green  state,  82.8  grams  when  dried,  and  containing 
358  milligrams  of  nitrogen — that  is  to  say,  40  times  as  much  as  the 
seed.  The  pea  vine,  which  was  1.40  meters  long,  produced  14  ripe 
pods;  the  gain  in  nitrogen  thus  realized  corresi^onds  to  about  255 
kilograms  per  hectare. 

In  another  experiment,  a  small  plant  of  lucerne  grass  provided 
with  tubercles  and  weighing  -10  grams,  and  likewise  in  a  soil  of 
sterile  sand,  gave  a  crop  weighing  332  grams  when  green,  85.5  when 


154 

dried,  and  containing  1.733  grams  of  nitrogen.  The  total  fixation 
of  nitrogen  amonnted  to  1.715  grams  for  the  surface  of  the  flowerpot, 
or  274  kilograms  per  hectare. 

It  is  a  remarkable  fact  that  before  the  formation  of  the  fruit  the 
nitrogen  in  the  Leguminosa^  is,  by  preference,  localized  in  their  roots. 
This  fact  is  due  to  the  great  richness  of  the  tubercles  with  which  they 
are  covered.  Breal  found  in  the  nodules  of  several  plants,  such  as 
kidney  beans,  peas,  lupins,  lentils,  acacia,  etc.,  as  much  as  7  part^ 
of  nitrogen  to  a  hundred  of  dried  material,  i^ven  when  the  fibers  of 
the  roots  never  contained  more  than  2.5. 

Another  fact,  not  less  interesting,  brought  to  light  at  the  same  time 
by  the  experiments  of  Hellriegel  and  AVilfarth,  is  the  difference 
shown  by  arable  soils  in  their  capacity  to  initiate  the  appearance  of 
tubercles  upon  the  roots  of  leguminous  plants.  Some  of  them  are 
ver}'  efficient  in  this  respect ;  others  are  much  less  so.  There  are  even 
some  soils  which  are  more  favorable  to  the  production  of  tubercles 
in  certain  species  of  plants  than  in  others.  This  is  a  fact  very  diffi- 
cult of  explanation,  for  the  solution  of  which  further  and  bacteriolog- 
ical researches  will  be  necessary,  because  variations  of  this  kind  can 
only  be  due  to  a  difference  in  the  microbe  itself,  the  penetration  of 
which  into  the  roots  produces  these  nodules. 

In  the  experiments  of  Hellriegel  and  Wilfarth  the  sowings  were 
made  with  the  washings  from  earth,  containing,  as  we  know,  a  mul- 
titude of  micro-organisms  having  different  functions.  Some  of  them, 
it  is  true,  Avere  made  with  a  liquid  containing  a  little  of  the  white 
substance  which  comes  from  the  nodules  Avhen  they  are  crushed,  but 
all  i^recautions  had  ]iot  been  made  to  get  rid  of  the  germs  which  the 
water  itself  might  haA^e  contained,  or  Avhich  might  have  been  brought 
either  by  the  young  plant  or  by  the  atmospheric  dusts. 

It  was  therefore  necessary  in  order  to  be  sure  that  the  fixation  of 
the  nitrogen  was  really  due  solely  to  the  bacteria  of  the  nodule,  to 
repeat  the  preceding  experiments  Avith  all  the  precautions  required 
by  microbic  researches. 

This  Avork  of  revision  was  carried  out  Avith  scientific  rigor  by 
Prazmoffski,  in  Cracow,  with  great  success. 

The  A'essels  used  for  groAving  the  plants  Avere  provided  A\'ith  a 
cover,  which  fitted  tightly  and  had  four  holes  pierced  in  it.  One  of 
these  holes,  made  in  the  center,  permitted  the  young  plant  to  pass 
through  it.  The  three  others  jillowed  of  Avatering  and  of  the  pas- 
sage of  a  current  of  pure  air.  All  these  holes  Avere  closed  with  plugs 
made  of  a  sterile  Avadding,  which  preA^ented  the  entrance  of  all  germs 
of  exterior  organisms. 

The  so'il  was  formed  of  about  3,500  grams  of  siliceous  sand,  pre- 
viously washed  in  boiling  hydrochloric  acid,  then  in  Avater,  and 
finally  heated  red  hot.  Pure  mineral  fertilizers  Avithout  any  nitro- 
gen AAhatcA^er  Avere  then  added  to  it. 

The  Avhole  mass  was  then  sterilized  bA'  being  heated  for  at  least 
tAvo  hours  from  140°  to  150°  C. 

In  these  A'essels  peas  which  had  been  prcA^iously  sterilized  Avere 
sown.  To  effect  this  they  Avere  first  plunged  into  a  solution  of  cor- 
rosiA^e  sublimate,  then  Avashed  in  alcohol,  Avhich  latter  was  finally 
set  on  fire  and  burned  upon  the  seed  itself. 

Some  of  the  A^essels  receiA^ed  also  bacteroidal  germs  contained 
in  a  nonnitrogenized  bouillon  culture  liquid. 


155 

But  in  spite  of  all  of  thoso  precautious  it  was  not  always  possible  to 
prevent  the  })enetratiou  of  foreign  organisms  to  the  tubercles.  In  a 
certain  number,  liowi'xcr,  of  tlie  successful  experiments  in  which  the 
bacteria  alone  remained  in  contact  with  (he  roots  (he  results  obtained 
were  identical  with  those  obtained  by  IIellriei>el  and  Wilfarth. 
There  was  a  Hxation  of  nitr()<i-en  in  all  the  pots  in  whicii  the  hav- 
teria  were  sowed,  and  in  those  only. 

Thus  in  a  sterile  soil,  without  microbes,  a  pea  containin*^-  12  milli- 
^•rams  of  nitrooen  ])roduced  only  l.KK)  grams  of  dried  crop,  in  whicli 
18.2  milligrams  of  nitrogen  were  found,  or  about  as  much  as  was  con- 
tained in  the  seeds  sown.  Where  microbes  were  present,  on  the  (con- 
trary, the  dried  crop  weighed  3.544  grams  and  contained  82. (>  milli- 
grams of  nitrogen.  Therefore  the  bacteria  had  given  to  the  plant 
the  faculty  of  taking  from  the  air  TO  milligrams  of  nitrogen  inde- 
pendently of  all  other  microbic  intervention  and  under  the  same 
exterior  conditions. 

By  using  water  in  the  place  of  sand  Prazmoffski  also  obtained  the 
same  results.  Some  peas  grown  in  a  nutrient  solution  without  nitro- 
gen and  sterilized  gave  only  9  milligrams  of  nitrogen,  whereas  others 
grown  in  a  similar  liquid  but  supplied  with  bacteria  gave  from  2(5  to 
82  milligrams. 

These  experiments  then  verify  in  the  most  complete  manner  the 
views  of  Hellriegel  and  Wilfarth;  the  fixation  of  nitrogen  by  the 
leguminoseiv  is  a  consequence  of  their  symbiotic  union  with  an 
infinitely  small  organism  whose  germs  are  profusely  scattered  abroad 
and  which  enables  these  plants  to  grow  sometimes  with  vigor  without 
any  artificial  inoculation  in  soils  destitute  of  all  nitrogenous  food. 

It  was  these  germs  which  "enabled  (1.  Ville  to  first  observe  the 
fixation  of  atmospheric  nitrogen  by  these  same  plants,  and  it  was 
their  irregular  dissemination  which  caused  the  inequality  in  his 
experiments,  and  if  Boussingault  found  it  .inii)ossible  to  olitain  the 
same  results  it  was  simply  l)ecanse  he  cultivated  his  plants  under  such 
conditions  that  they  could  not  acquire  sufficient  vitality  to  profit  by 
their  union  with  these  bacteroids. 

In  effect  at  the  beginning  of  vegetation  in  soils  without  nitrogen, 
but  into  whicli  microbes  have  been  introduced,  an  interval  of  stop- 
page of  growth  has  been  observed,  so  complete  as  to  make  us  fear  a 
rapid  decay  of  the  plant,  and  this  period  of  intermission  always 
coincides  Avith  the  api)earance  of  the  tubercles  on  the  roots  of  the 
plants.  At  this  time  the  invading  organisms  derive  their  nourish- 
ment from  the  juices  of  the  young  plant;  they  exhaust  it,  and  if  the 
latter  has  not  the  strength  to  resist  this  invasion,  which  then  con- 
stitutes a  sort  of  parasitism,  if  its  roots  are  not  able  to  develoj)  freely, 
or,  again,  if  its  leaves  remaiji  in  a  badly  ventilated  atmosphere, 
always  saturated  with  aqueous  vapor,  the  plant  Avill  inevitably  perish. 

If,  on  the  contrary,  it  can  resist,  it  will  very  soon  gain  the  advan- 
tage; it  then  takes  from  the  bacteria  the  nitrogenous  matter  which 
they  contain  and  compels  them  to  form  more  of  it  fi-om  the  nitrogen 
which  surroiuids  them.  Doubtless  on  its  side  the  bacteriod  pi-ofits 
as  much  as  the  plant  from  its  symbiosis;  it  is  probable  that  it  receives 
from  the  latter  hydrocarbons — sugars  or  others — in  exchange  for  the 
albuminoids  which  it  gives  to  the  plant,  and  thus  it  is  (ha(  this  uuion 
may  exist  until,  finally,  the  moment  arrives  when  the  plant,  having 


156 

attained  its  full  growth,  entirely  consumes  the  tubercles  in  order  to 
assimilate  them  and  thus  form  its  seed. 

It  is  then,  in  short,  l)y  means  of  their  roots  that  the  leguminoseix^ 
draw  the  nitrogen  from  the  air,  and  this  conclusion  agrees  with  the 
well-known  fact  that  a  living  leaf  is  incapable  of  modifying  the 
volume  of  nitrogen  into  which  it  may  be  plunged,  and  that  it  is  the 
root  which  in  the  first  stage  of  vegetation  always  shows  the  greatest 
richness  in  nitrogen. 

It  is  the  remains  of  these  roots  and  the  rupture  of  the  tubercles 
that  are  carried  on  them  which  determine  the  enrichment  of  the 
soils  of  meadows,  and  the  dispersion  of  the  germs  of  the  microbe 
that  fixes  the  nitrogen. 

It  has  been  objected  to  the  conclusions  of  Hellriegel  and  AVil- 
farth  that  up  to  the  present  time  it  has  been  impossible  to  observe  a 
fixing  of  nitrogen  by  the  bacteroids  alone  independently  of  their 
symbiotic  alliance  with  a  leguminous  plant.  This  is  true,  but  it 
must  be  remembered  that  the  obtaining  of  such  proof  is  fraught  with 
great  experimental  difficulties;  the  micro-organism,  cultivated,  we 
ivill  suppose  in  a  place  where  there  is  no  nitrogen,  Avill  certainly  take 
the  nitrogen  from  the  air,  but  not  more  than  is  necessary  for  the 
formation  of  its  tissues;  that  is  to  say,  an  extremely  minute  quantity, 
for  the  microbe  itself  weighs  very  little,  and  thus  it  happens  nec- 
essarily that  the  phenomenon  remains  undetected  by  even  the  most 
delicate  methods  of  analysis. 

In  order  that  the  al)sorption  may  be  manifest  it  would  be  necessary 
that  we  should  be  able,  as  the  Leguminosa?  actualh^  are,  to  take  from 
the  bacteroids  their  nitrogenous  substance  as  fast  as  it  is  produced, 
or  that  it  should  be  cultivated  in  such  quantities  that  the  dry  Aveight 
should  attain  measurable  quantity.  Shall  we  ever  discover  the  means 
of  making  this  experiment  ?  It  is  impossible  to  say  at  this  moment, 
but  what  we  can  affirm  is  that  it  is  not  correct  to  conclude,  as  certain 
authorities  have  done,  that  the  bacteroids  are  incapable  of  fixing 
nitrogen  gas  when  alone,  basing  their  objections  solely  on  the  ground 
that  up  to  the  present  moment  it  has  not  been  ]:>ossible  to  prove  such 
a  fixation  of  nitrogen. 

Besides,  atmosplieric  nitrogen  is  but  a  part  of  the  comi^lete  nour- 
ishment of  the  Leguminosa^;  since,  in  common  with  other  species  of 
plants,  they  can  assimilate  the  nitrates  and  ammoniacal  salts, 
although  in  a  less  degree. 

When  a  pea,  a  bean,  or  a  lupin  grows  in  a  fertile  soil  it  never  shows 
that  tendency  to  perish  due  to  a  ''  famine  of  nitrogen,""  which  charac- 
terizes the  same  plants  in  a  sterile  soil;  the  plant's  Adtality  is  great 
at  the  beginning  of  its  growth  and  it  is  for  this  reason  that,  in  order 
to  insure  the  success  of  his  experiment,  G.  Ville  advised  that  a 
small  quantity  of  niti'ogenous  fertilizer  be  added  to  the  mineral  sub- 
stances that  are  given  to  the  sand  in  which  the  plants  were  culti- 
vated; in  this  case,  however,  the  tubercles  are  less  abundant  and  the 
sum  total  of  the  nitrogen  borrowed  from  the  atmos))here  is  lower. 

If  this  bacteroidal  action  be  not  the  only  one  capalile  of  furnishing 
to  leguminous  plants  the  nitrogen  necessary  to  them,  there  is  evi- 
dently no  occasion  to  draw  an  absolute  line  of  demarcation  between 
these  plants  and  others,  which  being  less  qualified  to  associate  them- 
selves with  the  microbes  (doubtless  because  the  medium  that  these 
offer  to  them  is  less  favorable  to  their  development)  derive,  therefore, 


ir)7 

more  benefit  fi'Diii  iiitro^jonous  fertilizers.  Between  the  Papilioiiacea^ 
and  the  cereals,  which  occupy  extreme  positions  in  regard  to  the 
capacity  for  fixing  atmospheric  nitrogen,  there  exist  probably  other 
intermediate  s})ecies  capable  of  exercising  the  same  function  in  every 
degree.  These  latter  nnist  be  less  imi)r()ving  to  the  soil  than  the  Legu- 
minosa'.  but  they  must  assuredly  be  less  exhausting  than  wheat, 
Indian  corn,  or  beets,  and  it  is  impossible  to  exjilain  otherwise  than 
by  reasons  of  this  kind  the  continued  growth  of  forests  and  meadows 
which  continue  incessantly  to  furnish  crops  in  soils  which  never 
cease  to  be  much  richer  than  our  cereal  soils,  although  they  never 
receive  any  fertilizers. 

According  to  Ville,  the  Cruciferte  in  particular  aiv  capable  of 
taking  a  part  of  their  nitrogen  directly  from  the  air.  On  the  other 
hand,  we  know  that  the  roots  of  certain  species  of  forest  trees  form  a 
symbiosis  with  some  kinds  of  mushrooms  which  are  not  yet  well 
knoAvn  and  Avhich  i)erhaps  act  in  the  same  way  as  the  bacteroids 
of  the  nodules.  I  shall  not,  however,  insist  upon  facts  which  are 
liable  to  discussion  and  Avhich  require  to  be  studied  more  minutely 
and  with  all  the  care  which  has  been  bestowed  upon  the  study  of  the 
Leguminosea". 

I  have  now  only  one  more  ])oint  to  examine  in  regard  to  this  ques- 
tion, a  point  which,  although  still  involved  in  obscurity,  is  neverthe- 
less very  interesting.  All  planters  are  well  aware  of  the  fact  that  a 
leguminous  plant  can  only  be  grown  for  a  few  years  in  the  same  soil. 
After  being  very  flourishing  for  a  short  time  a  field  of  clover  or  of 
lucerne  dwindles  away,  the  croj^s  rapidly  become  less  abundant,  and 
finally  the  soil  is  invaded  by  the  (iraminea\  which  raj)idly  transform 
the  artificial  meadow  into  a  natural  one.  unless  precautions  have  been 
taken,  by  clearing  the  land,  to  prevent  the  phenomenon.  To  what  can 
we  attribute  this  spontaneous  transformation?  The  microbe  has  had 
at  its  disposal  all  the  elements  necessary  for  its  growth  and  its  dis- 
semination. Why  does  it  cease  all  of  a  sudden  to  exercise  its  favor- 
alile  influence?  Perhaps  there  is  in  this  something  very  important, 
which  I  can,  hoAvever,  only  express  in  the  form  of  an  hypothesis,  but 
which,  nevertheless,  I  think  is  worthy  of  having  your  attention  called 
to  it.  Pasteur  has  shown  us  that  certain  inferior  organisms  change; 
their  nature,  lose  their  noxiousness,  or  become  more  virulent  if  they 
are  made  to  pass  from  one  species  of  animal  to  another.  May  it  not 
l)e  that  the  bacterium  of  the  nodules  undergoes  also  a  modification  By 
its  prolonged  contact  with  the  roots  of  the  Leguminosa*  and  that  it 
Avould  be  necessary  for  it,  in  order  to  resume  its  former  functions,  to 
pass  to  some  other  species  of  plants — in  other  words,  to  change  its 
surroundings?  Experience  alone  will  solve  this  question.  I  will 
content  myself  here  with  putting  it  before  you. 

Scientific  researches  sooner  or  later  always  find  their  practical 
applications;  these  that  I  have  had  the  honor  of  bringing  before 
you  can  not  fail  to  render  important  services  to  agriculture.  The 
"  restoring  "  part  played  by  the  Leguminosa^  is  known  to  all  agri- 
culturists; it  has  become  an  axiom  of  agriculture  and  forms  the  basis 
for  the  rotation  of  all  crops;  but  after  the  experiments  which  we 
have  just  passed  in  review  it  assumes  for  us  a  strictly  scientific  char- 
acter which  it  did  not  possess  before.  The  modus  operandi  of  the 
process  has  been  determined,  and  by  a  simple  modification  of  the  proc- 
esses of  cultivation  now  in  use,  by  assigning  a  still  more  extended 


158 

sphere  to  legiiniinous  plants,  it  will  be  easy  for  us  to  profit  b^'  this 
newly  acquired  knowledge  in  order  better  than  before  to  preserve 
our  lands  in  a  state  of  suitable  fertility.  Suppose,  for  example,  that 
clover,  let  us  say,  has  been  sown  with  any  cereal  and  that  it  is  left  to 
grow  freely,  after  the  harvest ;  this  clover  will  take  a  certain  quan- 
tity of  nitrogen  from  the  air,  by  the  help  of  the  nodules  on  its  roots. 
If  this  clover  is  plowed  under  before  the  next  time  of  sowing,  in  the 
spring  or  autumn,  so  as  to  serve  as  a  green  fertilizer,  we  shall  have 
obtained,  with  no  other  expense  than  the  price  of  the  seed,  a  manure 
derived  wholly  from  the  air  of  the  atmosphere. 

This  practice,  first  reconnnended  by  Ville,  has  been  recently  shown 
by  Deherain  to  have  another  advantage  quite  as  important.  By  keep- 
ing the  surface  of  the  soil  in  a  state  of  constant  evaporation  the  inter- 
polated cultivation  of  the  clover  diminishes  the  drainage  to  a  notable 
extent;  all  the  nitrates,  which  then  are  formed  in  large  quantities  and 
which  would  be  lost  if  the  earth  remained  uncovered,  are  held  and 
assimilated,  being  rendered  insoluble  by  the  vegetation,  and  when 
plowed  under  will  augment  by  so  much  the  more  the  natural  reserves 
of  the  soil. 

This  method,  whether  Ave  consider  it  as  the  cultivation  of  a  fallow 
field  or  whether  we  call  it  "  sideration," "  as  proposed  by  Ville, 
aifords  two  advantages  of  primary  importance — it  prevents  in  a  great 
measure  the  losses  due  to  excessive  nitrification  of  the  soil  in  autumn, 
and  restores  to  the  earth  a  certain  quantity  of  nitrogen  which  has 
passed  from  a  gaseous  state  to  the  state  of  organic  matter.  I  do  not 
think  it  an  exaggeration  when  I  say  that  the  gain  from  this  practice 
alone  is  equivalent  to  a  strong  artificial  manuring  of  the  soil,  and  it 
may  sometimes  even  attain  a  value  of  many  hundred  francs  per  hec- 
tare, which  will  be  realized  in  subsequent  crops. 

Finally,  among  other  examples  of  the  application  of  this  new 
knowledge  there  is  a  most  curious  fact  which  has  just  been  pointed 
out  by  Salfeld,  in  Germany,  and  which,  if  proved,  will  be  a  further 
confirmation  of  the  immortal  doctrines  of  Pasteur.  After  clearing 
a  peat  bog  situated  on  the  banks  of  the  Ems,  on  the  frontier  of  Hol- 
land, horse  beans  and  vetOhes  were  sown.  The  soil  was  everywhere 
enriched  with  mineral  fertilizers,  but  on  one  part  only  of  the  field  a 
small  quantity  of  good  arable  earth  was  spread,  in  the  proportion  of 
about  40  kilograms  to  the  are.'' 

The  effect  of  the  addition  of  this  latter  element  was,  as  it  appears, 
most  surprising;  under  its  influence  the  crop  was  doubled.  This 
result  is,  in  Salfeld's  opinion,  similar  to  the  results  obtained  by 
Hellriegel  and  Wilfarth  in  their  laboratory  experiments;  if  this  is 
really  so — and  it  is  possible — there  Avill  be  in  the  near  future  a  new  era, 
a  sort  of  revolution,  so  to  speak,  in  practical  agriculture. 

Perhaps  the  time  is  not  far  distant  when  our  farmers  will  add  to 
the  fertilizers  of  commerce  [the  so-called  soil  improA^ers  and  complete 
manures,  etc. — C.  A.]  true  culture  broths,  pre]:)ared  according  to  the 
methods  in  use  in  microbic  researches,  and  which  will  furnish  to 
plants  the  germs  of  organisms  capable  of  fixing  nitrogen  [the  nitro- 
gen fixers],  or,  perhaps,  others  still,  favorable  also  to  their  develop- 

a  This  medical  term  for  atrophy  or  mortification  does  not  seei»  quite  appro- 
priate in  this  case. — C.  A. 

6  The  are  is  about  110  square  yards,  or  100  square  meters,  or  1,071  square  feet. 


159 

nient  and  Avhicli  ^vill  cause  their  ci-ops  continually  to  increase  and 
Avill  finally  enrich  the  soil  to  the  extreme  limit  of  its  possible  fei-tility. 

This  would  undoubtedly  be  a  vast  extension  of  that  admiral)!e 
humanitarian  work  for  which  we  are  indebted  to  Pasteur;  but  this 
is  anticipation,  and  I  only  proposed  in  this  lecture  to  point  out  the 
jjresent  state  of  the  question.  I  shall  therefore  close  by  sunnninjij 
up  what  I  have  said  in  a  few  words. 

Experiments  made  by  Ville,  and  repeated  and  \erified  by  many 
other  observers,  have  shown  us  that  certain  plants,  i)articularly  those 
of  the  species  of  the  Leg^uminosic.  have  taken  iroin  the  atmosphere  a 
part  of  the  nitrojren  that  they  contain. 

Berthelot,  and  also  Gautier  and  Drouin,  have  shown  that  the  soil 
alone  can  to  a  slight  extent  enrich  itself  by  means  also  of  a  direct 
fixation  of  gaseous  nitrogen. 

Berthelot  has  also  shoAvn  that  this  phenomenon  corresponds  with 
the  development  of  certain  microbes  preexisting  in  the  soil;  and, 
finally,  Hellriegel  and  Wilfarth  have  discovered  this  micro-organism 
in  the  nodules  on  the  roots  of  the  Leguminosae. 

This  last  work  is  certainly  one  of  the  greatest  interest,  and  does 
the  greatest  honor  to  the  physiologists  who  have  succeeded  in  bring- 
ing it  to  a  final  result ;  but  it  is  proper  to  recognize  that  the  route 
to  l»e  followed  had  already  been  marked  out  l)y  previous  researches. 
The  problem  was  ripe  for  solution,  and  it  was  in  our  own  country — 
in  France— that  the  great  problem  of  the  assimilation  of  nitrogen 
had  been  proposed  and  in  a  great  part  solved,  which  is  no  more 
than  Avas  to  be  expected  from  so  great  a  center  of  production  and 
agri(;ultural  progress. 


Professor  Frank,  of  the  agricultural  institute  in  Berlin,  finds  that 
the  tul)ercles  uuiy  be  removed  from  the  plant  without  stopping  the 
])r()cess  of  taking  nitrogen  from  the  air.  Fvideiitly,  therefore,  the 
subject  has  to  be  investigated  still  further.  (Agr.  Sci.,  Vol.  lY, 
p.  68.) 

Frank  has  also  shown  that  the  symbiosis  in  the  tubercles  of  the 
Leguminosa^  is  of  an  entirely  difi'erent  character  from  that  which 
occurs  in  the  roots  of  any  other  plants.  Furthermore,  when  the 
soil  is  rich  in  humus  the  microbic  parasite  does  no  special  service  to 
the  host,  but  when  the  supply  of  humus  is  insufficient  the  microbe 
symbiont  is  of  the  greatest  service  to  the  host.  (Agr.  Sci.,  Vol.  IV, 
p.  266.) 

H.  J.  Wheeler,  of  the  Rhode  Island  Experiment  Station,  gives 
(Agr.  Sci.,  Vol.  IV,  p.  55)  an  account  of  the  work  done  by  Professor 
Hellriegel  at  Bernburg,  (Jernuiny,  along  the  line  of  investigation 
conducted  by  Boussingault  and  Ville  in  France,  Lawes  and  Gi.lbert 
in  England,  and  W.  O.  Atwater,  of  the  Storrs  School  Agricultural 
Experiment  Station.  In  the  present  state  of  the  question  it  may  be 
considered  as  settled  that  certain  plants  are  able,  if  supplied  with 
all  the  other  essential  elements,  to  draw  their  supply  of  nitrogen  from 


160 

the  air,  either  directly  or  indirectly,  by  means  of  minute  organisms 
now  generally  termed  microbes.  These  microbes  can  be  connnuni- 
cated  by  direct  inoculation  from  one  plant  to  another  that  has  been 
previously  free  from  them.  Experiments  are  in  progress  as  to  the 
possibility  of  cultivating  these  microbes  artificially,  and  when  this 
has  been  accomplished  successfully  it  will  mark  a  great  step  toward 
the  solution  of  the  question  as  to  the  plant's  method  of  obtaining 
nitrogen,  and  not  only  that,  but  a  great  step  toward  success  in  agri- 
culture, since  every  one  will  be  able  to  inoculate  his  own  plants,  and 
thus  immensely  stimulate  the  yield  of  crops. 

T.  Leone  has  shown  that  a  great  number  of  germs  obtain  their- 
nitrogen  more  easily  by  decomposing  the  nitrates,  and  only  when 
these  salts  are  used  up  do  they  begin  to  nitrify  the  ammoniacal  com- 
pounds, and  after  that  possibly  attack  the  free  nitrogen  of  the  air. 
He  has  also  shown  that  these  take  the  nitrogen  as  a  gas  from  the 
nitric  acid  in  the  nitrates  and  do  not  convert  it  into  ammonia.  ( Agr. 
Sci.,  Vol.  V,  p.  82.) 

Leone  also  shows  that  the  phenomena  of  nitrification  and  denitri- 
fication  occur  alternately  according  to  the  relative  amount  of  nutri- 
ment and  number  of  bacteria  present  in  the  water.  The  manuring  of 
soil,  therefore,  gives  rise  to  a  cycle  of  phenomena,  nitrification  being 
first  arrested  and  the  nitrates  and  nitrites  reduced  until  a  maximum 
formation  of  ammonia  is  attained,  when  nitrification  again  com- 
mences. The  destruction  of  the  nitrates  and  nitrites  in  the  soil  is 
complete  or  partial  according  as  the  supply  of  manure  is  abundant 
or  otherwise.     (Agr.  Sci.,  Vol.  V,  p.  107.) 

The  experiments  made  in  Europe  by  Boussingault,  Hellriegel,  and 
others  as  to  the  method  by  which  plants  obtain  the  nitrogen  from  the 
atmosphere  have  been  repeated  and  extended  by  C.  D,  Woods,  of  the 
Storrs  School  Agricultural  Experiment  Station.  His  results  are 
summarized  as  follows: 

(1)  Peas,  alfalfa,  serradella,  lupine,  probabl}^  clover,  and  appar- 
ently all  leguminous  plants,  have  the  power  of  acquiring  large  quanti- 
ties of  nitrogen  directly  from  the  air  during  their  growth.  There 
is  no  doubt  that  the  free  nitrogen  of  the  air  is  thus  acquired  by  these 
plants.  This  acquisition  has  something  to  do  with  the  tubercles  on 
the  roots  of  these  plants,  but  the  details  of  the  process  are  still  to  be 
solved.  The  cereals,  oats,  etc.,  with  which  experiments  have  been 
brought  to  completion,  do  not  have  this  power  of  acquiring  nitrogen 
from  the  air,  nor  do  they  have  such  tubercles  as  are  formed  on  the  roots 
of  the  legumes.  They  get  their  nitrogen  from  the  nitrates  or  nitrogen- 
ous fertilizers.  The  tubercles  on  the  roots  of  the  legumes  may  1  )e  formed 
either  after  or  entirely  without  the  addition  of  solutions  or  infusions 
containing  micro-organisms,  and  a  ijlausible  supposition  is  that  vrhen 
such  infusions  are  not  furnished  the  spores  of  the  organisms  were 


161 

floating-  in  the  air  and  were  deposited  in  the  pots  in  which  the  plants 
grew.  As  a  rule,  the  greater  the  abundance  of  tubercles  the  more 
vigorous  were  the  plants  and  the  greater  the  gain  in  nitrogen.  The 
gain  of  nitrogen  froin  the  air  by  the  legumes  explains  why  they  act  as 
renovating  crops.     (Agr.  Sci.,  Vol.  IV,  p.  22.) 

From  some  careful  experiments  by  A.  Petermann  on  yellow  lu})ins 
(Li/ pi /I  lis  hitei(s)  the  author  concludes  that  the  physiological  role  of 
the  tubercles  must  not  be  exaggerated.  They  can  not  be  the  only 
cause  of  the  fixation  of  nitrogen,  although  their  presence  may  explain 
why  the  intervention  of  atmospheric  nitrogen  is  most  marked  in  the 
case  of  the  Leguminosse.  He  further  shows  that  sodium  nitrate  is  not 
injurious,  but  beneficial,  to  lupins.  The  trouble  in  its  use  results 
niostlj'^  from  the  fact  that  it  is  very  soluble  and  is  soon  washed  down 
by  the  rain  out  of  the  reach  of  the  roots,  which  must  then  draw  their 
nitrogen  from  the  atmosphere  by  means  of  the  microbic  organisms. 
(Agr.  Sci.,  Vol.  IV,  p.  264.) 

Pagnoul  has  measured  the  loss  and  gain  of  nitrogen  by  the  soil  as 
the  result  of  the  cultivation  of  special  crops.  He  sowed  grass  and 
clover  in  four  pots,  but  left  two  others  Avithout  any  crop.  The  gain 
of  nitrogen  permanently  fixed  in  the  soil  in  one  year — March,  1888,  to 
March,  1889 — was  as  follows:  With  no  crop  the  soil  gained  at  the 
rate  of  29  kilograms  per  hectare  per  year,  with  the  grass  crop  394 
kilograms,  and  with  the  clover  crop  904  kilograms.  On  the  other 
hand,  the  total  proportion  of  nitrogen  removed  from  the  soil  by  the 
drainage  water  was  in  each  case  as  follows:  No  crop,  85;  grass,  5; 
clover,  18.     (Agr.  Sci.,  Vol.  IV,  p.  325.) 

20G7— 05  M 11 


Chapter  IX. 

RELATIONS   OF  CROPS   TO   MANURES,  FERTILIZERS,  AND 
ROTATION. 

The  preceding  section  having  shown  how  easily  all  the  valuable 
nitrates  are  dissolved  and  washed  away  by  rain  and  how  completely 
the  permanent  fertility  of  a  field  depends  upon  microbic  action 
within  the  soil,  and  especially  wdien  attached  to  leguminous  plants, 
we  shall  therefore  not  be  surprised  to  learn  that  expensive  and  arti- 
ficial chemical  fertilizers  and  guanos  are  often  less  important  than 
the  enrichment  that  comes  more  naturally  by  the  rotation  of  crops. 

ARTIFICIAL   FERTILIZERS   AND   MANURES. 

As  the  result  of  tw^elve  years'  experience,  J.  W.  Sanborn,  of  Mis- 
souri, states  that  although  both  science  and  practice  assert  the  efficacy 
of  artificial  fertilizers,  yet  their  profitahle  use  is  a  matter  of  grave 
concern  both  in  the  granite  soil  of  New  England  and  in  the  richer 
soil  of  the  Mississippi  Valley.  His  general  conclusions  are  that  we 
do  not  need  to  use  as  much  nitrogen  in  this  climate  as  in  Europe, 
especially  as  in  England,  nor  as  much  as  has  generally  been  consid- 
ered necessary;  that  enriching  by  rotation  of  crops  is  the  preferable 
method;  that  nitrogen  (viz,  fertilizers)  may  be  profitably  bought 
only  for  a  few  winter  or  early  and  narrow-leaved  plants,  but,  as 
a  general  truth,  broad-leaved  plants  and  those  maturing  in  late  sum- 
mer and  in  the  fall  do  not  require  addition  of  nitrogen  to  the  soil. 
(Agr.  Sci.,  Vol.  I.  p.  227.) 

From  the  extensive  experiments  with  fertilizers  made  at  the  Ohio 
Agricultural  Experiment  Station  the  following  results  have  been 
secured,  based  on  both  station  work  and  that  done  by  cooperating 
farmers  throughout  the  State: 

Maize. — On  soils  capable  of  producing  50  bushels  of  shelled  corn  to 
the  acre  no  artificial  fertilizer  is  likely  to  produce  an  increase  of 
crop  sufficient  to  pay  the  cost.  On  soils  deficient  in  fertility,  phos- 
phoric acid  may  be  used  with  profit. 

Wheat. — As  a  rule  no  more  wheat  has  been  harvested  from  plats 
treated  with  commercial  fertilizers  than  from  those  receiving  no 
fertilizers,  whereas  farm  manures  produced  a  marked  increase.  At 
the  present  prices  of  grain  and  fertilizers  the  increase  of  crops  will 
not  cover  the  cost  of  the  fertilizer. 

Oats. — Plats  receiving  nitrates  showed  a  marked  superiority  in  the 
growing  season,  but  lodged  badly  before  harvest.  Muriate  of  potash 
gave  an  insignificant  increase.     (Agr.  Sci.,  Vol.  IV,  p.  237.) 

(102) 


163 

E.  F.  Ladtl,  of  the  Agriciiltuiv  Plxjx'riineiit  Station  at  Geneva, 
N.  Y.,  urges  the  necessity  of  a  more  thorough  and  systematic  study 
of  climate  and  soil  (Agr.  Sci.,  Vol.  IV.,  p.  36)  in  order  that  we  may 
better  understand  the  great  diversity  and  contradictions  in  the  experi- 
mental field  work,  so  called.  Thus  one  year's  experiments  at  the  same 
station  and  with  all  possible  care  will  show  that  the  "  Welcome  " 
oats  are  vastl}^  more  productive  than  the  "  \Miite  Russian,"  and  the 
very  next  year  reverses  this  decision.  In  the  same  year  a  neighboring 
experiment  station  operating  on  the  same  varieties  arrives  at  opposite 
conclusions.  In  1887  the  observations  showed  that  fertilizers  did  not 
alfect  the  chemical  composition  of  the  grasses,  but  in  1888  the  influ- 
ence was  very  marked.  Ladd  finds  that  the  contradictions  in  the 
reports  of  oat  crops  for  188.5  and  1886  at  the  Ohio  and  Ncav  York 
stations  are  apparently  due  to  considering  only  such  factors  as 
monthh'  rainfall  and  temperatures.  He  urges  that  the  soil  tempera- 
tures, sunshine,  wind,  the  humidity  in  the  soil,  and  the  aeration  of 
the  soil  are  equally  important  factors.  Any  season  will  give  some 
sort  of  a  crop,  but  the  maximum  crop  must  depend  upon  the  ferti- 
lizer and  the  relation  of  the  fertilizer  to  the  season.  Thus  Waring- 
ton  has  shown  that  a  dry  and  warm  season  is  most  favorable  for  the 
action  of  nitrate  of  soda,  while  a  moderately  wet  season  is  most  favor- 
able for  the  action  of  sulphate  of  ammonia.  The  reason  of  this 
appears  to  be  that  plants  are  unable  to  appropriate  to  their  use  the 
sulphate  of  ammonia  until  the  salt  has  become  nitrified,  and  this  phe- 
nomenon of  nitrification  does  not  take  place  except  under  the  influence 
of  a  certain  amount  of  moisture  in  the  soil.  A  soil  that  conserves  its 
moisture  for  a  considerable  time  and  is  properly  cultivated  to  permit 
the  free  permeation  of  the  air  gives  the  best  results  with  sulphate  of 
ammonia,  but  does  not  necessarily  give  the  best  results  with  the 
nitrate  of  soda,  since  this  is  so  soluble  as  to  be  soon  drained  away  out 
of  reach  of  the  plants.  Thus  in  different  seasons,  with  different  ferti- 
lizers, we  have  the  crops  of  wheat  shown  in  the  following  table: 


Hecto- 
liters per 
hectare. 


Nitrate  of  Hoda  and  a  wet  season  ( 1882) 

Nitrate  of  soda  and  a  dry  warm  season  (1^*87)  - 

Sulphate  of  ammonia,  wet  season  (1882) 

Sulphate  of  ammonia,  warm  dry  season  (1887)  . 


23.45 
Sl.r,7 
28.86 
23.  .56 


Again,  crops,  like  animals,  have  a  certain  limit  to  their  capabilities; 
if  the  maximum  yield  is  50  bushels  per  acre,  then  it  is  a  waste  to  put 
on  more  fertilizer  than  needed  to  attain  this  limit.  Evidently,  there- 
fore, we  have  to  study  the  relation  of  the  climate  to  tiie  fertilizers 
and  the  soil  in  order  to  ascertain  a  very  important  item  in  the  relation 
between  climates  and  crops. 


164 

Many  specific  results  as  to  the  relation  between  climates  and  crops 
on  a  large  scale  are  entirely  altered  from  season  to  season  by  the  chem- 
ical influence  of  the  climate  on  the  fertilizer  and  the  soil  in  general. 
We  have  here,  therefore,  a  source  of  discrepancy  that  has  contributed 
appreciably  to  obscure  the  influence  of  the  climate  on  the  plant. 

PRIZE    CROPS. 

Evidently  crops  of  seed  or  grain  depend,  primarily,  on  the  amount 
of  nitrogen  in  the  sap,  and,  secondarily,  on  the  elaboration  of  those 
precious  nitrates  into  albuminoids.  Hence  the  recognized  need  of 
manures,  fertilizers,  and  leguminous  crops.  But  the  study  of  the 
remarkable  crops  of  corn  raised  as  so-called  prize  crops  in  1889  dem- 
onstrates that  excellent  results  may  be  obtained  on  some  soils  without 
manures,  and  is  otherwise  very  instructive,  since  the  heavy  manuring 
in  many  cases  must  have  been  largely  counteracted  by  the  waste 
caused  by  rain.  I  condense  the  folloAving  from  the  monthly  reports 
of  the  department  of  agriculture  of  South  Carolina  for  March,  1890, 
pp.  233-243: 

In  1889  the  American  Agi-iculturist  olfered  a  prize  of  $500  for 
the  largest  crop  of  corn  that  should  be  groAvn  on  1  measured  acre  of 
ground  during  the  year  1889.  Forty-five  leading  competitors  ap- 
peared, of  whom  10  were  from  South  Carolina.  The  average  of  these 
10  prize  crops  from  that  State  gave  105  bushels  per  acre,  whereas  the 
n\erage  of  the  25  crops  from  other  States  was  103.5  bushels  per  acre. 
The  accompanying  table  gives  most  of  the  more  appropriate  statis- 
tics for  the  7  best  results  in  this  list  of  45  : 

Data  relative  to  the  best  7  of  the  Jin  competing  crops. 


Serial 
No. 


Locality. 


Soil.  I  Quantity  of  fertilizer. 


Z.  J.  Drake,  Marlboro  County, 

S.C. 
Alfred    Rose,    Yates    County, 

N.Y. 
George      Gartner ,      Pawnee 

County,  Nebr. 
J.  Snelling,  Barnwell  County, 

S.C. 
L.  Peck,  Rockdale  County,  Ga.. 


Poor  san'^y  soil.-|  (") 

Sandy  loam 8(K)  pounds  Mapes  corn  manure. 

Rich  black  loam.j  90  loads  barnyard  manure. 

I 
Sandy  loam I  SK)  bushels  stable  manure:  'M)  bush- 
els cotton  seed. 


lo I  4  loads  stable    manure:    30  bushels 

heated  cotton  seed:  1,000  pounds 
Packard  standard  fertilizer;  500 
pounds  cotton-seed  meal. 

B.     Gedney ,     Westchester     Clay  loam '  HOO  pounds  Mapes  corn  manure. 

County,  N.  Y. 

E.  P.    Kellenberger,    Madison     Sandy  loam No  fertilizer  at  all. 

County,  Ul.  1 


<'Prise  crop  No.  1. — The  sandy  soil  had  been  fertilized  in  1887  by  Mr.  Drake  and  had 
yielded  in  1888  the  great  crop  of  917  pounds  to  the  acre  of  lint  cotton,  and  was  therefore 
already  profiting  by  the  heavy  enrichment  that  is  had  received  that  year.  In  Feb- 
ruary, 1889,  in  preparation  for  the  present  contest,  Mr.  Drake  began  a  new  course  ot 
manuring,  and  from  that  date  until  .lime  11  the  following  material  was  added  to  the  soil : 
One  thousand  bushels  stable  manure :  867  pounds  of  German  kainit ;  867  pounds  ot 
cotton-seed  meal;  200  pounds  of  acid  phosphate;  1.066  pounds  of  manipulated  guano; 
200  pounds  of  animal  bone;  400  pounds  nitrate  of  soda;  600  bushels  of  whole  cotton 
seed.  The  total  cost  of  this  manure  was  .$220  iind  (he  work  in  applymg  it,  together  with 
the  frequent  culture  that  was  given,  made  the  whole  expense  of  the  crop ^(264.  Ihe  value 
of  the  corn  that  was  raised  was  .$206,  and  the  value  of  the  manure  left  in  the  soil  for  the 
next  year's  crop  was  at  least  $150. 


165 


Data  relative  to  the  best  7  of  the  J.T  compethui  erops — rontimioil. 


1 

Average 
Variety  of  seed.         distance 

Statistics  of  harvested  crops. 

Serial 

Green  weight. 

Dry  weight. 

Bushels  of  kernels. 

Water 

No. 

Cobs. 

Ker- 
nels. 

Cobs. 

Ker- 
nels. 

Green. 

Crib 
cured. 

Chem- 
i^lly 
dry. 

1 

2 
3 
4 
5 
6 

Ft.      In. 

Gourd     variety    of    4. Ox  6.0 

southern      white 

Dent  improved  by 

20  years  of  careful  I 

selection     on    his 

plantation. 

Early  Mastodon 3. 0  x  12. 0 

do 3.0x36.0 

White  Gom-d 4.0x12.0 

Large  White.. .5..5x48.0 

King  Philip 3.5x  3.0 

Eclipse  variety  early    6. 0  x  30. 0 

yellow  Dent. 

3,133 

4,134 
1,821 
1,393 
1,826 
1,776 
1.497 

14,273 

11,764 
9,559 
7,316 
7,305 

7^311 

2,726 

2,954 
1,174 
1,212 
1,367 
1,154 
617 

12,  i;« 

9,764 
7,647 
6,218 
6,136 
5,717 
.5.:349 

255 

213 
171 
131 
130 
119 

i;« 

239 

191 
151 

121 
112 
105 

217 

174 
137 
111 
110 
102 
95 

P.ct. 
14 

20 

22 
15 
18 
19 
31 

With  regard  to  the  weather  and  other  items  during  this  season 
of  1889  at  these  seven  stations  I  have  found  only  the  following  notes 
referring  to  the  prize  crop  No.  1 : 

C'ldti ration. — The  seed  was  planted  March  2,  5  or  G  kernels  to 
each  foot  of  a  row ;  the  plants  began  to  sprout  on  the  16th ;  there  was  a 
good  stand  the  25th,  and  the  stalks  were  thinned  out  to  1  every  5  or  « 
inches  on  April  8 ;  no  hilling  was  done,  but  the  whole  acre  was  kept 
perfectly  level.     The  crop  was  harvested  November  25. 

Weather. — In  March  the  weather  was  warm  and  laiu!  moist. 
Good  rains  on  March  3,  10,  and  15;  rain  on  24th;  1  inch  of  rain  on 
May  2G;  G  inches  of  rain  May  30;  rain  on  June  4  and  5;  rain  on 
June  9.  The  season  in  general  was  rainy  and  wet  as  compared  with 
other  years;  rains  following  frequently,  and  no  irrigation  was  neces- 
.sary. 

The  record  of  largest  corn  crop  up  to  this  date  had  been  that  of 
Doctor  Parker,  Columbia,  S.  C,  in  1857,  who  raised  200  bushels  to 
the  acre.    ' 

The  exact  measures  of  all  these  45  competing  crops  have  been  uiade 
the  basis  of  a  comparison  showing  that  on  the  average  of  the  IT  east- 
ern crops  the  percentage  of  nitrogenous  matter  was  10.78,  but  for  14 
southern  crops  it  was  10.33,  and  for  14  we.stern  crops  10.2(),  .showing 
an  imperceptible  difference  slightly  in  favor  of  the  eastern  climate 
and  soil  and  seeds. 

In  respect  to  the  general  advantage  of  fertilizers,  and  notwith- 
standing the  apparent  advantages  gained  by  some  of  the  heavy 
manuring  in  these  competing  crops,  attention  is  called  to  the  fact  that 
competitor  No.  7  raised  a  very  fine  crop  of  130  bushels  green  or  05 
dry  bushels  to  the  acre  without  any  fertilizer  whatever,  and  that  the 
crops  reported  by  Nos.  4,  5,  and  6  were  even  less  than  his  in  their 


166 

green  weight,  although  Lirger  in  their  (h\v  weight,  after  what  would 
ordinarily  be  called  very  heavy  manuring.  These  facts  are  quite  in 
accord  with  the  general  results  of  work  at  experimental  farms,  wdiich, 
according  to  the  South  Carolina  department  of  agriculture,  have 
shown  that  increasing  the  amounts  of  the  fertilizers  bej^ond  a  certain 
point  gives  no  corresponding  increase  in  the  amount  of  grain,  and 
but  few  of  the  applications  pay  for  their  cost.  There  is  abundant 
experimental  proof  that  for  any  given  soil  there  is  a  limit  to  the 
amount  of  profitable  manuring.  The  process  of  improving  the  soil, 
like  the  process  of  fattening  cattle,  is  comparatively  gradual  and 
requires  time.  The  margin  of  profit  in  the  application  of  manures  is 
narrower  than  is  generally  supposed.  It  is  equally  important  to 
attend  to  the  selection  of  the  seed,  the  thorough  cultivation,  and  the 
natural  fertilization  that  results  from  the  cultivation  of  the  Legu- 
minosa?  and  the  rotation  of  crops. 


PART  II.-EXPERIENCE  IN  OPEN  AIR  OR  NATURAL  CLIMATE. 


Chapter  X. 
STUDIES  IN  PHENOLOGY. 

Lender  the  general  heading  we  shall  consider,  first,  the  wild  plants 
and  their  natural  habits;  second,  the  plants  cultivated  at  experi- 
ment stations  under  instructive  experimental  conditions,  and,  third, 
the  statistics  of  each  and  the  experience  of  farmers  in  general  from 
a  practical  point  of  view.  The  study  of  the  forest  or  natural  habits 
of  plants  leads  us  into  the  phenology  of  plant  life. 

Phenology  is  a  term  first  applied  by  Ch.  IVIorren  to  that  branch  of 
science  which  studies  the  periodic  phenomena  in  the  vegetable  and 
animal  world  in  so  far  as  they  depend  upon  the  climate  of  any 
locality.  Among  the  prominent  students  of  this  subject,  one  of  the 
most  minute  observers  was  Karl  Fritsch,  of  Austria,  who  in  his  In- 
structions (1859)  gives  some  account  of  the  literature  of  similar 
works  up  to  that  date.  He  distinguishes  the  following  epochs  in  the 
lives  of  plants,  and  especially  i-ecommends  the  observation  of  peren- 
nial or  forest  trees  that  have  remained  undisturbed  for  at  least  sev- 
eral years.     His  epochs  are : 

(1)  The  first  flower. 

(2)  The  first  ripe  fruit. 

The  next  important  are,  for  the  annuals: 

(3)  The  date  of  sowing. 

(4)  The  date  of  first  visible  sprouting. 

In  order  to  assure  greater  precision  he  adds : 

(5)  The  first  formation  of  spikes  or  ears. 

As  Fritsch  considers  that  the  development  of  the  plant  so  far  as 
its  vegetative  process  is  concerned  depends  princii)ally  upon  tempera- 
ture and  moisture,  but  that  its  reprodlictive  process  depends  prin- 
cipally upon  the  influence  of  direct  sunlight,  therefore  he  adds  a 
sixth  epoch  for  trees  and  shrubs — viz: 

(0)   The  first  unfolding  of  the  leaf  or  the  leaf  bud  or  frondescence. 

This  is  the  epoch  when  by  the  swelling  of  the  buds  a  bright  zone 
is  recognized  which  opens  out  and  the  green  leaf  issues  foi-th.     Cor- 

(Kh) 


168 

responding  with  the  formation  of  the  leaf  is  its  ripening  and  fall 
from  the  tree,  which  Fritsch  adds  to  his  list  of  epochs,  viz : 

(7)  The  fall  of  the  leaf  or  the  time  when  the  tree  has  shed  fully 
one-half  of  its  leaves;  as  the  wind  and  heavy  rains  accelerate  this 
process  the  date  is  liable  to  considerable  uncertainty  independent 
of  the  vitality  of  the  plant.  Therefore,  in  this,  as  in  all  other  epochs, 
Fritsch,  in  endeavoring  to  lay  the  foundations  of  the  study,  rejected 
those  cases  in  which  any  unusual  phenomenon,  such  as  wind  or 
drought  or  insects,  had  a  decided  influence  on  the  observed  dates. 

Many  plants  blossom  a  second  time  in  the  autumn,  although  they 
ma}^  not  ripen  their  fruits;  therefore  in  special  cases  Fritsch  adds  an 
eighth  epoch,  viz : 

(8)  The  second  date  of  flowering.  Of  course  it  is  understood  that 
if  the  second  flowering  is  brought  about  artificially,  as  by  irrigation, 
pruning,  or  mowing,  that  fact  must  be  mentioned. 

"When  the  flowers  blossom  in  clusters,  such  that  the  individuals 
are  lost  sight  of  in  the  general  effect,  then,  in  addition  to  the  first 
flower,  we  note  the  following  item : 

(9)  The  general  flowering  or  the  time  when  the  flowers  are  most 
uniformly  distributed  over  the  plant. 

For  118  varieties  Fritsch  gives  in  detail  the  phenomena  that  char- 
acterize the  date  of  the  ripening  of  the  fruit.  He  also  gives  an  equally 
elaborate  system  of  observations  on  birds,  mammals,  fishes,  reptiles, 
and  insects,  and  especially  the  mollusks  or  garden  snails  and  slugs. 

THE  RELATION  OF  TEMPERATURE  AND  SUNSHINE  TO  THE 
DEVELOPMENT  OF  PLANTS— THERMOMETRIC  AND  ACTINO- 
METRIC  CONSTANTS. 

Reaumur  was  the  first  to  make  an  exact  comparison  of  the  different 
quantities  of  heat  required  to  bring  a  plant  up  to  the  given  stage  of 
maturity,  and  since  then  many  authors  have  written  on  this  subject. 

I  will  here  give  a  brief  summary  of  views  that  have  been  held  by 
prominent  authorities  as  to  the  proper  method  of  ascertaining  and 
stating  the  relation  between  temperature  and  the  development  of 
plants. 

Reaumur  (1735)  adopted  simply  the  sum  of  the  mean  daily  tem- 
peratures of  the  air  as  recorded  by  a  thermometer  in  the  shade  and 
counting  from  any  given  phenological  epoch  to  any  other  epoch. 
He  employed  the  average  of  the  daily  maximum  and  minimum  as  a 
sufficiently  close  approximation  to  the  average  daily  temperatures, 
and  evidently  in  the  absence  of  hourly  observations  any  of  the  recog- 
nized combinations  of  observations  may  be  used  for  this  purpose. 
Reaumur  found  from  his  observations  that  the  sum  of  these  daily 
temperatures  was  approximately  constant  for  the  period  of  develop- 
ment of  any  plant  from  year  to  year;  hence  this  constant  sum  is 
called  a  thermal  constant  in  phenology.     For  the  three  growing 


169 

months — Api-il,  May,  and  Juno,  lT3-t — the  sum  of  the  daily  tempera- 
tures for  ninety-one  days  was  equivalent  to  1,1()0°  C,  but  for  1735 
it  was  1.015°  C,  whence  he  concluded  that  the  ripening  of  the  vege- 
tation Avould  be  retarded  in  1785  as  compared  with  the  preceding 
year. 

This  idea  had  been  familiar  to  Reaunuu-  for  some  time  j)i'evi<)usly, 
and  in  1735,  as  cited  by  Gasparin,  Met.  Agric,  Vol.  II,  1st  ed.,  Paris, 
1844,  he  says : 

It  would  be  interesting  to  continue  such  comparisons  between  the 
temperature  and  the  epoch  of  ripening  and  to  push  the  study  even 
further,  comparing  the  sum  of  the  degrees  of  heat  for  one  year  with 
the  similar  sums  of  temperatures  for  many  other  years;  it  would  be 
interesting  to  make  comparisons  of  the  sums  that  are  eft'ective  during 
any  given  year  in  warm  countries  with  the  effective  sums  in  cold  and 
temperate  climates,  or  to  compare  among  themselves  the  sums  for  the 
same  months  in  different  countries. 

Again,  Reaumur  says : 

The  same  grain  is  harvested  in  very  different  climates.  It  would  be 
interesting  to  make  a  comparison  of  the  sum  of  the  temperatures  for 
the  months  during  which  the  cereals  accomplish  the  greater  part  of 
their  growth  and  arrive  at  a  perfect  maturity  both  in  warm  coun- 
tries like  Spain  and  Africa,  in  temperate  countries  like  France,  and 
in  cold  countries  like  those  of  the  extreme  north. 

This  passage,  says  Gasparin,  is  the  germ  of  all  the  works  which 
have  been  executed  since  that  time  in  order  to  determine  the  total 
quantity  of  heat  necessary  to  the  ripening  of  the  different  plants  that 
have  been  cultivated  by  man. 

Adanson  (1750)  disregarded  all  temperatures  below  0°  C,  and  took 
only  the  sums  of  the  positive  temperatures.  He  expressed  the  law  as 
follows:  The  development  of  the  bud  is  determined  by  the  sum  of 
the  daily  mean  temperatures  since  the  beginning  of  the  year. 

Humboldt  early  insisted  upon  the  necessity  of  taking  the  sunlight 
itself  as  such  into  consideration  in  studying  the  laws  of  plant  life. 

Boussingault  (1837),  in  his  Rural  Economy,  introduces  the  idea 
of  time  by  adopting  the  principle  that  the  duration  of  any  vegetating 
period  nndtiplied  by  the  mean  temperature  of  the  air  during  that 
period  gives  a  constant  product.  He  takes  the  sum  of  the  tempera- 
tures from  the  time  when  vegetation  begins  and  finds  the  length  of 
the  period  of  vegetation  from  germination  up  to  any  phase,  to  vary 
from  year  to  year,  inversely  as  the  total  smns  of  the  daily  temper- 
atures. 

Thus,  for  winter  wheat  to  ripen,  he  found  that  there  was  necessary 
a  sum  total  of  from  1,900°  to  2,000°  C.  of  mean  daily  air  tempera- 
tures in  the  shade,  which  constant  sum  is  equivalent  to  saying  that  the 
average  temperature  of  the  growing  period  is  found  by  dividing  this 
number  by  the  number  of  days.     This  method  of  computation  takes 


170 


no  account  of  any  temperature  at  which  the  growth  of  wheat  ceases. 
A  lower  limit  for  such  temperature  has  been  adopted  by  several 
investigators,  such  as  the  0°  C,  alrea'dy  mentioned  as  adopt'ed  by 
Adanson.  An  upper  limit  has  not  yet  been  ascertained.  Edwards 
and  Colin  put  it  at  22°  C. ;  but  in  Venezuela  Codazzi  found  wheat  to 
mature  under  a  constant  temperature  of  23°  or  24°  C.  throughout  the 
whole  period  of  vegetation,  and,  as  we  shall  see  hereafter,  the  upper 
limit  undoubtedly  depends  upon  the  humidity  of  the  air,  the  moisture 
of  the  soil,  and  the  total  radiation  from  the  sun  quite  as  much  as  upon 
temperature.  Similarly  Marie-Davy  calls  attention  to  the  fact  that 
maize  grows  poorly  at  Paris,  where  it  is  cloudy  and  warm,  but  well  in 
Alsace,  where  it  is  dry  and  clear,  the  temperature  of  the  air  averaging 
about  the  same  in  both,  the  dirt'erence  being  in  the  quantity  of  sunshine 
and  rain. 

Gasparin  (1844)  adopted  the  mean  temperature  of  the  day  as  de- 
rived from  observations  made  at  any  convenient  hours  and  took  the 
sum  of  such  temperatures  from  and  after  the  date  at  wdiich  the  plants, 
especially  the  cereals,  begin  to  actively  develop,  or  to  vegetate,  or 
when  the  sap  flows  readily  throughout  the  day.  For  this  "  effective 
temperature  "  he  adopts  5°  C. 

Subsequently  Gasparin  adopted  a  thermometer  placed  in  full  sun- 
shine on  the  sod  as  giving  a  temperature  more  appropriate  to  plant 
studies,  but  still  retaining  the  lower  limit  of  5°  C.  for  the  mean  daily 
temperature  of  the  initial  date.  Thus  he  obtained  for  wheat  a  sum 
total  of  2,450°  C.  as  the  sum  of  the  effective  daily  temperatures  from 
sowing  to  maturity. 

Gasparin  also  observed  the  temperature  of  a  blackened  metallic 
disk  in  the  sunshine  and  the  temperature  of  the  sunny  side  of  a  ver- 
tical wall,  and  again  the  temperature  of  a  thermometer  at  the  surface 
of  a  sandy,  horizontal  soil,  all  in  full  sunshine.  He  recognized  that 
the  loss  of  heat  by  evaporation  must  keep  the  temperature  of  the  soil 
slightly  lower  than  that  of  the  surface  of  the  wall ;  but,  in  default  of 
better  methods,  he  kept  a  record  of  the  temperature  of  the  wall  for 
many  years.     From  his  average  results  I  give  the  following  abstract : 


Observations  hy  Gasparin  at  2  p.  m 

daily. 

Year. 

January. 

August. 

Locality. 

Air. 

Wall. 

Air. 

Wall. 

1836-1850 

1838-m50 

1786 

().7 

4.0 

-1.3 

15.4 
6.3 
11.0 

30.2 
23.6 
14.6 

44.1 

•S0.2 

22.0 

The  warmth  in  the  sunshine  is  to  the  warmth  of  the  air  in  the  shade 
as  though  one  had  been  transported  in  latij^ude  from  3  to  6  degrees 
farther  south. 


171 

Another  study  into  the  total  riuliation  received  by  the  phmts  in 
sunshine  was  made  by  Gasparin  by  phicing  a  thermometer  in  the  cen- 
ter of  a  <>h)be  1  decimeter  in  diameter,  made  of  thin  copi)er  and  cov- 
ered with  a  layer  of  laini)black.  Having  found  by  comparison  that 
Inilbs  of  dili'ercnt  sizes  gave  diti'erent  temperatures,  he  recommends 
this  size  to  all  meteorologists;  but  I  do  not  know  of  observations 
made  by  others  until  Violle  (1879)  urged  the  same  construction  and 
size  for  his  conjugate  bulbs.  This  bulb  in  the  full  sunshine  and  at  a 
standard  distance  above  the  ground  seemed,  to  Gasparin,  to  give 
what  he  calls  the  temperature  of  a  dry  opaque  body.  The  differ- 
ence betAveen  this  and  the  temperature  of  the  air  gave  a  surplus  show- 
mg  the  effect  of  solar  radiation  on  the  leaves;  again,  the  difference 
between  this  dry,  black,  bulb  and  the  temperature  of  the  surface  of 
tlie  moist  earth  gave  him  some  idea  of  the  nature  and  amount  of  the 
influence  of  the  sunshine  on  the  surface  of  the  soil,  which  he  illustrates 
by  the  following  table,  derived  from  seventeen  years  of  observations : 


Teuipcrature  at  2  p.  vt. 


Month. 

Soil. 

Black 
bulb  in 
the  air. 

Month. 

1 
Soil. 

1 

Black 
bulb  in 
the  air. 

19.1 
25.5 
27.6 
40.9 
45.3 

15.4 
22. 0 
28.5 
2<).4 

:^.4 

39.4 
43.4 

August 

September  _. 

October 

November 

December 

Average 

'      43.1 

31.4 

1      20.2 

'      12.1 

5.9 

44.1 

February _ .-- 

March 

April .- 

May 

38.9 
28.7 
19.4 
15.4 

June 

1      24.4 

29.  ti 

July. 

1 

On  this  table  (jasparin  remarks: 

We  see  how  much  the  difference  of  temperatures  of  the  stems  and 
the  roots  ought  to  modify  the  flow  of  the  sap,  and  there  is  here  an 
interesting  subject  for  physiological  study  which  should  redound  to 
the  profit  of  agriculture.  The  solar  heat  contributes  also  in  a  remark- 
able manner  to  cause  the  differences  in  the  vegtation  of  the  moun- 
tains and  the  plains.  On  mountain  tops  it  is  the  heat  of  the  surface 
soil  and  the  roots  in  the  sunshine  and  the  effect  of  sunshine  on  the 
leaves  that  makes  possible  the  existence  of  a  great  variety  of  phieno- 
gams.  The  direct  action  of  the  solar  heat  is  the  explanation  of  the 
{possibility  of  raising  cereals  and  other  southern  croi)s  in  high  north- 
( rn  latitudes. 

(lasparin  (1852.  p.  100)  gave  the  following  table,  compiled  for  west- 
ern Europe,  showing  the  mean  temperatures  of  the  day  during  which 
the  respective  plants  leaf  out,  flower,  or  ripen.  This  early  effort  to 
ni)ply  meteorological  data  to  the  study  of  plants  takes  no  account,  as 
the  author  himself  says,  of  other  meteorological  conditions  than  tem- 
perature such  as  introduce  considerable  variations  into  the  pha-nolog- 
ical  phenomena,  but  he  gives  it  in  hopes  of  helping  thus  to  fix  the  rela- 


172 

tions  of  natural  vegetation  to  cultivated  plants.  If  in  addition  to 
recording  temperature,  rainfall,  sunshine,  and  other  meteorological 
elements,  we  could  keep  a  parallel  record  of  the  stages  of  development 
of  cultivated  and  uncultivated  plants  we  could  use  the  latter  as  an 
index  to  the  effect  of  the  weather  during  any  season  and  predict  from 
that  the  behavior  of  the  cultivated  plants. 

Teiiiiieriit lives   at    the   respective  phanological   epochs   for   plants   in    European 
climates  (by  Gasparin). 

(1)    LEAFING. 

*  "C. 

Wild  honeysuckle   (Lonicera  perycUmenum) 2.0 

Thorny  gooseherry  {Ribes  uva  erispa) 5.0 

Lilac    - 5-  0 

Ordinary  currant  (Kibes  rubra) '- <>•  0 

Broad-leafed  willow  (.S'«//./"  caprwa) 0.0 

Horse-chestnut    {^sculus  hippocastannm) 7.") 

Apple  tree  (Mains  eonimunis)  ;  cherry  tree  (Cerasus  communis) 8.0 

Fig  tree  (Ficus  carica) f^- 0 

Grapevine    shoots '•^-  •* 

Mulberry  tree  covered  with  leaf-buds  :  walnut  tree 9.  8 

Sprouting  of  lucerne  grass 10.0' 

Alder   tree 12.  0 

Oak;  mulberry  tree  developing  leaves 12.  7 

Acacia  (Robinia  pseudoacucia) 13-  ■"> 

(2)    FLOWERING. 

Hazelnut  tree  (Coryliis  avellana)  ;  cypress 3.0 

Furze  or  gorse  (Ulex  europoeus)  ;  box  (Buxus  seninc'rirens)  ;  white  ]>op- 

lar  (Populus  alba) 4.0 

Broad-leafed  willow;  honeysuckle •'i.  0 

Peach  tree 5.  4 

Almond  tree;  apricot  tree 0.0 

Pear  tree ''^-  ^ 

Elm;  apple  tree 7.5 

Chei'ry  tree;  colza 8.0 

Lilac;  strawberry  plant 9.5 

Broom  (Genista  scoparia) 10.0 

Beans H-  ^ 

Horse-chestnut 12-  0 

Hawthorn  or  may  (Mespilus  oxycantha) 12.5 

Sainfoin  or  French  grass  (Hedysarum  onobrychis.  Leguminosiie) 12.7 

Acacia   (Robinia) I-*- 0 

Eye 14.  2 

Buckthorn  (Rhamnus  paliurns) 15.  0 

Oats 10.0 

Wheat;  barley 10-  3 

Chestnut  tree : 

First  flower l 10.  0 

Full  flower 17.  5 

Grapevine : 

Full  flower 18.  2 

Flower  passed 19.  0 

Indian  corn;  hemp;  olive  tree 19.0 


173 

(3)    RIPENING. 

During  increasing  heat :        '  "  C. 

Fruit  of  the  elm  tree 12.0 

Green   peas 14.  2 

First  cherries;  hroad  beans 16.0 

First  mowing  of  sainfoin 17.0 

Currants;  raspberries;  strawberries;  cherries 17.8 

Morella  cherry  tree;  apricot;  plum  tree;  barley;  oilts 18.0 

Rye 19.  0 

Peach  tree:  harvest  of  corn 20.0 

First  figs  ;  green  gage  plums 21.0 

First  grapes,  called  madeleine ;  melons  in  free  earth 22.5 

Hemp  . 22.  6 

During  decreasing  heat  (for  fruits  which  have  received  a  sufficient  quan- 
tity of  increasing  heat)  : 

Horse-chestnut 18.  2 

Indian  corn;  potatoes 17.0 

Walnuts  and  chestnuts 16.2 

Pomegranates 15.0 

Saffron 13.0 

Olives 10.  0 

Note. — It  can  be  easily  understood  that  the  fruits  which  require  the  greatest 

I.rolongatiou   of   heat  ripen   last   and   are   gathered    at   periods   of   the   lowest 

temperatures. 

Lachmann,  in  his  Entwickelung  der  Vegetation,  counts  the  sum 
total  of  all  the  temperatures  at  his  station  (Braunschweig,  Germany) 
from  February  21  onward. 

Linsser,  for  north  temperate  countries,  counts  from  the  date  when 
the  temperature  0°  C.  is  attained,  but  for  warmer  countries  he  counts 
from  the  date  when  the  lowest  temperature  of  the  year  is  attained; 
which  date  would,  according  to  his  calculations,  be  the  8th  of  Febru- 
ary at  Braunschweig  instead  of  the  21st  of  February;  but,  according 
to  the  normal  values  resulting  from  the  thirty  years  of  observation 
by  I^achmann.  this  change  would  only  make  his  sum  totals  about 
10°  C.  larger. 

Tomaschek,  as  quoted  by  Fritsch  (18G6,  LXIII,  p.  297),  takes  the 
mean  of  all  positive  temperatures  as  observed  at  ()  a.  m.,  2  p.  m.,  and 
10  p.  m.,  omitting  the  individual  negative  observations  instead  of  the 
negative  daily  averages.  He  counts  the  sums  from  January  1 ;  this 
method  gives  figures  that  agree  very  closely,  at  least  in  Europe,  with 
those  given  by  Fritsch's  method. 

Kabsch,  as  .quoted  by  Fritsch,  attempted  an  improvement  on  the 
method  of  Boussingault.  His  fornnda  is  especially  appropriate  to 
the  annuals,  but  not  to  the  perennial  plants.  His  method  of  comput- 
ing the  thermal  constant  is  exi)ressed  by  Fritsch  in  the  following 
formula : 


my- 


174 

where  the  notation  is  as  follows :  C  is  the  total  heat  from  the  date  of 
sowing  up  to  the  date  of  sprouting ;  x  is  the  thermal  constant  from  one 
phase  to  the  next,  such  as  from  sprouting  to  flowering ;  t  is  the  num- 
ber of  days  from  sprouting  to  flowering;  c  is  the  mean  daily  tempera- 
ture from  sjjrouting  to  flowering ;  t  c  is  the  total  sum  of  mean  daily 
temperatures  from  sprouting  to  flowering;  as  this  temperatvire  is 
principally  active  during  the  daytime,  therefore  one-twelfth  of  ^  c 
represents  the  efficient  heat  during  an  hour;  h  is  the  duration  in. 
hours  of  an  average  growing  day,  viz,  from  sunrise  to  sunset;  there- 
fore one-twelfth  of  the  product  e  h  t  represents  the  total  heat  that 
has  been  utilized  by  the  plant. 

The  method  of  reasoning  by  which  Kabsch  arrives  at  the  above 
formula,  which  I  have  quoted  from  Fritsch,  is  not  known  to  me. 

Sachs,  by  direct  experiment,  finds  that  for  each  plant  there  is  a 
temperature  most  favorable  to  its  growth  and  two  other  limits,  mini- 
mum and  maximum,  beyond  which  it  will  not  grow. 

Deblanchis  finds  that  the  temperature  on  which  vegetation  depends 
is  not  the  ordinary  temperature  of  the  air  as  given  by  a  sheltered 
thermometer;  he  prefers  to  approximate  to  the  temperature  of  the 
leaf  of  the  plant  by  the  use  of  his  "  vegetation-thermoscope,"  which 
is  an  ordinary  minimum  thermometer  covered  with  green  muslin  and 
kept  moist,  as  in  the  ordinary  wet-bulb  thermometer.  He  places 
his  thermometer  at  one  and  a  half  meters  above  the  soil  and  in  full 
exposure  to  sun  and  sky.  Evidently  the  sum  total  of  his  tempera- 
tures will  be  between  the  sums  of  the  ordinary  wet-bulb  and  the 
ordinary  dry-bulb  thermometers,  but  must  differ  greatly  from  the 
temperature  of  the  roots  on  which  the  growth  of  the  plant  primarily 
depends. 

Hoffmann  prefers  to  take  for  the  daily  temj^erature  the  excess  above 
freezing  of  the  maximum  thermometer  exposed  to  full  sunshine  and 
free  air.  Hoffmann's  temperatures  approach  more  nearly  the  tem- 
perature of  the  roots  within  a  few  inches  of  the  surface  of  the  ground. 
Besides  taking  the  sums  of  the  average  daily  temperatures  of  the 
shaded  air  thermometer,  omitting  all  negative  values  or  all  those 
below  freezing  point,  Hoffmann  also  took  the  sum  of  the  bright  bulb 
in  vacuo  and  of  the  black  bulb  in  vacuo,  both  in  full  sunshine ;  these 
latter  temperatures  are  generally  higher  than  those  of  the  roots  and 
much  higher  than  those  of  the  leaves.  Hoffmann  prefers  to  use  the 
readings  of  the  l)right  bulb  in  vacuo. 

Herve  Mangon  (1870)  modifies  Gasparin's  method  slightly  in  that 
he  takes  account  of  the  shade  temperatures  of  the  air  from  the  date 
of  sowing  up  to  the  date  of  harvest,  rejecting  all  cases  where  the 
mean  daily  temperature  in  the  shade  is  less  than  6°  C. ;  he  had  been 
led  to  think  that  the  vegetation  of  cereals  and  other  important  crops 
ceases  below  this  temperature.     Thus  he  determines  the  sum  total 


175 


)i'  tlic  varioties  of  wheat   ordinarily 


uoedod   for  ripening  tlie  crops  of  tlie    ^.    ... 

cultivated  in  Xormandy,  as  shown  in  the  following  table: 


Date  of  sow- 
ing. 

Date  of  har-, 
vesting. 

Sums  of  daily  temperatures. 

From 

sowing 

to  Feb. 

29. 

From 
Mar.  1  to 
harvest. 

Total. 

Nov.  17,1869 
Nov.    5,1870 
Nov.  27,1871 
Nov.   5,1872 
Nov.  27,1874 
Nov.    4,1875 
Nov.  18, 1876 
Dec.    6,1877 
Dec.  21,1878 

Average, 

Nov.  17.__- 

Aug.  12,1870 
Aug.  2tX  1871 
Aug.    4,1872 
Aug.    3,1873 
Aug.  10, 1875 
Aug.    3,1876 
Aug.    2,1877 
Aug.    7,1878 
Sept.   1,1879 

Aug.  8 

°  C. 

a56 
a59 

:395 

6:^2 
339 
490 
701 
367 
171 

°  C. 
2,  (MX) 
2,1.58 
1,914 
1,806 
1,880 
1,828- 
1,769 

2,oa5 

2,085 

°  C. 

2,a56 

2,517 

2,309 

2,438 

2,219 

2,318 

2,470 

2,402 

2,256 

455 

1,924 

2,379 

By  similar  calculations  Herve  Mangon  obtains  for  other  crops  as 
cultivated  in  Normandy  the  following  results :  • 


Mean  date. 

Sums  of 

daily 
temper- 
atures 
from 
sowing 
to  har- 
vest. 

• 

Sowing. 

Harvest- 
ing. 

Oats 

Mar.    7 
Nov.   8 
Apr.  13 
Mar.    3 
June  10 

Aug.    5 
Aug.  20 
Aug.  18 
Aug.  25 
Sept.  10 

1,826 
2,197 
1,810 

Do 

Beans. 

2,210 
1,525 

Buckwheat 

Herve  Mangon  concludes  his  essay  with  two  important  practical 
rules,  deduced  from  his  data  relative  to  the  climate  and  crops  of  the 
department  of  La  Manche:  (1)  In  a  mild  and  uniform  climate,  like 
that  of  the  northwest  of  France,  there  is  always  an  advantage  in 
sowing  the  seed  early  in  the  autumn;  (2)  by  computing  annually  the 
sums  of  the  degrees  of  temperature  observed  since  the  date  of  sowing 
and  by  consulting  the  numerical  tables  given  in  this  memoir  one  can, 
with  great  accuracy,  calculate  four  or  six  weeks  in  advance  the  date 
of  the  ap])roacIiing  harvests  of  the  resj)ective  plants. 

The  tables  given  by  jSlangoii  for  his  locality  can  be  reproduced  for 
American  stations  wherever  the  meteorological  observations  and  the 
dates  of  planting  and  harvesting  are  recorded:  although  it  may  be 
possible  to  consider  more  minute  details  of  climate  and  soil  than  he 
has  done,  yet  the  success  attained  by  him  in  his  elementary  collation 
of  fundamental  data  niu.st  stimulate  to  siiiiiiai-  work  in  this  country. 


176 


From  the  data  given  by  Mangon,  ]SIarie-Davy  deduces  some  further 
phenological  constants  ^Yhich  will  be  useful,  viz,  for  winter  wheat 
in  Normandy,  the  sum  of  the  daily  temperatures  in  the  shade,  reject- 
ing all  below"  6°  C.,  from  sow^ing  to  germination  is  85°  C. ;  from  ger- 
mination to  heading,  555°  C. ;  from  heading  to  maturity,  1,810°  C. 
This  gives  from  sowing  to  heading  G10°  C,  Avhereas  Gasparin,  fol- 
lowing his  owni  rule,  which  takes  the  sum  of  all  temperatures  after 
the  date  at  which  the  temperature  of  5°  C.  is  attained,  finds  430° 
for  this  constant. 

Wheat  begins  to  grow  visibly  whpn  the  mean  daily  temperature  is 
about  6°  C.  This  mean  daily  temperature  is  attained  on  the  average 
of  many  years  on  the  dates  given  in  the  second  column  of  the  fol- 
lowing table.  (See  Marie-Davy,  1881  and  1882,  p.  184.)  The  aver- 
age dates  of  harvest  are  given  in  the  third  column;  the  interval  or 
growing  period  in  the  fourth  column;  the  fifth  column  contains  the 
sums  of  the  mean  daily  temperatures  of  the  air  in  the  shade  (after 
the  date  on  which  a  mean  temperature  of  6°  was  attained),  the  sixth 
column  gives  the  sums  of  the  mean  daily  temperatures  of  the 
thermometer  in  the  full  sunshine,  as  determined  by  Gasparin.  The 
close  agreement  of  the  two  latter  numbers  is  considered  by  Marie- 
Davy  an  argument  in  favor  of  the  idea  that  temperatures  in  the  sun- 
shine are  better  than  those  in  the  shade  as  a  measure  of  the  influence 
of  heat  and  light  on  the  growth  of  plants. 


Place. 

Date  of 
6°C. 

Wheat 
harvest. 

Grow- 

*?for- 

Sum  of 
.shade 
temper- 
atures. 

Slim  of 
sunshine 
temper- 
atures. 

Orange 

Mar.    1 
Mar.  15 
Apr.  20 
June  15 

June  25 
Aug.    1 
Aug.  20 
Aug.  27 

138 
122 

•c. 

1,601 

1,9T0 

1,545 

675 

2,468 

Paris                - 

2,433 

Upsala 

Balland  (see  Marie-Davy,  1881,  p.  186)  has  made  a  perfectly  simi- 
lar computation  with  reference  to  the  ripening  of  wheat  cultivated  on 
a  large  scale  at  Orleansville,  in  Algeria,  with  the  following  results: 

1878 2,  498 

1879 2,433 

Average 2,462 

The  results  of  Mangon,  Balland,  and  Gasparin  agree  so  closel}^  that 
a  strong  argument  seems  to  be  afforded  in  favor  of  using  the  ther- 
mometer ex^30sed  to  the  full  sunshine.  The  differences  in  their  results 
are  quite  comparable  to  the  differences  found  by  Vilmorin  to  exist 
between  different  varieties  of  the  same  seed. 

The  values  of  the  thermometric  constants,  as  computed  by  Herve 
Mangon's  method,  for  other  grains  cultivated  in  Normandy  are  given 


177 

in  the  following  table,  where  the  figures  represent  the  sums  of  sun- 
shine temperatures  necessary  to  complete  the  growth  from  germi- 
nation to  harvest. 


Plant. 

Sunshine 
temper- 
ature. 

Plant. 

Sunshine 
temper- 
ature. 

2,462 
2,365 
2,197 

°  C. 
1,810 

2,210 

■MnvmaTidy  naf.s 

Normandy  buckwheat 

1,579 

Marie-Davy  (1881),  in  his  chapter  on  the  influence  of  heat  on  the 
time  required  for  vegetation,  adopts  the  principle  enunciated  by 
Boussingault,  of  the  equality  of  the  sum  total  of  the  temperatures, 
but  thinks  that  the  temperature  required  to  bring  a  plant  to  the 
flowering  stage  is  the  sum  of  the  mean  daily  temperatures  in  the  full 
sunshine,  and  not  the  temperature  of  the  air  in  the  shade.  According 
to  his  view,  the  heat  is  needed  in  the  soil  in  the  early  part  of  the 
growth  of  the  plant;  but  after  the  flower  is  formed,  or  during  the 
process  of  perfecting  the  fruit,  sunlight  is  needed,  and  during  this 
stage  he  uses  the  actinometric  degrees  of  the  Arago-Davy  actinometer 
as  an  index  of  the  progress  of  the  plant.  I  have,  therefore,  in  the  fol- 
lowing table  collated  the  figures  given  by  him  for  wheat.  The  third 
column  gives  the  sum  total  of  the  mean  daily  shade  temperatures, 
counted  from  February  1  of  each  year  up  to  the  date  at  which  the 
total  amounts  to  1,264°  C,  or  within  half  a  day  thereof,  that  being 
the  adopted  shade  constant  for  the  flowering  of  wheat  that  was  sown 
on  or  about  the  21st  of  March.  The  fourth  and  fifth  columns  give 
the  dates  and  sum  totals  of  temperatures  observed  with  a  naked-bulb 
thermometer  on  the  grass  in  the  full  sunshine,  assuming  1,569°  C. 
jis  the  thermal  constant  for  this  thermometer.  The  sixth  column 
gives  the  observed  dates  of  flowering.  As  these  dates  agree  with  those 
in  the  fourth  column  better  than  with  those  in  the  second  column, 
Marie-Davy  considers  them  as  confirming  him  in  the  use  of  tlie 
unprotected  solar  thermometer.  In  order  to  bring  out  the  total  effect 
of  sunlight  and  sun  heat  Marie-Davy  has  comi)uted  the  sum  total  of 
actinometric  degi-ees  from  February  1  up  to  the  dates  given  in  column 
2  and  in  column  4,  respectively.  These  results  are  given  in  columns 
7  and  8,  which  show  that  1878  was  a  very  precocious  year,  as  com- 
pared with  the  others,  in  that  the  date  of  flowering  was  very  early, 
but  the  sum  total  of  its  actinometric  degrees  was  very  small  and  its 
crops  were  very  poor.  1879  and  1877  show  larger  actinometric  sums, 
but  the  largest  sums  are  given  by  the  years  1873,  1874,  1875,  and  1876, 
which  were  also  very  excellent  crop  years. 

2667—05  M 12 


178 


Date  of  floircriiifi  of  irhcat  at  Moiitroiige,  France. 
[See  Marie-Davy,  1880,  pp.  181-215.] 


Year. 

Shade  tempera-     Sun  thermom- 
tures.                       eter. 

Observ- 
ed date 

of 
flower- 
ing. 

Actinometric 
percentages. 

Date. 

Sum 
total. 

Date. 

Sum 
total. 

Shade 
dates. 

Sun 
dates. 

1879 

June  21 
June   6 
June  13 
June  15 
June   7 
June  10 
June  19 

"C. 

1264 

1268 

1374 

1269 

1364 

1277 

1256 

June  21 
June  10 
June  15 
June  19 
June  13 

.0.1 

1569     June  21 
1566 

4063 
3467 
3976 
4376 

4298 
4506 
4296 

4063 

1878 

3666 

1877.. 

1578 
1567 
1574 

June  15 
June  19 

4075 

1876 

4588 

1875 

4603 

1874 

June   9 

1873 _ 

Marie-Davy  concludes  that  by  keeping  a  daily  summation  of 
actinometric  degrees  it  becomes  possible,  even  at  the  epoch  of  flower- 
ing of  wheat,  to  estimate  in  a  very  approximate  manner  what  will  be 
the  final  value  of  the  resulting  harvest.  At  this  moment,  even  if  we 
have  already  measured  the  sum  of  the  products  which  should  be 
applicable  to  the  formation  of  grain,  we  can  not  be  absolutely  cert  in 
that  the  harvest  will  correspond  to  our  expectations.  A  certain  time 
is  necessary  for  the  nutrient  particles  to  traverse  the  various  parts  of 
the  stem  up  to  the  seed,  and  a  certain  quantity  of  water  is  necessary 
for  this  transportation.  An  excessive  dryness  or  heat  will  interfere 
wdth  this  movement  and  will  give  a  poorly  developed  grain,  notwith- 
standing the  abundance  of  nutrition  reserved  for  it  within  the  plant. 
But  although  water  and  nutrition  are  as  important  as  heat  and  light, 
still  we  find  that  predictions  based  on  actinometric  degrees  alone  are 
very  reliable. 

According  to  Georges  Coutagne,  the  law  that  connects  the  rate  of 
development  of  a  plant  with  its  temperature  must  be  such  that  it  has  a 
maximum  value  for  a  special  temperature  and  diminishes  as  we  depart 
from  this  down  to  a  zero  rate  at  the  freezing  point  and  also  to  zero 
at  some  higher  temperature  at  present  unknown;  all  this  is  on  the 
assumption  that  the  sunlight,  moisture,  and  winds  are  such  as  to 
enable  the  plant  to  do  its  very  best  at  the  given  temperature.  If 
this  law  were  known  we  could  then  determine  whether  a  plant  would 
live  and  flourish  in  any  given  climate. 

This  law  of  growth  has  been  expressed  by  Georges  Coutagne,  as 
quoted  by  Marie-Davy  (1883,  p.  227),  by  the  following  notation  and 
formula.     Let — 

r  be  the  rate  of  development  of  the  plant,  assuming  that  other 
conditions  are  so  adjusted  that  it  attains  the  maximum  gi-owth 
possible  for  the  given  temperature ; 

X  be  the  temperature  of  the  plant; 


179 

a  be.  a  coefficient  that  defines  the  rate  of  development  so  that  tlic 
reciprocal  of  a  defines  the  longevity  of  the  plant; 

n  be  a  coefficient  that  defines  the  sensitivene.ss  of  the  plant  to  tem- 
perature, so  that  as  n  increases  a  given  change  in  x  has  a  less  effect 
on  the  rate  of  growth  and  therefore  the  plant  can  flourish  in  a  wider 
range  of  temperature;  therefore  its  geographical  distribution  may 
be  wider,  hence  Coutagne  calls  n  a  coefficient  of  ubiquity ; 

c  be  the  temperature  at  Avhich  the  most  rapid  development  is  possi- 
ble under  the  most  favorable  conditions  of  growth  or  the  temperature 
optinnnn ;  plants  with  a  large  value  of  c  must  live  nearer  the  equator 
than  those  having  small  values  of  r-;  therefore  c  is  called  the  index 
of  tropica lity. 

According  to  Coutagne  these  quantities  are  bound  together  by  the 
formula : 


v=a  e 
This  formula  represents  the  momentary  rate  of  development,  so 
that  the  total  duration  of  the  growth^is  to  be  found  by  integrating 
this  expression,  which  result  is  written  as  follows : 


'^Sr\ 


ax 


Van  Tieghem,  like  Coutagne  and  others,  finds  that  for  each  special 
phase  of  vegetation,  germination,  heading,  flowering,  or  ripening,  and 
for  each  age  of  a  perennial  plant  there  exists  a  special  relation 
between  the  temperature,  the  light,  the  moisture,  and  the  chemical 
composition  of  the  soil  and  water  that  is  most  favorable  to  growth. 
We  have,  therefore,  to  decide  whether  the  same  formula  of  develop- 
ment can  represent  the  growth  in  each  of  these  phases  as  well  as 
throughout  the  whole  career  of  the  plant.  As  we  have  before  said,  the 
plant  can  only  rearrange  the  inorganic  products  that  it  receives  and 
develop  its  own  structure  by  utilizing  the  molecular  energy  contained 
in  the  sunshine  or  some  equivalent  light.  Its  growth  does  not  depend 
upon  any  force  contained  within  the  plant  nor  on  the  temperature,  as 
such,  but  on  the  quality  of  the  radiation ;  therefore  any  formula  that 
considers  temperature  only  must  be  a  very  imperfect  presentation 
of  the  growth,  especially  in  those  stages  subsequent  to  the  full  develop- 
ment of  the  leaf  and  flower. 

Lippincott  (1863,  p.  506)  gives  a  few  items  relative  to  the  phenol- 
ogy' of  wheat  in  America  and  the  origin  of  the  varieties  known  as 
Lambert's  Mediterranean  China  (or  Black  Tea),  Hunter's,  Fenton, 
Piper's,  which  were  all  due  to  judicious  selection  and  careful  culture. 

The  average  wheat  crop  of  England  is  stated  to  be  36  bushels  per 
acre  and  that  of  the  United  States  15  or  less,  which  large  difference 
is,  he  thinks,  the  result  of  judicious  cultivation  and  care  in  the  choice 


180 

of  seed  rather  than  the  influence  of  climate,  since  large  crops  have 
been  and  can  be  raised  in  this  country. 

The  injurious  influence  of  hot,  moist,  and  rainy  weather  has,  he 
thinks,  a  general  tendency  to  deteriorate  the  quality  of  American 
wheat,  as  the  plant  needs  a  hot  and  dr}'  climate.  jNIoisture  defines 
the  southern  limit  of  wheat  cultivation  while  the  northern  limit  has 
not  yet  been  found.  In  1853  the  growing  season  in  England  was  too 
cold  to  ripen,  the  average  being  57°  F.  for  July  and  59°  F.  for 
August,  so  that  only  one-half  or  one-third  of  the  usual  crop  of  wheat 
was  harvested. 

In  Bogota,  Colombia,  where  the  temperature  of  the  high  plains  is 
quite  low,  wheat  that  is  sown  in  February  is  harvested  in  the  last 
week  of  July,  or  in  147  days,  at  a  mean  temperature  of  58°  or  59°  F. 
At  Quinchuqui  wheat  is  sown  in  February  and  reaped  in  July  at  a 
mean  temperature  of  57°  or  58°  F.  Hence  Lippincott  concludes 
that  in  general  wheat  requires  a  mean  temperature  of  60°  during  the 
last  month  of  its  maturity,  or  a  mean  temperature  of  56°  during  the 
whole  period  of  growth.  * 

In  England  in  1860  wheat  sown  March  28  ripened  August  20.  Of 
these  145  days  there  were  133  that  had  temperatures  above  42°  F. 
In  1861  130  da^^s  were  required  of  temi:)eratures  above  42°  F. 

When  the  temperature  of  the  soil  during  the  last  phase  of  growth 
(viz.,  from  earing  to  maturit}^)  falls  below  58°  to  60°  F.  no  progress 
is  made  in  the  growth,  and  unless  60°  is  exceeded  the  crop  never 
fairly  ripens.  These  figures  appear  to  accord  closely  with  the 
requirements  of  the  wheat  plant  in  the  United  States,  where  it  is 
found  that  those  regions  having  a  mean  temperature  for  May  be- 
tween 58°  and  60°  F.  can  not  mature  the  wheat  in  May,  but  those 
having  a  June  temperature  above  61°  can  ripen  the  wheat  in  that 
month.  Those  having  a  temperature  of  61°  in  July  can  mature 
spring  wheat  which  is  sown  the  10th  of  April  or  the  10th  of  May. 
Those  having  a  mean  temperature  of  61°  in  May  can  mature  the 
winter  wheat  in  that  month. 

Lippincott  gives  the  following  items:  At  Arnstadt,  Germany, 
wheat  requires  from  flowering^to  maturity  53  days  at  a  mean  tem- 
perature of  63°  F.,  or  a  total  of  3,339°  F. :  ' 

At  Richmond,  Va.,  Japan  wheat  headed  April  30,  I860,  and  was 
reaped  June  14,  or  46  days,  with  a  sum  total  of  mean  daily  tempera- 
tures of  3,086°  F. : 

At  Haddonfield,  X.  J.,  Mediterranean  wheat  sown  early,  headed 
May  18,  1864,  and  matured  June  30,  or  44  days,  with  a  sum  total  of 
3,024°  F.  of  mean  daily  shade  temperatures : 

In  Monroe  County,  X.  Y.,  wheat  headed  May  10,  1859,  and  matured 
July  8,  or  56  days,  with  a  sum  total  of  3,562°  F. 

The  preceding  meager  data  are  all  that  Lippincott  was  able  to  find 


181 

with  regard  to  wheat  in  America  after  an  extensive  research,  bnt 
within  the  past  few  years  mucli  more  iittention  has  been  given  to  this 
subject. 

The  differences  between  the  quantities  of  heat  required  in  England 
and  America  and  the  differences  in  the  varieties  of  the  wheat  were 
apparent  to  Lippincott.  Thus,  he  finds  that  in  England  the  lengths  of 
the  periods  and  the  sums  of  the  temperatures  were  as  foUows:  In 
1860  a  period  of  59  days  and  a  sum  of  3,562°  F. ;  in  1861  a  period  of 
50  days  and  a  sum  of  3,225°  F, ;  in  1862  a  period  of  56  days  and  a 
sum  of  3,406°  F.  The  reduction  of  the  mean  temperature  during 
two  months  of  1853  by  merely  2°  F.  cut  off  one-third  of  the  crop  and 
brought  a  famine  that  was  already  foreseen  in  July,  1853.  On  the 
other  hand,  it  increased  the  exportation  of  wheat  and  flour  from  the 
United  States  from  $14,000,000  in  1852  and  $19,000,000  in  1853  to 
$49,000,000  in  1854. 

A  careful  study  of  the  sum  totals  of  rainfall,  temperature,  and  sun- 
shine should  enable  one,  in  general,  to  foresee  similar  failures  and 
corresponding  successes  in  the  crops  of  any  region. 

QUETELET. 

The  suggestive,  but  sketchy,  studies  of  earlier  writers  on  thermal 
constants  Avere  supplemented  by  more  elaborate  investigations  and 
calcuhitions  of  statistics  by  Quetelet  (1849)  in  his  Climate  of  Bel- 
gium, from  his  own  summary  (p.  62),  etc.,  I  take  the  following 
notes : 

The  details  hitherto  given  show  sufficiently  that  the  relative  condi- 
tions of  vegetation  change  at  all  times  of  the  ,vear  in  two  countries 
situated  at  a  distance  from  each  other.  Acceleration  and  retardation 
are  quantities  essentially  variable,  and  it  is  erroneous  to  say  that  one 
locality  has  its  budding  period  ten  or  twenty  days  sooner,  for 
example,  than  another.  This  difference  may  be  correct  for  one  sea- 
son of  the  year  and  entirely  wrong  for  another;  and,  moreover,  we 
can  onlv  pretend  to  state  a  fact  which  applies  to  the  majority  of 
plants.  ■ 

Nevertheless  the  differences  in  the  periods  of  budding  are  not  so 
variable  but  that  we  can  assign  to  them  values  very  useful  to  consult 
in  jn-actice.  On  the  other  hand,  science  needs  to  establisli  some  well- 
determined  facts  in  order  to  arrive  later  at  the  knowledge  of  the 
laws  upon  which  these  variations  depend.  I  believe  that  in  the 
a(;tual  state  of  things  I  shall  be  able  to  settle  upon  the  following 
epochs,  in  order  not  to  multiply  too  much  the  terms  of  comparison. 
Moreover,  the  "numerical  tables  justify,  to  a  certain  extent,  the  dis- 
tinctions which  I  lay  down. 

Let  us  first  observe  that  the  awakening  of  the  })lants  is  brought  about 
by  the  cessation  of  the  cold,  and  it  suflices  to  consult  the  tables  of 
temperatures  for  the  different  countries  to  determine  the  average 
epoch  at  which  many  plants  will  put  out  their  leaves  or  their  flowers. 
These  first  indications,  which  it  is  well  to  collect,  still  do  not  deter- 
mine,   however,    the    general    niovenient    of    vegetation    which    may 


182 

manifest  itself  more  or  less  slowly.  They  are  given  by  the  budding 
of  the  Galantus  nivalis^  of  thei  Crocus  vernus,  by  the  appearance  of 
the  catkins  of  the  Corylus  avellana^  of  the  leaves  of  the  Rihes  grossu- 
laria^  of  the  Samhucus  nigra^  of  the  honeysuckle,  and  of  some  spireas. 

The  falling  of  the  leaves  is  also  determined  by  the  temperature, 
and  in  our  climate  generally  takes  place  after  the  first  frosts.  This 
period  and  that  previously  mentioned  come  ordinarily  at  the  two 
limits  of  Avinter,  and  they  separate  to  make  place  for  the  different 
stages  of  vegetation  in  proportion  as  the  cold  of  winter  has  a  less 
duration.  The  winter  sleep  lasts  in  our  climate  from  three  to  four 
months;  in  southern  countries  it  is  very  much  shorter.  We  can  even 
imagine  a  line  on  the  surface  of  the  globe  where  it  ceases  altogether 
for  the  generality  of  plants." 

The  great  movement  of  vegetation  commences  in  Belgium  in  the 
middle  of  March  and  terminates  at  the  end  of  April.  I  will  call 
this  the  period  of  leafing  (feuillaison),  because  during  this  interval 
the  different  plants  are  covered  with  their  v^erdure  and  some  of  them 
show  their  first  flowers. 

The  second  period  is  that  of  flowering  (floraison),  which  in  our  cli- 
mate would  include  the  months  of  May  and  June  and  the  first  half 
of  July. 

The  third  period  would  then  come,  Avhich  is  that  of  ripening 
(fructification). 

These  three  great  periods  should  undoubtedly  be  in  their  turn  sub- 
divided, but  the  present  state  of  the  observations  does  not  allow 
of  such  detail.  It  is  understood,  moreover,  that  the  names  T  have 
given  to  them  only  serve  to  designate  the  principal  phases  of  vege- 
tation which  take  place.  Thus,  in  making  the  general  table  [omit- 
ted—C.  A.]  I  have  classed  the  different  plants  according  to  the 
following  seasons : 

Awakening  of  the  plants. — This  period  is  determined  by  the  plants 
comprised  in  the  [omitted]  table. 

Leafing. — This  period  comprises  the  plants  which,  in  Brussels, 
put  out  their  leaves  from  the  15th  of  March  to  the  30th  of  April, 
and  Avhich  bud  during  the  same  two  months. 

Flowering. — I  have  made  use  of  the  plants  which  have  flowered  or 
brought  forth  their  fridt  from  the  1st  of  May  to  the  15th  of  July. 

o  As  I  have  already  observed  elsewhere,  the  awakening  is  an  epoch  that  is  not 
the  same  for  all  plants.  I  mean  to  speak  here  only  of  the  epoch  when  the  sap 
begins  to  circulate  in  the  majority  of  the  plants  which  grow  in  our  climate. 
'All  plants  do  not  begin  to  vegetate  at  the  same  period,"  says  M.  Ch.  Martins, 
in  the  Botanical  Expedition  along  the  Northern  Coasts  of  Norway.  "  Thus  in 
some  the  sap  begins  to  mount  when  the  thermometer  is  only  a  few  degrees  above 
zero  (centigrade)  ;  others  need  10  or  12  degrees  of  heat,  while  those  in  warm 
climates  require  a  temperature  of  from  15°  to  20°  C.  In  a  word,  every  plant  has 
its  own  thermometric  scale,  whose  zero  corresponds  with  the  minimum  tempera- 
ture at  which  vegetation  is  possible  for  it.  Consequently,  when  we  wish  to  deter- 
mine the  sum  total  of  the  temperature  that  has  determined  the  date  of  tlowering 
(fleuraison)  of  each  of  these  plants  it  is  logical  to  only  consider  for  eacli  plant 
the  sum  of  the  degrees  of  temperature  above  zero  (centigrade),  since  these  tem- 
peratures are  the  only  ones  that  have  been  efficient  in  inducing  or  sustaining 
their  growth."  In  tropical  countries  the  great  fluctuations  in  the  vegetable  king- 
dom are  not  regulated  by  the  same  meteorological  elements  as  are  effective  with 
us;  there  the  rainy  season  produces  very  nearly  the  same  effects  as  the  cold 
season  does  in  our  climates. 


183 


Ripening. — This  period  ooiiiprisos  the  sta^e  of  vegetation,  which, 
for  Brussels,  extends  from  the  l.-)th  of  July  to  the  fallin«;  of  the 
leaves,  the  last  limit  of  the  period  with  whieh  we  are  oeeupied  here. 

This  classification  has  allowed  nie  to  put  into  [the  omitted]  table 
the  observations  gathered  from  other  sources,  as  well  as  from  the 
s^ystem  of  comparative  observations  which  the  Royal  Academy  of 
Belgium  has  succeeded  in  establishing  at  Brussels. 


The  (ireratjc  iiifluciicc  of 

location 

on  the 

annual  progress  of  vegetation 

LocaUty. 

Position. 

Acceleration   or   retardation  of 
phases  of  vegetation  relative  to 
Brussels. 

Longi- 
tude from 
Paris. 

Lati- 
tude 
north. 

Alti- 
tude. 

Awak- 
ening. 

Leaf-  Flow- 
ing,   ering. 

Fruit- 
ing. 

Fall 

of 

leaf. 

Naples.... 

m.  s. 
47  40  E. 

6  57E. 
40    4  E. 
31  59  E. 
33  15E. 
15  15  E. 
17  11 E. 
24  17E. 
10  48E. 

0    0 

0  30W. 
15  14  W. 

40  52 

44  7 

45  26 
44  48 
44  55 

46  12 
46  31 
48  59 
4"  19 

48  58 

49  0 

49  31 

50  15 

Meters 

Days. 

Days. 

-1-38 

Days. 

Days. 

Days. 

Alais 

143 
11 
49 

408 
538 
380 
240 
37 
140 

4-1i 

J.^'> 

+40 
+30 
+51 
+49 
+12 

Parma 

+  2       +2 
-f-14       4-  7 

+16 
+18 
-  6 
4-11 

10 

Guastalla 

Geneva 

-11 
-3 

-f-27 
+41 
+36 

-  1 

-  2 

Lausanne 

Carlsruhe  - 

-  3  1    -M5 

-  1       -1-6 
+  6       -1-5 

-5i     -12 
0  1         1 

+15 

+11 
+18 

Dijon 

Paris 

+14 
+19 

Valognes 

Polperro,  England 

-1-10 

—  2 

Swafifham,  England 

-  4 

-  r 

-  5 

^ 

9  45W. 
19  25W. 
12  46E. 

9  26E. 

8    6E. 

5  34E. 

3  33E. 

2  20E. 

51  30 
55  35 
50  39 
50  53 

50  51 

51  3 
51  13 
51  14 

30 
64 

60 

-1-32-1-6 

i    -1-  2 

-t-  6            0 

Makerstoun 

Liege 

0 

-  2 
0 

+  1 

-  3 

-  8 

-  5 

-  6 
+  4 
-15 
-18 
-15 

-  3 

Louvain 

-  1 
0 

-  3 

-  3 

0 

-  4 

-  3 

-  8 
-16 
-18 
-18 
-10 
-23 
-19 
-19 
-22 
-20 
-20 
-23 
-27 
-27 
-27 
-14 
-24 
-57 

-30 

Brussels 

0 
0 

Ghent 

+1"' 

Bruges 

Ostend.. 

-  4 

-  6 
-15 
-24 

-  9 
-20 
-20 

-22 
-44 

-  9 

-15 

-  1 

+  3 

Lochem 

Utrecht 

11    8E. 

52    5 

-3 

Vught,  Holland. 

Joppe,  Holland 

Groningen 

16  56E. 

37  5  E. 
48  20E. 
26  51E. 
44  14  E. 
48  54E. 
22  16E. 

38  31  E. 

53  13 
48    9 
50    5 
48  31 

52  31 

53  25 
53  34 
57  42 
57 
59 

59  23 
59  46 
68  30 

43 

2 
528 

178 
331 
36 

-29 

Munich 

Prague  

+  7 

Tubingen 

Berlin.. 

Stettin.. 

-14 
-22 

-  6 

Jevers.. 

Gottenborg 

Grippenberg 

Nasinge 

Carlstadt 

44    4E. 

49 



Arosia 

Lapland 

United  States  of  America,  central 
New  York 

184 

This  table  of  average  intervals  shows  how  variable  is  the  accelera- 
tion of  one  place  over  another  during  the  difl'erent  seasons  of  the 
year.  This  acceleration  even  often  changes  into  retardation,  conse- 
quently the  isanthesic  lines  are  far  from  remaining  parallel.  AYe 
therefore  conclude  that  latitudes  and  longitudes  are  not  the  only 
and  principal  causes  which  regulate  the  phenomena  that  are  enga- 
ging our  attention,  because  these  unchangeable  causes  could  not  pro- 
duce different  effects;  it  is  the  same  with  regard  to  altitudes,  we 
must  only  consider  them  as  intermediary  agents,  and  we  shoidd 
do  wrong  to  take  them  as  the  basis  of  calculations  for  determining 
the  epochs  of  natural  phenomena."  Let  us  see  whether  temperatures 
will  give  more  satisfactory  results.  In  order  to  facilitate  the  com- 
parison I  have  gathered  in  the  table  (which  unfortunately  has  not 
been  completed  for  all  the  localities)''  the  average  temperatures  for 
3^ears,  seasons,  and  months.''  I  must  limit  myself  to  consulting 
these  elements,  as  I  have  not  the  necessary  data  to  compute  the  base 
of  daily  temperatures  and  particularly  to  take  the  action  of  the  sun 
into  consideration.  This  first  work  will  perhaps  make  us  feel  the 
incompleteness  of  the  system  of  meteorological  observations  adopted 
at  present  (1849)  in  Europe.  I  have  also  been  obliged  to  exclude  the 
influence  of  the  temperature  of  the  earth,  although  it  is  absolutely 
necessary  to  consider  it,  in  order  to  treat,  the  phenomena  of  vegetation 
in,  a  complete  manner.'' 

The  mean  temperature  in  winter  at  Brussels  is  2°  C.  The  most 
favored  localities  in  comparison  with  it  are  Naples,  Alais,  and  Pol- 
perro  (near  Lands  End,  England).     I  have  not  been  able  to  deter- 

o  It  will  be  uuderstood  that  I  wish  here  to  speali  only  of  the  actiou  of  geo- 
graphical circumstances  considered  outside  of  the  influence  of  temperature. 
This  action  has  been  but  little  studied  up  to  the  present  time,  but  it  is  well 
worthy  of  our  consideration.  The  following  is  what  one  of  the  most  distinguished 
living  botanists  of  the  present  time  has  written  to  me  on  this  subject :  "  The 
distribution  and  extension  of  each  species  of  plant  over  the  earth  shows  us 
that  the  plants  in  general  and  each  species  as  a  unit  are  subject  to  organic 
changes  dependent  upon  longitude  and  latitude.  Each  has  a  limited  range; 
between  tliese  boundaries  it  has  its  paradise,  where  it  thrives  best.  The  organic 
changes  which  take  idace  in  individual  plants,  if  one  compares  those  that  are 
native  in  different  i)laces,  are  such  that  -we  might  presume  that  even  their 
rieriodic  phenomena  must  be  affected.  For  example,  all  plants  are  stunted  in 
height  and  in  the  number  of  their  leaves  toward  their  northern  limit  (or  rather 
polar  limit).  They  change  their  general  appearance  in  going  from  east  to  west 
on  the  same  parallel ;  they  alter  as  to  the  extent  of  inflorescence  and  the  size 
of  flowers  in  going  north  or  south  on  the  same  meridian.  Now,  as  it  is  only 
by  means  of  these  organs  that  the  plant  vegetates  in  the  presence  of  the  world 
outside  of  it,  it  is  necessary  in  our  observations  to  begin  with  the  relation  of 
those  organs,  or  rather  the  consideration  of  the  developed  organs  onglit  to  enter 
into  our  notation  of  their  vital  action.  It  further  follows  from  this  that  we 
ought  to  study  plants  whose  natural  boundaries  are  known  to  us ;  these  are 
the  true  barometers  for  vegetable  life"  [i.  e.,  as  the  barometer  is  the  measure 
of  the  activity  of  the  atmospheric  forces,  so  the  natural  geographic  boundaries 
are  the  measures  of  the  vital  activity  of  plant  life].  (Letter  of  M.  de  Martin's 
Observation  of  periodic  phenomena,  "  Mem.  Acad.  Royal,"  Brussels,  Vol.  XVI, 
p.  11.) 

6  Further,  it  has  sometimes  been  necessary  to  give  the  temperature  of  a  neigh- 
boring locality  instead  of  that  of  the  place  itself :  thus  for  the  temperature  of 
Polperro  I  hjive  taken  that  of  Penzance,  and  the  temperature  of  Makerstouu 
has  been  replaced  by  that  of  Edinburgh,  etc. 

c  I  have  omitted  these  figures  in  my  copy  of  Quetelet's  table. — C.  A. 

d  I  should  have  liked  to  supplement  this  work  with  maps  showing  the  princi- 
pal epochs  in  vegetation,  but  the  collected  observations  are  not  yet  suQiciently 


185 

mine  the  epoch  of  the  awakening  of  the  plants  in  the  first  two  places, 
but  in  the  last  mentioned  the  acceleration  is  forty-one  days.  This 
acceleration  is  also  very  great  at  the  other  stations  of  England,  as 
well  as  at  Valogne,  which  has  also  probably  a  sea  temperature. 

It  has  also  been  impossible  for  me  to  fix  the  time  of  awakening  for 
places  where  the  winter  is  the  most  rigorous,  such  as  Lapland, 
Sweden,  and  the  United  States.  We  have  seen,  however,  that  there 
is  twenty  days  retardation  in  places  where  the  mean  temperature  is 
very  little  below  zero.  Jever  seems  to  be  an  exception  to  this  rule; 
but  the  results  obtained  in  this  place  were  only  deduced  from  three 
observations. 

The  epoch  of  leafing  corresponds,  as  we  have  said,  with  the  end  of 
March  and  the  month  of  April,  and  that  of  the  flowering  with  the 
months  of  ]May  and  June.  The  first  includes  the  commencement  of 
spring,  the  other  the  end  of  it.  Thus  the  temperature  of  Brussels 
in  spring  is  10°  C.  The  greatest  variations  besides  are  at  Naples  and  at 
Alais.  It  is  also  in  these  places  that  the  leafing  takes  place  first. 
Venice,  Parma,  and  Guastala  are  very  little  in  advance,  but  the 
month  of  March  and  the  beginning  of  April  are  scarcely  any  warmer 
than  at  Brussels.  The  dift'erence  of  temperature  is  only  felt  in  a 
marked  manner  in  the  following  months.  The  flowering  also  takes 
place  about  eighteen  days  sooner. 

Polperro,  in  regard  to  leafing,  is  about  t^n  days  in  advance.  The 
temperature  in  March  is  much  higher  than  that  of  Brussels,  while 
in  April  it  is  about  the  same.  The  advantage  is  lost  in  the  following 
months,  when,  as  regards  flowering,  Brussels  is  in  advance  of  Pol- 
perro, as  well  as  of  the  localities  in  England. 

Brussels  is  about  eighteen  to  twenty  days  ahead  of  the  towns  of 
Holland  and  Germany  in  the  epoch  of  leafing,  and  is  behind  in  the 

complete  to  allow  of  undertaking  such  a  task.  The  first  chart  would  have  shown 
by  a  series  of  lines  drawn  over  Europe  the  awakening  of  plants  for  each  ten 
days,  that  is  to  say,  a  first  line  would  indicate  the  localities  where  the  awakening 
first  takes  place  immediately  after  the  coldest  day  of  the  year,  which  with  us 
is  about  the  20th  of  .January ;  a  second  line  would  pass  through  places  where 
tlie  awakening  is  on  an  average  ten  days  later,  and  so  on.  Another  system  of 
similar  lines  traced  upon  a  second  chart  would  have  indicated  in  the  same  way 
the,  beginning  of  budding,  always  proceeding  I)y  intervals  of  ten  days.  We 
should  also  have  made  similar  charts  for  tiowering  and  ripening  and  the  fall 
of  the  leaves.  By  comparing  these  charts  we  should  be  able  to  see  at  a  glance 
the  princii>al  changes  which  take  place  in  these  various  systems  of  lines.  In 
order  to  cimiplete  this  study  we  should  imagine  other  systems  of  lines  relating 
to  temperatures.  Thus  one  system  would  show  the  localities  in  Europe  where 
frosts  first  cease,  always  advancing  at  intervals  of  ten  days ;  then  iuiother  sys- 
tem for  places  which,  at  successive  intervals  of  ten  days,  and  beginning  from  the 
awakening  of  the  jtlants,  have  reached  a  sum  total  of  temi)eratures  amounting 
to  18;^°  JL\,  corresponding  to  tlie  epoch  of  leafing:  further,  a  third  system  of 
lines  which  should  pass  through  places  tiiat,  counting  from  the  time  of  awaken- 
ing, have  successively  attained  the  total  nunii)ei-  of  degrees  of  temperature 
necessary  f<n-  the  flowering  of  plants ;   and  so  on  for  further  systems. 

The  charts  relating  to  vegetation  and  those  relative  to  teniperatiu'es  would,  by 
comparing  them,  give  much  cinMous  information.  Unfortunately  the  observa- 
tions we  jiossess  of  daily  temi)eratin'es  are  still  as  rai-e  as  those  of  the  fiower- 
ing.     I  have  therefore  been  compelled  to  renounce  that  i)ortion  of  my  work. 


186 

flowering  season,  particularly  as  regards  Prague,  where  the  tempera- 
ture in  April,  May,  and  June  is  a  little  higher  than  that  of  Brussels. 

The  retardation  for  stations  in  Sweden,  the  United  States,  and 
Lapland  is  sufficiently  explained  by  an  examination  of  the  tempera- 
ture tables,  and  also  in  regard  to  the  epoch  of  ripening  (fructifi- 
cation). 

I  have  already  had  occasion  to  call  attention  elsewhere  to  the  fact 
that  the  falling  of  the  leaves  (effeuillaison)  depends  less  upon  the  tem- 
perature of  the  year  than  upon  the  effects  of  the  first  cold.  Thus  the 
leaves  fall  sooner  in  the  north  than  in  the  south,  unless  they  fall 
sooner  here  on  account  of  a  season  of  great  dryness  or  excessive  heat. 

It  w*ould  be  superfluous  to  consider  the  influence  of  the  other  me- 
teorological agents  when  we  still  possess  so  little  information  as  to 
the  mode  of  action  of  the  princii^al  cause,  which,  in  our  climate, 
dominates  in  some  degree  all  the  phenomena  of  vegetation. 

The  temperature  month  by  month  at  Geneva  and  Lausanne  vary 
little  from  that  observed  at  Brussels.  The  winter  months  there  are 
a  little  colder  and  the  vegetation  is  a  little  behind.  Toward  the  time 
of  ripening  this  retardation  changes  into  an  advance.  The  tempera- 
ture, however,  in  spring  and  winter  is  no  higher  than  that  of  Brussels. 

Is  not  this  advantage  to  be  attributed  to  the  fact  that  Geneva  and 
Lausanne,  having  a  higher  elevation,  enjoy  purer  air  and  a  more 
efficient  solar  radiation,  elements  which  are  not  indicated  by  the  ther- 
mometer? By  folloAving  the  mode  of  calculation  generally  adopted 
one  would  say  that  the  difference  of  latitude  between  Brussels  and 
the  two  Swiss  cities  is  compensated  by  their  different  altitudes.  Ge- 
neva and  Lausanne  are  4°  30'  farther  south  than  Brussels,  while  their 
elevation  averages  about  420  meters  greater,  which  shoAvs  that  a  de- 
gree of  latitude  farther  north  is  about  equal  to  an  increase  in  height 
of  120  meters.  At  Munich  and  Groningen  the  same  plants  flower 
almost  simultaneously,  yet  their  latitudes. and  elevations  are  very 
different.  Munich  is  5°  4'  farther  south,  but  is  524  meters  higher. 
Here  again  a  degree  of  south  latitude  nearly  compensates  100  meters 
of  elevation.  It  is  to  be  regretted  that  we  do  not  knoAv  the  annual 
temperature  of  Groningen.  Berlin  and  Stettin  seem  to  approach 
that  locality  very  nearly  in  the  natural  epochs  of  their  plants.  In- 
deed there  is  very  little  difference  in  their  latitudes,  their  elevations, 
and  probably,  also,  in  their  temperatures. 

Carlsruhe  and  Brussels  have  about  the  same  annual  temperature. 
The  winter  and  early  spring  are  a  little  colder  in  the  first  than  in  the 
second  of  these  cities,  consequently  the  vegetation  is  a  little  later; 
on  the  other  hand  the  months  of  April  and  May  are  warmer,  there- 
fore, we  see  the  vegetation  changes  its  retardation  into  an  advance. 

Carlsruhe  is  about  2  degeees  south  of  Brussels.  For  this  reason 
alone  vegetation  should  be  about  eight  days  in  advance  as  at  Paris; 
but  on  the  other  hand  its  altitude  is  about  300  meters  greater  than  that 
of  Brussels,  and  its  vegetation  should  for  this  reason  be  about  twelve 
days  later.  Combining  the  effects  of  these  two  causes,  Carlsruhe 
would  still  have  a  retardation  of  more  than  four  days,  which  is  con- 
firmed by  experience  for  the  first  portion  of  the  year;  but  in  the 
second  part  we  see  this  retardation  change  to  an  advance  of  fifteen 
days.     Should  we  not  here  again  remark,  as  was  done  before,  that, 


187  . 

otlior  thiiifjs  boiiio;  equal,  vo<2:otatioii  is  much  more  active  on  high 
phiteaus.  where  the  radiation  is  or(>ater.  as  well  as  in  loealili<'s  where 
the  annual  variations  are  very  marked  '.  This  activity  is  further  reeii- 
foreed  if  the  locality  is  near  the  polar  re«2:i()ns,  where  the  light  acts 
almost  uninterruptedly  when  once  the  awakening  of  the  plants 
has  taken  place.  In  this  respect  Russia  and  Lai)land  present  us  with 
notable  examples  of  this  reenforcement. 

Kui)rt'er,  in  his  '"■  Note  relating  to  the  temperature  of  the  soil  and 
of  the  air  at  the  limits  of  the  region  of  cultivation  of  cereals,"  gives 
the  following  temperatures  for  the  three  principal  boundary  points 
of  this  reoion : 


Longi- 
tude. 

Lati- 
tude. 

Alti- 
tude. 

Mean  temperature. 

Year. 

Win- 
ter. 

Spring. 

Sum- 
mer. 

Au- 
tumn. 

Ii-kutsk 

101  15 
117    1 

52    17- 
51    18 

1,300 

2,100 



°  C. 
-0.25 
-3.2 

+0.7 

-14.1 

-21.7 
-10.0 

°  C. 
-0.2 
-1.0 
-0.2 

°  C. 
+12.5 
+12.9 
+11.5 

"  C. 
+  0.8 

Nertchinsk 

Archangel 

-2.9 

+  1.5 

"A  comparison  of  the  curves  for  Nertchinsk,  Irkutsk,  and  Arch- 
angel demonstrates  in  a  striking  manner,''  says  Kupifer,  "  under 
what  climatic  conditions  the  cultivation  of  cereals  can  be  carried  on 
notwithstanding  the  lowness  of  the  average  annual  temperature.  All 
the  curves  agree  together  in  spring  and  autumn,  Avhence  it  results 
that  it  is  especially  the  temperature  of  spring  and  autumn  which 
influences  the  cultivation  of  cereals;  it  is  in  these  seasons,  in  fact, 
that  occur  the  two  most  important  periods  of  the  year  for  agricul- 
ture— the  time  of  sowing  and  the  time  of  reaping.  In  the  cultiva- 
tion of  rye  autumn  plays  a  still  more  important  part,  because  rye  is 
sowed  also  in  autumn."  Kupffer  calls  attention  in  another  part 
of  his  note  to  the  fact  that  some  kinds  of  farming  are  carried  on 
where  the  soil  below  the  surface  is  frozen.  ''  Experiments  in  farm- 
ing," he  says,  "  have  been  made  at  Irkutsk,  on  a  very  small  scale  it 
is  true,  but  which  in  many  respects  have  been  a  success.  This  is 
due  to  the  fact  that  the  soil  be(;omes  soft  on  the  surface  and  is  thus 
capable  of  developing  the  germs  received  by  it ;  its  mean  temperature 
is  above  zero  four  months  in  the  year,  which  is  sufficient  to  ripen  the 
cereals  in  a  country  where  continuity  of  the  sunshine  makes  up  for 
the  weakness  of  solar  action.  Snow  often  falls  upon  the  sheaves,  but 
still  they  harvest  them."  These  examples  confirm  what  we  have 
said  in  regard  to  annual  changes  of  temperature.  In  no  locality  in 
the  world  are  these  variations  greater  than  here;  at  Yakutsk  the  dif- 
ference of  temj^erature  between  the  warmest  and  the  coldest  month 
of  the  vear  is  50.9°  C;  at  Irkutsk,  it  is  24°. 1;  at  Nertchinsk,  39.°1; 
at  Archangel.  28.2°  C. 

It  might  be  said,  it  is  true,  that  the  average  temi)erature  of  the  year 
should  not  be  considered  here,  not  even  that  of  the  free  air,  so  long 
as  the  plants  are  covered  by  snow  to  shield  them,  for  in  this  case 
the  temperature  of  the  air  does  not  at  all  rei)resent  that  of  the  ])lants. 
In  this  respect  the  conditions  of  vegetation  would  be  the  same  at  each 


■  188 

locality  about  the  time  of  the  ^Yintel■  awakening,  and  we  should  par- 
ticularly consider  the  temperature  that  follows  after  the  thermometer 
has  passed  the  freezing  point,  as  well  as  the  quantit}'  of  light  radiated 
by  the  sun. 

It  must  therefore  be  admitted  that  cold,  as  long  as  it  does  not 
destroy  the  life  of  the  phmt,  may  be  more  or  less  severe  or  more  or  less 
prolonged,  and  thus  lower  the  average  j^early  temperature,  without 
causing  an}?^  marked  ditference  in  the  epochs  of  vegetation.  This 
reflection  explains,  independent  of  all  hypothesis,  that  for  any  equable 
mean  annual  temperature  the  acceleration  in  vegetation  should  be 
in  favor  of  localities  where  the  annual  variation  is  the  greatest,  par- 
ticularly in  northern  countries,  where  the  frost  prevails  during  many 
months  of  the  year  and  where  duing  many  of  the  following  months 
the  sunlight  never  ceases  to  fill  the  sky.  Admitting  the  hypothesis 
that  the  action  is  proportional  to  the  sum  of  the  squares  of  the  tem- 
peratures, the  results  are  still  more  positive;  for,  other  things  being 
equal,  the  greater  the  annual  variation  the  greater  will  be  the  sum  of 
the  square  of  the  jjositive  ordinates  in  the  curves  of  temperatures. 

I  will  now  present  some  conclusions  that  one  can  deduce  from  all 
that  precedes.  I  must  first  of  all  warn  my  readers  that  this  work 
must  be  considered  only  as  an  attempt  to  solve  a  problem  as  difficult 
as  it  is  interesting,  the  principal  elements  for  the  solution  of  which 
are  still  wanting. 

1.  A  great  number  of  factors  combine  to  produce  variations  in  the 
periodic  phenomena  of  vegetation,  the  most  important  of  which 
in  our  climate  is  temperature. 

2.  It  may  be  estimated  that  the  progress  of  vegetation  is  in  pro- 
portion to  the  sum  of  the  temperatures,  or,  better,  to  the  sum  of  the 
squares  of  temperatures,  calculated  above  the  freezing  point,  starting 
with  the  epoch  of  the  awakening  of  vegetation  after  the  winter  sleep. 

3.  The  cold  of  winter,  if  it  does  not  injure  the  vitality  of  the  plant, 
does  not  cause  any  perceptible  retardation  in  its  future  development, 
particularl}^  if  the  ground  has  been  covered  with  snow. 

The  effects  that  can  be  produced  by  the  cold  of  winter  must,  how- 
ever, be  considered,  and  especially  the  condition  of  the  plant  when 
it  entered  upon  its  winter  sleep,  a  condition  which  should  correspond 
to  a  certain  sum  of  acquired  temperatures  (or  heat  stored  up).  As 
to  the  ripening  of  the  harvest  and  because  plants  develoj)  under  the 
infl-uence  of  the  sun,  we  must  consult  a  thermometer  exposed  to  its 
direct  action,  and  not  a  thermometer  exposed  to  its  direct  action,  and 
not  a  thermometer  placed  in  the  shade,  as  is  connnonly  done. 

4.  The  temperatures  at  night  are  not  comparable  with  those  of  the 
day  as  to  their  effects  on  vegetation.  The  (piantity  of  light  received 
by  the  plants  must  also  be  taken  into  consideration. 

5.  An  increase  of  1°  in  latitude  produces  about  the  same  retarda- 
tion in  vegetation  as  an  increase  in  elevation  of  100  meters;  that  is  to 
say,  in  our  climate,  a  retardation  of  about  four  days. 

This  result  should  be  looked  upon  as  only  a  kind  of  average  of 
quantities  that  vary  during  the  year,  the  differences  of  latitude  and 
elevation  having  scarcely  any  real  influence  furtlier  than  as  they 
produce  differences  of  temperature. 

6.  The  variations  of  temperature,  other  things  being  equal,  are 


189 

favorable  to  vegetation,  and  the  same  may  be  said  of  high  plateaus 
where  radiation  is  more  powerful. 

7.  The  isanthesic  lines,  or  lines  of  simultaneous  flowering,  do  not 
preserve  any  parallelism  at  different  periods  of  the  year;  thus,  the 
line  which  shows  where  the  lilac  blooms  on  a  given  day  of  the  month 
passes  ten  days  afterwards  throuo;h  another  series  of  places  where 
the  same  phenomena  is  then  occurring. 

Now.  the  zone  comprised  between  these  two  lines  has  not  the  same 
breadth  throughout  its  whole  extent,  as  would  be  the  case  with  a  zone 
between  two  parallels  of  latitude.  It  is  not  even  constant,  since,  for 
example,  a  m(mth  later  the  isanthesic  lines  will  have  quite  different 
forms,  and  localities  that  ^vere  backward  as  compared  with  others 
may  then  be  in  advance. 

8.  The  falling  of  the  leaves  is  a  phenomenon  which  in  our  climate 
depends  as  nuich  upon  the  current  temperature  as  upon  those  which 
have  preceded.    It  is  generally  controlled  by  the  first  cold  of  autumn. 


Karl  Fritsch  (1881)  gives  the  results  of  about  ten  years'  observa- 
tions of  plants  growing  in  the  Botanical  Garden  at  Vienna  (1852- 
1861).  His  list  of  plants  embraced  all  those  recorded  in  the  previous 
lists  of  Quetelet,  Sendtner  (1851),  and  his  own,  in  all  1,600  species 
and  varieties,  but  of  wdiich  he  has  only  used  889.  The  epochs  ob- 
served by  him,  as  uniformly  as  possible  throughout  the  ten  years, 
were  the  following : 

(1)  The'first  visibility  of  the  upper  surface  of  the  leaf. 

(2)  The  complete  development  of  the  first  flower, 

(3)  The  complete  ripening  of  the  first  fruit. 

(4)  The  date  at  which  a  tree  or  bush  has  lost  all  of  its  foliage. 
Having  endeavored  in  vain  to  establish  a  connection  between  the 

moisture  of  the  air  and  the  growth  of  the  plant,  and  finding  it  imprac- 
ticable to  take  account  of  the  moisture  in  the  earth,  Fritsch  resolved 
to  reject  observations  made  during  special  droughts  or  floods  or  otl^er 
abnormal  conditions  and  to  consider  only  the  sum  of  the  average 
daily  temperatures.  These  mean  daily  temperatures  he  deduced  from 
the  observations  at  6  a.  m.  and  2  and  10  p.  m.,  made  at  the  Central 
Meteorological  Institution  in  Vienna,  where  the  thermometer  was 
about  50  feet  above  the  ground.  The  summation  of  the  mean  daily 
temperatures  for  comparison  with  phenological  phenomena  counts 
from  the  1st  of  Januarj^  to  the  date  of  the  observed  epoch,  and  omits 
all  clays  whose  mean  temperatures  are  0°  Reaumur  or  lower  than  that. 
A  comparison  of  the  observations  made  on  successive  years  on  the  same 
plant  shows  that  the  time  of  blossoming  is  uncertain  by  only  one  or 
two  days  in  96  per  cent  of  all  the  plants,  and  the  so-called  "  temi)era- 
ture  "  or  "  thermal  constant  "  is  uncertain  by  8  per  cent  of  its  amount 
or  less,  in  97  per  cent  of  all  the  plants.     Similarly,  for  dates  of  ripen- 


190 

ing  of  fruits  the  dates  of  ripeiiino-  as  predicted  by  the  temperature 
constants  have  an  uncertainty  of  one  or  two  days  only  in  94  per  cent 
of  the  cases.  In  "the  choice  of  the  date  from  which  to  begin  taking 
the  sum  of  the  mean  daily  temperatures,  it  would  seem  that  for 
annual  plants  the  date  of  sowing  the  seed  would  be  proper,  but  that 
for  perennial  plants  the  whole  winter  since  the  end  of  the  preceding 
growing  season  would  be  proper;  but  instead  of  the. latter,  Fritsch  has 
adopted  that  epoch  at  which  the  mean  temperature  of  the  day  has  its 
minimum  value  in  the  course  of  its  annual  variation,  and  this,  com- 
bined with  the  ease  of  computation,  leads  him  to  adopt  the  1st  of 
January  for  all  perennials.  For  the  biennials  and  the  annuals  he 
would  have  preferred  to  count  from  the  time  of  sowing  the  seed,  but 
as  the  latter  date  was  frequently  not  recorded  and  as  most  of  the 
temperatures  are  below  freezing  in  the  early  part  of  the  year,  he  finds 
no  large  error  introduced  by  adopting  the  1st  of  January  for  these 
also,  and  this  is  very  nearly  equivalent  to  Quetelet's  method  of  count- 
ing from  the  time  of  the  permanent  awakening  of  the  activity  of  the 
plant  in  the  spring. 

In  the  following  list  I  have  given  all  of  Fritsch's  results,  and  with 
reference  to  the  practical  application  of  these  figures  to  the  prediction 
of  similar  phenomena  elscAvhere  quote  his  statement  that  he  had  con- 
vinced" himself  in  many  ways  that  the  trees  and  shrubs  observed  by 
him  in  the  Botanical  Gardens  at  Vienna  blossomed  at  the  same  time 
as  those  in  the  open  country,  but  for  all  herbs  this  is  true  to  a  less 
extent,  and  only  in  a  few  cases  are  the  departures  important. 

Although  many  plants  do  not  ripen  in  the  short  season  at  Vienna, 
yet  he  was  able  to  determine  their  thermal  constants  for  the  date  of 
blossoming. 

In  general  the  plants  and  their  seed  had  by  long  cultivation  in 
Vienna  become  acclimated  to  that  locality,  so  that  by  applying 
Linsser's  theorems  to  Fritsch's  results  they  become  applicable  to  the 
phenomena  that  would  be  manifested  by  these  plants  in  other  parts 
of  the  world. 

As  concerns  the  temperature  of  the  soil,  Fritsch  states  that  the 
perennial  grasses  were  partly  shaded  by  trees  until  1852,  after  which 
they  were  cultivated  in  a  sunny  spot.  The  annual  grasses  were  uni- 
formly in  a  sunny  region,  slightly  inclined  toward  the  north. 

The  orders  or  families,  with  the  genera  and  species  and  sometimes 
varieties  included  within  them,  are  arranged  in  the  table  as  given 
by  Fritsch,  who  states  that  it  is  in  accordance  with  the  natural  sys- 
tem of  Endlicher.  which  is  generally  adopted  in  Austria  as  prefer- 
able to  a  chronological  or  alphabetical.  But  for  the  convenience  of 
American  readers  I  have  added  to  each  of  Fritsch's  orders  the  num- 
ber by  which  it  is  designated  on  pages  5  and  736  of  Gray's  Manual  of 


191 

the  Botany  of  tho  Northern  UiiitcHl  States,  sixth  edition,  ISiK),  as  re- 
vised by  Watson  and  CouUer.  Tliese  numbers  will  be  found  in  the 
brackets  followin*;  the  names  of  the  orders  in  the  following;  (able, 
e.g.,  [G.  120]. 

TlicniKil  coiistdiils  for  the  J)l().<i><(>)iiiii!/  aiiil  riiicniuf/  of  SS!)  pimils  {nr  the  .sinus  of 
tlic  iiicaii  (laili/  tciiijx'i'dl lire  ahorc  zero  dcurvc-s  Urniiiiiiir  coiiiil iin/  from  .hni- 
nary  1st),  as  dctcnuhird  hu  Karl  Fritsch  from  obscrnifioiis  in  the  Botanical 
Garden,  in  Mcn)ia,  diiriiuf  the  ijcars  1852-1861,  incliisire. 

ISee  Denksclirifton,  Akad.  Vienna,  1S(>8,  Vol.  XXI.] 
[See  end  of  table  for  footnotes.] 


Designation  of  plant:  Order,  genus,  and  specie.s. 


Flowering. 


Ripening. 


I.  Graminex  [G.  1S9]. 

(1)  Zca  mays  L.  (sown  Apr.29) July 

(2)  Alopecurus  pratensis  L May 

(3)  Plileum  pratense  L.  var.  nodosom I  June 

(4)  Phalaris  arundinacea  L June 

(5)  Holcus  lanatus  L ,  June 

(6)  Holcus  mollis  L I  July 

(7)  Anthoxanthum  odoratum  L j  May 

(8)  Panicum  miliaceiun  L.  (Apr.  26) •.  July 

(9)  Stipa  capillata  L June 

(10)  Stipa  pennata  L June 

(11)  Agrostis  alba  L.  (A.stoloniferaL. -y,  flagellare) June 

(12)  Agrostis  vulgaris  With July 

(13)  Calamagrostis  Epigejos  Roth ,  July 

(14)  Avena  pratensis  L j  May 

(15)  Avena  .sati va  L.  ( sown  Apr.  12) !  July 


(16)  Sesleria  caerulea  Arduin 

(17)  Poa  compressa  L 

(18)  Poa  nemoralis  L , 

(19)  Poa  pratensis  L 

(20)  Briza  media  L 

(21)  Melica  ciliata  L , 

(22)  Dactylis  glomerata  h 

(23)  Cynosurus  cristatus  L 

(24)  Festuca  glauca  Lam 

(25)  Festuca  ovina  L 

(26)  Festuca  rubra  L 

(27 )  Bromus  ereetus  Huds 

(28)  Lolium  perenne  L 

(29)  Triticum  caninum  L 

(30)  Triticum  pinnatum  Monch  var.  caespitosum  . 

(31)  Triticum  repens  L 

(32)  Triticum  vulgare  Vill.  hibernum 

(33)  Secale  cereale  L.  hibernum 

(34)  Elymus  arenarius  L 

(35)  Hordeum  vulgare  L.  (Apr.  12) 


Con- 
stant. 


°Rtauvi. 

1,082 
425 
981 
824 
812 

1,144 
478 
907 

1,095 
698 

1,091 

1,157 

1,244 
618 
984 
221 
922 
765 
631 
760 
856 
677 
937 
707 
655 
754 
751 
784 
787 
823 
982 
758 
626 
749 
648 

1,671 


July  28 
July  2 
June  28 


June  10 
July  22 
July  24 
July  1 
July  16 
July  25 
July  22 
June  11 
July  20 
May  13 
July  16 
June  26 
June  15 
June  17 


Con- 
tant. 


June  20 
July  14 
June  20 
June  16 
June  24 
July  1 
July  9 
July  3 
June  29 
July  9 
July  3 
June  29 
Aug.  19 
July  16 
Aug.  16 


1,.595 
1,143 
1,111 


1,184 
1,532 
1,154 
1,376 
1,500 
1,488 

873 
1,200 

504 
1,371 
1,075 

925 


999 
1,371 
984 
922 
1,0.55 
1,1.55 
1,269 
1,272 
1, 115 
1,267 
1,183 
1,145 
1,990 
1,1.50 
2, 046 


192 

Thcrnial  coii-stoiit.-t  for  the  hlossoming  and  riijeuinr/of  889  plants,  etc. — Continued. 


Designation  of  plant:  Order,  genus,  and  species. 


Flowering. 


Con- 
stant. 


Ripening. 


II.  Cyperaceas  [G. 


(37)  Carex  distan.s  L 

(38)  Carex  glauca  Seopol 

(39)  Carex  hirta  L 

(40)  Carex  hornschuhiana  Hoppe 

(41)  Carex  humili.s  Leyss 

(42)  Carex  intermedia  Good 

(43)  Carex  maxima  Scop - 

(44)  Carex  montana  L 

(45)  Carex  paludo.'^a  Good 

(46)  Carex  pilulifera  L 

(47)  Carex  praecox  Jacq 

(48)  Carex  Schreberi  Schrank 

(49)  Carex  supina  Wahlb 

(50)  Carex  tomentosa  L 

(51)  Cyperus  longus  L 

III.  Commelynacex  [G.  120]. 

(52)  Tradescantia  virginica  L.  var.  rubra 

IV.  AUsmacex  [G.  125]. 


(53)  Alisma  plantago  L 

V.  Melanthacex  [G.  — ;  see  G.  116.] 

(54)  Veratrum  album  L 

(55)  Veratrum  nigrum  L 

(56)  Bulbocodium  soboliferum  End 

(57)  Colchicum  autumnale  L (57) 

(58)  Colchicum  autumnale  L.  var.  albiflorum 

(59)  Colchicum  autumnale  L.  var.  subtessellatnm 

VI.  Liliacese  [G.  116]. 

(60)  Erythronium  dens  canis  L 

(61)  Tulipa  gesneriana  L 

(62)  Tulipa  oculus  soils  St.  Amand 

(63)  Tulipa  praecox  Tenor 

(64)  Tulipa  silvestris  L 

(65)  Tulipa  snaveolens  Roth 

(66)  Fritillaria  imperialis  L 

(67)  FritOlaria  meleagris  L 

(68)  Lilium  bulbiferum  L 

(69)  Lilium  candiuum  L 

(70)  Lilium  croceum  Chaix.  var.  saturatum 

(71)  Lilium  martagon  L 

(72)  Lilium  monadelphum  M.  Bieberst 

(73)  Funkia  grandiflora 

(74)  Funkia  lanceifolia  Sieb 

(75)  Funkia  ovata  Spreng 

(76)  Funkia  sieboldi  Lindl .  var.  cucullata 

(77)  Funkia  subcordata  Spr 

(78)  Muscari  azurea  Fenzl 

(79)  Muscari  botryoides  D.  C.  (later  under  the  name  Mus- 
»    cari  racemosum  parvlflorum ) . 

(80)  Muscari  comosum  Mill 

(81)  Muscari  moschatum  Desf 


May  7 
Apr.  26 
May  10 
Apr.  25 
Apr.  1 
May  7 
May  21 
Apr.  7 
May  7 
Apr.  12 
Apr.  13 
Apr.  25 
Apr.  2 
Apr.  29 
July     6 


May   30 

July  23 

(54) 
July  13 
Mar.  18 
Sept.  2 
Sept.  10 
Sept.  17 


Mar.  31 
May  12 
May  11 
Apr.  22 
May  2 
Apr.  19 
Apr.  21 
....do... 
June  5 
June  23 
June  3 
June  16 
May  26 
Aug.  19 
Aug.  5' 
July  11 
June  22 
Aug.  23 
Mar.  16 
Apr.  18 


■Reaum. 
417 


June  12 
..do.... 
478  June  26 
309     June  12 


417 
542 
214 
449 
234 
139 
345 
172 
352 
1,224 


(54) 
1,358 
107 
2,134 
2,243 
2,328 


1,066 

754 

927 

653 

1,935 

1,718 

1,314 

1,025 

1,957 

92 


July     6 


Aug. 


Sept.  13 


June    1 
July    6 


June    8  821     July  23 

Apr.   21  332 


Sept.  7 
Aug.  8 
July  27 


U)3 


'lltenind  coiit^liiiils  I'nr  Ihr  hlo 


DesignntiDii 


(/  rijiniliii/  iif  S^'9 2)l(i)ilx,  I'lv. — ('()iitinuc<l. 
Flowering. 


inliT.  Kt'iKi!^.  hikI  specios 


VI.  Liliaciiv  [a.  i /(>•]—<_'( 

(82)  Muscari  racemosum  Willd 

( 83)  Hyacinthus  amethystinus  L 

(84)  Hyaointlms  orientalis  L 

1,85)  Agraphia  companulata  Lk 

(86)  Agraphis  patula  Beh 

(87)  Seilla  amoena  L 

(88)  Seilla  autumnalis  L 

(89)  Seilla  i talica  L 

(90)  Seilla  pratensis  M.  and  R 

(91)  Ornithogalum  pyrenaicnm  L.  v: 


r.  nnrboneiise,  mon- 


strosum 

(92)  Ornithogalum  umbellatum  L 

(93)  Myogalum  nutans  Link 

(94)  Puschkinia  seilloides  Willd 

(95)  Allium  eepa  L '. 

(96)  Allium  fistulosum  L.  var.  altaicum 

(97)  Allium  molly  L 

(98)  Allium  paniculatum  Aut.  (?) 

(99)  Allium  porrum  L 

(100)  Allium  roseum  L.  var.  bulhiferum 

(101)  Allium  .sativum  L 

(102)  Allium  sehonoprasum  L 

(103)  Allium  scorodoprasum  L 

(104)  Allium  serotinum  Schleich 

(105)  Allium  ursinum  L 

(106)  Allium  victorialis  L 

(107)  Eremerus  caucasicus  Stev 

(108)  Asphodelus  ramosus  L 

(109)  Asphodelus  luteus  L 

(110)  Hemerocallis  flavaL 

(111)  Hemerocalli.s  fulva  L 

(112)  HemerocalliH  graminea  Audrev.  vnr.  bracteosa 

(113)  Antherieum  liliago  L 

(114)  Anthericum  ramosum  L 

(1 15)  Asparagus  officinalis  L 

VII.  SmUucc:)'  [G.  — ;  sec  G.  110]. 

(116)  Convallaria  majalis  L 

(117)  Convallaria  jfolygonatum  Dosf 

(118)  Smilaeina  racemosa  Dosf 

VIII.  Dioscorew 

(119)  Tamus  communis  L 


Date. 


Apr.  12 
May  16 
Apr.  10 
Ma>-  10 
....do... 
Apr.  27 
Sept.  7 
Apr.  21 
May   20 


May  31 
May  12 
Apr.  15 
Apr.  1 
.luly  9 
May  23 
June  5 
July  23 
June  27 
May  31 
July  24 
June  23 
July  14 
Aug.  24 
May  14 
May  18 
May  19 
July  19 
May  10 
June  3 
June  23 
May  23 
June  3 
July  6 
May  20 


Con- 
stant. 


°Riaum. 
223 

512 
224 
463 
457 
339 
2,376 
300 
584 

732 

470 

249 

184 

1,274 

603 

785 

1,487 

1,104 

718  _ 

1,477* 

1,051 

1,314 

2,027 

520 

503 

567 

1,479 

%  451 

737 

1,012 

605 

750 

1,242 

572 


Ripening. 


[G.  im. 


May  8  428 

May  7  418 

May  18  542 

May  24 


IX.  Iridea'  [G.  lU]. 

(120)  Irisbiflora  (Aut.?) 

(121)  Irisbiglumis  Vahl 

(122)  Iris  germanica  L.  var.  saturata 

(123)  Iris  notha  M.  Bieb.  var.  live.scens.. 

(124)  Iris  pseudacorus  L 

(125)  Iris  pumila  L 

(126)  Iris  .sibiriea  L.  var.  saturata 

(127)  Iris  virginica  Gronov 

(128)  Iris  xyphium  L 

(129)  Gladiolus  communis  L 

2667—05  .M 13 


May  9 
Apr.  28 
May  14 
June  9 
May  28 
Apr.  22 
May  11 
June  8 
June  10 
June  13  I 


Date. 

Con- 
stant. 

June  17 

°Jifattm. 
955 

June  26 
Jinie    7 

1,091 
791 

July  22 

1,466 

June    3 

731 

July     1 

1,169 

Aug.  28 
June  28 

2,076 
1, 120 

July  29 

1.617 

Oct. 

15 

June 

22 

June 

24 

July 

2 

July 

18 

J\ilv 

28 

July  14 
July  23 
Aug.  29 
June  25 


Aug.    8 
Aug.    5 


Aug.  12 


July  29 


July 


879  !  July  29 


194 


Thermal  constants  for  the  blossoming  and  ripening  of  8S9  plants,  etc. — Continued. 


Designation  of  i)laul:  order,  genus,  and  species. 


Flowering. 


Ripening. 


Con- 
stant. 


Con- 
stant. 


(130) 
(131) 
(132) 
(133) 
(134) 
(135) 
(13G) 
(137) 
(138) 
(139) 
(140) 
(141) 
(142) 
(143) 
(144) 
(145) 

(140) 

;i4-) 

(148) 
(149) 
;L50) 
(151) 
(152) 
[153) 
(154) 
(155) 
(15G) 
(157) 
(158) 
(159) 
(160) 


IX.  Iridese  [G.  i;5]— Continued. 

Gladiolus  segetum  Ker 

Crocus  imperati  Tenor 

Crocus  luteus  Lam 

Crocus  nudiflorus  Smitli 

Crocus  odorus  Bor 

Crocus  pallasii  Goldb 

Crocus  prsecox  Hock 

Crocus  sativus  L 

Crocus  sauveolens  Bertol 

Crocus  speciosus  Host 

Crocus  susianus  Ker 

Crocus  thomasii  Tenor 

Crocus  variegatus  Hoppe 

Crocus  vernus  Willd.  var.  lilacinus 

Crocus  vernus  Willd.,  /3,  albiflorus 

Crocus  versicolor  Ker 


X.  AmarylUdex  [G.  IIU]. 

Galanthus  nivalis  L 

Galanthus  plicatus  M.  Bieb 

Leucojum  vernuni  L 

Sternbergia  colchiciflora  M.  et  K 

Sternbergia  lutea  Schult.  til 

Narcissus  biflorus  Curt 

Narcissus  grandiflorus  Hav 

Narcissus  italicus  Kor 

Narcissus  major  Curt 

Narcissus  odorus  L 

Narcissus  poeticus  L 

Narcissus  prsecox  Teflor 

Narcissus  pseudonarcissus  L.  var.  plenus. 

Narcissus  seratus  Hav 

Narcissus  tazeta  L 


XI.  Aruidcx  [G. 
Aurum  maculatum  L. .'. . . 
Acorus  calamus  L 


*-ee  G.  123] . 


.June    7 
Oct.    21 
Mar.  16  ' 
Oct.    21  j 
Oct.    13  i 
Oct.     4  I 
Mar.    3 
Oct.      6 
Mar.  IS 
Sept.  23 
Mar.     5 
Oct.    13 
Mar.  28 
...do... 
Mar.  24 
Mar.  21 


Mar.  3 
Mar.  1 
Mar.  20 
Sept.  17 
Sept.  25 
May  10 
Apr.  29 
Apr.  23 
Apr.  20 
Apr.  16 
Apr.  28 
Apr.  18 
...do... 
...do... 
Apr.  16 

May  18 
May  27 


°Maum. 

824 

2, 730 

103 

2,  701 


XII.  TyplMcex  [G.  1-22]. 

Typha  angustifolia  L 

Typha  latifolia  L 

XIII.  Cupressinx  [(r.  — ,-  see  G.  107]. 

Juniperus  communis  L.  var.  vulgaris 

Juniperus  phoenicea  L.  -T 

XIV.  Abietinx  [G.  —;  see  G.  107] . 

Pinus  eedrus  L 

Pinus  cembra  L 

Pinus  laricio  Poir.  var.  gibbosa 

Pinus  larixL |  Apr.  14 

Pinus  nigra  Ait ;  May     5 

Pinus  picea  L Apr.  28 

Pinus  pumilis  Hiinke May  24 

Pinus  silvestris  L May  17 

Pinus  strobus  L.  var.  compressa (175) 

Pinus  uncinata  Ramond i  May  24 


June  14 
June  11 


Apr.  30 
Apr.   13 

Sept.  25 

(168) 
May  20 


67 

2, 529 

111 

81 

2,543 

j 

144 

142 

162 

117 

73 

120 

2,385 
2,419 

464 

366 

320 

265 

298 

348 

323 

285 

218 

311 

548 

.Tuly  14 

1,377 

873 
372 

Oct.  26 

Aug.  26 

2,737 

2,025 

(168) 
565 

215 

393 

353 

630 

517 

(175) 
603 

105 


T/iermal  cuiLitanlx  for  the  hlosminiiuj  and  lijunimj  uf  iS89  plants,  etc. — Contiiuied. 


Designation  of  plant:  order,  genus,  and  speei 


(177) 
(178) 


(179) 
(180) 
(181.) 
(182) 


(183) 
(IM) 
(185) 
(186) 
(187) 
(188) 
(189) 
(190) 
(191) 
(192) 
(193) 

(194) 
(195) 

(196) 
(197) 

a98) 

(199) 
(200) 
(201) 
(202) 
(203) 


(205) 
(206) 

(207) 
(208) 
(209) 
(210) 
(211) 
(212) 
(213) 
(214) 
(215) 
(210) 
(217) 


XV.   Taxinex  [G.  — ;  see  0. 107]. 

Taxus  Imecata  L 

Salisburia  adiantifolia  Sm.  cT 


XVr.  Betulacese  [G.  — ;  sfe  G.  103]. 

Betula  alba  L.  var.  dalecarlica 

Alnus  cordifolia  Tenor 

Alnus  glutinosa  L.  var.  pinnatiftda 

Alnus  subcordata  C.  H.  Meyer 


XVII.  Ouputiferse  [G.  /ft!]. 

Ostrya  vulgaris  Willd 

Curpinus  betulus  L 

Carpinu.s  orientalis  Lam 

Corylu.s  amerieana  Rich 

Corylu.s  avellana  L.  var.  globe*, 

Corylus  colurna  Willd 

Quereus  alba  L 

Quercu.s  cerris  L 

Quereus  pedunculata  Ehrh 

Fagus  silvatica  L 

Fagus  silvatica  L.  var.  pendula 

XVIII.   Ulmacese  [G.  —:  see  G.  99]. 
Ulmus  campestris  L.  montana  tortuosa  . . . 

Ulmus  efTu.«a  Willd 

XIX.  Celtidex  [G.  —:  ser  G.  90] . 

Celtis  australis  L 

Celtis  occiden talis  L 


XX.  Morex  [G.  — ;  m-  G.  09] . 

Morus  alba  I,,  morettiana 

Moras  alba  L.  fructu  nigro 

Moms  scabra  Willd 

Madura  aurantiaca  Nuttal  9 

Brous-sonetia  papyrifera  Vent,  cf  cncullata  . 
Ficus  carica  L 


Flowering. 


Aug. 


May 
Mav 


XXI.  Cannabinex  [G.—;  wc  G.99]. 

Humulus  lupulus  L.  ,f 

XXII.  Plataruif  [G.  110]. 

,Platanus  occidentalis  L 

Platan  us  orientalis  L.,  /3,  aeerifolia,  /sp,  granrtifolia  . 
XXIII.  Salicincx  [G.  101,]. 

Salix  babylonica  L.  9 

Salix  daphnoidcs  Vill.  rj .: 

Salix  purpurea  L 

Salix  ropens  L.  rf 

Populusalba  L.  9  anglica 

Populus  balsar»rfera  h.  rf  fi  suaveolens 

Populus  eanescens  Smith,  rf  belgica 

Populus  dilatata  Ait.  9  rf ^^I""-     9 

Populus  grseca  Ait.  9 Mar.  27 

Populus  nigra  L.  9 A[)r.   12 

Populus  tremula  L.  cf  9 ^'"f-  -'' 


Mar. 
Mav 


(179) 
Apr.     S 
Mar.  11 
Feb.   11 


May  :; 
Apr.  20 
May  X, 
Mar.  21 
Mar.  1 
...do.. 

(189) 
May    12 
May     C, 
.May     o 
May     7 


Con- 
stant. 


Mar.  30 
Mar.  31 


Apr. 
Apr. 


May  15 
May  K; 
May  17 
.June  7 
May  II 
(2031 


Apr.  It) 
Mar.  31 
Apr.  II 
Apr.  15 
Apr.  1 
Apr.  12 
Mar.  28 


°Riaum. 
149 
431 


(179) 
199 

97 
55 


Ripening. 


Date. 


Con- 
stant. 


°  limn  1,1. 
1,87 


Sept.  30 
Sept.  2:5 
Sept.  27 


279 
370 
138 
72 
72 
(189) 
475 
420 


Aug.  20 


Sept.  21 
Sept.  14 
Aug.     2 


163  '  May   18 
162     Mav   20 


231  

350  Aug.  15 

.509  .lune  18 

545  Juno  21 

549  July     8 

818  

491 
(203) 


407 
420 


2r,2   

Ml    

229     May  19 

238    

179    

212  1 

145  I 

220  j  May  31 
131  1  May  1 
■2S6  I  May  30 
137  i  May    8 


2,524 
2,404 
2,436 


1,836 


2,335 
2,2.36 
1,617 


540 
574 


970 
1,015 
1,280 


703 
371 
(-.8:) 
418 


1% 

TJiermal  constants  for  the  blossoming  and  ripening  of  8S9  plants,  etc. — Continued. 


Flowering. 


Designation  of  plant:  order,  genus,  and  species. 


Ripening. 


May  12 
June  11 


XXIV.  Cheiwpodesp[G.87]. 

(218)  Spinacia  oleracea  L 

(219)  Beta  vulgaris  L 

:S.yiY.  Polygovetr  [G.'s9]. 

(220)  Rheum  emodi  Wall I  June    4 

(221)  Rheum  hybridum  Ait.  (later  R.  rhapontieum  L.) May  16 

(222)  Rheum  palmatum  L.  (also  later  R.  rhapontieum  L. ) . . .  May  17 

(223)  Rheum  rhapontieum  L May  11 

(224)  Rheum  unduiatum  L May  13 

(225)  Polygonum  amphibium  L June  28 

(226)  Polygonum  bistorta  L May  21 

(227)  Polygonum  fagopyrum  L.  (sown  Apr.  24) June  10 

(228)  Rumex  acetosa  L.  9  rf June    1 

(229)  Rumex  acetosella  L.  multifldus May   27 

(230)  Rumex  crispus  L June    4 

(231)  Rumex  nemolapathum  Ehrh June  18 

(232)  Rumex  patientia  L.  conferta May  27 

(233)  Rumex  scutatus  L May  26 

XXVI.  Daphnoidese  [G.  —;  see  G.  M]. 

(234)  Daphne  alpina  L May     8 

(235)  Daphne  laureola  L Mar.  28 

(236)  Daphne  mezereum  L Jan.   25 

XXVII.  Elxagnex  [G.  95] . 

(237)  Hippophse  rhamnoides  L.  cf May  10 

(238)  Elseagnus  hortensis  M.  B.  augustifolius June    7 

XXVIII.  Aristolochiex  [G.  91] . 

(239)  Aristolochia  clematitis  L May   11 

(240)  Aristolochia  sipho  L May  21 

XXIX.  Plantaninex  [G.83\. 

(241)  Plantago  cynops  L May  18 

(242)  Plantago  lanccolata  L May     8 

(243)  Plantago  media  L May  25 

(244)  ;Plantago  saxatilis  M.  Bieb --- Apr.  28 

XXX.  Pliimbar/inai-  [G.60]. 

(245)  Armeria  vulgaris  Willd May  19 

(246)  Statice  caspia  Willd -Tuly  24 

(247)  Statice  incana June  14 

(248)  Statice  latifolia  Sm '  July  22 

(249)  Statice  limonium  L July  11 

XXXI.  Valerkinfif  [G.  n.'i]. 

(250)  Centranthus  ruber  D.  C June    1 

(251)  Valeriana  officinalis  L June   ; 

(2-52)  Valeriana  phu  L May  22 

XXXII.  Dipsacex  [G.229]. 

(253)  Dipsacus  f  ullonum  L July  H 

(254)  Dipsacus  sylvestris  Huds '  July  16 

(255)  Cephalaria  tatarica  Schrad.  gigantea July     2 

(256)  Knautia  eiliata  Coult June    4 

(257)  Scabiosa  cauca.sica  M.  Bieb.  heterophylla July  16 

(258)  Scabiosa  columbaria  Coult j  June  30 

(259)  Scabiosa  ochroleuca  L j  June  29 

(260)  Scabiosa  succisa  L 


°Maum. 

484 
816 

770 
494 
501 


1,165 
583 
552 
709 
(501 
752 
972 
669 
627 

432 
150 


Aug. 


425 
620 

359 

.566 
1,  .544 

927 
1,47C. 
1,332 

746 
801 
586 

1,313 
1,384 
1,264 

782 
1,370 
1,130 

1,127 
1,677 


June  21 

1,018 

July  18 

1,412 

June  21 

1,021 

June  18 

983 

June  15 

921 

June  17 

956 

June  14 

946 

July  IS 

1,096 

July  17 

1,399 

July    2 

1,145 

July  14 

1,412 

June  28 

1,121 

June  20 

997 

June  21 

1,011 

June    8 

804 

Sept.  12 

2,267 

Sept.    2 

2, 130 

July     9 

1,298 

June  28 

1,157 

July  16 

1,373 

June  29 

1,148 

June  21 

1,036 

July  28 

1,564 

July  30 

1,626 

July     1 

1,179 

June  26 

1,127 

Aug.  10 

1,741 

Aug.  11 

1,792 

Aug.    4 

1,689 

July  22 

1,482 

July  30 

1,-597 

:  Sept.    6 

2,188 

197 


Thermal  conMantx/or  Ihr  hloKKoming  and  ripening  of  SS9  plants,  c/r.— Continued. 

Flowering. 


Designation  ^'f  pliuil:  order,  geniis,  iuul  s^pecies. 


(261) 
(2G2) 
(263) 
{264) 
(265) 
(266) 
(267) 
(268) 
(269) 
(270) 
(271) 
(272) 
(273) 
(274) 
(275) 
(276) 
(277) 
(278) 
(279) 
(280) 
(281) 
(282) 
(283) 
(284) 
(285) 
(286) 
(287) 
(288) 
(289) 
(290) 
(291) 
(292) 
(293) 
(294) 
(295) 
(296) 
(297) 
(298) 


(aui) 
(302  J 
(303) 
(304) 
(305) 
(306) 
!307) 
(308) 
(309) 
(310) 
(311) 
(312) 
(313) 


XXXIII.  Composite  [(?.  5.5]. 

Eupat(^ium  ageratoides  L 

Eupatorium  cannnbinuin  L 

Eupatorium  purpureura  (Ant.?) 

Eupatorium  syriacum  Jacq 

Tussilago  petasites  L 

Tussilago  farfara  L 

A.ster  alpinus  L 

Aster  amellus  L.  latifolius 

Aster  grandiflorus  L 

Aster  novae  anglise  Ait 

Aster  novi  belgii  Nees 

Aster  pilosus  Willd 

Aster  pyrenseus  Desf 

Erigeron  acre  L 

Erigeron  canadensis  L 

Solidago  altissima  L 

Solidago  canadensis  L 

Splidago  conf ertiflora  D.  C . . .  ^. 

Solidago  laevigata  Ait 

Solidago  rigida  Ait 

Solidago  virgaurea  L 

Linosyris  vulgaris  Cass 

Inula  britannica  L 

Inula  germanica  L 

Inula  helenium  L 

Inula  hirta  L 

Inula  oculus  christi  L 

Inula  saliclna  L 

Inula  squarrosa  L 

Inula  thapsoides  Spr 

Silphinm  laciniatum  L 

Silpliium  integrifolium  Mieh.x 

Silphium  perfoliatum  L.  hornemaiini 

Silphium  ternatum  L.  utropurpureuni .^ 

Heliopsisscabra  Dun 

Echinacea  purpurea  Monch 

Rudbeckia  fulgida  Ait 

Rudbeckia  hirta  L 

Rudbeckia  speciosa  Wenderoth 

Obeliscaria  pinnata  Cass 

■^^ailiopsis  bicolor  Rcichb.  (sown  June  13) 

Coreopsis  lanccoluta  L 

Helianthus  annuus  I 

Ilelianthusgiganteus  L (304) 

Helianthus  gros.se-serraHis  Mert 

Helianthus  nmltiflorus  L 

Helianthus  orygalis  D.  C.- 

Helianthus  tuberosus  L 

Helianthus  tracheliformis  Willd  

Bidens  tripartita  L 

Vcrbesina  phaetusa  Cassin 

Tagetes  patula  L.  (sown  June  13)  

(iaillardia  aristata  Pursh 


Date. 


Con- 
stant. 


July  23 
July  5 
Aug.  9 
Sept.  24 
Apr.  6 
Mar.  10 
May  15 
Aug.  13 
Oct.  18 
(270) 
(271) 
Sept.  12 
Sept.  9 
June  14 
July  9 
Aug.  21 
Aug.  4 
May  24 
Oct.  15 
Aug.  10 
June  26 
Aug.  31 
July  23 
July  2 
July  11 
June  3 
June  29 
June  22 
July  8 
July -19 
July  29 
July  10 
July  5 
May  3 
July  11 
Aug.  2 
June  25 
June  26 
July  27 
July  18 
Sept.  13 
June  22 
Aug.  16 
Aug.  13 
Oct.  2 
July  22 
Sept.  15 

(308) 
Aug.  6 
Aug.  25 
Oct.  10 
Aug.  10 
June    9 


°R6aum. 
1,481 
1,231 
1,774 
2, 375 

194 
94 

479 
1,904 
2,579 
(270) 
(271) 
2, -^8 
2,179 

902 
1,264 
1,921 
1,674 

626 
2,613 
1,760 
1,082 
2,093 
1,458 
1, 182 
1,310 

754 
1,003 
1,026 
1, 253 
1,449 
1,600 
1,313 
1,232 
1,189 
1,336 
1,653 
1,049 
1,099 
1,520 
1,468 
1,394 
1,026 
1,511 
1,783 
2,426 
1,472 
2,299 
(308) 
1,712 
2,005 
2,508 


Ripening. 


Date. 


Sept.  2 
Aug.  9 
Sept.  19 


May  2 

Apr.  17 

July  2 

Oct.  4 


July  11 
July  22 
Sept.  26 
Sept.  7 
June  22 


Oct.  18 
Aug.  13 
Oct.  6 
Aug.  26 
Aug.  19 
Aug.  11 
Aug.  13 
July  24 
Aug.  20 
Aug.  25 
Sept.  13 
Sept.  23 
Sept.  7 
Aug.  21 
....do... 
Sept.    1 


Con- 
stant. 


°Riauvi. 
2,191 
1,745 
2,351 


Aug.    2 
Sept.  21 


July  25 
Sept.  15 


Sei)t.  19 


Sept.  26 

2,437 

July  12 

1,334 

198 

Thermal  constants  for  the  hloxsomiug  and  ripeniiu/  of  SS9  plants,  etc. — Continued. 


Flowering. 


Designation  of  plant:  order,  genus,  and  species. 


Con- 
stant. 


Ripening. 


Con- 
stant. 


XXXIII.  Compositx  [G.  .W]— Continued. 


(314) 
(315) 
(316) 
(317) 
(318) 
(319) 
(320) 
(321) 
(322) 
(323) 
(324) 
(325) 
(326) 
(327) 
(328) 
(329) 
(330) 
(331) 
(332) 
(333) 
(334) 
(335) 
(336) 
(337) 
(338) 
(339) 
(340) 
(341) 
(342) 
(343) 
(344) 
(345) 
(346) 
(347) 
(348) 
(349) 
(350) 
(351) 
(352) 
(353) 
(354) 
(355) 
(356) 
(357) 
(358) 
(359) 


(362) 
(363) 
(364) 
(305) 


Gaillardia  drummondii  D.  C 

Gaillardia  lanceolata  Mich 

Gaillardia  pulchella  Fouger 

Helenium  autumnale  L.  serratifolium 

Anthemis  nobilis  L 

Anthemis  tinctoria  L.  pallida 

Achillea  magna  Hanke 

Achillea  millefolium  L 

Achillea  nobilis  L 

Achillea  tomentosa  L 

Anacyclus  pyrethrum  D.  C 

Ptarmica  alpina  D.  C 

Ptarmica  vulgaris  D.  C 

Matricaria  chamomilla  L 

Pyrethrum  chinense  Sab 

Pyrethrum  parthenium  L 

Chrysanthemum  coronarium  L.  (sown  June  17). 

Artemisia  absinthium  L 

Artemisia  vulgaris  L.  coarctata 

Tanacetum  leucantbemum  Schultz 

Tanacetum  vulgare  L 

Doronicum  pardalianthes  L 

Cacalia  suaveolpns  L 

Senecio  aquaticus  Huds 

Senecio  coriaeeus  Ait 

Senecio  jacobsea  L 

Senecio  jacobsea  L.  campestris 

Echinops  ritro  L.  polycephala 

Echinops  sphaerocephalus  L 

Haplotaxis  albescens  D.  C 

Carlina  vulgaris  L 

Centaurea  aspera  L 

Centaurea  calocephala  D.  C.  mixta 

Centaurea  dealbata  Willd!  var.  major . .  .• 

Centaurea  Jacea  L.  lacera,  incana 

Centaurea  lagdunensis?  (tar.  of  C.  montana'?^... 

Centaurea  rupestris  L.  aculeosa 

Cnicus  benedictus  L.  (sown  May  5) 

Carthamus  tinctorius  L.  (sown  May  4) 

Onopordon  acanthium  L.  horridum 

Onopordon  virens  D.  C 

Cynara  cardunculus  L 

Cynara  scolymus  L 

Carduus  crispus  L 

Cirsium  acaule  All 

Cirisum  bulbosum  D.  C 

Cirsium  lanceolatum  Scop 

Cirsium  pannonicum  D.  C 

Cirsium  pratense  D.  C 

Lappa  major  Giirtn 

Lappa  tomentosa  Lam 

Rhaponticum  cinaroides  Les.sing 

Rhaponticum  pulchrum  Fischer  et  Meyer 


June  5 
June  4 
June  6 
Aug.  1 
June  27 
June  11 
June  12 
June  21 
June  17 
May  24 
May  20 
June  23 
...do... 
j  May  19 
Oct.  25 
June  9 
Aug.  25 
\vm.  10 
July  19 
May  21 
July  17 
May  6 
July  25 
June  5 
June  23 
July  27 
June  7 
July  22 
July  9 
July  28 
...do... 
June  27 
June  23 
May  24 
July  13 
May  2 
June  17 
July  9 
July  21 
July  7 
June  27 
July  26 
July  31 
July  10 
July  13 
June  18 
July  24 
July  7 
July  18 
July  15 
July  14 
July  8 
June  13 


July  12 
July  8 
Aug.  31 
July  28 
July  25 
Aug.  10 


1,416 

565 
1, 422 

413 
1,510 

753 
1,045 
1,518 

830 
1,467 
1,285 
1,640 
1,612 
1,086 
1,  057 

632 
1,3d1 

575 

952 

896 
1,071 
1,215 
1,088 
1,551 
1,624 
1,275 
1,321 

970 
1,522 
1,247 
1,400 
1,370 
1,364 
1,301 

909 


Aug.  12 

i;807 

July  28 

1,599 

July     4 

1,202 

Aug.  24 

2,018 

Aug.  21 

1,968 

July  19 

981 

July  17 

1,427 

Sept.  16 

'      2,377 

June  27 

1, 092 

Aug.  21 

1,988 

May  29 

693 

Aug.  30 

2,066 

Sept.  12 

1,307 

July  15 

1,379 

Aug.  22 

1,918 

July   13 

1,305 

Aug.  20 

1,963 

Aug.  23 

2,002 

Sept.    6 

2,  .86 

July  22 

1,489 

June  15 

926 

July  18 

1,414 

Aug.    7 

1, 722 

July  30 

1,590 

Sept.  14 

2,273 

Sept.  28 

2,442 

Aug.    4 

1,690 

Aug.    9 

1,761 

July     6 

1,251 

Aug.  21 

1,983 

July  22 

1,495 

Aug.  21 

1,948 

....do... 

1, 941 

July  14 

1,3-J3 

199 


Thermal  comta)ils  fur  the  hlom^omhuj  and  ripening  of  889  plants,  etc. — Continued. 


Designation  of  idant:  order,  genus,  and  species. 


(367) 
(368) 
(369) 
(370) 
(371) 
(372) 
(373) 
(374) 
(375) 
(376) 
(377) 
(378) 
(379) 
(380) 
(381) 
(382) 
(383) 
(384) 
(385) 
(386) 
(387) 


(389) 
(390) 
(391) 
(392) 
(393) 
(394) 
(395) 
(396) 
(397) 


(400) 
(401) 
(402) 
(403) 
(404) 


(405) 
(406) 
(407) 
(408) 
(409) 
(410) 
(411) 


XXXIII.— CtwnposJto  [G.  55]— Continue! 

Serratula  coronata  (L. ?) 

Serratula  tinctoria  L 

Catananche  eaerulea  L 

Ciehorium  intybus  L 

Hypoehaeris  radioiita  L 

Podospermum  jacquiniannm,  Kooli 

Tragopogon  porrifolius  L 

Tragopogon  pratensis  L 

Scorzonera  austriaca  L 

Scorzonera  hispaniea  L 

Pieridium  tingitanum  Desf.  (sown  June  IS) 

Lactuca  sativa  L 

Lactuea  virosa  L 


July  27 
...do... 
June  22 
June  24 
June  7 
May  14 
May  31 
May  22 
May  13 
May  27 
Aug.  12 
July  5 
June  27 
Chondrilla  juncea  L I  July  22 


Flowering. 
Date 


Con- 
stant. 


Tara.xacum  dens  leonis  Desf 

Hieracium  aurantiacum  L 

Hieracium  murorum  L 

Hieracium  pratense  Tausch 

Hieracium  saxatile  Jacq 

Hieracium  umbellatum  L.  pectinatum 
Hieracium  virosum  Pallas 


XXXIV.  Lobeliacea-  [G.  56] 

Lobelia  syphilitica  L 

XXXV.  Campanidacese  [G.  !>", 

Phy  teuma  spicatum  L 

Campanula  aliariaefolia  Willd 

Campanula  bononiensis  L.  ruthenica. 

Campanula  caespitosa  Scop,  alba 

Campanula  glomerata  L 


Apr.  21 

May  30 

May  19 

May  27 

July  13 

Aug.  1 

July  12 


July  23 


May  23 
June  23 
July  2 
July  4 
...do... 


Campanula  media  L i  June  11 

Campanula  pyramidalls  L i  July  23 

Campanula  rapunculus  L June    4 

Campanula  trachellum(L.) July    5 

XXXVI.  Rubiaceie  [f/.  5?]. 

Galium  mollugo  L June    2 

Galium  verum  L.brachyphyllum June  29 

Rubia  tinctorum  L June  28 

Asperula  galioides  M.  Bieb July     2 

Asperula  odorata  L May     7 

Asperula  tinctoria  L May  26 

Cephalanthus  occidentalis  R.  S July  21 

XXXVII.  Loniccrex  [G.  —:  kcc  G.  51]. 

Lonicera  caprifolium  L I  June    1 

Lonicera  grata  .\it !  June  U, 


Lonicera  iberica  M.  Bieb  . . . 
Lonicera  periclymeuum  L.. 
Lonicera  tatarica  L.  pallida 

Lonicera  xylosteum  L 

Viburnum  lantana  L 


June  5 
June  11 
May  6 
May  7 
May     3 


1,5,50 

1,515 

999 

1,065 

817 

503 


486 

657 

826 

1, 182 

1,110 

1,534 

299 

^  675 

622 

659 

1,358 

1, 732 

1,350 


589 
1,050 
1,199 
1,210 
1,201 

861 
1,543 

781 
1,222 


708 
1,149 
1,118 
1,172 
453 
651 
1, 513 


Ripening. 


Aug.  21 
Aug.  7 
July  25 
June  27 


June  16 
July  16 


June  25 
Sept.  9 
July  26 
July  18 


May     8 
June  20 


June  12 
July  30 
Aug.  23 
Aug.  11 


July   10 


July     9  1,297 

Aug.  24  2, 


July  21 


Aug.  18 
Aug.  23 


July   21 


July  28 
June  22 
June  28 
Aug.    2 


200 

Thermal  cunstantx  for  the  blossoming  and  ripening  of  889  plants,  etc. — Continued. 


Designation  of  plant:  order,  genus,  and  species. 


XXXVII.  Lonicerrif  [G. 

(412)  Viburnum  opulus  L 

(413)  Sambucus  ebulus  L 

(414)  Sambucus  nigra  L 

(415;i  Sambucus  racemosa  L  . 


itee  G.  .5i]— Continued. 


Flowering. 


May  17 
June  23 
May  22 
May     1 


XXXVIII.  Olearex  [G.  65\. 

(416)  Ligustrum  vulgare  L 

(417)  Fraxinus  excelsior  L 

(418)  Fraxinus  excelsior  L.  aurea 

(419)  Fraxinus  excelsior  L.  pendula 

(420)  Fraxinus  ornus  L 

(421)  Fraxinus  tamariscifolia  Vahl 

(422)  Syringa  josikea  Jacq i  May  21 

(423)  Syringa  persica  L May  12 

(424)  Syringa  vulgaris  L 

XXXIX.  Apocynaceie  [G.  66]. 

(425)  Vinca  herbacea  M.  et  K 

(426)  Vinca  minor  L.  variegata i  Apr.   16 

XL.  Asdeinadea-  [G.  67]. 

(427)  Periploca  graeca  L June    6 

(428)  Vincetoxicum  f  uscatum  Endl May  24 

(429)  Vincetoxicum  nigrum  Monch June    2 


June  3 
Apr.  14 
...do..-. 
Apr.  20 
May  18 
Apr.     8 


May 


Apr.   26 


Con- 
stant. 


(430)  Vincetoxicum  oflRcinale  Monch 

(431)  Asclepias  syriaca  L 

XLI.  Genlianese  [O.  69] 

(432)  Menyanthes  trifoliata  L 

XLII.  LabiatH-  [G.S-2]. 

(433)  Lavandula  spica  D.  C 

(434)  Lavandula  vera  D.  C 

(435)  Mentha  crispa  L 

(436)  Mentha  piperita  L 

(437)  Mentha  pulegium  L 

(438)  Mentha  rotundifolia  L  . 


(449)  Origanum  vulgare  L 

(450)  Thymus  serpyllum  L.  vulgaris. . . 

(451)  Thymus  vulgaris  L 

(452)  Hyssopus  ofiBcinalis  L 

(453)  Calamintha  clinopodium  Benth  . 

(454)  Calamintha  grandiflora  Monch., 

(455)  Calamintha  nepeta  K.  et  Hoffm. 


Ripening. 


°Riauvi. 

507     July   23 

1,042     Aug.  11 

579  j  Aug.     7 

350     June  22 


May   16 
June  24 


Apr.  29 


Aug.  4 
June  26 
July  14 
July  22 
July  21 
July  23 


(439)  Lycopus  europaeus  L j  July     5 

(440)  Salvia  argentea  L j  June  10 

(441)  Salvia  austriaca  L !  May  22 

(442)  Salvia  glutinosa  L '  July  27 

(443)  Salvia  officinalis  L ;  June    1 

(444)  Salvia  pitscheri  Torr 

(445)  Salvia  pratensis  L 

(446)  Salvia  .sclarea  Jacq 

(447)  Salvia  silvestris  L 


Oct.  13 
May  16 
June  18 
May  23 

(448)  Monarda  fistulo.sa  L |  July  10 

June  22 
May  22 
June  1 
July  1 
June  20 
June  6 
July    2 


746 
248 
277 
296 
537 
222 
597 
478 
424 


Sept.  9 
July  23 
May  22 
July  11 


Aug.  26 


Con- 
stant. 


1,482 
1,817 

1,004 


2,254 
1,443 


529 
1,044 


Aug.  12 
Aug.  20 
Aug.  24 


1,696 
1,093 
1,368 
1,496 
1,475 
1,488 
1, 247 

879 

606 
1. 559 

722 
2,616 

526 


1,294 

1,028 

589 

721 

1,164 

1,003 

791 

1,183 


Sept.  24 
Aug.    3 


Aug.  19 
July  13 
June  15 
Aug.  29 
July     6 


June  9 
July  27 
June  21 
Aug.  23 
Aug.  9 
June  16 


Aug.    4 


1,.S16 
1,9;,5 
1,947 


2,430 
1,650 


2,052 
1,241 


823 
1,562 
1,015 
1,960 
1,736 
1.018 


Aug.  17 


201 

Tliermal  constantK /or  the  bloxi^omiuf/  mid  rl])t'iil)i(/  of  SSf)  /ilmilx,  rtc. — Coiitimied. 


Dosignatioii  of  plant:  order,  fronus,  and  species. 


(456) 
1457) 
(458) 
(459) 
(460) 
(461) 
(462) 
(463) 
(464) 
(465) 
(46(5) 
(467) 
(468) 
(469) 
(470) 
(471) 
(472) 
(473) 
(474) 
(475) 
(476) 
(477) 
(478) 
(479) 
(480) 


(482) 
(483) 
(484) 
(48.5) 
(486) 
(487) 


(490) 
(491) 
(492) 

(493) 
(494) 
(495) 


XLII.  Labiatije  [G.  S2]— Continued. 

Melissa  officinalis  L 

Prunella  granditiora  Munch 

Prunella  vulgaris  L 

Scutellaria  alpina  L.  hipnlina  purimniscens 

Scutellaria  galericulala  L 

Nepeta  cataria  L 

Nepetji  mussini  M.  Bieb.  var.  salviaefolia  . . 

Xepeta  glechoma  Benth 

Dracoeephalum  austriacum  L 

Melittis  mclissophylluin  L 

Phy.sostegia  speciosa  Sweet 

Lamium  orvala  L 

Leonurus  eardiaca  L 

Stachys  alpina  L.  var.  intermedia 

Stachys  germanica  L.  var.  oblongilolia 

Betonica  officinali-s  L 

Sideritis  .scordioides  L 

Marrubium  vulgare  L 

Ballota  nigra.  L 

Phlomis  tuberosa  L 

Teucrium  chama'drys  L 

Tcucrium  montanum  L 

Teucrium  scordium  L 

Ajuga  genevensis  L 

Ajuga  reptans  L 

XLIII.  Globalariav  [a.  —:  «r  O.  1]. 
Globularia  vulgaris  L 

XLIV.  Asperijoliu-  [a.  —;  see  G.  7-2]. 

Cerinthe  minor  L 

Echium  vulgare  L ; 

Pulmonaria  officinalis  L 

Pulmonuria  mollis  Wollf 

Lithospermum  pairpureocaTuleum  1> 

Anchusa  officinalis  L 

Myosotis  palustris  Roth 

Symphytum  officinale  L 

XLV.  Convolvuhicea-  [G.  7.i]. 

Calystegia  sepium  R.  B 

Convolvulus  tricolor  L.  (sown  June  18) 

Pharbitis  hispida  Choix.  (sown  June  18)  ... 

XLVI.  Polemoniacciv  [G.  70]. 

Phlox  cordata  Elliot  grandiflora 

Phlox  speciosa  Pursh 

Polemonium  cteruleum  L 


XLVII.  Holamiceiv  [G.  7i 

(496)  Datura  stramonium  L 

(497)  Hyoscyamas  niger  L 

(498)  Physalis  alkek^ngi  L 

(499)  Solanum  dulcamara  L 

(500)  Solanum  nigrum  L.  (sown  Apr.  26). 

(501)  Atropa  belladoniiM  I 


Flowering. 


July 
June 
June 
May 
July 
June 
Apr. 
Apr. 
May 
May 
July 
May 
June 
June 
June 
June 
June 
June 
July 
June 
June 
June 
July 
May 
May 


May 


Apr. 
June 
Apr. 
Apr. 
May 
May 
May 
May 

June 
Aug. 
J\ine 

July 
Aug. 
Mav 


Con- 
stant. 


June  18 
May  16 
M^y  30 
July  17 
July  4 
Mav   27 


1, 267 
933 

1,017 
605 

1,166 

1,058 
379 
224 
613 
575 

1,321 
400  [ 
839  1 

1,052 


Ripcuing. 


Aug.  6 
July  18 
July  17 
June  22 


May  31 
June  21 


Con- 
stant. 


°Riaum. 

1,720 
1,142 


1,149 

770 

787 
1,185 

722 
1,036 
1,045 
1,273 

483 


Aug.  8 
June  2 
July  19 
July  27 
July  23 
Aug.  7 
July  9 
July  17 
Aug.  10 
July  12 
Aug.  10 
Aug.    5 


863 

1,063 

8.55 


636     June  28 


*i26 

533 

719 

1,437 

«<;7 

661 


1,443 
1,582 
1,529 
1,805 
1,285 
1,417 
1,766 
1,311 
1,796 
1,742 


1,253 


May  29 


July  17  '         1,382 
June  27  1,0.56 


June  27  1,093 

July  20  1,462 


Aug.     4 

1,332 

July   31 

1,638 

Aug.  11 

1,755 

Oct.      1 

2,474 

Aug.  31 

1,744 

Julv   19 

1,4.58 

202 

Tliermal  coiiMdutii  fur  the  blossoming  and  ripening  of  SS9  plants,  etc. — Continued. 


Designation  tif  plant:  order,  Kenns,  and  species. 


Flowering. 


Con- 
stant. 


Ripening. 


XLVIII.  Scroplndannx  [G.  75]. 

(502)  Verbascum  gnaphaloides  M.  Bieb July  26 

(.i03)  Verbascum  lychnitis  L.  fil.  rub.  lanatum  flocosuni June    8 

(504)  Verbascum  nigrum  L.  lasianthum May  25 

(505)  Verbascum  phlomoides  L June  19 

(506)  Verbascum  phcEnlceiun  L May   16 

(507)  Verbascum  speciosum  L.  genuinum June  20 

(508)  Verbascum  thapsus  L June  26 

(509)  Serophularia  nodosa  L May   28 

(.510)  Linaria  genistifolia  Mill July     1 

(511)»Llnaria  vulgaris  Mill July     8 

(512)  Antirrhinum  ma  jus  L June    6 

I  .ilo)  Pentstemon  barbatus  Benth.  robustum July     4 

(514 )  Pentstemon  digitalis  Xutt June  11 

(515)  Pentstemon  pubescens  Poland May  30 

(516)  Digitalis  lutea  L June    9 

(517)  Digitalis  purpurea  L June    6 

(518)  Paulownia  imperialis  Siebold (518 ) 

(519)  Dodartia  orientalis  L June    6 

(520)  Gratiola  officinalis  L lune    4 

(521)  Veronica  austriaca  L.  var.  pinnatifida May  17 

(.522)  Veronica  latifolia  L.  var.  major 

(523)  Veronica  officinalis  L 

(524)  Veronica  spicata  L.  var.  crlstata 

XLIX.  Acaiitharea'  [G.  SO]. 

(525;  Acanthus  spinosus  L 

L.  Bignoniacex  {G.  ~8]. 

(526)  Catalpa  syringaifolia  Sims 

(527)  Tecoma  grandiflora  Sweet 

(528)  Tecoma  radicans  Juss  var.  flammea 

LI.  Primulacex  [G.  61]. 

(529)  Primula  auricula  L 

(530)  Cyclamen  europseum  L 

(531)  Dodecatheon  meadia  L 

(532)  Lysimachia  nummularia  L 

(533)  Lysimachia  punctata  L 

LII.  Ebenacew  G.  [6S] . 

(.534)  Diospyros  lotus  L.  cf 

LIII.  Enmcex  {G.58]. 

(.535)  Erica  carnea  L 

LIV.    UmbcllifirH'  [G.  4,s1 . 

(536)  Eryngium  amethystinum  W.  and  K 

(537)  Eryngium  maritimum 

(538)  Eryngium  planum  L 

(539)  Cicuta  viro.sa  L. . « 

(540)  Apium  graveolens  L 

(.541)  Petroselinum  sativum  Hoffm , 

(542)  Carum  carui  L 

(543)  Sium  sisarum  L 

(544)  Bupleurum  ranunculoides  L.  v.  elatium 


June 

"^i 

May 

16 

July 

5 

June 

19 

July 

3 

July 

28 

Aug. 

8 

Mar. 

15 

July 

18 

May 

13 

June  21 

June 

16 

June 

16 

Mar. 

10 

July 

14 

July 

15 

July 

3 

June 

25 

June  11 

June  20 

Apr. 

25 

July 

20 

June 

4 

°Reaum. 
825 


.^1U 

1,074 

1,086 

652 

1, 188 

1,220  ^ 

816  i 

1,227 

865 

690 

845 

ITl 

(.518) 

797 

758 

504 

761 

.523 

1,226 


July  25 
Aug.  12 
Jnlv   13 


Aug.  13 
July  12 
Aug.  6 
Aug.    8 


1,193 
1,602 
1,746 


113 
1,437 

453 
1,021 

926 


1,380 
1,388 
1,189 
1,025 
885 
989 

1,436 
751 


Sept.  8 
Sept.  5 
Aug.  3 
Aug.  1 
July  20 


Aug.  8 
July  12 
Aug.  2 
June  26 


Aug.  29 
Aug.  28 
Aug.     5 


Aug.  16 
Aug.  11 
June  12 


July  21 


208 


Thermal  comtantsfor  tlie  blossoming  and.  ripcnin;/  of  ,^89  plnnlx,  rlr. — Continued. 


Flowering. 


Designation  of  plant 


(Ut,  fienus.  ami  ]ilii 


LIV.   UmbcUifcnr  [O.  iw]— Continued. 
CEnanthe  phellandrium  I.nni 


(545) 
(51G) 
(547) 
(548) 
(549) 
(550) 
(551) 
(552) 
(553) 
(554) 
(555) 
(556) 
(557) 
(.558) 
(559) 


(560) 
(561) 


(562) 
(563) 
(564) 


(565) 
(566) 
(567) 
(568) 
(569) 
(570) 


(571) 
(572) 
(573) 

(574) 
(575) 
(576) 
(577) 
(578) 
(579) 

(580) 
(581) 

(582) 


lune 

.l<:thTisa  oynapium  L .luly 

Famiculum  vulgare  Giirtn .Tune 

Sescli  campestre  Bessei" Tune 

Libanotis  vulgaris  D.  C Tunc 

Levisticum  officinale  Koeli .Tune 

Archangelica  officinalis  HofTm June 

Peucedunum  cervarium  Cass .)uly 

Peucedanum  imperatorium  Endl j  May 

Peucedanum  officinale  L I  July 

Pastinaca  sativa  L '. [  July 

Daucu.s  carota  L June 

Anthryscus  cerefoliuni  Hoffm |  June 

Anthryscus  silvestris  Hoffm.  vnr.  pilosula [  May 

Conium  maculatum  L [  June 

LV.  Ainpf'lidea'  [G.  —;  see  G.  -28]. 

Cissu.s  hederacea  Pers 

Vitis  vinifera  L.  var.  alexandrina 

LVI.  Corneie  [G.50]. 

Comus  alba  L 

Comas  mas  L 

Cornus  sanguinea  L T 

LVII.  Crafniildceic  [G.  .%']. 


June  : 
June 


Sedum  acre  L 

Sedum  album  L 

Sedum  latifolium  Bertol 

Sedum  reflexum  L.  var.  recurvatum  , 

Sedum  sexangulare  L 

Sedum  Sieboldii  Hort 


May 
Mar. 
June 


May 
June 
Aug. 
June 
June 
Oct. 


LVIII.  Saxifragacex  [G.  .* 
Saxifraga  crassifolia  L.  var.  obovata. 

Saxifraga  cordifolia  Haw 

Heuchera  americana  L 

LIX.  Ribegiacf.r  [G 

Ribes  alpinum  L 

Ribes  aureum  Pursli.  var.  .si 

Ribes  gro.s.sulari!i  L 

Ribes  nigrum  L 

Ribes  rubrum  L 

Robsonia  specicsu 


see  G.  5.5] . 


uiguineum. 


LX.  Magiioliaee: 

Magnolia  acuminata  L 

Liriodendron  tulipifera  L. . . 

LXI.  Dilleniacea-  [G. 

Actaa  .spicata.  L 


[G.2]. 


Apr.  19 
Apr.  13 
May  26 


Apr.  17 
...do... 
Apr.   10 

(577) 
Apr.   18 
May   15 


Con- 
stant. 


°Reaum. 

984 
1,173 
T.ni 

910 
1.113 

858 

769 
1,417 

1,176 

1,272 

973 

410 

407 

1,010 


1,057 
805 


ee  G.  1]. 


(580) 
(.581) 


May     7  1 


682 
1,072 
1,726 
1,005 

871 
2,  .'■)88 


290 
256 
657 

237 
261 
226 
(.577) 
2(i9 


(.580) 
(.581) 


Ripening. 


Con- 
stant. 


Aug.  21 
July  17 
Aug.  15 
Aug.  25 
June  30 
Aug.  13 
Aug.  9 
Aug.     2 


June  J6 
Aug.    2 


Aug.  27 
Sept.    5 


July  4 
Aug.  19 
Aug.  16 


Aug.  3 
Sept.  12 
Aug.  2 
July   26 


July  14  l,34.n 


June  29 

l.lO.s 



June    8 

868 

- 

204 


Thermal  rondmits  far  flu-  Jdoxxomlng  nnd  ripening  of  SS9  planti^,  c/o.— Continued. 

Ripening. 


Designation  of  plants:  order,  genus,  and  species. 


Flowering. 


Con- 
stant. 


Date. 


Con- 
stant. 


LXII.  Eanunculaceee  [G.  1]. 
(riS'6)  Clematis  augustifolia  Jacq.  lasiantha 

(584)  Clematis  ereeta  Allion.    Clematis  recta  L 

(585)  Clematis  flammula  L.  var.  vulgaris 

(586)  Clematis  integrifolia  L.  var.  elongata 

(587)  Clematis  ofientalis  L 

(588)  Clematis  sibirica  L..  Atragene  sibirica 

(.589)  Clematis  virginiana  L [ 

(.590)  Clematis  vitalba  L.  var.  bannatipa  I 

(591)  Atragene  alpina  L , 

(592)  Thalietrum  aquilegifolium  L 1 

(593)  Thalietrum  flavum  L 

(594)  Thalietrum  minus  L 

(595)  Anemone  japonica  S.  et  Zucc 

(596)  Anemone  nemorosa  L | 

(597)  Anemone  pratensis  L 

(598)  Anemone  Pulsatilla  L 

(599)  Anemone  ranunculoides  L. . . ; j 

(600)  Anemone  silvestris  L.  var.  minor I 

(601)  Anemone  virginiana  L.  var.  angustifolia 

(602)  Hepatica  angulosa  Lam 

(603)  Hepatica  triloba  Chaix 

(604)  Adonis  vernalis  L 

(605)  Ranunculus  aeris  L.  var.  .silvatieus 

(606)  Ranunculus  nemorosus  D.  C 

(607)  Ficaria  ranunculoides  Roth,  variegata 

(608)  Caltha  palustris  L | 

(609)  Eranthis  hiemalis  Salisb j 

(610)  Helleborus  niger  L 

(611)  Helleborus  odorus  W.  Kit I 

(612)  Helleborus  purpurascens  W.  Kit 

(613)  Helleborus  viridis  L 

(614)  Aquilegia  atrata  Koch 

(615)  Aquilegia  atropurpurea  Willd 

(616)  Aquilegia  glandulo.sa  Monch 

(617)  Aquilegia  vulgaris  L.  var.  rosea 

(618)  Delphinium  consolida  L 

(619)  Delphinium  grandiflorum  L 

(620)  Delphinium  intermedium  .\it.  var.  alpinuni 

(621)  Delphinium  triste  Fisch 

(622)  Aconitum  cammaruni  L 

(623)  Aconitum  japonicum  L 

(624)  Aconitum  lyeoctonum  L.  var.  puberulum 

(625)  Aconitum  napellus  L 

(626)  Botrophis  aeteeoides 

(627)  Pseonia  albiflora  Pallas,  var.  rosea 

(628)  Pseonia  moutan  L.  var.  papaveracea 

(629)  Pfeonia  officinalis  Retz.  var.  puberula   

(630 )  Pa'onia  tenuifolia  L 

LXIII.  Berber iden'  [O.  5]. 


(631)  Leontiee  vesicaria  Pall 

(632)  Epimedium  alpinum  L 

(633)  Berberis  aquifolium  Pursh.  v.  repens 

(634)  Berberis  provincialis  Audib.  Schrad.  Lodd. 


June  3 
June  4 
July  21 
May  31 
Aug.  24 
Apr.  22 
Aug.  12 
Aug.  2 
May  4 
May  22 
July  3 
May  23 
Aug.  19 
Apr.  10 
Apr.  6 
Mar.  29 
Apr.  17 
May  6 
June  7 
Mar.  6 
Mar.  10 
Apr.  16 
May  14 
May  -20 
Apr.  4 
Apr.  28 
Feb.  27 
Oct.  19 
Mar.  24 
Mar.  28 
Apr.  10 
May  5 
Apr.  16 
May  20 
May  18 
May  26 
June  28 
June  7 
June  1 
July  19 
Sept.  17 
June  18 
June  25 
July  1 
May  28 
May  16 
May  18 
May     7 


Apr.  19 

Apr.  26 

Apr.  22 

May  11 


"Reaum. 

745 

765 
1,476 

701 
1,988 

313 
1,857 
1,671 


1, 142 
616 

1,869 
224 
200 
1.51 
275 
413 
791 
78 
118 
260 
499 
549 
191 
349 
79 

2,677 
136 
142 
197 
341 
282 
562 
.511 
663 

1,135 
811 
723 

1,444 

2, 292 
952 

1 ,  069 

1,141 
672 
514 
548 
442 


July  18 


July   14 
July  30 


July  13 
Sept.    7 


May  23 


June  14 
Aug.  13 


May  24 


June  17 
June  27 


July     4 
May  16 


June  17 
June  18 
May  29 
June  28 
....do.. 
July  26 
Aug.    8  j 
July  12  I 
July    1  I 
Aug.  23  j 


Aug.    5 
July   30 


205 


Thermal  constants  for  the  blossoming  and  ripening  of  889  plants,  etc. — Continued. 


Pcsignatioii  oi  plant:  order,  genus*,  and  species. 


Flowering. 


(636) 
(637) 
(638) 
(639) 
(640) 

(641) 
(642) 
(«3) 
(6«) 
(645) 
(616) 
(647) 
(648) 
(649) 
(650) 
(651) 
(652) 
(653) 


(6.54) 
(655) 

(656) 
(657) 

(658) 
(659) 

(660) 
(661) 
(662) 
(663) 
(664) 
(665) 

(666) 
(667) 
(668) 
(669) 
(670) 
(671) 
(672) 
(673) 
(674) 
(675) 
(676) 
(677) 
(678) 
(679) 


LXIV.  Papavcracea-  [G.  S]. 

Chelidonium  maju.s  L 

Papaver  orientalc  L 

Papaver  rhoeas  L  (from  self-sown  seed) 

Papaver somniierum  L  (from  self-sown  seed) 

Glaucium  luteiim  Scop 

Fumaria  officinalis  L 


LXV.  Cnirifrnr  [G.  W]. 

Barbarea  vulgaris  R.  Br 

Arabis  alpina  L 

Berteroa  incana  D.  C 

Alyssum  saxatile  L 

Armoracia  rusticana  L 

Cochlearia  officinalis  L 

Iberis  sempervirens  L 

HesperLs  matronalis  L 

Sisymbrium  austriacum  Jacq 

Erisymimi  crepidifolium  Reichb 

Isatis  tinctoria  L 

Brassica  melanosinapis  Koch  (sown  May  2) . 
Raphanus  sativus  L.  (sown  Apr.  28) 

LXVI.  Resedaccie  [G.  12]. 

Reseda  lutea  L 

Reseda  luteola  L 


[G.6]. 


LXVII.  Nymphxai 

Nymphtea  alba  L 

Nj-mphaea  lutea  Sm 

LXVIII.  Cistacex.  \_G.  IS]. 
Helianthemum  oelandicum  Wahlenb 
Helianlhemum  vulgare  Giirtn 

LXIX.   Violaricx  [(;.  11^] . 

Viola  arenaria  D.  C 

Viola  hirta  L.  ambigua 

Viola  montana  L 

Viola  odorata  L 

Viola  praten.sis  M.  et  K 

Viola  tricolor  L 


LXX.  Car ijophy liar  [G.  15] . 

Cerastium  arvense  L 

Dianthus  carthusianorum  L.  medius. 

Dianthus  deltoides  L 

Dianthus  plumariua  L.  var.  virens 

Gj'psophila  altis.sima  L 

GM)sophila  fastigata  L.  elatior 

Saponaria  officinalis  L.  plena 

Silene  Inflata  Smith 

Silene  nutans  L.  albiflora  

Silene  pseudotites  Bess 

Silene  saxifraga  L 

Lychnis  coronaria  Lam 

Lychnis  flos  Jovis  Lam 

LychnLs  viscaria  L.  plena , 


May  5 
May  25 
May  19 
June  17 
June  1 
Apr.   24 


Apr.  28 
Apr.  8 
June  13 
Apr.  19 
May  15 
Apr.  5 
Apr.  23 
May  20 
May  6 
May  4 
May  6 
May  31 
June  12 

May  20 
May     9 

May  25 
May  26 

May  20 
May  23 

Apr.  14 

Apr.  6 

Apr.  9 

Mar.  30 

Apr.  26 

Apr.  9 

May  7 
June  4 
May  28 
May  22 
May  28 
June  13 
July  16 
June  4 
May  17 
May  31 
June  1 
June  27 
June  13 
May  18 


Con- 
stant. 


Ripening. 


June  5 
June  28 
June  16 
July  10 
July  21 
June    8 


Con- 
stant. 


^Rtaum. 

785 

1,149 


342  June  30  , 
196  June  3  j 
895  j  July  21  j 
283     June    8  I 


512 

June  27 

1,103 

214 

May  31 

703 

317 

June  25 

1,074 

544 

July     6 

1,261 

396 

June  22 

1,012 

377 

July    4 

1,231 

416 

June  14 

893 

•^5 

703 

Aug.    5 

1,376 

6''7 

437 

July  17 

957 

649 

646 

July  28 

2,046 

576 

June  22 

1,002 

595 

...:do... 

1,025 

244! 

174    

182  I 

157  I  June  2 
325  I  J'une  15 
234     June  12 


419 

June    9 

824 

769 

July  14 

1.346 

657 

June  25 

1,064 

592 

June  26 

1,070 

689 

June  30 

1,139 

890 
1.399 

July  20 

1,454 

759 

June  29 

1,141 

526 

June  12 

873 

716 

July     7 

1,276 

733 

June  25 

1,036 

1,165 

882 

1 

546 

June  16 

890 

2U6 


Thermal  couHfantsfor  the  blossoining  and  ripening  of  889  plants,  etc. — Continued. 


Flowering. 


Designation  of  plant:  order,  genus,  and  species. 


Con- 
stant. 


Ripening. 


Con- 
stant. 


(680) 


(681) 
(682) 
(683) 
(684) 
(685) 
(686) 
I  087) 
(688) 


(691) 
(692) 


(695) 
(696) 

(698) 
(699) 
(700) 
(701) 
(702) 
(703) 
(704) 
(705) 


(706) 
(707) 
(708) 
(709) 
(710) 


(712) 
(713) 
(714) 


LXXI.  Phytolaccacem  {G.  8S\. 

Phytolacca  decandra  L 

LXXII.  Malvacea-  [G.  20]. 

Lavatera  thuringiaca  L > 

Althaea  cannabina  L 

Althaea  ticifolia  Cav 

Altheea  officinalis  L 

Althaea  rosea  Cav 

Malva  rotuudifolia  L 

Malva  sil vestris  L 

Hibiscus  moscheutos  L 

Hibiscus  syriacus  L 

LXXIII.  Tiliaceie  [G.  21]. 

Tilia  argent ea  L.  fructu  depressji 

Tilia  grandifolia  Ehrh.  latebracteata  Host .. . 
Tilia  parvifolia  Ehrh.  ovatifolia,  variegata... 
LXXIV.  Hypericinew  [G.  — ] . 

Hypericum  perforatum  L 

LXXV.  Humiriacex  [G.  — ]• 

Tamarix  gallica  L.  var.  libanotica 

LXXVI.  Acerineu-  [G.  —:  see  G.  •ZO]. 

Acer  campestre  var.  tauricum 

Acer  eriocarpum  Miehx  ^ 

Acer  monspessulanum  L 

Acer  obtusatum  Kitaib.  var.  neapolitanum  . . 

Acer  platanoides  L 

Acer  pseudoplatanus  L.  variegatum 

Acer  sanguineum  Spach 

Acer  saccharinum  L 

Acer  striatum  L 

Acer  tataricum  L 

Negundo  fraxinifolium  Nuit  cf 

LXXVII.  Sapindacex  [G.  29]. 

Kolreuteria  paniculata  L 

..Esculus  flava  Ait 

^Esculus  hippocastanum  L 

iEsculus  macrostachys  Michx 

jEscuIus  pavia  L 

LXXVIII.  Staphylacex  [G.  —;  see  G.  29]. 

Staphylea  pinnata  L 

LXXIX.  Celastrinex  [G.  26] . 

Euonymus  europaeus  L 

Euonymus  latifolius  L 

Celastrus  scandens  L 


'  °Reaum. 
July  12  '        1,325 


,  July  4 
.!  July  27 
.  July  5 
.'  ,ruly  14 
.:  July  4 
.1  May  27 
.  June  5 
.  Aug.  23 
.,  Aug.  11 

.1  July  4 
.  June  11 
.    June  21 


Apr.  30 
Mar.  21 
Apr.  2 
Apr.  10 
Apr.  14 
May  1 
Apr.     2 

(702) 
May     1 
May   12 
Apr.  11 


June  24 
May  11 
May  5 
July  10 
May     9 

May     7 

May  23 
May  11 
May  24 


1,222 
1,535 
1,229 
1,365 
1,187 
612 
801 
1,943 
1,803 


°Rcaui 
Sept.  11  i         2,i 


Aug.  2 
Aug.  23 
Aug.  2 
Aug.  12 
July  31 
July  19 
July     7 


1,225 

Sept.    9 

2,138 

871 

July  29 

1,607 

1,021 

July  21 

1,609 

942 

Aug.  23 

1,988 

740 

365 

Sept.    7 

2,200 

125 

292 

Sept.    3 

2,095 

232 

Aug.  20 

1,856 

246 

Sept.  20 

2,469 

373 

Sept.    9 

2,192 

176 

(702) 

478 

Aug.  13 

1,827 

228 

1,061 

Aug.  27 

2,062 

460 

409 

Sept.  13 

2,267 

1,300 

Sept.  11 

2.219 

448 

428 

601 

466 

Aug.  15 

1,864 

634 

Aug.  11 

1,791 

207 


Thermal  constants  for  the  blossoming  and  ripening  of  889  plants,  etc. — Continued. 


Designation  of  plant:  order,  genus,  and  species. 


(715) 
(716) 
(717) 
(718) 


(71&) 
(720) 
(721) 
(722) 
(723) 
(724) 


(725) 
(726) 
(727) 
(728) 

(729) 
(730) 


(731) 
(732) 


(733) 


(735) 


(736) 
(737) 
(738) 


(739) 
(740) 

(741) 


(742) 
(743) 


(744) 


LXXX.  Ithamne«[0.27]. 

Paliurus  aculeatus  Lam 

Rhamnns  cathartica  L 

Rhamnus  frangula  L 

Ceanotus  amerieanus  L 


LXXXI.  Euphorbixeir  [a.us]. 

Euphorbia  cyparissias  L , 

Euphorbia  esula  L 

Euphorbia  lathyris  L , 

Euphorbia  pilosa  L.  var.  luberculata 

Mercurialis  perennis  L 

Buxus  sempervirens  L 

LXXXII.  Jufjlandcx[O.101]. 

Juglans  cinerea  L 

Juglans  nigra  L 

Juglans  regia  L.  var.  maxima 

Juglans  regia  L.  var.  serotina ; 

LXXXIII.  Anacanliace.r  [0.30], 

Rhus  cotinus  L 

Rhus  typhina  L 

LXXXIV.  Zanthoxykie  [G.  —;  see  G.  -2 

Ptelea  trifoliata  L 

Ailanthus  gland ulosa  Desf 

LXXXV.  Diosmex  [G.—\. 

Dictamnus  fraxinella'Pers 

LXXXVI.  Rjitacex  [G.  24]. 

Rnta  graveolens  L 

LXXXVII.  Zyf/ophi/llea-  [G.  — ] . 

Zygophyllum  fabago  L 

LXXXVIII.  Gaaniaccie  [G.  23]. 

Geranium  praten.se  L 

Geranium  pyrenaieum 

Geranium  sanguineum  L 

LXXXIX.  Lineu-  [G.22]. 

Linum  austriacum  L 

Linum  glandulosum  Monch.  var.  flavum  . 
Linum  usitatissimum  L.  (sown  Apr.  29)  . . . 
XC.  Ozalidae  [G.  —;  see  G.  23] . 

Oxalis  acetosella  L 

Oxalis  strlcta  L 


Flowering. 


June    7 

(716) 
May  20 
June  30 


Apr.   10 
May     5 


XCL  Phiki'Mpliea'  [G.- 
Philadelphus  coronarius  L 


see  G.  35] . 


May  2 
Apr.  26 
Apr.   16 

May  5 
May  15 
May  13 
June  10 


May  22 
June  12 


June    9 
June  17 


May  26 


July     4 


June  8 
May  25 
May  19 


May  5 
June  8 
June  22 


Apr.     8 
May  25 


May  31 


Con- 
stant. 


^Riaum. 

882 

(716) 

558 

1,195 


Ripening. 


July     7 


226  '  June    4 

430  \ 

July  27 
June  16 


Sept.  12 


Con- 
stant. 


Aug.  21 
Sept.  12 


July   19  1,448 


Aug.  21  1,954 


June  2« 
July  2.S 
July  24 


208 


Thermal  constant.^  for  Uic  blossoming  and  ripeninfj  of  889  plants,  etc. — Continued. 


Designation  of  plant:  order,  genus,  and  species. 


Flowering. 


Con- 
stant. 


Ripening. 


(745) 
(746) 
(747) 
(748) 


(749) 
(760) 


(751) 
(752) 
(753) 
(754) 
(755) 
(756) 
(7571 
(758) 
(759) 
(760) 
(761) 
(762) 
(763) 
(764) 
(765) 
(766) 
(767) 
(768) 
(769) 
(770) 
(771) 

(772) 
(773) 
(774) 
(775) 
(776) 
(777) 
(778) 
(779) 
(780) 
(781) 
(782) 
(783) 
(784) 
(78.5) 
(786) 
(787) 
(788) 
(789) 
(790) 


XCII.  (Enotherex  [6.  —;  see  G.  1,2]. 

CEnothera  biennis  L 

(Enothera  pumila  L 

Epilobium  angustifolium  L 

Epilobium  hirsutiim  L 

XCIII.  Lythmviae  [G.  W]. 

Ly thrum  salicaria  L . 

Ly  thrum  virgatum  L 

XCIV.  Pomacex  [G.  —;  see  G.  S3]. 

Cydonia  chinensis  Thuin 

Cydonia  japonica  Pers 

Cydonia  vulgaris  Pers , 

Pyrus  americana  Spr 

Pyrus  aria  Ehrh.  var.  oblonga 

Pyrus  baccata  L 

Pyrus  chamEemespilus  Lindl  

Pyrus  communis  L.  var.  .sanguinea - 

Pyrus  lanuginosa  D.  C 

Pyrus  nivalis  L 

Pyrus  mains  L.  var.  acerba 

Pyrus  prunifolia  Willd.  xanthoearpa  minor 

Pyrus  sorbus  Gart.  var.  pyriformis 

Pyrus  torminalis  Ehrh 

Mespilus  germanica  L 

Amelanchier  canadensis  F.  and  A.  Gr.  subcordata 

Cotoneaster  vulgaris  Lindl 

Crateegus  monogyna  Jacq 

Crataegus  oxyacantha  L.  splendens,  rosea,  plena  . 

Crataegus  sanguinea  Pallas ■ 

Crateegus  virginica  Michx  

XCV.  Eo.'^arcs-  [G. —]. 

Rosa  alba  L 

Rosa  alpina  L.  (R.  t-anina  L.  var.  plena) 

Rosa  canina  L 

Rosa  centifolia  L T 

Rosa  dama.scena  L 

Rosa  eglanteria  L 

Rosa  gallica  L 

Rubus  fruticosus  L.  plenus  roseus 

Rubus  idaeus  L 

Rubus  odoratus  L 

Fragaria  collina  Ehrh 

Fragaria  vesca  L 

Potcntilla  alba  L ' 

Potentilla  an.serina  L 

Potentilla  argentea  L.  impolita 

Potentilla  argentea  L 

Potentilla  atrosanguinea  Don 

Potentilla  aurea  L 

Potentilla  chrysantha  Trevir.  minor 


June  15 
June  12 
June  29 
July     5 


June  19 
July  16 


May  13 
Apr.  14 
May  13 
May  19 
May  11 

(756) 
May  7 
Apr.  28 
May  5 
May  2 
May  20 
Apr.  26 
May  13 
....do.. 
May  20 
Apr.  18 
Apr.  22 
May  11 
May  15 
May  in  I 
May  16 


°Iieaiim. 

918 

858 

1,113 

1,217 


June  9 
May  19 
June    3 

(775) 
June  10 
May  26 
June  15 
June  27 
May  20 
June  17 
May  4 
Apr.  27 
Apr.  8 
May  12 
May  19 
May  5 
June  15 
Apr.  29 
Apr.  30 


492 
268 
481 
571 
463 
(756) 
420 
336 
410 
395 
535 
343 
491 

579 
335 
312 
464 
512 
475 
.532 

855 
547 
753 
(775) 
877 
648 
874 
1,103 
562 
909 
410 
345 
218 
4.53 


°Maun 
Aug.     2  1,€ 

July  10  '         1,2 


Aug.    8 


Sept.  13  2, 269 

Sept.  17  I  1,443 

Aug.  25  I  1,934 


July  16 

1,360 

July     6 

1,248 



July  27 

1,538 

Aug.    7 
Sept.  26 

1,758 
2,418 

June  26 
Aug.  12 
Aug.  19 
July  27 
Aug.  12 


July  24 
Aug.  20 

1,500 
1,947 

July  22 

1,499 

June  26 

1,080 

June    6 
....do... 

790 

787 

20U 


Theniial  conxldiitsjar  thr  lilnxxunihig  and  ripcn'nxj  of  SS9 phnd^,  etc. — Continued. 


Flowering. 


Designation  of  plant:  oriler,  genus,  and  species. 


X('^'.   Ho.iaa 


(791) 
(792) 
(793) 
(79J) 
(795) 
(7%) 
(797) 
(798) 
(799, 
(800) 
(801) 
(S02) 
(803) 
(804) 
(805) 
(«0(i) 
(807) 
(808) 
(809) 
(SIO) 
(811) 
(812) 
(813) 
(814) 
(815) 
(816) 
(817) 

(818) 
(819) 
(820) 
(821) 
(822) 
(823) 
(824) 
(825) 
(82fi) 
(827) 
( 828) 
(829) 
(S30) 
(831) 
(832) 


I'otentilla  frulieosa  L I  May   15 

Potentilla  hirta  L May  25 

Potentilla  pennsylvaniea  L '  .Tune  18 

Potentilla  puleherrima  Lelnn.  minuta Tune    2 

Potentilla  reptans  L : do . . . 

Potentilla  rupestris  L May     9 

Agrimonia  eupatorinm  L.  eafTia lune  22 

Agrimonia  odorata  Mill Tuly  27 

Alchemilla  montana  Willd May     A 

Sanguisorba  offieinalifi  L.  aurienlata (800) 

Poterium  sanguisorba  L J[a y  27 

Waldsteinia  geoides  Willd Ai>r.     7 

Geum  eoccinenm  Sib May  29 

Geum  rivale  L May     9 

Geum  silvaticum  Desrouss May   15 

Geum  urbanum  L May   19 

Coluria  geoides  R.  Br Apr.   17 

Kerria  japonica  D.  C !  May  15 

Spiraea  acuminata  L June    5 

Spira?a  chamaedryfolia  L.  var.  oblongifolia May      1 

Spira-a  filipendula  L June    4 

Spiraea  hypericifolia  D.  C May     9 

Spiraea  hypericifolia  D.  C.  var.  Phikenetii Apr.  20 

Spiraea  opulifolia  L ^lay  26 

Spiraea  sorbifolia  L June  16 

Spiraea  ulmaria  L.  var.  variegata June  21 

Spira?a  ulmifolia  Scop May   17 

XCVI.  Amygdalew  [a.  — ] . 

Amygdalus  communis  L.  variegata i  Apr.   13 

Amygdalus  divaricata Apr.     2 

Amygdalus  nana  L Apr.   20 

Amygdalus  persica  L.  i)lena  rosea Apr.   24 

Prunus  acida  Ehrh Apr.   23 

Prunus  americana Apr.  19 

Prunus  avium  L do  . . . 

Pnnni.s  cerasifera  Ehrh do  . . . 

Prunus  domestica  L.  var.  Claudiana  seniipleiia May      1 

Prunus  mahalob  L Apr.  29 

Prunus  padus  L Apr.  28 

Pruinis  .sibirica  L Apr.     8 

Prunus  .serotina  Ehrh i  May  24 

Prunus  spinosa  L Apr.  24 

Prunus  virginiana  L May     4 

XCV'II.  Papiiionaeav  [(1. — ; 
Lupinus  polyphyllus  Dougl 


/i'J. 


(834)  Ononis  natrix  L. 


(834) 


(835)  Ononis  spinosa  L I  line 

(836)  Ulex  enropaeus  L May 

26H7— 05  -M 14 


Con- 
stant. 


Ripeniug. 


Con- 
stant. 


1 ,  025 

Aug.  18 

1,923 

1 .  407 

Sept.  20 

2, 414 

40" 

663 

June  26 

1,075 

216 





June  20 
June  18 
July  6 
May   28 


July  13 


June  28 
June  23 
July  11 
Aug.  10 
July  22 


(uly 


9(55   P'^  '\ 

[Aug.  9 

.069      Aug.  5 

.540     Julv  6 


971 

1,243 

690 


410    

787    

389  .Tune  20  ,              983 

762  July   14             1,325 

425  June  13                927 

288  \ 

641  July     9            1,295 

930  Aug.     8            1,741 

1,022  ....do...           1.734 

510  July   18               970 


Sept.    8 


1,123 
1,054 
1,330 
1,763 
1,178 
1,147 


1,167 
l,!i25 
1.810 
1.710 
1,216 


210 


Thermal  nmxta)il.'<  for  the  lih, 


iiKj  and  riprnuuj  of  S'S9  />laiils,  etc. — Continued. 


Designation  of  plant:  order,  genus,  and  specie 


Flowering. 


XCVII.  Papilionaceie  [G.  —;  see  0.  32]  —Continued.  | 

(837)  Spartium  juneeum  L I  June 


(838)  Genista  tinctoria  L.  virgata 

(839)  Cytisus  alpinus  Mill,  macrostachj 

(840)  Cytisus  biflorens  Host 

(841)  Cytisu.s  elongatus  M.  and  K 

(842)  Cytisus  laburnum  L 

(843)  Cytisus  nigricans  L 

(844)  Anthyllis  montana  L 

(845)  Medicago  .sativa  L 

(84G)  Melilotus  officinalis  L 

(847)  Trifolium  alpestre  L 

(848)  Trifolium  montanum  L 

(849)  Trifolium  pratense  L 

(850)  Trifolium  repens  L 

(851)  Dorycnium  herbaceum  Willd 


July 
May 
May 
Apr. 
May 
June 
May 
June 
June 
June 
May 
May 
June 
June 

Tetragonolobus  siliquosus  Roth I  May 

June 
June 
June 
June 


(853)  Amorpha  fruiticosa  L 

(854)  Psoralea  acaulis  Steven 

(855)  Glycyrrhiza  glabra  L 

(856)  Galega  officinalis  L 

(857)  Robinia  hispida  L 

(858)  Robinia  pseudoacacia  L.  var.  inermis  . . 

(859)  Robiniaviscosa  L 

(860)  Caragana  arborescens  Lam 

(861)  Caragana  frutescens  L.  silvatica 

(862)  Colutea  arborescens 

(863)  Astragalus  cicer  L 

(864)  Astragalus  galegiformis  Sibth 

(865)  Astragalus  illyricus  Bernh 

(866)  Astragalus  maximus  Willd 

(867)  A.stragalus  onobrychis  L.  microphyllus. 

(868)  Pisum  sativum  Poir  (sown  May  2) 

(869)  Ervum  lens  L.  (sown  May  2) 

(870)  Lathyrus  latifolius  L 

(871)  Lathyrus  silvestris  L.  var.  ensifolius 

(872)  Orobus  albus  L.  rubescens 

(873)  Orobus  niger  L 

(874)  Orobus  roseus  Ledeb 

(875)  Orobus  veruus  L.  var.  fiaccidus 

(876)  Orobus  versicolor  Gmel 

(877)  Coronilla  emerus  L 

(878)  Coronilla  minima  L 

(879)  Coronilla  montana  L 

(880)  Coronilla  varia  L 


(881)  Onobrychis  satia  L 

(882)  Phaseolus  vulgaris  Savi.  (sown  May  2) 

(883)  Cladrastis  tinctoria  Raf 

(884)  Styphnolobium  japonicum  ScUott 


May 
May 
May 
May 
May 
June 
May 
May 
June 
June 
July 
June 
June 
June 
May 
May 
May 
Apr. 
May 
May 
May 
May 


June  12 

May  22 
July  2 
June  4 
Aug.    4 


Con- 
stant. 


1,018 
667 
389 
362 
497 
994 
555 
827 
855 
766 
548 
687 
670 
957 


634 

778 

765 

1,672 


Ripening. 


Aug.  13 


July  22 
June  24 
June  25 
July  29 
Aug.  15 
July  19 
Aug.  5 
Aug.  7 
July  14 
June  24 
June  25 


July  27 
July  2 
Sept.  16 
July  25 
Aug.  13 
July  30 


Aug.  27 
July  14 
June  26 
July  14 
July  12 
July     8 


July  20 
July  28 
July  30 
July  26 
Aug.    2 


June  22 
July  21 


June 


July  12 
July  7 
Aug.  1 
rJuly  26 
Aug.  15 
June  29 
Aug.    8 


211 


Tfiermal  constants  for  the  hlo-^somiiuj  <uid  ripcniiiy  of  8S9  plants,  etc. — Ctjutinued. 


Designation  of  plant:  onU-r.  genus,  and  spoi'ies 


XCVII.  Papilionaceiv  [(?.—;  see  G.  52]— Cor.tinued.  ^..^^ 

(><85)  Cercis  canadensis  L '. May     8^  149 

(886)  Cereis  siliqnnstrum  L May  16  1  511 

(887)  Gleditschia  triacanthos  L.  inerniis June    5  I  756 

(888)  Gymnocladns  canadensis  Lam June    4|  763 

(889)  Cassia  marylandiea  L July  —  1 ,  631 


Oct.      5  \         2,430 
Sept.  20  I         2,332 


■  54.  Very  rarely  blossoms. 

57.  The  fruit  ripens  during  the  following  season. 

168  and  175.  Did  not  bloom  during  the  ten  years. 

179  and  1S9.  Tree  too  young  to  blossom. 

203.  The  concealed  blossoms  can  not  be  accurately  observed. 

270  and  271.    The  dates  of  blossoming  are  too  variable  to  allow  of  determining  a  thermal  constant. 

304.  These  figures  obtain  for  moist  years,  but  for  dry  years  we  have  September  9  and  2237,  respec- 
tively. 

308.  Blossomed  only  once  during  these  ten  years. 

518.  The  blossoming  of  the  tree  is  not  easy  to  observe. 

677.  The  tree  died  in  1855. 

580  and  581.  Too  young  to  blossom. 

702  and  775.  Did  not  blossom. 

716.  Blo-ssomed  only  once  and  died  in  18-57. 

756.  Did  not  blossom  and  died  in  1856. 

800.  Dates  are  too  variable  to  allow  determining  a  thermal  constant. 

834  and  880.  The  dates  when  the  hull  hardens  and  colors  and  when  it  springs  open,  allowing  the 
fruit  to  fall,  are  both  given. 


LINSSER. 


The  most  elaborate  and,  I  believe,  the  most  important  investigation 
into  the  relation  between  plant  life  and  climate  is  that  published  by 
Karl  Linsser  in  a  first  memoir  (St.  Petersburg,  1867)  and  in  a  sec- 
ond memoir  of  1869.  My  personal  association  with  him  during  1865 
and  1866  greatly  stimuhited  my  own  early  interest  in  the  subject. 
The  conclusions  arrived  at  by  Linsser  are  based  upon  the  study  of  all 
available  European  observations.  His  knowledge  of  physics  and 
skill  in  numerical  computations  as  the  chief  of  the  computing  divi- 
sion of  the  Imperial  Astronomical  Observatory  at  Poulkova  has 
given  his  results  a  precision  based  on  the  well-established  principles 
of  probabilities  and  a  clearness  of  interpretation  that  specially  com- 
niend  them  to  the  physiological  botanist.  Linsser  states  that  the 
l)rincipal  hypotheses  that  had  up  to  his  time  been  framed  as  to  the 
form  of  the  connection  between  the  phenomena  of  temperature  and  of 
phenology  are  the  following  three: 

(1)  That  for  the  same  plant  the  same  stage  of  vegetation  occurs 
from  year  to  year  on  the  attainment  of  the  same  mean  daily  temper- 
ature. 


212 

(2)  That  the  same  stage  of  vegetation  is  attained  when  in  the 
course  of  any  year  the  sum  total  of  the  mean  daily  temperatures 
above  freezing  attains  the  same  value. 

(3)  That  the  same  stage  of  vegetation  is  attained  when  in  the 
course  of  any  year  the  sum  of  the  squares  of  these  positive  tempera- 
tures attains  a  certain  constant  value. 

The  first  of  these  hypotheses  has,  he  states,  long  since  been  given 
up  as  of  insufficient  accurac}^  not  only  for  any  given  station,  but  still 
more  when  Ave  consider  the  temperatures  belonging  to  a  giA^en  stage 
of  A^egetation  of  the  same  plant  in  localities  that  differ  much  in  lat- 
itude or  longitude. 

The  third  hypothesis  is  that  Avhich  Avas  favored  by  Quetelet,  and 
the  second  is  .that  which  had  for  a  hundred  years  been  generally 
adopted  by  botanists.  Both  of  these  tAvo  latter  hypotheses  Avere 
most  thoroughlA'  investigated  by  Erman  in  his  memoir,  published  in 
1845  and  1819.^' 

Erman  demonstrates  that  both  these  hypotheses  are  unsatisfac- 
tory, but  Linsser  proposes  to  reinvestigate  the  question  on  the  basis 
of  a  much  larger  collection  of  material,  both  phenological  and  mete- 
orological. 

The  first  step  in  Linsser 's  iuA'estigation  consists  in  finding  a  method 
of  computing  the  sums  of  the  temperatures  or  the  sums  of  the 
squares  of  the  temperatures  aboA^e  freezing  when  the  aA^erage  tem- 
perature of  any  day  of  the  year  is  expressed  by  the  so-called  sine 
and  cosine  formula  of  Bessel.  He  computes  the  coefficients  of  Bes- 
sel's  formula,  and  therefore  knows  the  equations  that  express  the 
mean  daily  temperature  for  any  day  in  the  year  and  for  each  of  his 
stations  of  obserA^ations.'' 

The  summation  of  the  squares  of  the  mean  daily  temperatures  Ava:-; 
computed  by  Linsser  by  the  method  knoAvn  as  mechanical  quadra- 
tures.    The  folloAving  table  illustrates  his  results  for  scA^en  groups  of 


o  I  very  much  regret  that  I  have  not  been  able  to  examine  these  memoirs, 
which  are  published  in  the  Archiv  fiir  Wissenschaftliche  Kentnisse  Russlantl, 
A'ols.  IV  and  VIII.— C.  A. 

6  A  similar  computation  had  been  made  by  Erman,  but  for  the  benefit  of  those 
who  may  in  the  future  have  to  go  through  similar  labors  I  would  suggest  that 
it  is  not  more  laborious  and  is  certainly  more  perspicuous  to  compute  the  actual 
daily  temperature  for  every  fourth  day  of  the  year,  beginning  with  .January  0. 
and  in  the  adjoining  column  make  up  the  continuous  summations.  The  diffei*- 
ence  between  the  sums  for  any  two  dates  is  then  the  total  mean  daily  tempera- 
ture to  which  the  plant  has  been  subjected. — C.  A. 


213 


plants  that  wore  observed  at  Brussels 
miles  south  of  8t.  Petersbure:  : 


and  at   Poulkova.  which 


Group 
plants. 

Date  of  blossom- 
ing. 

Sums  for  Brussels. 

i 

Sums  for  Poul- 
kova. 

Brussels. 

Poul- 
kova. 

Temper- 
ature. 

Squares 
ot  tem- 

ture. 

Temper- 
ature. 

Squares 
of  tem- 
pera- 
ture. 

1 

3 

4 

5 

6 

Days. 
85.4 
5)8.9 
119.9 
138.0 
160.4 
181.6 
222.0 

Dayx. 
137.4 
149. 0 
161.4 
169. 5 
184.3 
190.5 
223.0 

"C. 

347 

347 

550 

773 

1,102 

1,471 

2,219 

"  C. 
1,022 
1,751 
3,730 
6,497 
ll,50(i 
17,764 
31,615 

°  C. 
180 
300 
458 
575 
807 
912 

1,460 

°  C. 
1,145 
2,:i94 
4,411 
6,100 
9,776 
11,527 
20,700 

In  takino^  these  sums,  which  all  relate  to  positive  temperatures  on 
the  centigrade  thermometer  only,  Linsser  begins  with  April  8  at 
Poulkova,  because  on  that  date  the  gradually  rising  daily  tempera- 
tures pass  through  the  freezing  point.  -It  would  have  made  no 
difference  if  he  had  begun  with  January  1,  or  December  1,  or  with 
the  date  of  lowest  mean  temperature,  which  would  be  about  the 
middle  of  January.  On  the  other  hand,  for  Brussels  his  sums  begin 
with  January  15,  which  is  the  date  at  which  the  lowest  mean  daily 
temperature  occurs,  which  temperature  is  about  -|-2-'">°  C.  so  that 
if  he  had  begun  with  January  1  there  would  have  been  a  constant 
slight  addition  to  all  the  numbers  in  that  column.  The  dates  of 
blossoming  are  given  in  days  counting  consecutively  from  the  1st  of 
January,  and  may  be  converted  into  the  days  of  the  month  or  vice 
versa  by  the  following  table : 


Day  of  the 
year. 


January 
February  1 
March  1 
April  1  - 
Slay  1  _ . 
Juuf  1 . . 
July  1.. 


Date. 

O'-^*-     Leap 
nary.     ^*"*'i'- 

•1 -       --- 

yl 

1              I 
:{2          iii 

60            61 

If  we  take  the  dilference  between  the  sums  of  the  temperatui-es  for 
the  first  and  seventh  grou])s  of  plants  in  the  preceding  table  we  obtain 
for  Brussels  1,972°  C,  and  for  Poulkova  1,280°  C,  or  a  difference  of 
about  700°  C.,  which  corresi)()nds  to  about  forty  days  at  Poulkova.  so 
that  we  must  immediately  conclude  that  the  same  stages  of  develop- 


214 


merit  are  attained  by  means  of  very  ditJ'erent  sum  totals  of  tempera- 
tures at  Poulkoya  and  Brussels. 

But  possibly  we  should  have  taken  the  initial  i^oint  of  vegetation 
at  some  other  temperature  than  0°  C.  In  order  to  test  this  point 
Linsser  performs  the  computations  of  the  sums  of  temperatures  above 
1°,  2°,  3°,  4°,  5°,  and  6°  C,  respectively.  His  result  for  6°  C.  is  as 
follows : 


Group,    i  Brussels. 

Poulkova. 

Group. 

Brussels. 

Poulkova. 

1                <                I 

"C. 
21 
72 
155 

! , 

6 

412 

9a5 

1,154 

368 
435 

2 1              20 

3 '              97 

4 212 

224 

None  of  these  successive  hypotheses  as  to  the  initial  temperature 
for  vegetation  gives  a  uniform  constant  any  more  than  does  the 
original  hypothesis  of  0°  C 

A  similar  study  of  the  sums  of  the  squares  demonstrates  a  similar 
result,  so  that  in  general  at  different  places  the  same  phase  of  develop- 
ment of  vegetation  requires  different  mean  daily  temperatures,  dif- 
ferent sums  of  temperatures,  and  different  sums  of  the  squares  of 
temperatures,  and  there  is  no  zero  point  that  can  be  adopted  that  will 
make  these  sums  equal. 

Linsser  then  shows  that,  notwithstanding  this  result,  there  still  is 
a  thermal  law  concealed  in  the  above  figures.  For  evidently  the 
sums  for  Brussels  and  Poulkova  go  on  steadily  increasing  through  the 
whole  period  of  vegetation,  and  at  any  stage  the  numbers  are  very 
nearly  in  the  same  proportion,  and  that  proportion  is  very  nearly  the 
same  as  the  proportion  between  the  sum  total  for  the  year  at  the  two 
places.  These  annual  sums  total  are  for  Brussels  3,687.  and  for  St. 
Petersburg  2,253.  If  now  the  numbers  in  the  fourth  and  sixth- col- 
umns of  the  table  on  page  213  be  divided  by  these  annual  sums, 
respectively,  we  obtain  the  following: 

Ratio  of  the  iiidiridiKil  smnn  to  the  total  annual  ftunis  of  tonijeratiire  ahore  0°  C. 


Group  of 
plants. 

Brussels. 

Poulkova. 

Group  of 
plants. 

Brussels. 

Poulkova. 

1 

0.07 
.0<» 
.15 
.21 

0.08 
.13 
.20 
.36 

5 

0.30 
.40 
.60 

0.36 
.40. 
.65 

2 ... 

3 _-.. 

4 ._. 

6 _. 

,The  agreement  of  these  numbers  is  quite  close  enough  to  justify  the 
conclusion  that  in  two  different  localities  the  sums  of  i)OsitiA'e  daily 
temperatures  for  the  same  phase  of  vegetation  is  proportional  to  the 


215 

annual  sum  total  of  all  positive  tcnipeiatiiros  for  the  respective  locali- 
ties. The  discrepancies  between  the  above  figures  also  show  that  a 
systematic  influence  is  at  work  to  slightly  increase  the  ratio  for  the 
northern  stations,  since  the  ratios  for  Poulkova  are  appreciably  larger 
than  those  for  Brussels.  This  influence,  as  Linsser  suggests,  is  prob- 
ably to  be  found  in  the  fact  that  a  larger  j^roportion  of  heat  is  con.- 
suuied  at  the  northern  stations  in  melting  the  snow  without  changing 
the  temperature,  which  heat  is  therefore  lost  to  the  growth  of  plants. 

The  law  thus  discovered  by  Linsser  is  tested  by  him  for  each  of  the 
15  phenological  stations  studied  in  his  first  memoir,  and  not  only  does 
the  ratio  appear  the  same  for  each  phase,  but  the  slight  increase  as 
the  latitudes  increase  is  also  confirmed,  or,  in  other  words,  the  ratio 
increases  slightly  as  the  annual  sum  total  of  positive  temperatures 
diminishes,  the  increase  being  nothing  for  the  first  group  of  plants 
that  blossom  early  in  the  spring  and  about  0.1  for  the  seventh  group 
of  plants  that  blossom  in  midsummer  per  diminution  of  '2.000°  C.  in 
the  annual  sums. 

Linsser  also  states  this  law  in  the  following  form,  in  whicii  it  has  a 
more  popular  expression : 

Every  individual  plant  possesses  the  ability  to  regulate  its  vital 
activity  as  demanded  by  the  total  heat  available  in  its  dwelling  place 
and  according  to  the  habit  inherited  from  its  ancestors,  so  that  indi- 
viduals of  the  same  species  living  in  difl'erent  places  arrive  at  the 
same  phase  of  development  by  utilizing  the  same  proportions  of  the 
total  heat  to  which  they  are  accustomed.  The  vegetable  world,  so 
far  as  we  consider  its  vital  phenomena,  is  indilferent  to  temperatures 
below  the  freezing  point. 

The  preceding  principle  has  been  deduced  primarily  from  the  study 
of  one  phase,  viz,  the  blossoming;  but  a  study  of  the  figures  of  the 
other  phases  gives  a  similar  result,  so  that  the  method  b}^  which  heat 
exercises  its  influence  on  plants  is  the  same  for  all  stages  of  develop- 
ment. 

The  phase  recorded  as  "  the  falling  of  the  leaves,''  which  indicates 
the  approach  of  the  winter  sleep  of  perennial  plants,  is  the  only  one 
that  to  a  high  degree  depends  upon  the  actual  temjicrature  at  that 
date. 

Apjjarently  the  statement,  frequently  assumed  as  a  general  law, 
that  the  dates  of  leafing  and  of  the  falling  of  the  leaf  at  the  same 
place  have  the  same  tenii)eratures  is  only  a})pr()ximately  true  for  a 
single  plant  and  a  special  locality,  as,  for  instance,  France  and  cen- 
tral Europe,  and  does  not  hold  good  for  the  same  jilant  for  northern 
or  southern  Europe. 

Linsser's  law  has  a  most  important  application  to  the  natural  dis- 
semination of  seeds  and  the  acclimatization  of  plants.  When  we, 
at  a  given  place,  from  year  to  year,  see  the  same  cycle  of  vegetation 
recur  without  changing  the  behavior  of  the  plant  with  rx'ference  to 
the  annual  sum  total  of  heat,  we  must  conclude  that  the  ability  to 
develop  itself  in  proportion  to  the  total  heat  is  transmitted  from  each 


216 

mother  plant  down  to  the  seed  produced  by  it.  Therefore  in  e\erv 
kernel  of  seed  there  is  concealed  the  whole  relation  between  the 
development  of  the  plant  and  the  total  heat  of  the  locality  where  it 
was  produced.  Two  seeds  of  the  same  species,  one  of  which  comes 
from  a  mother  plant  that  has  lived  under  the  influence  of  an  annual 
total  heat  of  M.  but  the  other  of  which  conies  from  another  mother 
l^lant  that  has  lived  under  a  total  annual  heat  of  N,  possess  powers  of 
development,  or  a  sensitiveness  to  equal  temperature  influences,  that 
are  inversely  proportional  to  the  sums  M  and  N;  or,  in  other  words, 
the  rate  of  development  is  equal  to  the  sum  of  the  effective  tempera- 
tures divided  by  the  normal  values  of  the  total  annual  sums  for  the 
mother  plant. 

Applying  this  law  to  seeds  that  are  artificially  transported  from 
their  homes  to  other  places  having  different  climates  as  to  tempera- 
ture we  are  enabled  to  predict  approximately  what  their  behavior 
will  be.  Thus  Yon  Baer  observed  that  cress  seeds  that  had  been 
raised  in  St.  Petersburg  (lat.  60°)  and  transported  to  Matotschkin- 
Schar  (lat.  73°)  developed  in  July  at  only  one-third  the  rate  that 
they  did  in  St.  Petersburg  in  the  month  of  May.  iSTow  the  annual 
sum  of  positive  temperatures  for  St.  Petersburg  is  2,253°  C,  and 
the  average  temperature  of  the  month  of  May  in  St.  Petersburg  is 
11.2°,  while  that  of  the  month  of  July  at  Matotschkin-Schar  is  -1.4°. 
Therefore  the  rates  of  development  per  dav  of  the  same  seed  at  these 
two  places  will  be  in  the  ratio  of  11.2  to  4.4,  or  2.6  to  1.  Again,  for 
cress  seeds  raised  at  Matotschkin-Schar,  where  the  annual  total  heat 
is  330°  C,  the  rate  of  development  will  in  general  be  ^^,  or  6.8 
times  more  rapid  than  the  development  of  seeds  brought  from  St. 
Petersburg.  Vice  versa,  seeds  carried  from  Matotschkin-Schar  to 
St.  Petersburg  the  rate  of  development  will  be  6.8  times  more  rapid 
than  for  those  that  are  native  to  the  latter  climate. 

Linsser  was  thus  able  to  enunciate  the  first  step  in  the  rational  ex- 
planation of  a  phenomenon  with  which  agriculturists  had  long  been 
familiar — viz,  that  the  seeds  raised  in  northern  zones  retain  the 
power  of  rapid  development,  so  that  when  sown  in  southern  regions 
they  grow  more  rapidly  and  ripen  earlier  and  give  a  richer  harvest 
than  those  that  are  sown  in  their  native  warm  locality.  Similarly, 
seeds  of  mountain  plants,  when  carried  by  rivers  into  the  warmer 
plains  of  the  lowlands,  develop  plants  whose  blossoms  antedate  the 
spring  blossoms  of  the  plants  native  to  the  lowlands."  We  may  thus 
accept  the  general  statement  that  plants  or  seeds  transported  to 
colder  countries  reach  a  given  stage  of  vegetation  later  than  the 

"A  beautiful  illustration  of  this  law  is  found  in  the  abnormal  early  iiowering 
of  seeds  brought  from  the  cold  uplands  and  lodging  on  High  Island,  on  the 
Potomac,  about  5  miles  aliove  Washington.  I).  C. 


217 


native  plants,  hut  wIumi  transported  to  warnior  ivirions  they  blossom 
and  ripen  earlier.  Thus  in  1851)  Schueheler  sowed  (Crowed  barley  that 
had  been  raised  in  Alten  (hit.  70  X.).  where  it  i-ecpiired  only  nine 
weeks  to  ripen,  in  Christiania  (hit.  (iO  X.),  where  it  ripened  in 
eight  weeks.  In  the  same  year  some  of  the  same  bai'ley  was  carried 
from  Breslau,  where  it  rexpiired  nine  and  a  half  weeks,  to  Christiania, 
where  it  ripened  in  twelve  to  fourteen  Aveeks.  Linsser  arranged  these 
experiences  as  shown  in  the  following  table,  in  which  he  assumes  that 
both  at  Alten  and  at  Christiania  the  barley  is  sown  when  the  mean 
daily  temperature  is  about  8°  C. 


Barley  i-aised  at— 

Date  of 
sowing. 

Date  of 
ripening. 

Interval. 

Sums  of 
tempera- 
ture. 

June  14 
May    .5 

Aug.    16 
June   29 
Aug.  1-9 

Weeks. 
9 
8 
13 

70() 

Christiana  and  sown  at  Christiana 

1,400 

1 

The  annual  sum  totals  of  heat  are  1,300  in  Alten  and  2,000  in  Chris- 
tiania. Therefore  we  see  that  the  heat  required  by  seed  acclimatized  at 
Alten  (700)  is  to  that  required  by  seed  acclimatized  at  Christiania 
(1,400)  in  the  same  ratio  as  the  annual  sum  totals. 

It  can  also  be  shown  that  barley  acclimatized  at  Christiania  and 
transported  directly  to  Alten  can  not  ripen  in  the  latter  place,  since 
the  1,-1:00°  C.  required  by  it  at  Christiania  are  not  received  at  Alten. 
It  is  onl}^  by  gradual  progressive  acclimatization  at  numerous  inter- 
mediate places  that  the  plant  has  been  enabled  to  adapt  itself  to  suc- 
cessively smaller  sum  totals  of  heat.  In  continuation  of  this  process 
the  barley  that  is  now  accust*omed  to  ripen  at  Alten  can  be  used  to 
pioneer  the  further  northward  progress  of  its  species.  The  attempt 
to  transport  barley  from  Denmark  to  Iceland  has  thus  far  failed,  but 
doubtle.ss  barley  from  Alten  would  succeed.  Barle}'  cultivated  in  the 
Caucasus  at  an  elevati(m  of  7,000  feet  and  transported  to  St.  Peters- 
burg should,  according  to  Linsser's  computation,  experience  an  accel- 
eration, so  far  as  climate  is  concerned,  as  though  it  were  coming  to  a 
wanner  climate,  but  this  acceleration  may  be  more  than  counter- 
balanced by  the  differences  in  the  nature  of  the  two  species  of  plants, 
as  it  is  well  known  that  the  Turkish  oats  {Avena  orientalU)  re(|uirc 
more  time  to  ripen  than  the  ordinary  oats  of  northern  Europe;  the 
variations  in  times  recpiired  by  different  kinds  of  oats,  barley,  and 
wdieat,  and  even  winter  rye,  are  oftentimes  larger  than  the  variations 
due  to  differences  of  climate.  But  such  variations^,  as  observed  in 
plants  that  are  only  partially  acclimatized,  Avill  disappear  after  a  few 
generations  if  the  plant  has  the  power  of  adapting  its  internal  organ- 


218 

ization  to  a  new  climate.  The  geographical  limits  of  any  species, 
in  latitude,  so  far  as  these  limits  depend  upon  temperature  alone, 
are  those  points  at  which  a  certain  sum  of  positive  temperatures  can 
be  attained  l^etween  the  first  and  the  last  killing  frost.  The  northern 
and  southern  boundary  lines  of  such  a  limiting  area  are  the  curves 
corresponding  to  two  very  different  sums  total  of  positive  tempera- 
tures, the  northern  limit  having  a  smaller  sum  and  the  southern  limit 
a  larger,  beyond  either  of  which  the  plant  is  unable  to  modify  its 
internal  organization  so  as  to  properly  utilize  the  respective  prevail- 
ing small  or  large  quantity  of  heat. 

Linsser  notes  that  different  plants,  especially  those  that  blossom 
early  in  the  year,  show  a  strong  tendency  in  certain  years  to  blossom 
a  second  time,  and  he  finds  that  when  the  excess  of  the  total  heat  in  a 
favorable  year  exceeds  the  normal  annual  total  by  a  quantity  equal 
to  that  ordinarily  required  for  the  first  blossom  (and  this  can  easily 
happen  on  account  of  the  small  sum  required  for  the  early  spring 
blossom)  then  the  plant  produces  a  second  blossom." 

In  regard  to  the  effect  of  daylight  as  such,  Linsser  says  the  opinion 
has  been  expressed  that  possibly  the  duration  of  the  daylight,  which, 
during  the  growing  period,  increases  as  we  go  northward,  must 
compensate  for  the  diminishing  sum  total  of  heat;  but  his  figures 
show  nothing  of  this  influence,  since  the  discrepancies  or  departures 
between  his  observed  and  computed  figures  have  altogether  the  char- 
acter of  accidental  errors.  In  fact,  his  law  of  the  constant  quotient  or 
jDercentage  of  heat  implies  that  the  plant  does  not  need  any  com- 
pensation as  the  heat  is  diminished,  but  directly  adapts  its  cycle  of 
operations  to  the  diminished  sum  and  transmits  this  power  to  all 
further  generations.  In  addition  to  this,  however,  since  the  impor- 
tance of  light  to  the  plant  is  proven,  it  is  necessary  to  remember 
that  with  the  increasing  duration  of  the  day  as  we  go  northward 
there  is  a  steady  diminution  in  the  intensity  of  the  daylight  because 

o  Ought  we  not  to  infer  from  this  that  after  a  perennial  phint  has  received 
sufficient  heat  to  blossom  and  eventually  to  ripen  its  fruit  it  then  at  once  begins 
to  repeat  this  cycle  of  processes,  and  is  ordinarily  only  delayed  by  the  cold 
of  winter?  If  this  is  true,  it  must  be  considered  that  with  the  warm  weather 
of  spring  the  plant  takes  up  these  vital  processes  at  the  point  where  they  were 
left  in  the  autumn.  Therefore,  in  such  cases,  our  sums  total  of  temperature, 
jnoisture,  etc.,  should  all  begin  to  be  counted  with  the  ripening  of  the  fruit, 
or  the  fall  of  the  leaf,  and  not  merely  with  the  opening  of  vegetation  in  the 
spring. — C.   A. 


219 


\\\c  suiTs  :iltiui(l( 
I  able." 


iiiiinislios.     This  Linssoi-  sliows 


(Ik 


Maximum  dura-    Altitude  of  sun  at ;  Relative  quantity  of  heat  re- 
tion  of  aunshin*.  noon.  i      ceived  by  the  ground  in  1 

day  under  an  atmosphere 

St  Pe-         whose  transparency  is  0.70. 


i(lat^4&.4  I  (lat  (i„o  |^ia,^*»-*  ,  (lat.()0° 


N.). 


N.). 


N.). 


j    Hours.   I    Hours. 

January  1(! 9.0  j  li.S 

February  ir. 10.3  |  i».^ 

Marchlti 11.9  j  11.8 

Apriliri 13.5  U.5 

May  16 14.8  17.2 

.Timelo 15.6  18.8 

Julyl6 15.3  18.1 

Augustl6... U.l  15.6 

Septemberl5 -..  12.6  13.0 

October  16 10.9,  10.;> 

November  15 9.5  7.6 

December  16 8.7  1  6.0 


Dcfjrce.s. 
2:^.7 
31.5 
42.8 
54.3 

67.8 
66.0 

58.4 
47.7 
35.8 
26.2 
21.3 


Degrees. 
9.0 


49.1 
53.4 
.51.5 
43.9 

m.2 

21.2 
11.6 
6.7 


Lat. 

40ON. 

Lat. 

50°  N. 

150 

70 

210 

1.55 

400 

295 

.5r>0 

450 

615 

570 

650 

625  ! 

630 

585  1 

.5.50 

480 

430 

;a5 

;i8() 

ia5t 

180 

85  t 

13;-. 

.,. 

Lat. 

60°  N. 


570 
.525 

:Rt5 

230 
90 
20 
2 


Lat. 

70°  N. 


In  reference  to  the  first  part  of  this  table  Linsser  remarks  that 
the  intensity  of  the  light  of  the  sun  varies  as  the  sine  of  the  aiii>iilar 
altitude  of  the  sun,  so  that  from  the  maximum  altitude  on  any  day 
Ave  get  an  approximate  idea  of  the  influence  of  sunshine;  and  Ave  see 
also  that  the  fartiier  north  we  go  the  longer  duration  of  the  sunshine 
is  partly  counterb;Uanced  bv  the  diminishing  intensity  of  its 
influence.'' 

I^insser  remarks  that  the  theory  of  compensation  between  duration 
of  the  day  and  intensity  of  sunshine  may  also  be  tested  by  considering 
the  eifect  of  ascending  a  mountain,  wdiere  there  is  no  increase  of  dura- 
tion but  a  great  increase  in  the  intensity,  of  sunshine.  If  the  rapid 
development  of  the  plants  on  the  mountains  is  due  to  the  increase  in 
the  intensity  of  the  light,  then  how  can  the  diminution  of  intensity 
in  northern  regions  bring  about  the  rapid  development  that  is  demon- 
strated in  the  experiments  of  Von  Baer  and  Schuebeler  and  Ruprecht 
which  are  quoted  and  analyzed  in  the  following  paragraphs? 

o  To  which  I  have  added  three  columns  of  relative  intensity  of  the  total  heat 
received  in  twenty-four  hours  on  each  date.  a>;  interpolated  from  .Vnjiofs  tables, 
for  a  coefficient  of  transparency  equal  to  0.70. — C.  A. 

''  The  exact  figures  that  yive  the  relative  sum  total  of  the  direct  sunshine 
and  the  diffuse  daylight  for  various  latitudes  and  solar  altitudes  for  clear  and 
cloudless  days  have  been  published  l)y  Marie  Davy.  Angot.  Wiener,  and  others. 
The  fi.irnres  that  I  have  given  in  the  last  jiart  of  the  al)ove  tables  from  .Vngot 
show  still  more  clearly  to  what  e,\tent  the  effect  of  sunshine  diminishes  as  we 
approach  the  pole,  but  how  surprisingly  powerful  are  the  consecutive  twenty- 
four  hoiu's  of  sunshine  on  .Tune  1.^  within  the  Arctic  Circle. — C.  A. 


220 

111  his  socond  meuiuir  Liiissi-r  (iSiU))  begins  by  showing  that  many 
well-recognized  facts  liave  been  found  which  harmonize  with  the 
conclusions  at  which  he  had  previously  arrived.  Thus,  in  the  tiri-t 
and  second  halves  of  the  eighteenth  century  the  northern  limit  of  the 
cultivation  of  grain  had  not  passed  beyond  latitude  60°  30'  X.,  a::(l 
many  unsuccessful  attempts  had  been  made  to  ri^^en  the  grains  in 
more  northern  regions;  but  in  1829  Erman  found  a  small  successful 
beginning  going  on  at  Yakutsk,  and  since  then  it  has  spread  in  all 
directions  and  has  extended  to  barley,  oats,  rye,  and  wheat.  Similarly 
in  Lapland  the  cultivation  of  grain  succeeded  only  for  a  long  time  in 
the  southern  regions,  but  now  it  extends  to  the  north  and  even 
among  the  mountains.  In  Lapland  this  cultivation  succeeded  only 
when  the  seed  w^as  brought  from  near  by,  not  from  a  distance,  and 
Von  Baer  says  that  it  was  commonly  said  that  the  grain  had  accli- 
matized itself,  or,  as  he  expresses  it,  "  It  seems  to  me  that  gradually 
a  quick-ripening  variety  or  '  sport '  has  developed  that  is  not  injured 
hj  the  early  frosts  of  summer  nights." 

F.  C.  Schiibeler  (1862)  in  his  memoir  on  the  cultivated  plants  of 
Norway  states  that  in  1852  the  seed  of  yellow^  maize  brought  to  Nor- 
W'ay  from  Hohenheim,  near  Stuttgart,  was  sown  on  the  26th  of  May 
and  reaped  one  hundred  and  twenty  days  later,  but  after  continued 
annual  cultivations,  in  which  every  harvest  came  a  little  earlier  than 
its  predecessor,  Schiibeler,  in  1857,  sowed  the  seed  on  May  25  and  har- 
vested it  in  ninety  days,  while  the  seed  of  the  sa«ie  variety  brought 
fresh  from  Breslau  and  sowed  on  the  same  date  ripened  only  after 
one  hundred  and  tw^enty-two  days.  Even  Kalm  had  remarked  that 
maize  when  transported  from  a  southern  to  a  northern  latitude 
gradually  overcomes  the  difficulty  of  ripening  and  eventually  gives  a 
nearly  constant  variety  of  grain. 

Morren,  in  the  Belgique  Ilorticole  (1859-60),  says  the  principal 
problem  to  be  resolved  in  Xorway  in  the  amelioration  of  its  agricul- 
ture is  the  introduction  of  new  varieties  and  the  development  of 
precocity.  This  precocity  increases  year  b}^  year,  as  if  the  plant  could 
not  all  of  a  sudden  obey  the  new  climatic  influences  under  which  it 
had  been  brought.  Plants  cultivated  many  years  in  succession  under 
a  northern  climate  when  transported  to  a  southern  climate  preserve 
something  of  their  former  rate  of  development  and  are  more  preco- 
cious than  plants  of  the  same  species  that  have  remained  in  their  first 
situation.  Just  as  wdieat  carried  from  Germany  northward  into  the 
Baltic  Provinces  of  Russia  fails  to  ripen  its  grain,  so  grain  carried 
from  the  valleys  up  to  the  highlands  in  Switzerland  fails  to  ripen. 

Bastian  quotes  an  old  English  author  Avho  says  that  in  the  accli- 
matization of  plants  the  graduation  of  the  process  is  the  principal 
necessity,  and  that  a  sudden  acclimatization  in  a  new  home  is  impos- 
sible, so  that  a  plant  gradually  learns  to  live  in  a  climate  in  which 


221 

its  molhor  plr.iit  Avas  sickly  and  its  <)^raiidinotlier  would  havo  died  at 
oneo.  It  was  iii  recognition  of  this  view  that  in  the  eiji:hteenth  cen- 
tury the  hotanical  warden  at  Teneriffe  was  established  (the  so-calleil 
acclimatization  <i:arden  at  Durasno  and  the  Colegan  (larden  at  Oro- 
tava,  at  an  altitude  of  1,040  feet)  in  order  to  furnish  a  temporary 
resting  place  for  tropical  plants  that  they  mii?ht  accustom  them- 
selves to  a  cooler  climate  preparatory  to  their  cultivation  in  southern 
Europe.  According-  to  Dollen,  the  same  principle  is  applied  in  the 
acclimatization  garden  at  Algiers  to  tropical  African  i)lants  before 
their  transportation  into  southern  France. 

.  As  the  guiding  thought  of  his  second  memoir,  Linsser  now  remarks 
that  we  must  divide  the  vegetable  phenomena-  of  the  world  into  two 
divisions,  viz,  those  in  which  temperature  controls  the  annually  re- 
curring cycle  of  phases,  as  is  the  case  in  the  Temperate  Zone,  and  thosi^ 
in  Avhich  moisture  controls,  as  in  the  Tropical  Zone.  Thus,  on  the 
grassy  plains  of  South  America,  where  the  year  is  divided  into  a  dry 
and  a  wet  season,  the  entire  course  of  vegetation  depends  upon  the 
latter;  the  hottest  and  driest  season  exerts  upon  the  vegetable  life  an 
influence  like  that  of  the  northern  winter,  bringing,  namely,  rest  and 
even  death.  Such  a  contrast  is  even  found  at  Madeira,  where,  accord- 
ing to  Heer,  the  weeds  of  northern  P]urope  begin  to  vegetate  in  the  fall 
after  the  dry  summer  months  of  trade  winds  and  when  the  first  rains 
fall,  whereas  in  the  hottest  summer  time  all  these  Aveeds  slumber  or 
die,  as  with  us  in  winter.  Tn  the  steppes  of  Orenburg,  Russia,  when 
the  sun  melts  the  snow  in  April,  it  starts  the  first  sprouts  and  the 
blossoms,  and  by  the  beginning  of  May  the  vegetation  of  the  steppes 
has  attained  its  highest  brilliancy,  being  distinguished  by  the  great 
number  of  many-colored  tulips,  as  has  been  so  often  described  by 
travelers;  but  this  beauty  passes  b}^  with  remarkable  rapidity,  and 
when  in  June  the  dry,  hot  summer  of  the  steppes  begins,  all  the  \cr- 
dure  is  dry  and  dead,  and  in  place  of  the  blossoms  there  are  seen  only 
the  dry,  empty  hulls;  so  that  the  wdiole  life  of  the  plants  on  the 
steppes  is  condensed  into  the  short  space  of  eight  weeks. 

We  thus  see  that  for  large  portions  of  the  earth  the  heat  as  such 
ceases  to  be  the  principal  regulator  of  plant  life,  and  moisture  becomes 
the  controlling  influence. 

It  is  evident  that  the  life  of  plants  depends  upon  both  temperature 
and  moisture.  In  situations  where  there  is  always  sufficient  moisture 
the  influence  that  decides  whether  or  not  a  plant  shall  develop  is  the 
heat;  but  in  regions  Avliere  there  is  always  sufficient  heat  that  deciding- 
influence  is  moisture.  Therefore  Linsser  proposes  in  his  second  me- 
moir to  first  state  the  influence  of  heat  on  vegetable  phenomena  more 
precisely  than  he  had  previously  done,  and  then  to  develop  the  influ- 
ence of  moisture. 


222 

Tjinsser's  second  study  is  based  upon  a  much  larger  mass  of  i^lieno- 
logical  observations  than  that  previously  used  by  him,  and,  in  fact, 
more  than  has  ever  been  used  by  any  other  investigator  of  this  sub- 
ject. The  accompanying  table  gives  for  each  of  his  stations  the 
initial  and  final  dates  when  the  normal  mean  daily  temperature  is 
0°  C,  or  the  date  when  the  minimum  of  the  year  occurs  if  that  mini- 
mum is  above  0°  C ;  these  are  the  limiting  dates  between  which  the 
smmiiation  of  temperature  is  made  according  to  Linsser's  method. 
The  sums  total  of  positive  temperatures  for  the  whole  year  are  given 
in  the  third  column  ni  centigrade  degrees. 


Initial 
date. 


Final 
date. 


Ajiniial 
sums  of 
positive 
tempera- 
tures. 


Lins- 
ser's 
zones. 


Parma 

Venice 

Dijon 

Heidelberg . 

Paris 

Namur 

Ghent 

Kischineflf . 

Vienna 

Ostend 

Brussels 

Prague  

Swaflfham  . . 
Brunswick  . 

Sarepta 

Stavelot 

Munich 

Tubingen. . . 

Stettin 

Kief 

Kreuzburg  , 

Gorlitz 

Breslaii 

Orel 

Moscow 


Christiania . . . 
Abo 

St.  Petersburj 
Carlo 


Jan.  15 

Jan.  17 

Jan.  11 

Jan.    5 

Jan.  14 

Jan.  13 

...do... 

Jan.  12 

Mar.    2 

Feb.    8 

Jan.  14 

Jan.  16 

Feb.  16 

j  Jan.  20 

Feb.    8 

I  Mar.  27 

Jan.  20 

Feb.  14 

Feb.    9 

'  Feb.  18 

Mar.  16 

I  Feb.  28 

!  Feb.  19 

i  Mar.    2 

I  Apr.    1 

Apr.    4 

Mar.  26 

-     .do... 


Dec.  31 
...do.. 
...do.. 
...do.. 
...do.. 
...do.. 


Apr.  3 
Apr.  8 
Apr.  19 


....do... 
Dec.  8 
Dec.  18 
Dec.  31 
....do... 
Dec.  16 
Dec.  31 
...do... 
Nov.  12 
Dec.  31 
Dec.  16 
Dec.  1 
Dec.  18 
Nov.  21 
Dec.  16 
Dec.  6 
....do... 
Nov.  13 
Nov.  4 
Nov.  22 
Nov.  11 
Nov.  13 
Nov.  9 
Oct.  30 


"C. 

5,226 

4,797 

4,669 

4,251 

8,933 

3,929 

3,865- 

3,815 

3,799 

3,757 

3,737 

3,687 

3,582 

3,520 

3,433 

3,271 

3,151 

3, 125 

3, 125 

3,115 

3,035 

3,018 

2,975 

2,953 

2,807 

2,631 

2,574 

2,389 

2,303 

2,253 

1,898 


A  plant  has  access  to  water  by  two  methods — through  its  roots  it 
absorbs  the  water  in  the  soil,  whereas  its  leaves  come  in  contact 
with  the  vapor  and  the  rain  in  the  atmosphere;  but  Linsser  con- 
siders that  the  relation  of  the  plant  to  the  water  in  the  soil  is  the 
important  feature  that  decides  as  to  the  develojjment  of  the  peren- 


22H 

iiial  pliuits  of  toiiipcinlr  rciiioiis,  which  arc  lh()>c  coiisulcrcil  in  his 
second  memoir.  So  he  h'aves  the  stiuly  of  atmospheric  vapor  and 
plant  life  to  the  future,  while  confining  himself  at  present  to  the 
relation  between  rai:ifall  and  the  periodic  phenomena  of  vegetation. 

It  is  not  necessary  to  reproduce  the  tables  of  normal  monthly  rain- 
fall given  by  Linsser  for  each  of  his  stations,  and  generally  based 
upon  many  years  of  observations.  Of  course,  these  numbers  express- 
ing the  local  rainfalls  are,  as  is  well  known,  less  directly  applicable 
to  a  neighboring  locality  than  are  the  mean  monthly  temperatures, 
and  they  must  l)e  used  with  correspondingly  less  confidence. 

The  constant  fractional  part  of  the  annual  sum  total  of  heat,  as 
previously  established  by  Linsser.  afforded  him  a  valnable  suggestion 
or  a  working  hypothesis  as  to  the  relation  between  the  life  of  the 
plant  and  other  factors,  such  as  sunshine,  rainfall,  nutrition,  and  in 
fact  every  factor  that  influences  the  life  of  the  plant.  If,  namely,  a 
plant  utilizes  one-tenth  of  its  annual  cycle  of  heat  in  order  to  bring 
it  to  the  leafing -stage,  why  may  it  not  also  require  one-tenth  of  its 
annual  cycle  of  rain  or  sunshine  or  some  similar  constant  fractional 
part  ?  Xow.  in  the  development  of  a  plant  there  is  necessary,  first,  the 
material,  viz,  rainfall,  or  irrigation  water  with  the  nutrition  con- 
tained therein,  and  on  the  other  hand  one  or  more  forces,  such  as 
sunshine  and  heat,  by  the  help  of  which  the  plant  can  utilize  that 
material  in  its  process  of  assimilation.  The  different  phases  of  the 
development  of  the  plant,  such  as  the  appearance  of  the  blossoms 
and  the  ripening  of  the  fruit,  are  work  accomplished;  in  this  work 
the  water  supplies  the  principal  material,  while  the  heat,  says  Linsser, 
plan's, the  role  of  the  principal  force;  but  the  work  of  the  plant — that 
is  to  say,  its  progressive  development — will  onl}^  be  in  proportion  to  the 
force,  so  long  as  the  latter  finds  a  sufficient  quantity  of  material  present 
to  insure  the  complete  utilization  of  the  force.  Evidently  a  force  that 
is  competent  to  convert  a  certain  quantity  of  material  to  the  use  of 
the  plant  will  only  be  half  utilized  if  only  half  of  this  quantity  of 
material  is  present.  In  other  words,  the  development  of  the  plant 
goes  on  in  proportion  to  the  quantity  of  heat  only  so  long  as  the  plant 
has  at  its  disposal  the  maximum  (juantity  of  material  that  can  be 
worked  over  by  this  heat. 

Therefore  any  further  investigations  as  to  the  relation  of  the  life 
of  a  plant  to  its  external  factors  must  necessarily  consider  the  dis- 
tribution of  material  with  reference  to  the  distribution  of  heat.  In 
our  present  case  it  is  the  distribution  of  the  quantity  of  rain  with 
reference  to  the  heat,  and  if  such  relative  distribution  is  not  considered 
then  its  omission  is  only  permissible  under  the  assumption  that  dur- 
ing the  whole  period  of  vegetation  the  material  necessary  to  the 
growth  of  the  plant  is  ahvays  present  in  such  quantity  that  at  any 


224 

inoinent  the  force  then  acting  can  be  completely  utilized.  This 
assumption  as  to  rainfall  is  actuall}^  fulfilled  over  by  far  the  largest 
part  of  the  European  area  hithei'to  studied  by  Linsser. 

Of  course,  we  can  not  speak  of  absolute  quantities  of  heat  or  nour- 
ishing material.  We  have  to  do  only  with  their  relative  distribution 
during  the  period  of  vegetation — that  it  to  say,  with  the  ratio  of  the 
quantity  of  material  (/)  to  the  quantity  of  heat  {w).  If  we  con- 
sider tliait  the  quantity  of  material  that  a  definife  quantity  of  heat  is 
able  to  work  up  for  the  use  of  the  plant  is  directly  proportional  to  this 
quantity  of  heat,  then  the  ratio  f/iv  will  ha^e  for  each  plant  and  phase 
a  certain  definite  value  that  may  be  called  the  most  favorable  ratio 
and  for  which  value  the  material  on  hand  is  completely  used  up  by  the 
heat  or  active  force  that  is  present.  If  the  material  that  is  present 
is  not  sufficient  for  the  heat,  then  f/ir  is  smaller  than  this  most  favor- 
able value,  and  in  this  case  the  material  is  completely  used  up ;  but 
a  portion  of  this  heat  remains  unused  and  wasted.  If,  on  the  other 
hand,  the  heat  is  not  sufficient  to  iise  up  all  the  material,  then  f/tr  is 
loo  large  and  the  heat  is  completely  used,  but  a  portion  of  the  material 
is  Avasted. 

The  fractional  portion  of  the.  annual  sum  total  of  heat  that  is 
needed  to  bring  a  plant  up  to  any  stage  of  vegetation  is  by  Linsser 
called  the  "  physiological  constant ""  for  that  phase  and  plant,  and  is 
constant  wherever  the  plant  is  acclimatized.  The  ratio  f/w,  as  com- 
piled by  him  month  by  month  for  each  of  his  stations,  is  a  local  cli- 
matic constant,  which  is  large  Mhen  the  climate  is  favorable  to  the 
growth  of  the  plant — that  is  to  say,  when  there  is  abundance^  of 
rain — but  is  small  when  the  climate  is  more  or  less  unfavorable-to  the 
plant — that  is  to  say,  when  the  summer  rains  are  deficient. 

The  vegetation  of  the  Avhole  Avorld  is,  according  to  Linsser's  vieAvs, 
to  be  diA^ded  into  zones  (A,  B,  C,  D,  E,  F),  according  to  the  annual 
distribution  of  the  monthly  ratios  f/n\  Thus  in  the  highest  lati- 
tudes (Linsser's  zone  A)  and  in  the  greater  part  of  the  European 
region  covered  by  Linsser's  researches,  there  is  during  the  entire  year 
a  deficiency  of  heat,  but  a  sufficiency  of  moisture  and  of  material  to 
employ  all  the  heat  force  that  is  aA'^ailable.  In  the  Steppes  of  Rus- 
sia, however,  there  is  a  deficiency  of  moisture  during  the  summer  and 
autumn,  and  the  fraction  f/w  becomes  quite  small  for  the  zone  B. 
The  other  localities  that  haA^e  a  wet  and  a  dry  period  annually  may 
be  diAnded  into  three  classes,  viz,  C,  Avhere  the  drought  comes  during 
the  months  of  July  and  December ;  D,  where  the  drought  comes  dur- 
ing the  months  of  January  and  June,  or  E,  Avhere  there  are  two 
annual  droughts,  January  to  March  and  June  to  August.  This  latter 
arrangement  is  shown  in  ^Madeira  in  the  A'egetation  of  certain  kinds 
of  apples.     Finally,  we  may  haA'e  in  zone  F  a  perpetual  abundance 


225 

of  both  heat  and  moisture,  in  which  case  all  annual  periodicity  dis- 
appears and  the  plant  goes  through  its  cycle  of  vegetation  independ- 
ent of  the  months  of  the  year,  as  in  the  warm  and  rainy  regions  of 
Java. 

As  before  said,  the  absolute  value  of  the  ratio  f/w  need  not  be 
considered  at  present,  and  in  fact  it  changes  with  the  units  of  time, 
of  temperature,  or  rainfall,  etc.  Linsser  divides  the  depth  of  the 
monthly  rainfall,  expressed  in  Paris  or  French  lines,  by  the  average 
temperatures  of  the  respective  months  expressed  in  degrees  Centi- 
grade. 

In  order  to  ascertain  which  of  his  European  stations  lies  in  the 
zone  A  and  which  in  the  zone  B  it  is  necessary  to  adopt  some  limit- 
ing value  for  the  ratio  /Ai',  and  to  this  end  Linsser  examines  these 
latios  in  connection  with  the  phenomena  of  plant  life,  adopting  the 
principle  that  as  two  plants  from  different  places,  accustomed  to 
different  quantities  of  heat,  behave  differently  when  they  both  receive 
the  same  quantity  of  heat,  so  also  two  plants  from  places  having  dif- 
ferent distributions  of  rain  will  behave  differently  and  arrive  at  the 
same  phase  at  different  times  when  they  are  brought  into  the  same 
place  or  under  the  same  local  climatic  influences  as  to  moisture  and 
temjjerature. 

In  order  to  decide  as  to  the  limiting  value  Linsser  studies  the 
I'atios  for  the  hottest  months  of  the  year,  which  all  relate  to  the 
ripening  phases  of  vegetation,  and  finds  that  for  the  units  of  measure 
adopted  b}"  him  the  value  of  ratio  f^'W^  that  rej)resents  approximately 
a  dividing  line  between  the  stations  that  have  an  abundance  of  rain 
in  summer  relative  to  the  summer  heat  and  those  that  have  little  rain 
relative  to  the  heat,  is  1.2.  I  have  indicated  in  the  preceding  table 
by  the  letters  A  and  B  the  stations  that  have  //i«>1.2  and  /Ay<1.2, 
and  which  Linsser  puts  into  his  zones  of  abundant  and  scanty  sum- 
mer rains,  respectivel3\ 

I  give  in  the  following  table  some  of  the  more  striking  and  perma- 
nenth^  important  results  of  Linsser's  computations.  Plis  original 
work,  based  on  about  30,000  observations,  gives  for  each  of  his  31  sta- 
tions and  for  118  species  of  plants  and  for  each  of  the  three  phases — 
leafing,  blossoming,  and  ripening — the  ordinary  phenological  con- 
stant or  sum  total  of  mean  daily  temperatures  above  0°  C.,  and  also 
his  own  physiological  constant,  which  is  the  ratio  of  this  sum  total 
to  the  annual  sum  total  for  the  station.  In  the  following  summary 
I  give  the  physiological  constant  as  it  results  from  the  average  of 
all  the  individual  stations  in  the  zone  A ;  but  for  the  sake  of  quicker 
comparison  between  the  results  for  zones  A  and  B  the  summary  gives 
not  the  physiological  constant  for  B,  but  its  departure  or  difference 
2667—05  M 15 


226 

from  that  of  zone  A.  For  example,  for  Acer  campestre  the  constant 
in  zone  A  for  leafing  is  0.131,  but  for  zone  B  it  is  less  than  that  by 
0.039,  and  would  therefore  be  0.092. 

Tabular  siinimari/  of  Linssers  results. 


Orders,  suborders,  and  species. 


Physiological  con- 
stants for  zone  A. 


Leaf-  Bloom-  Ripen- 
ing,       ing.        ing. 


Departures  of  phys- 
iological constants 
for  zone  B  from 
those  of  zone  A. 


Leaf-    Bloom-  Ripen- 
ing,      ing.        ing. 


Sapindaceae  (Acerineae): 

Acer  campestre 

Acer  platanoides 

Acer  pseudoplatanus 

Acer  tataricum 

Sapindese: 

Aesculus  hippocastanum . 

Aesculuslutea 

Aesculus  pavia  _ 

Cupuliferae  (Betuiese): 

Alnus  glutinosa 

Amygdaleae: 

Amygdalus  communis 

Amygdalus  persica 

Aristoloc*hiace£e : 

Aristolochia  sipho 

Berberidace«: 

Berberis  vulgaris 

Cupuliferae  (Betulaceaa): 

Betula  alba 

Betula  alnus 

Bignoniacese: 

Bignonia  catalpa 

Euphorbiacese: 

Buxus  sempervirens 

Papilionaceae: 

Caragana  arborescens 

Cupuliferae: 

Carpinus  betulus 

Leguminosas  (Papilionacefe): 

Cercis  siliquastrum 

Colutea  arborescens 

Tiliaceae: 

Corchorus  japonicus 

Comacese: 

Cornusalba.. 

Cornus  mascula 

Cornus  sanguinea .... 

Cupuliferae: 

Corylus  avellana 

Pomaceae: 

Cotoneaster  vulgaris 

Rosacea? : 

Crataegus  coccinea 

Crataegus  oxyacantha 

Leguminosas: 

Cytisus  laburnum 


0.131 
.100 
.132 
.132 

.107 
.114 
.132 


0.170 
.105 
.161 


.875 
.808 
.752 

.821 


-0.072 

-  .019 

-  .067 


227 


Tahuhtr  siniiDiaru  of  Liiisscr'x  results — Continued. 


Ordei-s,  suborders,  and  species. 


Thymelseacesp  (Daphnoidre): 

Daphne  laureola 

Daphne  mezereum 

Celasti-aceae: 

Euonymus  europaeus 

Euonymus  latifolius 

Euonymus  verrucosus 

Cupuliferse: 

Fagus  castanea 

Fagus  sylvatica 

Oleacese: 

Fraxinus  excelsior. 

Fraxinus  ornus 

Leguminosaj  (Papilionaceae): 

Gleditschia  triacanthos  ... 
Araliacese: 

Hedera  helix. 

ElaeagnaceaB: 

Hippopht©  rhamnoides 

nicineffi  (Aquifoliacese): 

Ilex  aquif olium 

Juglandaceae: 

Juglans  nigra 

Juglanaregia 

Oleacese: 

Ligustrum  vulgare 

Mignoliaceae: 

Liriodendron  tulipif era  . . . 
Capri  foliacese: 

Lonicera  caprif olium 

Lonieera  periclymenum  . . 

Lonicera  symphorycarpos 

Lonicera  tatarica 

Lonieera  xylosteum 

Pomacese: 

Mespilus  germanica 

Magnoliacese: 

Magnolia  yulan 

Urticaceae: 

Morns  alba 

Morus  nigra 

Saxifragaceao: 

Philadelphus  coronarius  . . 

Philadelphus  latifolius 

Coniferse  ( Abietinese): 

Pinuslarix 

Platanac«e: 

Platanus  occidentalis 


Physiological  con- 
stants for  zone  A. 

Departures   of   phys- 
iological   constants 
for    zone     B    from 
those  of  zone  A. 

Leaf- 
ing. 

Bloom- 
ing. 

Ripen- 
ing. 

Leaf- 
ing. 

Bloom- 
ing. 

Ripen- 
ing. 

0.05)0 

O.WO 

0. 375 

-t-0.030 

.061 

.039 

.433 

-fO.009 

-  .026 

-0.1*3 

.110 

.228 

.852 

-  .0.36 

—  .078 

-  .232 

.106 

.192 

.767 

-  .006 

-  .029 

-  .147 

.094 

.253 

.  775 

-  .034 

-  .105 

.148 

.a52 
.183 

.804 
.737 

-  .038 

-  .050 

.152 

-  .053 

-  .217 

.161 

.  136 

.845 

-  .049 

-  .a5o 

-  .*15 

.156 

.184 
..310 

.806 

-  .066 

-  .036 

-  .0.50 

-  .094 

.176 

.120 

.779 

-  .020 

-  .097 

.116 

.m 

.630 

-^  .053 

-  .003 

.095 

.231 

+  .0.55 

-  .111 

.203 

.227 

.798 

-  .102 

-  .077 

.161 

.196 

.794 

-  .059 

-  .060 

-  Am 

.082 

.32:5 

.841 

-  .017 

-   .055 

-  .121 

.142 

.343 
.  259 

.810 
.670 

-  .052 

-  .(m 

.05(J 

-  .060 

.049 

.286 

.663 

-  .009 

-  .033 

-  .13:3 

.072 

.2&5 

.177 

.7fi6 

.,587 

.048 

-  .008 

-  .040 

-  .227 

.085 

.190 

.624 

-  .018 

-  .0.54 

-  .254 

.130 

.246 

.921 

-  .070 

-  .068 

-  .121 

.137 

.108 

.880 

-  .0:57 

-  .008 

.166 

.249 

-  .tt57 

-  .088 

.  169 

.267 

..566 

-  .0.59 

-  .027 

-  .1.58 

.063 

.265 

.746 

-  .006 

-  .048 

-  .110 

.101 

.316 
.098 

.1 

.093 

-  .019 

-  .028 

.1(W 

.276 

.9:« 

-  .061 

-  .119 

228 


Tabular  summary  of  Linsscr's  results — Continued. 


Orders,  suborders,  and  species. 


Physiological   con- 
stants for  zone  A. 


Departures  of  phys- 
iological constants 
for  zone  B  from 
those  of  zone  A. 


Leaf-    Bloom-  Ripen-    Leaf-    Bloom-  Ripen- 
ing,       ing.        ing.        ing.        ing.        ing. 


Salicacese: 

Populus  alba 

Populus  balsamifera. 

Populus  canescens  . . . 

Populus  fastigiata  ... 

Populus  nigra 

Populus  tremula 

Amygdaleae: 

Prunus  armeniaca  _  _ . 

Prunus  aviiim 

Prunus  cerasus 

Prunus  domestica  . . . 

Prunus  padus 

Prunus  spinosa 


Ptelea  trifoliata. 


Pyrus  communis 

Pyrus  cy donia 

Pyrus  japonica 

Pyrus  malus 

Pyrus  spectabilis 

Cupiiliferae: 

Quercus  pedunculata . 

Quercus  robur 

Quercus  sessiliflora  . . . 
Rhamnacese: 

Rhamnus  cathartica. . 

Rhamnus  f rangula  . . . 
Anacardiacese: 

Rhus  cotinus 

Rhustyphina 

Saxifragacese: 

Ribes  alpinum  .... 

Ribes  grossularia 

Ribes  nigrum 

Ribes  rubrum.. 

Leguminosse: 

Robinia  pseudo-; 

Robin  ia  viscosa . 


Rosacanina 

Rosa  centifolia.- 

Rosagallica 

Rubus  idsBUS 

Rubus  odoratus. 


Salix  alba 

Salix  capraea. 
Salix  fragilis. 


0.124 

.108 


.110 
.107 
.091 


.150 
.130 
.186 

.114 
.128 

.176 
.147 

.072 
.051 


.158 
.147 


.111 
.104 
.082 


0.072 
.068 
.074 
.080 
.093 
.050 


.123 
.186 
.074 
.160 
.152 


.230 
.246 


0.517 
.300 


.480 
.175 

.621 
.421 
.419 
.659 
.545 


037 
-  .013 


033 
4-  .027 


-0.031 

■  .002 

■  .026 

-  .050 

-  .024 

-  .011 


-  .050 
+   .010 

-  .076 


.136 
.110 


297 

297 

.794 

315 

256 

.460 

348 

.480 

115 

.294 

a57 

.236 

116 

.340 

-1-  .011 
044 
074 


-  .067 

-  .048 


-  .050 

-  .101 

-  .072 

-  .042 

-  .067 

-  .027 


229 


Tabular  .tiiuniiar!/  of  Linsscr'.^  results — Continued. 


Orders,  siiborders,  and  species. 


Physiological  con- 
stants for  zone  A. 


Leaf-    Bloom-  Ripen- 
ing,       ing.        lug. 


Departures  of  phys- 
iological constants 
for  zone  B  from 
those  of  zone  A. 


Leaf-    Bloom-  Ripen- 
ing,       ing.        ing. 


Caprifoliaceae: 

Sambueus  ebulus 

Sambticus  nigra 

Sambueus  racemosa  - 


Sorbus  aueuparia  (or  Pjn'us  autn'.paria). 

Spirtea  bella 

Spirfea  hypericifolia 

Spiraea  Itevigata 

Spiraea  salicifolia 

Spiraea  sorbifolia 

Sapindaceae: 

Staphylea  pinna ta 

Staphylea  trifoliata 

Saxifragaceae: 

Syringa  persica 

Syringa  vulgaris. 

Coniferae: 

Taxus  baccata 

Tiliaceae: 

Tilia  europaea 

Tilia  graudifolia 

Tilia  parvifolia 

Urticaceae: 

Ulmus  campestris .• 

L^mus  effusa - 

Caprifoliacete  ( Lonicerae): 

Viburnum  lantana. 

Viburnum  opulus 

Vitacese : 

Vitis  vinifera 


0.105 
.067 


.183 
.174 


.073 
.063 


l-hO.005 

-  .066 

-  .018 

-  .047 


.07 


-  .156 

-  .156 


-  .046 

-  .087 


-  .028 

-  .015 


.057 
.075 


-0.150 

-  .053 

-  .173 


.025 
.128 


.242 
.108 


.152 
.258 


In  the  original,  from  which  the  foregoing  abstract  is  copied,  Linsser 
gives  the  so-called  probable  error  or  the  limit  of  uncertainty  as 
deduced  from  the  agreement  among  themselves  of  the  numerous 
individual  determinations  of  the  physiological  constants  in  zone  A, 
whereas  the  mean  values  alone  are  given  in  our  summary.  It 
appears  that  the  uncertainties  are  larger  for  the  ripening  jDhase  than 
for  the  leafing  and  blooming  phases,  if  we  consider  only  their 
absolute  values,  but  decidedly  smaller  if  we  consider  their  relative 
values.  In  general  the  uncertainty  of  the  constant  for  leafing  is 
about  one-twentieth  of  its  own  value,  the  uncertainty  of  the  constant 
for  blooming  is  about  one-fortieth  of  its  own  value,  and  the  uncer- 
tainty of  the  constant  for  ripening  is  about  one-fiftieth  of  its  own 
value. 


230 

The  values  of  the  constants,  as  deduced  from  stations  that  lie  in 
the  dry  zone  B,  vary  much  more  than  those  in  zone  A;  but  this  is  a 
necessary  consequence  of  the  law  of  growth,  since  in  such  dry  regions 
the  quantity  of  heat  required  to  produce  a  given  phase  ceases  to  be  a 
simple  constant  and  becomes  a  complex  function  of  the  available 
heat  and  moisture  and  depends  upon  the  individual  ratio  f/w  at  each 
station.  It  will  of  course  be  noticed  that,  with  few  exceptions,  the 
figures  in  the  columns  of  departures  are  negative,  thereby  indicating 
that  the  quantities  of  heat  actually  utilized  by  plants  in  the  dry 
localities  in  zone  B  are  less  than  the  quantities  utilized  by  the  same 
plant  when  it  has  an  abundance  of  moisture  in  zone  A.  Most  of  the 
17  positive  figures  among  these  departures  relate  to  the  period  of 
leafing,  and  many  of  them  are  but  little  larger  than  the  limit  of 
uncertainty  deduced  by  Linsser  for  the  respective  plants. 

All  of  the  plants  investigated  by  Linsser  belong,  as  is  seen  by  the 
above  list  of  names,  to  the  exogens.  They  are  also  perennials,  but 
his  intention  was  to  extend  this  investigation  to  the  herbaceous  annu- 
als, and  a  large  mass  of  work  in  this  direction  had  been  accomplished 
before  his  untimely  death  in  1871. 

The  conclusions  drawn  by  Linsser  from  the  data,  as  summarized 
in  his  published  tables,  may  be  presented  as  follows : 

Although  the  general  fact  above  mentioned,  that  plants  growing 
in  regions  that  have  scant  summer  rains  utilize  less  heat  and  less 
moisture  to  produce  a  given  phase  of  development  than  similar  plants 
having  the  same  quantity  of  heat  at  their  disposal  with  plenty  of 
rain  during  the  summer,  might  be  considered  as  only  a  further  con- 
sequence easily  deduced  from  the  principle  that  underlies  the  theory 
of  Linsser's  physiological  constant,  yet  we  may  also  consider  the  fact 
as  one  established  empirically  and  seek  for  the  most  probable  expla- 
nation. Any  general  relation  between  the  vital  phenomena  of  plants 
and  their  external  influences  can,  according  to  the  ideas  established 
in  Linsser's  first  memoir,  be  looked  upon  either  as  due  to  temporary 
influences  or  as  a  consequence  of  the  habits  of  the  plant.  If  we  adopt 
the  former  view,  then  the  cause  of  the  accelerated  development  of 
plants  in  zone  B  will  consist  in  the  fact  that  from  the  beginning  of 
vegetation  onward  one  or  more  accelerating  forces  have  come  into 
play,  the  intensit}^  and  duration  of  whose  action  is  greater  for  sta- 
tions in,  zone  B  than  in  zone  A.  Such  accelerating  forces  may  consist 
in  a  greater  quantity  of  heat  or  of  sunshine  or  possibly  other  influ- 
ences. But  when  we  come  to  examine  the  temperature  curves  for 
stations  in  the  two  zones  we  see  at  once  that  heat  alone  can  not  be 
considered  as  the  stimulating  force.  A  similar  comparison  shows  that 
rainfall  during  the  growing  season  can  not  be  the  stimulus.  Again, 
stations  such  as  Parma  and  Pessan  show  that  great  differences  in 


231 

sunshiiio  alone  fail  to  give  n  sufficient  explanation.  Finally,  a  natural 
and  sufficient  explanation  is  found  in  the  study  of  the  relation  of  the 
rainfall  in  summer  to  the  gi^^en  climatic  conditions,  as  has  already 
been  done  in  the  study  of  the  heat;  it  is  not  the  rainfall  of  the  spring 
months  that  stimulates  the  plant,  but  it  is  the  drought  of  the  suc- 
ceeding summer,  or,  as  it  were,  the  knowledge  of  that  approaching 
drought  which  stimulates  the  plant  to  hasten  and  complete  its  devel- 
opment in  the  springtime  or  earliest  summer.  The  plants  of  the 
north  are  accelerated  because  of  the  rapidly  approaching  autumn; 
the  plants  of  the  highlands  because  of  the  shortness  of  the  approach- 
ing summer;  the  plants  of  the  steppes  and  of  regions  with  rainless 
summers  hasten  in  order  to  have  their  work  finished  Avhen  the  time 
arrives  at  which  their  activity  should  come  to  an  end.  The  plants  at 
localities  in  our  zone  B  complete  their  labors  in  the  springtime  be- 
cause of  the  drought  of  the  coming  summer;  under  almost  the 
same  external  conditions  the  plants  at  Parma  hasten  their  develop- 
ment while  those  at  Venice  live  leisurely  along;  the  plants  at  Vienna, 
Breslau,  and  Kief  accelerate  their  growth,  while  the  same  plants  at 
Heidelberg,  Gorlitz,  and  Orel  live  leisurely. 

The  problem,  so  often  discussed,  of  the  reforestation  of  the  steppes 
is  thus  referred  back  to  another  -more  definite  problem,  viz.,  the 
acclimatization  in  the  steppes  of  those  plants  whose  normal  cycle  of 
vegetation  in  their  native  locality  is  such  that  when  transplanted 
to  the  steppes  these  processes,  especially  the  blossoming  and  leafing, 
can  go  on  with  sufficient  rapidity  to  be  completed  before  the  begin- 
ning of  the  hot,  dry  summer.  Quite  similarly  the  problem  of  culti- 
vation of  fruit  in  those  regions  can  be  thus  exactly  defined.  Thus 
Helmersen  states  that  experiments  with  fruit  trees  brought  from 
Hamburg  to  Orenburg  entirely  failed.  But  here  we  have  to  do  with 
a  double  violation  of  the  theory,  since  the  plants  brought  from  Ham- 
burg came  to  a  locality  having  a  much  smaller  annual  sum  of  heat 
and  were  not  yet  adjusted  to  the  dryness  of  the  Orenburg  summers, 
wherefore  they  continued  living  at  Orenburg  according  to  the  easy 
habit  acquired  at  Hamburg.  Linsser  suggests  that  success  would  be 
much  more  likely  if  plants  were  taken  to  Orenburg  from  Bokhara  or 
Khiva,  where  the  extraordinary  rapidity  of  development,  on  account 
of  the  great  drjaiess  of  the  summer  following  after  a  rainy  spring  is 
well  known. 

Further  questions  as  to  the  temporary  influence  of  rainfall  during 
any  part  of  a  cycle  of  vegetation  must  be  investigated  by  studying 
the  life  of  plants  at  localities  having  very  different  climates. 

After  studies  on  the  development  of  vegetation  in  various  climates 
throughout  the  world,  in  all  of  which  the  rainy  season  is  the  blossom- 


232 

ing  time,  while  the  dry  season  is  the  ripening  time,  Linsser  gives  the 
following  general  conclusions : 

There  are  two  especial  laws  regulating  the  life  of  every  individual 
plant,  (1)  the  individual  habit;  and  (2)  the  principle  of  econom3^ 
The  application  of  these  principles  explains  and  gives  us  a  better 
comprehension  of  the  course  of  vegetation  under  the  equator  as  well 
as  near  the  pole. 

The  principal  factors  in  the  life  of  plants  that  we  have  thus  far 
considered  are  heat  and  moisture.  If  the  former  is  that  whose 
periodicity  gives  warning  of  the  necessity  of  economy,  then  the 
whole  life  of  the  plant  is  intimately  dependent  on  the  course  of  this 
heat,  as  in  the  extreme  north  and  the  greater  part  of  the  Temperate 
Zone  where  the  moisture  is  otherwise  sufficient.  If  it  is  the  moisture 
that  is  subject  to  large  periodical  changes  and  the  question  of  suf- 
ficiency of  heat  becomes  unimportant  because  of  its  uninterrupted 
abundance,  then  the  cycle  of  vegetable  life  depends  upon  the  peri- 
odicity of  this  moisture,  as  in  Madeira.  If,  finally,  the  variations  of 
the  climate  are  such  that  there  is  sometimes  insufficient  heat  and 
moisture,  then  the  necessity  of  economy  in  the  use  of  both  of  these 
materials  is  enforced,  and  in  the  course  of  the  year  the  plant  seeks  to 
develojD  as  far  as  possible  in  accordance  with  both  these  necessities, 
as  in  the  Steppes  of  southern  Eussia  and  near  Bokhara  and  in  isolated 
shady  locations  such  as  mountain  sides. 

The  law  of  fractional  parts  of  the  total  annual  quantit}'^  of  heat,  as 
demonstrated  in  Linsser's  first  memoir,  is  therefore  now  seen  to  be 
only  a  special  case,  for  northern  and  temperate  latitudes,  of  the  gen- 
eral proposition  just  enunciated.  The  former  w\as  the  first  approxi- 
mation toward  a  rational  theory  of  the  periodical  phenomena  of  vege- 
tation, just  as  this  more  general  proposition  is  the  second  approxima- 
tion. 

We  have  thus  far  studied  principally  the  differences  in  the  life  of 
plants  due  to  differences  of  climate  in  different  localities.  It  still 
remained  for  Linsser  to  study  the  peculiarities  of  the  same  plants  in 
different  years  in  the  same  locality,  to  which  end  his  manuscript 
material  already  offered  a  sufficient  basis. 

Of  the  questions  proper  to  be  considered  in  this  second  category, 
viz,  the  study  of  plant  life  as  depending  on  temporary  variations  of 
local  climates,  Linsser  enumerates  the  following  as  having  already 
been  taken  up  by  him,  viz :  (1)  The  influence  of  cloudiness,  insolation, 
and  atmospheric  pressure;  (2)  the  especial  influence  of  the  various 
distributions  of  rain  on  the  individual  periods  of  vegetation;  (3)  the 
relation  of  the  length  of  the  da}^  and  the  night,  as  also  of  light 
itself,  on  the  plant;  (4)  the  influence  of  the  nonperiodic  variations 
of  temperature;  (5)  the  influence  of  cold  or  warm  winters  on  the  sub- 
sequent summer's  growth;   (6)  the  investigation  of  the  sums  of  tem- 


233 

perature  for  the  same  phases  of  phmt  life  from  year  to  year,  and 
the  reason  of  their  variations.  On  this  hist  point  he  concludes  by 
stating  that  it  is  well  known  these  sums  do  vary  from  year  to  year 
for  each  phenological  epoch.  For  the  present  he  states  only  that 
these  temperature  sums  are  not  only  apparently,  but  in  reality,  not 
constant,  and  from  his  preliminary  work  for  this  second  series  of 
studies  the  most  important  causes  that  determine  the  sum  total  had 
already  become  known  to  him.  Without  anticipating  too  much  the 
course  of  further  investigations,  he  states  that  studies  already  finished 
demonstrate  that  there  should  be  differences  annually  in  the  tempera- 
ture sums,  as  is  evident  from  the  folloAving  consideration :  If  seeds 
brought  from  Stuttgart  to  Christiania  accelerate  in  successive  gener- 
ations in  successive  years  because  of  the  smaller  sum  total  of  heat 
in  their  new  home,  then  exactly  the  same  w^ould  occur  if  the  plants 
remain  in  Stuttgart  and  w'e  at  that  place  offer  them  the  sum  total  of 
heat  peculiar  to  Christiania.  That  is  to  say,  seeds  that  have  ripened 
at  any  one  place  in  colder  years  produce  plants  that  develop  more 
rapidly  than  do  seeds  from  the  same  place  but  which  were  ripened  in 
warmer  j^ears. 

APPLICATION    OF    LINSSEr's    RESULTS. 

This  application  to  each  plant  and  each  locality  of  the  principle  of 
economy  which  Linsser  had  established  from  the  geographical  dis- 
tribution of  plants  offers  to  us  by  far  the  most  important  principle 
yet  discovered  and  well  established  to  guide  us  in  the  development  of 
grains  and  plants  appropriate  to  the  vicissitudes  of  our  climate.  For 
instance,  in  general  it  is  desirable  to  sow  and  plant  so  as  to  avoi(^ 

the  early  autumn  frosts  and  the  late  spring  frosts — that  is  to  say,  to  \ ^ 

secure  varieties  of  plants  whose  course  of  vegetation  will  be  complete 
in  the  very  short  time  that  is  free  from  danger  of  frost.  Therefore, 
if  we  wish  to  develop  plants  that  wall  ripen  in  the  earliest  summer, 
before  the  droughts  destroy  them,  as  in  the  region  from  Nebraska  to 
Texas,  then  Ave  have  to  remember  that  the  seed  perfected  in  Kansas  in 
a  dry  year  is  already,  by  its  own  experiences,  prepared  to  become  the 
best  seed  for  sowing  in  anticipation  for  the  next  dry  year.  The 
seeds  raised  in  dry  years  should  therefore  alwaj'^s  be  preserved  for 
sow-ing,  as  likely  to  be  far  more  appropriate  than  any  seed  that  may 
be  brought  from  a  distance,  unless  brought  from  a  region  where 
equally  dry,  short  seasons  prevail,  as  in  southern  Russia  and  Bokhara. 
The  rule  of  sowing  one  year  the  seed  raised  the  preceding  year  is, 
in  general,  not  the  best  rule.  By  always  utilizing  as  seed  that  which 
is  raised  in  the  driest  years  one  may  hope  speedily  to  develop  plants 
whose  vegetating  period  will  be  so  short  that  the  crop  will  rarely  be 
injured  by  the  dry,  hot  winds  of  July.  A  similar  rule  holds  good 
for  any  modification  we  desire  to  make  in  the  seed.     If  we  wish  to 


234 

raise  plants  peculiarly  fitted  for  wet  climates  or  for  cold  climates, 
we  begin  with  the  seed  that  was  rij^ened  in  wet  or  cold  seasons. 

I  think  that  probably  a  further  prosecution  of  Linsser's  studies 
would  have  led  to  the  conclusion  that  the  influence  of  sunlight  and  dif- 
fuse sky  light  is  the  next  important  factor  in  vegetation,  and  that  the 
quantity  and  quality  of  the  seeds  produced — that  is  to  say,  of  the  crop 
as  distinguished  from  the  mere  epoch  of  ripening — depends  upon  the 
ratio  of  the  nutrition  carried  up  in  the  sap  to  the  total  intensity  of 
sunshine.  The  grain  harvests  of  the  world  may  be  divided  into 
zones  «,  Z>,  (?,  analogous  to  the  phenological  zones  that  Linsser  has 
given,  and  in  which  the  quantity  of  the  harvests  is  large  when  the 
nutrition  is  sufficient  to  use  up  all  the  sunshine,  but  is  small  when 
either  nutrition  or  sunshine  is  deficient.  As  the  plant  begins  a  new 
cycle  so  soon  as  the  last  is  finished  and  usually  is  delayed  by  the 
speedj'^  approach  of  winter  cold  or  autumnal  drought,  therefore 
Linsser's  laws  would  lead  us  to  the  conviction  that  by  artificially 
regulating  the  temperature,  moisture,  sunshine,  or  artificial  light,  and 
the  nutrition  in  the  soil,  we  ought  to  be  able  to  develop  an  ideal 
method  of  cultivation  that  should  gi*eatly  increase  the  number  of 
crops  per  j^ear  and  the  yield  per  acre,  and  especially  so  within  small, 
limited  areas  that  are  protected  by  cover  from  injurious  frosts. 

The  need  of  water  for  the  varieties  of  plants  and  seeds  usually  cul- 
tivated has  led  to  great  engineering  projects  for  irrigation,  and  the 
scarcity  of  natural  rainfall  has  led  to  wholesale  condemnation  of 
many  arid  regions  as  being  unfit  for  profitable  agriculture,  but  the 
progress  of  knowledge  now  shows  us  that  nature  has  a  power  at  work 
gradually  overcoming  these  disadvantages,  and  that  man  by  taking 
advantage  of  her  ways  may  profitably  cultivate  crops  in  extreme  cli- 
mates and  soils,  not  so  much  by  irrigation  as  by  developing  seeds  and 
plants  that  suit  the  natural  circumstances,  just  as  our  own  ancestors 
developed  our  European  grains  from  the  grasses  of  Asia  or  our  wide- 
spread maize  from  the  weeds  of  Mexico.  It  is  the  duty  of  our  agri- 
cultural experiment  stations  to  lead  the  way  in  this  evolution  of  new 
varieties  quite  as  much  as  in  the  mere  introduction  or  acclimatization 
and  study  of  old  varieties.  Now  that  we  have  learned  the  secrets  of 
Nature's  method  of  evolution  we  must  hasten  to  apply  it  to  the  needs 
of  mankind. 

DOVE. 

In  184G  H.  W.  Dove  wrote  as  follows : 

In  the  tropical  regions  the  mean  temperature  of  an}^  year  differs 
but  little  from  that  of  any  other,  but  the  quantity  of  rainfall  differs 
largely.  The  result  is  that  the  yield  of  crops  varies  exceedingly,  not 
onh^  on  loAvlands  that  depend  upon  the  periodical  floods  of  the  rivers, 
but  also  on  the  islands,  where  there  are  no  large  rivers.  Therefore 
in  these  climates  the  agriculturist  cares  less  about  the  temperature 
than  about  the  rainfall. 


235 

In  Europe,  however,  the  connection  between  the  temperature  of  the 
air  and  vecvtation  is  so  intimate  that  some  investigators  maintain 
that  on  the  occurrence  of  a  given  tem[)erature  the  phmt  enters  at  once 
upon  a  corresponding  definite  stage  of  develojDment,  "while  others 
maintain  that  in  order  to  enter  into  this  stage  a  definite  sum  total  of 
heat  must  be  received.  Therefore  the  former  determined  the  stages 
of 'develoi3nient  by  the  ordinates  of  the  annual  curve  of  temperature, 
while  the  latter  determine  them  by  the  area  of  the  space  that  is 
bounded  by  such  ordinates.  Tt  is  evident  that  if  under  a  given  lati- 
tude the  temperature  of  the  atmosphere  is  the  principal  factor,  Avhile 
under  another  latitude  the  moisture  of  the  atmosphere  is  the  princi- 
pal factor,  tlien  neither  of  these  should  be  entirely  overlooked,  but  the 
part  played  by  each  must  be  examined.  To  this  end  the  study  of  the 
geogra23hical  distribution  of  plants  gives  very  little  information. 
Again,  the  study  of  the  influence  of  periodic  variations  of  the  atmos- 
phere on  plants  is  useless  in  the  attempt  to  distinguish  between  the 
effects  of  temperature  and  moisture,  because  as  a  general  rule  the 
atmospheric  conditions  all  attain  their  maxima  and  minima  at  about 
the  same  time.  The  study  of  the  nonperiodic  variations  gives  prom- 
ise of  greater  success.  But  in  studying  the  relation  of  temperature  to 
vegetation  the  data  given  by  thermometers  hung  in  the  shade,  as  to 
the  temperature  of  the  air,  can  have  little  to  do  with  the  life  of  the 
plant  as  compared  with  the  temperature  given  by  a  thermometer 
ex]:)Osed  to  the  full  sunshii\e  by  day  and  the  radiation  from  the  sky 
by  night. 

Dove  then  discusses  the  observations  of  maximum  sunshine  and 
minimum  radiation  thermometers  made  in  the  botanic  garden  at 
Chiswick,  near  London,  from  1816  to  1840,  and  shows  among  other 
things  that  when  the  mean  temperature  of  the  air  is  low  the  freely 
exposed  radiation  thermometer  is  especially  low,  and  when  the  aver- 
age temperature  is  high  the  freely  exposed  solar  thermometer  is  es- 
pecially high.  He  then  investigates  the  observations  of  earth  tem- 
perature made  by  Quetelet,  of  Brussels,  from  1834  to  1843,  and  shows 
that  the  upper  layers  of  soil,  whether  dry  or  wet,  have  temperature 
variations  parallel  to  those  of  the  temperature  of  the  air.  He  then 
studies  the  phenological  observations  of  Eisenlohr  at  Carlsruhe 
from  1779  to  1830.  These  show  that  a  plant  enters  into  a  definite 
stage  of  development  when  the  air  attains  a  definite  degree  of  tem- 
perature rather  than  when  the  plant  has  received  a  definite  sum  total 
of  heat,  this  conclusion  being,  of  course,  based  upon  the  internal 
agreement  of  the  computed  figures  for  these  fifty-one  years  of 
observations. 

Analogous  results  were  obtained  by  him  by  studying  similar  ob- 
servations made  in  the  State  of  New  York  and  at  Wurttemberg, 
Germany. 

With  regard  to  the  influence  of  rainfall.  Dove  finds  that  it  is  not 
so  plain  as  that  of  temperature,  and  that  it  is  not  so  much  the  quan- 
tity of  rainfall  that  is  important  as  the  frequency;  too  great  fre- 


236 

quency  is  injurious,  inasmuch  as  the  cloudiness  cuts  off  the  influence 
of  sunshine.  The  fact  that  years  of  low  temperature  are  always 
years  of  poor  crops  is  a  fact  that  must  be  generally  considered  as  a 
local  phenomenon  because  of  the  simultaneous  conpensation  as  to 
temperature  that  is  continually  going  on  in  contiguous  localities. 

HOFFMAN. 

Prof.  Dr.  H.  Hoffmann  published,  first  at  Giessen  and  afterwards 
in  the  Memoirs  of  the  Senckenberg  Association  at  Frankfort  (Vol. 
VIII,  1872),  the  details  of  a  work  which  he  began  in  Giessen  in  1866 
on  the  relation  between  the  development  of  plants  and  the  tempera- 
ture recorded  by  a  maximum  thermometer  in  full  sunshine.  Some 
account  of  that  work  and  its  subsequent  continuation  at  Giessen  is 
given  in  successive  papers  published  in  the  Journal  of  the  Austrian 
Meteorological  Association  (Zeitschrift  O.  G.  M.)  during  the  years 
1868  to  1891.  The  detailed  references  to  these  will  be  found  in  the 
list  of  papers  af)pended  to  this  present  report.  Hoffmann's  first 
conclusion,  as  stated  in  1868,  was  that  he  had  found  a  precise,  intel- 
ligible, and  comparable  expression  for  the  quantity  of  heat  that  is 
needed  for  the  attainment  of  any  definiie  phase  of  vegetation.  He 
would  take  the  sum  of  the  daily  maxima  of  a  thermometer  fully  ex- 
posed to  the  sunshine.  His  first  work  at  Giessen  was  done  with  a 
naked  glass  bulb,  self-registering,  mercurial,  maximum  thermometer, 
graduated  to  Reaumur's  scale,  attached  to  a  wooden  frame  and  set 
out  in  full  sunshine  4.5  French  feet  above  the  soil  or  green  sod  in  an 
open  portion  of  the  botanic  garden  at  Frankfort.  The  exposure  was 
indeed  not  perfectly  free,  but  was  such  that  the  sun  shone  upon  the 
thermometer  from  sunrise  to  2  p.  m.  in  January  and  until  4.30  p.  m. 
in  June.  Hoffmann's  summations  begin  with  midwinter,  or  January 
1,  and  he  gives  the  sums  of  the  positive  daily  maxima  (i.  e.,  above 
0°  Reaum. )  up  to  the  dates  of  leafing  and  flowering  for  10  plants. 

Apparently  preliminary  values  are  given  in  the  Journal  of  the 
Austrian  Meteorological  Society  for  1868  and  1869,  but  final  values 
in  the  memoir  published  at  Frankfort,  1872. 

In  the  Meteorologische  Zeitschrift  for  1875  Hoffmann  says  that 
after  four  years'  work  at  Giessen  (1866-1869)  his  thermometer  was 
broken.  A  new  one  was  constructed  by  Dr.  J.  Ziegler,  of  Frankfort, 
in  accordance  with  their  mutual  understanding;  this  had  a  mercurial 
bulb,  but  was  very  many  times  larger  than  the  former,  and  therefore 
very  much  more  sluggish.  Observations  with  such  instruments, 
graduated  to  accord  with  the  Reaumur  scale,  were  begun  in  1875  by 
Hoffmann  at  the  botanic  gardens  at  Giessen,  and  by  Ziegler  at  the 
gardens  at  Frankfort.  In  order  to  compare  these  two  series  together 
and  to  unite  them  with  the  earlier  Giessen  series  the  ratios  of  the 
sums  as  given  by  the  earlier  and  the  later  thermometers  for  the  same 


237 

plant  were  taken,  and  it  was  found  that  the  ratios  are  very  nearly  the 
same  for  all  jDlants;  therefore  the  ratio  given  by  the  best  series,  viz, 
for  Lonicera  alplgena  was  taken  as  a  standard  and  applied  to  the 
series  for  the  other  plants,  so  as  to  reduce  all  observations  with  the 
later  thermometers  back  to  agreement  with  what  would  have  been 
given  by  the  first  thermometer  had  it  not  been  broken.  The  ratios 
of  the  sums  observed  at  Giessen  with  the  new  thermometer  as  com- 
pared with  the  sums  observed  at  Frankfort,  also  with  a  similar  new 
thermometer,  agreed  closely  for  all  the  plants,  and  as  the  two  new 
thermometers  agree  closely  with  each  other  when  placed  side  by 
side,  it  was  assumed  that  the  ratios  thus  obtained  represent  the  reduc- 
tion from  the  climate  of  Frankfort  to  that  of  Giessen.  Adopting  the 
same  standard  plant  and  the  ratio  of  its  sums  for  any  place  to  its 
sums  at  Giessen  as  the  standard  ratio,  all  the  sums  for  plants  at  that 
place  can  be  reduced  to  what  would  have  been  given  by  the  same  plants 
at  Giessen  and  to  what  w^ould  haA^e  been  given  by  the  first  Giessen 
thermometer.  Although  these  reductions  are  very  arbitrary,  yet  the 
agreement  of  the  sums  thus  computed  for  Giessen  with  those  actually 
observed  was  quite  close.  But,  as  we  shall  see,^subsequent  years  of 
observations  have  shoAvn  that  such  agreements  do  not  always  recur. 

In  the  Zeitschrift  for  1881  Hofl'mann  shows  that  it  is  not  the  low 
temperatures  but  the  subsequent  too  rapid  thawing  that  injures  most 
plants;  thus  the  hill  stations  suffered  less  at  the  close  of  a  period 
Avhose  lowest  temperature  was  — 31°  Reaum.  than  did  the  plants  in 
the  lowlands;  the  shady  side  of  the  tree  suffered  less  than  the  sunny 
side.  It  i&  indifferent  Avhether  the  sudden  rise  in  temperature  is 
caused  by  great  solar  rays  or  by  a  sudden  warm  wind ;  the  sudden  rise 
from  — 12°  Reaum.  to  -|-13°  Reaum.  is  as  bad  for  plants  as  the  sud- 
den rise  from  — 20°  Reaum.  to  -(-5°  Reaum.;  the  amount  of  injury  is 
proportional  to  the  extent  and  to  the  suddenness  of  the  rise. 

In  the  same  volume  of  the  Zeitschrift  (p.  330)  Hoffmann  givew 
the  results  of  observations  at  Giessen  for  1880.  He  finds  that  the 
blossoming  in  spring-time  is  so  subject  to  disturbances  by  frost  that  the 
midsummer  and  autunmal  phases  of  vegetation  are  more  proper  to 
show  the  accuracy  of  his  methods.  He  finds  that  these  later  phases, 
as  observed  at  Giessen  (1866-1869),  when  reduced  to  the  new  stand- 
ard thermometer  at  Giessen  agree  within  1  per  cent  with  the  actual 
observations  of  1880  at  that  place.  For  plants  that  bloom  in  the 
spring  he  finds  that  if  these  are  protected  from  injur}'^  by  frost  by 
placing  them  under  glass  covers  there  is  then  a  better  but  still  unsat- 
isfactory agreement  between  the  observations  at  Giessen  and  Frank- 
fort. On  computing  the  mean  temperature  of  the  air  in  the  shade  for 
the  dates  of  blooming  at  Giessen  he  finds  no  apparent  connection,  so 
that  from  the  date  of  blooming  we  can  not  infer  the  mean  tempera- 
ture of  that  day  nor  can  we  reason  from  the  temperature  to  the  date. 


238 

The  sum  total  of  daily  maximum  sun  temperatures  at  Giessen  is 
much  more  nearly  constant. 

In  the  Zeitschrift  for  1882  Hoffmann  gives  the  sums  of  the  daily 
positive  readings  of  his  naked  bright-bulb  mercurial  thermometer  in 
the  full  sunshine;  he  also  gives  the  sums  of  the  temperature  in  the 
shade,  and  computes  the  average  discrepancy  or  probable  error  of 
these  numbers  as  deduced  from  their  internal  agreement  year  by  year. 
He  finds  the  jjrobable  uncertainty  of  the  sums  of  maxima  to  be  plus 
or  minus  1  per  cent  and  of  the  sums  of  shade  temperatures  to  be  plus 
or  minus  10  per  cent.  These  latter  sums  relate  to  low-lying  stations, 
such  as  Vienna  and  Dorpat,  and  these  discrepancies  diminish  very 
much  when  we  consider  high  mountain  stations,  where  the  shade 
temperatures  of  course  give  much  smaller  sum  totals.  He  recognizes 
that  the  advantage  of  using  the  shade  temperatures  lies  in  the  greater 
comparability  of  the  observations  made  at  different  stations  and  with 
different  instruments,  but  that  the  sunshine  method  is  also  greatly 
improved  if  the  thermometers  are  perfectly  similar  and  properly 
compared  together,  as  in  the  instruments  made  by  Doctor  Ziegler  at 
Frankfort.  (8ee  the  report  of  the  Senckenburg  Association,  1879- 
1880,  p.  337.)  Hoffman's  observations  with  a  varietj^  of  instruments 
convinced  him  that  this  difficulty  as  to  instruments  and  exposures 
is  not  insurmountable.  He  collects  comparative  readings  at  several 
places  and  shows  that  the  difference  between  the  average  tempera- 
tures in  the  sun  and  in  the  shade  is  larger  at  higher  altitudes;  thus 
at  Giessen  the  average  difference  in  summer  at  midday  is  5°  Reaum., 
and  the  whole  range  of  the  differences  between  sunshine  and  shade 
is  from  3°  to  15°  Reaum.  The  corresponding  average  in  the  Hochge- 
birge,  7,000  feet,  is  never  less  than  8°  Reaum.  At  the  Bernina 
hospice,  8,113  feet,  it  is  25°  Reaum.  The  average  temperature  of 
these  mountain  stations  is  16.4°  Reaum.,  corresponding  to  an  elevation 
of  about  6,000  feet.  Similarly,  J.  D.  Hooker  observing  a  black-bulb 
thermometer  in  the  sunshine  in  the  Himalayas,  found  a  difference  of 
— 15°  Reaum.  at  7,400  feet  elevation,  as  contrasted  with  4.4°  at  sea 
level.  R.  S.  Ball,  also  using  a  black  bulb,  finds  a  difference  of  18°  or 
20^  Reaum.  in  the  Hochgebirge  and  of  only  3°  at  Chiswick. 

These  differences  show  the  effect  of  the  great  dryness  and  mechan- 
ical purity  of  the  air  in  the  Hochgebirge.  Hoffmann  considers  the 
smoke  and  clouds  above  us  as  affecting  the  difference  between  the  sun 
and  shade  thermometers,  but  says  nothing  of  the  earth's  surface  which 
completes  the  "  inclosure  "  of  the  thermometer. 

The  date  from  which  Hoffmann  begins  his  summation  for  Giessen 
is  January  1 ;  but  as  it  would  seem  more  proper  to  begin  with  some 
definite  phase  of  vegetation,  therefore  he  investigates  the  accuracy 
with  which  we  can  determine  the  initial  phase  and  the  effect  of  errors 
therein  upon  the  ultimate  sums.     By  painting  the  buds  of  certain 


239 

trees  and  oxtimining  them  very  freciuently  Hoffinann  seeks  to  deter- 
mine how  accuratel}'  the  date  of  the  beginning  of  vegetation  or  the 
flow  of  sap  can  be  determined  by  the  swelling  of  the  buds  and  the 
visible  cracking  of  the  delicate  pencil  lines  of  paint.  lie  finds  that 
the  date  can  be  determined  to  within  one  day  when  spring  comes  on 
rapidly,  but  within  eight  days  when  it  comes  very  slowly.  The  cor- 
responding uncertainty  or  variability  of  the  sums  of  the  maximum 
sunshine  thermometer  from  the  swelling  of  the  buds  up  to  the  date 
of  the  first  blossom,  for  instance,  for  Castanea  vulgaris,  is  -t  per  cent 
while  the  uncertainty  of  similar  sums,  counting  from  January  1, 
is  only  1  per  cent.  These  and  similar  data  are  only  deducible  from 
observations  made  upon  the  same  tree  or  bush  from  year  to  year; 
the  variations  are  materially  increased  when  different  plants  in  dif- 
ferent localities  are  observed ;  moreover,  they  are  based  upon  observa- 
tions for  only  four  years,  which  period  is  not  long  enough  to  give  a 
reliable  value  of  the  relative  inicertainties.  As  in  previous  cases  in 
making  up  these  abstracts,  I  give  Hoffmann's  actual  figures  in  the 
following  summary,  which  I  have  compiled  by  collating  the  few 
observations  published  by  him  in  the  Zeitschrift  during  the  j^ears 
1870-1890.  I  have  selected  only  the  few  plants  for  which  he  has 
published  the  sums  for  several  years  or  for  two  localities,  so  that 
comparisons  may  be  made  and  a  judgment  arrived  at  as  to  the  pro- 
priety of  his  method.  It  will  be  observed  that  Hoffmann  has,  when 
possible,  observed  the  same  tree  or  bush  from  year  to  year,  so  that 
the  problem  of  the  influence  of  heat  is  much  more  definite  than  when 
different  plants  or  a  general  mass  of  plants  is  observed;  but,  on  the 
other  hand,  single  plants  are  more  liable  to  irregularities  produced 
by  special  disturbances  which  would  exert  no  appreciable  influence 
on  the  average  of  a  large  number  of  similar  plants. 

Temperature  sums  at  Glessen    (Iloffmanirs  method)   from   the  first  sivelliii(/  of 

the  buds  to  the  first  blossom. 

[Z.  O.  G.  M.,  Vol.  XVII,  1882,  p.  127.     All  in  Reaumur  degrees.] 


Castanea  vulgaris  . . . 
Catalpa  syringafolia. 
Lonicera  alpigena: 

First  specimen . . . 

Second  f  pecimen 
Persica  vulgaris: 

Fir.st  specimen 

Second  specimen. 
Syringa  vulgaris: 

First  specimen . . . 

Second  specimen. 
Vitis  vinifera: 

First  specimen  . . . 

Second  specimen. 


2,142 


2,085 
1,984 


1,058 
1,058 


1,315 
1,181 


1,04(J 

me, 


2,317 
2,547 


1,014 
1,032 


1,248 
1,16<> 


1,5:^1 
1,222 


240 


Temperature  sums  from  January  1  to  the  date  of  first  blossom   {by  Hoffmann's 
method)  at  Oiessen  and  at  Frankfort. 

[Z.  O.  G.  M.,  Vol.  X,  1875,  p.  251,  and  Vol.  XVI,  p.  331.     All  in  Reaumur  degrees.] 


Lonicera  alpigena 

Sambucus  nigra — 

Berber  is  vulgaris 

Prunusavium 

Syringa  vulgaris — 

Aesculus  hippocastanum  . 

Vitis  vinifera - 

Prunus  spinosa 


Giessen. 


ther-- 

mometer 

A. 


1,167 
1,678 
1,317 
1,077 

1,317 
2,600 


1,315 
1,091 

1,091 
1,069 
1,995 


mometer  mometer 
Bi.  Bo. 


Frank- 
fort, 1875, 

ther- 
mometer 


1,110 


Temperature  sums  {by  Hoffmann's  method)  at  Oiessen  from  January  1  to  fir^t 
blossom,  for  plants  that  blossom  in  midsummer  and  autumn. 


[Z.  o.  G. 


Vol.  XVI,  p.  331,  and  Vol.  XVII,  p.  130  ;  M.  Z.,  Vol.  I,  p.  407,  and  Vol.  Ill, 
p.  546.] 


Plant  (always  same  stock). 

Ther- 
mom- 
eter A, 
1866- 
1869. 

Thermom- 
eter Bi. 

Thermometer  Bo. 

1880. 

1881. 

1880. 

1881. 

1882. 

1883. 

1884. 

1885. 

1886. 

Aesculus  macrostachya  . . . 

3,353 
3,930 
3,710 
4,033 
5,318 
3,381 

3,504 
4,091 

2,872 
4,091 
5,495 
3,618 

3,479 
4,003 
2,855 
4,260 
5,261 
3,263 

3,191 
3,753 
2,603 
3,753 
5,054 
3,753 

3,254 

3,768 
2,639 
4,040 
5,017 
3,045 

3,929 
4,522 
3,113 
4,555 

3,846 
4,569 
3,228 
4,670 

3,639 
4,363 
3,010 
4,502 

3,546 

3,556 

Plumbago  em'opaea 

Pulicar ia  dysenterica 

5,386 

5,494 

The  contrast  between  the  ordinary  spring  of  1881  and  the  very 
early  spring  of  1882  with  its  preceding  warm  winter,  affords  a  test  of 
the  question  as  to  how  much  the  thermal  constant  is  liable  to  change 
with  the  variations  in  the  seasons.  Hoifmann  finds  that  although  the 
first  blossoms  in  the  spring  of  1882  occurred  fifteen  days  earlier  than 
usual,  yet  the  sums  of  the  maximum  temperatures  since  January  1 
^ere  not  much  changed.  The  figures  as  given  by  him  (Z.  O.  G.  M., 
A'ol.  XVII,  p.  460)  are  reproduced  as  follows: 


Thermal  sums. 


1882. 


Date  of  blossom- 
ing. 


1881. 


Carpinus  betulus 

Larix  euroi)aea 

Lonicera  alpigena 

Prunus  spinosa. 

Ribes  grossularia 

Crataegus  oxyacantha 
Sarothamnus  vulgaris 
Berbei-lH  vulgaris 


1,159.7 
789.9 
1,471.7 
1,159.7 
1,086.5 
1,681.6 
1,790.8 
1,681.6 


1,134.6 
759.9 
1,490.4 
1,091.6 
1,091.6 

1,751.9 
1,751.9 


Apr.  19 
Mar.  30 
May  6 
Apr.  19 
Apr.  16 
May  15 
May  20 
May  15 


Apr.  2 
Mar.  15 
Apr.  19 
Mar.  31 
Mar.  31 
Apr.  30 
May  1 
May    1 


241 

Many  of  the  plants  observed  by  Hoffmann  show  such  discordant 
sums  from  year  to  year  as  to  prove  that  his  method  has  no  meaning 
for  them,  but  for  others  the  agreement  is  such  that  he  reconnnends 
them  to  be  observed  in  connection  with  the  observations  of  the  sun- 
shine thermometer,  as  follows: 

For  the  following  plants  observe  the  temperature  sums  from  tlic 
first  swelling  of  the  buds  to  the  first  flower  blossom :  Castanea  vesca, 
Bupleurum  falcatum^  GovydaliH  fahacea^  Dianthus  cartiivsiano- 
rum^  Lonicera  alpigena^  Salix  dafhanoides^  Syringa  vulgaris,  Amyg- 
dalus  7ia7ia,  Alniis  incana,  Alnus  viridis,  Atrova  belladonna,  Betula 
alha,  Crataegus  oxyacantha,  Larix  europaea  (up  to  the  date  when 
the  pollen  first  falls  froni  the  anthers),  Ligustrum  vidgare,  Lonicera 
tatarica,  Prenanthes  purpurea^  Prunus  pad/us,  Pninvs  spinosa,  Rham- 
nus  fraiigida,  Rihes  aureiim,  Rosa  arvensis,  Rosa  alphia,  Salix  caprea, 
male  (for  the  catkin,  or  the  flowers  of  the  willow,  the  beginning  of 
pollination,  as  ascertained  bv  a  light  stroke  on  the  flower,  is  to  be 
considered  as  the  date  of  the  first  blossom). 

Hoffmann  also  applies  his  summation  of  sunshine  maxima  tempera- 
tures to  the  interval  from  January  1  to  the  ripening  of  the  fruits 
and  shows  an  excellent  agreement  between  the  numbers  for  1880  and 
those  for  1881  at  Giessen. 

In  the  Zeitschrift  for  1884  Hoffmann  gives  his  results  for  1882, 
1883,  and  1884  as  collected  in  the  preceding  table  and  says  that  the 
vexed  question  of  the  thermal  constant  for  vegetation  is  still  far 
from  being  settled ;  either  temperature  and  vegetation  are  independ- 
ent of  each  other,  which  no  one  can  easily  believe,  or  they  stand  to 
each  other  in  a  relation  for  which  the  correct  expression  is  still 
unknown.  Pfeffer  in  his  Pflanzen  Physiologic  (Vol.  II,  p.  114)  has 
stated  that  the  approximate  uniformity  of  the  sums  of  temperature, 
from  year  to  year,  can  onh^  mean  that,  in  general,  for  each  year  the 
heat  received  from  the  sun  amounts  to  about  the  same  sum  total  for 
the  same  date  annually;  but  this  is  not  in  strict  accordance  with 
facts,  for  if  it  were  true  a  small  change  in  the  date  should  make  a 
small  change  in  the  sums,  which  is  not  always  the  case.  Thus,  if 
for  Linosyris  vidgaris  the  dates  of  blossoming  are  August  15,  18,  or 
20,  the  sums  from  January  1  for  different  years  will  be  as  follows : 


Year. 

Aug.  15. 

Aug.  18. 

Aug.  20. 

1882                                                                                             

4,555 
4,597 
4,363 

4,637 
4,670 
4,452 

4,698 

1883 

4,728 

1884                                                                                  

4,500 

From  these  figures  we  see  that  the  sums  vary  from  year  to  year 
quite  independently  of  the  change  of  date. 

The  thermometer  Bj,  similar  to  B,,  having  been  sent  to  Upsala  for 
observations  at  that  place,  it  gave  from  January  1  to  the  first  blossom 

2667—05  M 16 


242 

sums  that  agree  so  well  with  those  found  at  Giessen  that  Hoffmann 
thinks  no  better  can  be  expected. 

In  the  Zeitschrift  for  1885  Hoffmann  continues  to  give  the  com- 
parative observations  at  Giessen  and  Upsala,  and  remarks  that  the 
question  is  not  as  to  whether  his  method  is  correct  and  the  others  are 
wrong,  but  as  to  which  of  all  methods  is  even  a  little  better  than  the 
others.  Of  these  others  only  one  can,  he  thinks,  be  compared  with 
his  own,  viz,  that  of  Karl  Fritsch,  who  takes  the  sum  of  all  positive 
mean  daily  shade  temperatures.  Hoffmann  applies  Fritsch's  method 
to  the  observations  at  Giessen  and  Upsala  and  finds  the  argument  not 
in  its  favor.  He  also  tries  another  form  of  thermometer,  viz,  the 
so-called  black  bulb  in  vacuo,  but  finds  it  too  sensitive,  which  he 
thinks  is  because  its  bulb  is  too  small. 

In  the  Zeitschrift  for  1886  (p.  546)  Hoffmann  gives  a  summary  of 
observations  at  Giessen  and  Upsala  during  1886.  In  general  the 
sums  are  smaller  at  Upsala  and  so  also  for  high  Alpine  stations.  He 
is  thus  led  to  the  laws  established  by  Karl  Linsser,  as  published  in 
St.  Petersburg  in  1867  and  1869,  which  laws  he  expresses  as  follows : 
"•  Every  wild  plant  has  in  the  course  of  time  so  adapted  itself  to  the 
surrounding  local  climate  that  it  utilizes  this  climate  to  the  best 
advantage.  For  any  given  phase  of  vegetation  it  uses  a  certain  pro- 
portional part  of  the  available  annual  sum  total  of  heat.  Thus,  if 
the  annual  sum  at  Venice  is  4,000  and  if  the  corresponding  sum  at  St. 
Petersburg  is  2,000  and  if  the  plant  utilizes  one-fourth  in  order  to 
bring  it  to  the  flowering  stage,  then  it  will  require  1,000  at  Venice 
and  500  at  St.  Petersburg."  From  Linsser's  law  he  concludes;  (1) 
plants  that  have  been  raised  in  the  north  and  are  transplanted 
to  the  south  reach  their  phenological  epochs  earlier  than  plants 
already  living  there,  while  southerly  plants  carried  to  the  north  are 
retarded  as  compared  with  those  already  acclimatized;  (2)  plants 
raised  on  colder  highlands  when  transplanted  to  the  warmer  low- 
lands have  their  epochs  accelerated  as  compared  with  those  already 
domesticated;  plants  raised  in  the  lowlands  and  transplanted  to  the 
colder  highlands  develop  more  slowly  than  the  acclimatized  plants. 

In  the  Zeitschrift  for  1886  (p.  113)  Hoffmann  determines  the  rela- 
tive retardation  of  vegetation  as  determined  by  the  dates  of  the  first 
blossom  of  several  plants  at  different  altitudes.  The  result  is  for 
the  Pyrus  communis  (pear  tree)  and  allied  varieties  a  retardation  of 
3.7  days  per  100  meters,  and  corresponding  to  this  a  retardation 
of  2.8  days  per  1°  of  latitude.  The  analogous  data  for  Pyrus  malus 
(apples)  are  2  days  per  100  meters  and  4.4  days  per  1°  of  latitude. 
Charts  are  given  showing  by  means  of  isophenological  lines  the 
gradual  progress  northward  of  the  development  of  vegetation  as 
spring  advances. 


243 

In  Petermanirs  Geog.  Mitth.  for  1881  Hoffmann  gives  a  general 
phenological  chart  for  central  Europe  showing  the  acceleration  or 
retardation  of  the  phases  of  vegetation  with  respect  to  Giessen. 

In  the  Zeitschrift,  1882,  Vol.  XVII,  page  457,  Hoffmann  gives  the 
results  of  his  study  of  observations  collected  by  Karl  Fritsch,  showing 
the  dates  of  blossoming  and  ripening  of  fruits  in  Europe,  as  reduced 
to  the  latitude  and  altitude  of  (xiessen;  and,  second,  the  thermal  con- 
stant by  Hoft'mann's  method  from  observations  at  (jiessen  for  the 
years  1881  and  1882,  as  collated  in  the  preceding  table.  He  also 
shows  that  the  advance  of  vegetation  in  the  early  and  very  warm 
spring  of  1882  did  not  materially  diminish  the  sums  total  of  maxi- 
mum temperatures,  the  figures  for  which  I  have  reproduced  in  the 
preceding  table  (p.  240). 

MARIE-DAVY. 

The  extensive  researches  conducted  at  the  observatory  of  Mont- 
souris  (Paris)  are  scattered  through  many  annual  volumes,  from 
which  I  have  culled  sufficient  to  show  the  views  held  by  Marie-Davy 
and  his  coworkers,  wiio  distinguish  very  clearly  between  thermometry 
and  actinometry,  and  attempt  to  determine  separately  the  constant 
amounts  of  air  temperature  and  of  sunshine  which  constitute  the 
total  molecular  energy  needed  to  develop  the  plant. 

In  his  Annuaire  for  1877  Marie-Davy  quotes  from  Tisserand  (1875) 
and  Schuebeler  (1862)  the  results  of  a  series  of  observations  on  the 
culture  of  grain  in  Europe.  Special  praise  is  given  to  the  records 
from  Norway  and  to  the  high  state  of  education  among  the  Norwegian 
farmers.  The  durations  of  the  periods  from  sowing  to  ripening  are 
as  follows : 


Lati- 
tude. 

Mean 
annual 
tempera- 
ture. 

Sowing  to  ripening. 

LocaUty. 

Sf 

Spring 
rye. 

Pour- 
row  bar- 
ley. 

Halsao 

Bodo 

Strand 

SMbotten. 

Algiers. 

"  N. 
59.47 
67.17 
68.46 
69.28 
36.45 

°  a 

6.3 
3.6 
2.9 
2.3 

Days. 
133 
121 
115 
114 
142 
139 

Days. 
139 
118 
116 
113 

Days. 
117 
102 
98 
93 

Paris  (Fouilleuse) 

48.50 

For  other  plants — oats,  peas,  Ijeans,  vetches,  etc. — the  duration  of 
the  vegetating  period  diminishes  in  a  similar  manner  as  the  latitude 
increases  or  as  the  temperature  diminishes;  therefore  we  can  not 
assume  at  once  that  warmth  hastens  the  ripening,  for  in  this  case  cold 
appears  to  hasten  it.  I  say  "'  appears,"  because  with  the  cold  comes 
in  another  influence,  viz,  the  amount  of  sunshine.     Thus  as  we  go 


244 


northward  we  have  a  greater  amount  of  possible  sunshine  during  the 
growing  period,  ahhough  the  actual  sunshine  is  very  materially 
diminished  by  the  quantity  of  cloud  and  fog.  Tisserand  calls  atten- 
tion to  the  maximum  possible  duration  of  sunshine  as  given  in  the 
following  table  for  the  season  of  spring  wheat  from  sowing  to 
ripening: 


Latitude 
north. 

Maxi- 
mum 
sunshine 
dura- 
tion. 

Correspond- 
ing locality. 

o          / 

Hours. 

48    30 

1.996 

Alsace. 

59      0 

1.795 

Christiania. 

59    30 

2,187 

Halsno. 

67      0 

2,376 

Bodo. 

68    00 

2,472 

Strand. 

69    30 

2,486 

SMbotten. 

These  numbers  of  possible  hours  of  sunshine  should  be  diminished 
to  actual  hours  of  sunshine  on  account  of  cloudiness.  Moreover, 
actual  actinometric  observations  would  have  shown  that  owing  to  the 
atmospheric  absorption  the  efficiency  of  the  sunshine  is  less  at  low 
altitudes  and,  therefore,  at  high  latitudes.  But  in  the  absence  of 
fundumental  climatic  data  Tisserand  is  probably  correct  in  conclud- 
ing that  the  temperature  of  the  air  has  apparently  little  to  do,  in  and 
of  itself,  with  the  duration  of  the  time  from  sowing  to  ripening,  but 
that  this  depends  principally  on  the  sunshine,  so  that  at  northern 
latitudes  the  wheat  ripens  best  in  localities  that  have  the  least  cloudi- 
ness or  the  sunniest  exposure.  On  the  other  hand,  the  temperature 
of  the  air  does  appear  to  materially  affect  the  chemical  constitution 
of  the  grain,  since  the  northern  crops  are  richer  in  hydrocarbons, 
and  the  proportion  and  quality  of  the  starchy  principle  increases 
and  the  nitrogenous  compounds  diminish  as  the  locality  ap^'oaches 
the  equator. 

The  acclimatization  of  plants  is  accompanied  b}'  notable  changes 
in  their  nature;  frequently  the  leaves  increase  in  size  relatively  to 
the  rest  of  the  plant,  and  their  colors  are  more  pronounced,  as  if  the 
plant  sought  to  supplement  the  low  temperature  by  a  more  complete 
absorption  of  the  solar  rays.  A  similar  change  as  to  the  leaves  and 
colors  takes  place  in  the  flora  of  high  mountains  as  compared  with 
that  of  the  plains  below.  The  aromatic  principles  of  plants  are  also 
developed  in  a  remarkable  manner  in  high  latitudes.  Thus  the  beans 
have  a  more  decided  flavor  in  Norway  in  proportion  as  we  go  north- 
ward, and  at  Alten  (lat.  70°  N.)  the  most  aromatic  cumin  {Cuminum 
cyminum)  of  all  Europe  is  cultivated. 

The  incident  sunshine  seems  to  be  the  productive  climatic  element 
in  effecting  the  growth  of  plants ;   it  furnishes  the  total  vis  viva,  or 


245 

the  mechanical  or  molecuhir  onorijy,  that  is  at  the  disposition  of  the 
plant,  but  it  is  also  the  last  consideration  to  l)e  studied  and  under- 
stood. 

The  temperature  is  the  next  important  climatic  element  and  that 
which  has  been  most  studied;  the  heat  involved  in  temperature  is 
the  mechanical,  molecular  energy  that  is  utilized  by  the  vital  powers 
of  the  plant."  Each  plant  utilizes  a  fraction  of  the  molecular  energy 
that  is  at  its  disposition,  according  as  its  sunshine,  temperature,  and 
sap  are  favorable  to  the  formation  of  the  chemical  substances  that  it 
can  elaborate  within  its  cells.  The  remaining  elements  important  to 
the  production  of  crops  are : 

(a)  The  water  that  enters  the  root,  which  may  be  natural  rain  or 
artificial  irrigation. 

(b)  The  chemicals  dissolved  in  the  water. 

(c)  The  soil  that  furnishes  these  chemicals. 

(d)  The  atmosphere  that  furnishes  nitrogen,  oxygen,  and  carbonic- 
acid  gas. 

(e)  The  evaporation  of  moisture  from  the  plant  and  soil,  mostly 
through  the  influence  of  the  wind  and  heat. 

Of  these,  only  the  rain  water,  the  gases  in  the  atmosphere,  and  the 
evaporation  are,  properly  speaking,  meteorological  or  climatic  ele- 
ments not  under  the  control  of  man;  whereas  the  irrigation  of  the 
soil  and  its  chemical  constitutents  are  largely  under  his  control. 

The  quantity  of  water  actually  consumed  by  the  plant  or  evapo- 
rated from  its  leaves  and  that  which  is  daily  evaporated  from  the  soil 
or  which  drains  away  to  other  localities,  and  thus  becomes  useless  to 
the  plant,  have  been  the  subject  of  many  experiments,  some  of  whose 
results  may  be  summarized  as  follows : 

Thus,  for  example,  Lawes  and  Gilbert,  at  Rothamsted,  England, 
from  experiments  in  vases  entirely  under  their  control,  derived  the 
following  numbers,  showing  the  weight  of  water  evaporated  relative 
to  the  weight  of  grain  produced  per  unit  area  of  ground: 


Manure. 

Weight 
of  grain. 

Weight 
of  evapo- 
rated 
water. 

Ratio. 

None 

Grams. 
9.6 
7.2 
4.2 

Grams. 

6,4:38 
3,627 

766 

882 

Mineral  and  ammoniacal  fertilizers 

864 

In  these  experiments,  therefore,  the  ground  during  the  wheat  sea- 
son consumed  water  equivalent  to  a  rainfall  of  from  184  to  212  milli- 
meters in  order  to  produce  a  harvest  of  30  hectoliters,  or  80  kilograms 
in  weight  per  hectare. 

0  Is  it  not  in  fact  the  vital  power  of  the  plant? — C.  A. 


246 


Thus,  again,  Risler,  at  Caleves,  in  France,  measured  the  harvest 
and  the  rainfall  in  an  open  field,  having  an  impermeable  subsoil. 
He  measured  the  quantity  of  rainfall  and  the  outflow  through  the 
drains,  and  allowed  for  the  moisture  in  the  soil  at  the  beginning  and 
end  of  his  experiments.  The  result  attained  was  that  a  field  of  winter 
wheat  consumed  256  millimeters  in  depth  of  water  from  April  to  July. 
He  does  not  give  the  quantity  of  grain  that  was  harvested. 

Marie-Davy,  at  Montsouris,  cultivated  winter  wheat  in  twelve  sam- 
ples of  earth  of  very  different  qualities,  in  1874.  The  soil  was 
enriched  with  compost,  with  results  as  in  the  first  part  of  the  follow- 
ing table. 

In  1875  the  soil  was  enriched  with  Joulie's  complete  fertilizer  for 
cereals  at  the  rate  of  1,000  kilogi^ams  per  hectare,  with  results  as  in 
the  second  part  of  the  table. 

Evaimration  and  crops  at  Montsouris. 


Experiment  of  1874. 

Experiment  of  1875. 

Sample  No.— 

Evapo- 
ration. 

Crop. 

Ratio. 

Evapo- 
ration. 

Crop. 

Ratio. 

1 

Kilos. 
380 
360 
348 
347 
340 
365 
344 
329 
339 
359 
346 
372 

Grams. 
394" 
187 
300 
380 
303 

z 

324 
312 
308 
313 
236 

1,924 
1,160 
913 
1,122 
1,426 
1,049 
1,015 
1,086 
1,165 
1,105 
1,576 

Kilos. 
362 
356 
345 
364 
356 
363 
366 
344 
346 
366 
346 
363 

Orams. 
394 
372 
474 
479 
425 

435 
424 
387 
379 
469 
379 

919 

2                                                     _ 

957 

3                  - 

728 

4                                                         

760 

5                   

837 

6                                                             

1,386 

7     .                --- 

841 

8                                                                  

811 

9....           

894 

10                                                                    

965 

11      _ __ _ _. 

738 

12                                                            

?58 

352 

303 

1,140 

356 

407 

877 

We  remark  that  in  these  two  years  the  quantity  of  water  evaporated 
has  remained  the  same,  but  the  harvest  changed  notably,  being  in 
both  cases  much  superior  to  those  of  Rothamsted  and  Caleves.  A 
box  of  earth,  similar  to  those  containing  the  wheat,  lost  by  evapora- 
tion from  January  2G  to  June  9,  1875,  114  millimeters,  while  a  box 
planted  with  wheat  lost  35G  millimeters,  and  the  Piche  evaporimeter 
lost  302  millimeters.  Similarly,  in  1876,  from  the  22d  of  February 
to  the  5th  of  July,  the  soil  covered  with  winter  wheat  lost  426  milli- 
meters, but  the  naked  soil  163  millimeters  and  the  I^iche  465  milli- 
meters. However,  in  this  connection  it  must  be  noted  that  while  the 
boxes  containing  naked  soil  received  only  the  natural  rainfall,  those 
containing  the  growing  plants  received  weekly  the  water  that  they 


247 

had  lost  by  evaporation  the  preceding  week.  These  hitter,  therefore, 
show  us  the  niaxinmni  elt'ect  that  water  can  have  on  vegetation  in  the 
climate  of  Paris.  The  proportion  of  water  that  is  consumed  is 
exaggerated,  but  the  crop  increases  at  the  same  time,  but  less  ra^iidly 
than  the  consumption  of  water.  We  may,  therefore,  say  that  to 
a  ccKtain  extent,  water  can  with  the  aid  of  the  sunshine  supplement 
the  fertilizers,  although  we  can  not  say  that  a  deficiency  of  fertilizer 
is  a  good  thing. 

In  general,  all  the  observations  recorded  in  France,  Switzerland, 
and  England  show  that  the  total  annual  evaporation  from  cultivated 
soils  is  TO  to  80  per  cent  of  the  total  annual  rainfall.  A  large  part 
of  the  rain  falls  in  the  autumn  and  winter  w^hen  vegetation  has 
ceased.  The  rains  of  these  seasons  j^artly  filter  into  the  earth  and 
feed  the  subterranean  springs,  but  they  must  first  return  to  the  soil  its 
own  water  supply.  Xow  the  more  the  soil  is  impoverished  by  cutting 
the  crops  the  more  it  will  take  up  of  the  autumn  rains  and  the  less 
will  be  received  by  the  subterranean  water  beds.  It  is  then  easy  to 
understand  that  in  cultivated  lands  the  mean  flow  in  the  water 
courses  diminishes  in  proportion  to  the  progress  of  the  cultivation. 
It  seems  certain  that  in  France,  and  especially  in  the  central  portions, 
the  grains  do  not  find  in  the  soil  all  the  water  that  they  could 
profitably  use  to  the  advantage  of  the  crop  and  that  irrigation  would 
be  advantageous  in  these  and  many  other  crops  wherever  there  is  a 
good  soil  and  an  abundance  of  sunshine. 

Notwithstanding  this  necessity  for  water,  the  rainy  years  are 
frequently  bad  for  cereals.  Rainy  summers  are  deficient  in  light 
and  dry  summers  have  too  much.  It  is  the  relative  distribution  of 
heat,  sunshine,  and  moisture  from  day  to  day  throughout  the  whole 
season  that  is  important. 

From  a  meteorological  point  of  view  we  should  say  that  from  the 
sowing  to  the  formation  of  the  embryo  grain  sunlight  is  indis- 
pensable, but  from  the  formation  to  the  maturity  it  is  far  less 
important. 

In  his  Annuaire  for  1878  (p.  468)  Marie-Davy  gives  a  summary 
of  the  meteorological  data,  month  by  month,  for  several  years,  as  a 
sample  of  what  may  be  done  by  way  of  explaining  the  general  rela- 
tions between  meteorology,  as  hitherto  pursued,  and  the  crops  of  the 
agriculturist.    He  says: 

Meteorology,  as  seen  from  the  agricultural  point  of  view,  has  for 
its  ultimate  object  to  enable  the  farmer  to  anticipate  the  future  of 
his  current  crop.  This  explains  why  we  think  it  necessary  to  study 
the  influence  that  each  of  the  meteorological  elements  has  on  the 
progress  of  the  development  of  the  plants  in  the  successive  phases 


248 

of  their  growth.  The  tables  of  statistics  of  the  climate  and  the 
crops,  or  the  corresponding  graphic  diagrams,  allow  us  to  take  exact 
account  of  the  features  of  the  past  years  and  to  approximately  com- 
pare these  characteristics  with  the  agricultural  features  of  the  cur- 
rent year.  Let  us  compare  among  themselves  the  five  crops  for  the 
years  from  1873  to  1877.  Of  these  five  years,  1873  gave  a  poor  crop. 
On  the  contrary,  1874  gave  a  very  good  crop,  both  as  to  quantity  and 
quality.  The  crop  of  1875  attained  an  average  as  to  quantity,  but 
the  quality  of  the  grain  was  below  the  average.  Notwithstanding 
the  great  irregularities  of  1876  it  gave  us  a  good  average  as  to  quan- 
tity and  excellent  grain  as  to  quality.  In  1877,  notwithstanding  a 
great  development  of  straw  or  stalks,  the  crop  of  grain  was  below 
the  average  as  to  quantity  and  quality;  therefore,  as  regards  their 
crops  of  grain,  these  years  can  be  classed  in  the  following  decreasing 
order:  1874,  1876,  1875,  1877,  1873. 

We  will  compare  these  harvests  with  the  following  meteorological 
tables  for  these  years,  as  based  on  observations  at  Montsouris : 

MONTHLY   RAINFALL. 


1874-75.      1875-76. 


October... 
November 
December 
January  .. 
February  _ 

March 

April 

May 

June 

July 

August 

September 


mm. 
65.2 
36.5 
6.0 
23.1 
17.5 
11.4 
16.1 
36.6 
47.8 
54.5 
23.1 
65.1 


mm. 
5L0 
44.2 
8L8 
63.2 
10.9 
8.6 
10.1 
24.6 
82.0 
82.1 
73.7 
32.8 


75.4 
22.4 
9.1 
57.8 
62.7 
24.3 
14.3 
70.6 
24.6 
72.3 
65.3 


mm. 
29. 
.51. 


MONTHLY  EVAPORATIONS,  AS  MEASURED  BY  THE  PICHE  EVAPORIMETER. 


October 

November . 


January  ... 
February  . . 

March 

April 

May 

June 

July 

August 

September. 


mvi . 

mm. 

mm. 

mm. 

58.2 

52.1 

47.1 

26.8 

55.4 

52.9 

34.1 

40.8 

48.3 

22.4 

32.0 

11.3 

36.8 
50.5 
80.6 

34.0 
25.0 
84.3 

8.0 
31.5 
63.3 

85.5 

110.5 

99.0 

135.0 

107.2 

121.7 

110.0 

115.0 

147.5 

97.4 

142.8 

92.3 

115.8 

121.7 

149.8 

81.5 

144.2 

129.7 

130.6 

84.7 

123.7 

72.4 

78.3 

65. 6 

44.2 

39.3 
33.1 
58.9 
58.3 

40.5 
46.5 
90.5 
90.8 
120.7 
99. 2 
93.8 
63.0 


249 


DEGREES  OF  HEAT  OR  MONTHLY  SUMS  OF  THE  MEAN  DAILY  TEMFERATURES. 


1872-73.     187»-74.     1874^76.     1875-76.     1876-77 


October . . . 
November 
December. 
Januai-y  .. 
February  . 

March 

April 

May 

June 

July 

August 

September 


"C. 

a26 

2()2 
152 
62 
254 
267 
375 
510 
628 
601 
435 


•  aw 

216 
99 
146 
120 
22:3 
312 
366 
528 
667 
561 
507 


291 

186 

3 
122 
205 
301 
355 
500 


594 
570 


DEGREES  OF  LIGHT  OR  MONTHLY  SUMS  OF  THE  MEAN  DAILY  ACTINOMETRIC 

DEGREES. 


October 

November 

December 

January  

Februai-y 

March.. 

April 

May 

June 

July 

August - .• 

September 


"Actin. 

°Actiu. 

°Actin. 

°Actin. 

552 

.598 

738 

604 

276 

403 

414 

372 

a32 

282 

285 

267 

440 

397 

363 

406 

353 

490 

426 

453 

791 

871 

766 

800 

909 

1,152 

1,248 

1,191 

1,401 

1,442 

1,453 

1,433 

1,398 

l,.5fi6 

1,359 

1,458 

1,702 

1,590 

1,428 

1,.569 

1,376 

1,311 

1,172 

1,243 

930 

945 

1,041 

900 

"Actin. 
583 
195 


a53 

763 

1,050 

1,134 

1,439 
1,254 


Our  summaries  are  divided  into  three  periods.  The  first,  October 
to  February,  corresponds  to  the  sowing  and  the  winter  season ;  the 
second,  March  to  Julj^,  corresponds  to  the  vegetation  of  the  cereals; 
the  third.  May  to  September,  corresponds  to  vegetation  of  the  vine. 
In  these  summaries  the  years  are  rearranged  in  the  order  of  tiie 
decreasing  value  of  the  grain  harvest. 

Siimniary  from  Octoher  to  February. 


1873-74. 

1875-76. 

1874-75. 

1876-77. 

.1872-73. 

Rainfall 

148 

215 

931 

2,187 

242 
118 
673 

2,102 

251 
172 

2.226 

200 

225 

1,2.33 

1,727 

376 

Degrrees  of  heat 

1,000 

1,953 

In  the  first  period,  or  the  winter,  the  climatological  facts  have 
very  little  ai)parent  bearing  on  the  crops.  The  sowing  period  may 
have  been  more  or  less  difficult,  but  very  pronounced  anomalies  in  the 
climate  must  occur  in  order  to  coini)romise  the  harvest  in  an  irremedi- 
able manner.     The  year  1872-73  is  the  only  one  that  i^resents  a  fact  of 


250 

this  latter  kind.  The  excessive  rains  of  autumn  drowned  the  wheat 
and  produced  disastrous  inundations.  Up  to  that  time  we  perceived 
the  influence  of  the  light,  which  strengthens  the  young  shoots  and 
gives  them  a  real  progress,  but  which  may  be  promptly  effaced  by  the 
subsequent  bad  weather. 

SuniDiary  from  March  to  July. 


1873-74. 

1875-76. 

1874-75. 

1876-77. 

1872-73. 

Rainfall 

166 

582 

2,096 

6,621 

197 

558 

1,995 

6,450 

207 

508 

2,053 

6,249 

320 

448 
2,007 
6,008 

307 

537 

Degrees  of  heat 

2,039 

Degrees  of  liglit 

6,201 

In  the  second  period  the  light  is  the  element  which  appears  to  be 
of  the  least  importance.  Its  variations  do  not  correspond  to  the 
value  of  harvest  attributed  to  each  year.  It  is  not  the  same  with  the 
rainfall,  which  increases  regularly  in  proportion  as  the  harvest 
becomes  less  favorable.  The  two  last  years,  1877  and  1873,  differ  little 
from  each  other  in  general  characteristics. 

Experience  shows  that  we  may  water  grain  planted  in  pots  or  in 
free  earth  every  day  and  only  increase  the  quantity  and  quality  of 
their  product  in.stead  of  diminishing  them.  It  is  not,  therefore,  that 
rain  water  in  itself  is  injurious — far  from  it :  but  rainfall  brings  with 
it  cloudy  weather,  Avhich  diminishes  the  light.  We  see  in  fact  that 
the  sum  of  the  actinometric  degrees  decreases  regularly  in  proportion 
to  the  increase  in  the  value  of  the  crop  year,  except  in  the  case  of  the 
last  year,  1873,  which  only  descended  to  this  rank  in  consequence  of 
the  meteorological  accidents  of  the  autumn.  In  reality  1873  would 
have  been  a  more  favorable  year  for  the  crops  than  1877  if  the  autumn 
had  not  been  so  exceptionally  unfavorable.  The  crop  of  1877  only 
recovered  its  value,  because  of  the  abundance  of  the  wheat  stalks. 
Thus  we  see  that  it  is  in  vain  that  the  season  be  favorable  as  regards 
weather  if  the  heads  of  the  grain  are  scarce. 


Resumes  from  May  to  September. 


Rainfall. 

Evaporation 

Degrees  of  heat. 
Degrees  of  light 


612 
2,629 
6,854 


2,709 
6,448 


468 
2,494 
6,347 


318 

543 

3,544 


This  third  period  relates  to  the  wine  crop.  Diri'ing  this  period,  as 
in  the  others,  heat  seems  to  play  only  a  very  secondary  part  for  the 
same  country.  There  would  not  be  the  same  difference  in  the  nature 
of  the  product  from  one  country  to  another.  On  the  contrary,  the 
quantity  of  light  decreases  regularly  from  the  first  or  best  crop  to 
the  year  l)efore  the  last  or  poorest  crop.  The  last  year,  on  the 
other  hand,  which  was  so  bad  at  the  beginning,  recovered  in  a  most 
extraordinary  manner  at  the  end,  and  as  regards  the  quality  of  the 


251 

wine  this  year  should  have  had  a  great  simihirity  with  1874.  Never- 
thelss,  the  Aviiie  of  187H  was  not  of  very  g-ood  quality,  which  can 
perhaps  be  attributed  to  a  too  prolonged  growth  of  the  vine  stems, 
caused  by  the  humidity  of  the  soil.  If  in  general  a  good  wheat  year 
corresponds  Avith  a  good  wine  year  this  rule  is  far  from  invariable. 
In  regard  to  quality  the  vintage  depends  but  too  often  on  the  late 
spring  frosts. 

The  extremely  important  part  played  by  light  in  agriculture  makes 
us  regret  that  the  actinometer  should  still  l^e  so  little  known.  It 
perfectly  replaces  the  thermometer  for  agricultural  purposes,  but  the 
thermometer  can  not  take  its  place. 


In  his  Annuaire  for  1882  Marie-Davy  gives  the  following  study  of 
the  development  of  cereals,  wine,  and  other  crops : 

Cereals. — The  cereals  offer  a  great  number  of  varieties,  and  this 
number  increases  annually,  but  often  the  differences  that  we  see  be- 
tween them  are  due  to  certain  influences  of  the  soil  and  climate 
which  disappear  by  change  of  locality.  However,  there  are  some 
varieties  whose  qualities  have  been  fixed  by  long-continued  cultiva- 
tion in  the  ordinary  way  or  by  long-continued  selection,  and  which 
jjresent  decided  advantages  for  the  specific  climates. 

The  varieties  brought  from  the  south  are  more  sensitive  to  cold 
than  those  from  the  north,  and  can  not  be  propagated  without  special 
precautions  in  higher  latitudes  or  at  greater  altitudes  than  belong 
to  the  localities  where  these  varieties  were  gradually  developed.  The 
varieties  brought  from  the  north  are  generally  more  precocious  and 
suffer  more  from  dryness.  The  expressions  "  early  "  or  "  late  "  have 
reference  to  their  behavior  in  the  new  localit_v.  The  grain  brought 
from  the  south  comes  to  maturity  at  a  later  date  than  that  raised  in 
the  north. 

Influence  of  heed  and  licjht  on  development  of  wheat. — We  shall 
divide  the  development  of  wheat  into  four  phases,  whose  dividing 
epochs  are  the  processes  of  (1)  sowing  and  germination,  (2)  heading 
out,  (3)  flowering,  and  (4)  ripening.  According  to  Gasparin  the  ger- 
mination of  wheat  begins  when  together  with  the  necessary  moisture 
it  also  enjoys  a  temi)erature  in  excess  of  5°  C.,  and  it  sprouts  when  it 
has  received  a  sum  total  of  effective  mean  daily  temperatures  (above 
5°  C.)  equal  to  84°  C.  Its  sprouts  shoot  above  the  soil  a  few^  days 
later.  Some  wheat  sown  by  Marie-Davy  April  23,  1880,  was  up  on 
the  4th  of  May,  the  sum  of  the  mean  temperatures  being  9()°,  so  that 
the  germinating  sprout  had  taken  about  two  days  to  grow  from  the 
seed  to  the  surface.  In  thy  following  table  columns  2,  3,  4,  and  5 
show  the  duration  in  days  of  the  period  required  for  the  germination 
of  wheat  supposed  to  be  sown  at  Montsouris  in  the  different  years  on 
four  different  dates — «,  h^  e,  d — as  stated  at  the  heads  of  the  columns. 
These  durations  are  calculated  to  the  nearest  whole  days,  on  the 


252 

assumption  that  the  sum  of  the  mean  daily  temperatures  in  the  shade 
must  be  84°  C. 

[Date  of  sowing:  a,  October  1;  b,  October  15;  c,  November  1;  d,  November  15.  Aver- 
age date  of  germination:  a,  October  7;  b,  October  22;  c,  November  14;  d,  December. 
18.  Average  date  of  heading :  a,  February  8 ;  b,  March  4  ;  c,  March  3 ;  d,  Feb- 
ruary 26.] 


Year. 

Duration  of  germinating 
stage. 

Duration  of  heading  stage. 

a. 

b. 

c. 

d. 

a. 

6. 

c. 

d. 

1873 

Days. 
5 

6 
5 
9 
6 

6 

Days. 
6 
6 

7 
10 
6 

9 

Days. 
12 

9 

9 
13 

8 
26 
11 
16 

Days. 
13 

40 
12 
17 
45 
94 
28 

Days. 
Ill 
151 
151 
59 
138 
1.51 
155 
86 

Days. 
159 
166 
165 
87 
130 
179 
156 
133 

Days. 
142 
163 
148 
93 
149 
151 
152 
125 

Days. 
142 

1874 

143 

1875 

118 

1876 

113 

1877 

137 

1878 

128 

1879 

57 

1880 

87 

6.4 

7.5 

13.0 

33.4 

124 

147 

140 

116 

Counting  from  the  date  when  the  mean  daily  temperature  is  5°  C. 
and  the  wheat  begins  to  sprout  to  the  date  when  the  wheat  begins  to 
head,  Gasparin  adopts  430°  C.  as  the  sum  of  the  mean  daily  shade 
temperatures.  Marie-Davy  finds  from  the  date  of  actual  sowing  of 
the  seed  to  the  date  of  heading  out  a  sum  of  555°  C.  after  rejecting  all 
daily  mean  temperatures  that  are  below  6°  C.  according  to  the  rule  of 
Herve  Mangon.  He  also  finds  639°  C.  for  the  sum  total  of  tempera- 
tures between  the  dates  of  germination  and  heading  out  after  reject- 
ing all  days  below  6°  C.  On  this  last  hypothesis  are  calculated  the 
duration  of  the  heading  stage  and  the  mean  dates  of  heading  for  the 
respective  years  as  given  in  the  columns  6  to  9  of  this  table.  These 
computed  dates  of  heading  out  show  that  the  sowing  of  wheat  on 
October  15  or  November  1  or  15  brings  it  to  a  head  at  the  end  of 
February  or  beginning  of  March,  but  when  the  sowing  occurs  on 
October  1  it  is  brought  to  a  head  so  much  earlier  in  February  as  to 
expose  it  to  great  chance  of  injury  by  the  frost;  for  although  the 
grasses  and  the  green  wheat  plant  resist  the  action  of  frost,  yet  the 
embryo  seed  in  the  ear  or  head  does  not  do  so,  and  if  once  destroyed 
by  frost  will  not  be  replaced  unless  the  soil  is  very  fertile. 

The  third  epoch,  or  the  flowering  of  the  wheat,  takes  place  in 
France,  according  to  Gasparin,  when  the  mean  temperature  has 
risen  to  1G°  C.  oi*  when  the  sum  total  of  daily  shade  temperatures 
has  amounted  to  813°  C,  counting  from  the  beginning  of  vegetation 
in  the  spring  or  from  the  date  when  the  mean  daily  temperatures 
is  5°  C.  in  the  shade.  This  figure  relates,  of  course,  to  an  average 
of  many  years,  and  the  individual  years  may  vary  very  considerably. 
Marie-Davy,  as  before,  adopts  the  views  of  Herve  Mangon  as  to 


253 


rejecting  all  mean  daily  temperatures  below  6°  C,  and  thus  finds 
1,496°  as  the  mean  value  of  the  sum  of  temperatures  from  the  date  of 
sowing  to  that  of  flowering.  The  similar  sum  from  the  date  of  head- 
ing to  flowering  is  8(50°,  or  1,490°  less  689°. 

The  fourth  epoch,  or  the  ripening  of  the  wheat,  occurs  when  the 
sum  total  of  the  mean  dail}^  shade  temperatures  since  the  date  of 
flowering,  rejecting  all  below  6°  C.,  amounts  to  815°  C.,  and  in  the 
climate  of  Paris  this  occurs  about  fortj^-five  or  forty-six  days  after 
the  date  of  flowering.  The  range  of  uncertainty  in  this  last  interval 
is  only  four  or  five  days,  owing  largely  to  the  uniformity  of  the 
climate  at  this  season.  It  is  the  best  defined  of  all  the  periods  and 
so  well  ascertained  that,  knowing  any  actual  date  of  floAvering  we 
can  safely  predict  the  date  of  ripening.  In  proportion  as  we 
approach  the  latter  date  the  process  of  ripening  seems  to  concentrate 
itself  more  and  more  within  the  wheat ;  water  and  sunlight  become 
less  and  less  important ;  rain  becomes  a  source  of  uneasiness  as  to 
the  harvest,  and  the  intensity  of  sunshine  has  only  an  indirect 
influence  on  the  quality  and  quantity  of  the  grain.  The  influence 
of  sunlight  during  the  first  phase  or  germination  is  negligible  and 
probably  nothing;  it  is  a  maximum  at  the  beginning  of  the  fourth 
phase,  but  diminishes  rapidly  as  the  fourth  phase  progresses  and  in 
proportion  as  the  wheat  becomes  more  yellow.  We  shall  therefore 
consider  the  amount  of  sunshine,  or  more  properly  the  total  radiation 
from  sun  and  sky,  during  the  first  thirty  days  after  flowering  and 
neglect  its  amount  during  the  remainder  of  the  period  up  to  maturity. 

The  following  table  shows  the  amount  of  radiation,  as  expressed 
by  Marie-Davy  in  actinometric  degrees  or  percentages  and  com- 
puted from  actual  observations  of  his  actinometer  at  Montsouris  for 
the  various  stages  of  growth,  viz,  the  second  or  heading  stage  from 
germination  to  heading,  the  third  or  flowering  stage  from  heading 
to  flowering,  and  fourth  for  the  first  thirty  days  of  the  fourth  or 
ripening  stage  immediately  following  the  flowering: 


Year  of  sow- 
ing. 

Total  radiation  received 
dviring  heading  stage. 

Total  radiation  received 
during  flowering  stage. 

Total  radiation  received 
during  30  days  of  ripen- 
ing stage. 

a. 

b. 

c. 

d. 

a. 

b. 

e. 

d. 

a. 

b. 

c. 

rf. 

1873 - 

1874 

1875 

842 
908 
904 

1,332 
1,191 
1  nnf) 

1,755 
1,663 
1,161 
f546 
977 
1,476 
1,582 
1,924 

1,848 
1,938 
1,247 
811 
1,255 
1,743 
1,600 
1,991 

3,205 
3,031 
3,214 

2,979 
2,933 
3,169 

2,870 
2,620 
3,169 

2.954 
2,4«2 
2  821 

1,176 
1,403 
1,419 

1,608 
1,220 
1,504 

1,548 
1,171 
1,526 

1,581 
1,194 
1,558 

1876 

652  i      698 
733        73fl 

1877           

2,096     2  :?02     2  282  :  2.2ns 

l,l(e 
1,330 
1,076 
1,391 

1,199 
1,496 
1,092 
1,433 

1,399 
1,131 
1,321 
1,433 

1,3(!0 

1,450 
1,184 
1,362 
1,486 

800 

840- 

1,000 

1,251 
1,578 

2,749 
3,095 
3,519 

2,634 
2,580 
3,106 

2,630     2,5()6 
2,658  1  2,607 
2,849  1  2,865 

1879 

1880 

Average  of 
6  years 

857 

1,117 

1,497 

1,653 

2,977 

2,808 

2,723 

2,629 

1,268 

1,363 

1,363 

254 


If  we  sum  up  the  second,  third,  and  fourth  series  of  fio:ures  we 
finally  obtain  the  sum  total  of  the  effective  radiation  received  during 
the  whole  interval  from  germination  to  ripening,  as  given  in  the 
following  table : 


Total  radiation  received  from 
germination  to  ripening. 


Rela- 
crop. 


1873. 
1874. 
1875. 
1876. 
1877. 
1878. 
^879 . 


5,223 
5,342 
5,537 


5,919 
5,344 


6,173 
5,454 
5,856 


5,614 


5,924 
5,438 
5,676 


5,011 
5,910 


4,240 
5,512 


4,658 
5,237 
5,561 


4,913 
5,433 
5,569 
6,345 


4,436 
5,263 
5,266 
6,145 


19.0 
26.5 
22.5 
15.2 
11.1 


Average  of  6  years. 


5,102      5,288       5,550      5,645 


The  relative  value  of  the  wheat  crops,  as  observed  at  two  stations, 
is  given  in  the  last  column  of  the  preceding  table,  and  the  comparison 
of  the  figures  shoAvs  that  a  deficiency  of  sunshine  has  a  decided  effect 
in  diminishing  the  relative  value  of  the  crop ;  but  the  converse  is  not 
true,  for  we  may  have  an  excess  of  sunshine  and  still  get  poor  crops, 
owing  to  a  deficiency  of  rain  or  irrigating  water.  In  fact,  the  pre- 
ceding study  only  shows  the  nature  of  the  influence  of  the  solar 
radiation ;  the  exact  quantitative  effect  on  the  amount  of  the  crop  must 
vary  with  the  irrigation  or  rainfall,  with  the  fertilizers  applied  to 
the  soil,  and  with  the  peculiarities  of  the  seed. 

As  to  the  rainfall,  it  was  in  the  preceding  cases  distributed  as  shown 
in  the  following  table: 


Rainfall  during  stages. 

Total 
sunshine 

from 
germina- 
tion to 
ripening. 

Year  of  sowing. 

Germi- 
nating. 

Heading. 

Flower- 
ing. 

Ripen- 
ing. 

1873 

1.19 
2.97 
1.84 

0.75 
1.36 

0.78 
0.99 
1.65 

1.72 
1.44 
1.94 

5,924 

1875 

5,676 

1878 

5, 263 

-  From  these  figures  we  conclude  that  the  excess  of  rain  in  the  wheat 
season  of  1878-79,  which  would  have  been  advantageous  with  a  clear 
sky,  as  in  Egypt,"  was  at  Paris  accompanied  by  too  little  sunshine, 
and  therefore  the  crop  suffered.  For  a  given  quantity  of  sunshine  a 
certain  quantity  of  water  is  best  for  the  crop;  if  the  sunshine  is 
diminished  the  plant  can  not  use  so  much  water,  and  that  must  be 
correspondingly  diminished. 


a  Or  as  in  the  case  of  irrigation  in  tlie  arid  portions  of  tlie  United  States. — C.  A. 


255 


The  influence  of  the  date  of  sowing  and  its  relation  to  sunshine 
and  frost  is  fully  shown  in  the  table  for  Montsouris,  which  gives  the 
sum  total  of  actinometric  degrees  from  the  time  of  germination  to 
maturity  for  seeds  sown  on  successive  weeks  in  1879,  1880,  and  1881, 
and  harvested  in  1880,  1881,  and  1882 : 


Date  of  sowing. 


Total  sun- 
shine fiMm 
arerminatiiii: 

to  ripening 
(actinomet- 
ric degrees) 


Total  sun- 
shine from 
germination 
to  ripening 
(actinomet- 
ric degrees). 


1879 

October  1 

Octobers 

October  15 

October  22 

November  1 

Novembers 

November  15 

November  22 

1880, 

Februarys 

February  15 

February  23 

March  1 

September  29  c 

October  6c... 

October  13 

October  20d 

October  27d 

November  3<i 

November  10 

November  17 


November  24 

December  1 

December  S_ 

December  15 

December  22  « 

December  29  e 

1881. 

January  5 

January  12 

January  19 

January  26 

February  2 

February  9 

February  16 

Februai-y  23 

March2 

March9 

Marchl6.. 

March  23 

March30. 

Apriia 


(/) 


,245 
,018 
,047 


a  Frozen  soil  prevented  sowing. 
*>No  sowing  during  this  interval. 
<•  See  note  1  in  text. 


d  See  note  2  in  text. 
eSee  note  Sin  text. 
/  Frozen  ground  prevented  sowing. 


Among  other  conclusions  that  may  be  drawn  from  these  figures  are 
the  following,  most  of  which  are  also  given  by  Marie-Davy : 

1.  The  season  1880-81  was  characterized  by  much  sunshine  and 
little  rain,  which  hastened  the  ripening,  but  delayed  the  flow  of  nap, 
and  therefore  of  nourishment  to  the  grain,  so  that  the  crop  was  rather 
poor. 

2.  For  the  crops  of  fall  wheat  the  sunshine  increased  more  and  more 
as  the  seed  was  sown  later  from  September,  1880,  even  to  the  end  of 
December;  then  it  began  to  diminish,  and  for  the  spring  wheat,  sown 
in  March,  1881,  it  was  too  small. 

3.  By  considering  other  weather  records  it  is  evident  that  the 
freezing  of  the  ground  in  January,  1881,  not  only  prevented  the  sow- 
ing of  the  seed,  as  noted  in  our  table,  but  prevented  the  germination 
of  the  seeds  sown  on  December  22  and  29,  1880,  which  would  other- 
wise have  sprouted  on  February  4  and  19, 1881,  respectively. 


256 

4.  The  wheat  sown  September  29  and  October  6,  1880,  which 
headed  out  December  oO  and  February  19,  was  injured  as  to  the  heads 
by  the  subsequent  frost. 

5.  The  seeds  sown  October  20,  27,  and  November  3,  1880,  flowered 
between  the  4th  and  8th  of  June,  1881,  but  at  this  time  there  was 
experienced  at  Paris  a  spell  of  very  cold  weather,  the  minimum  daily 
temperature  being  3.1°  C,  and  even  white  frosts  were  reported,  so 
that  wheat  which  was  then  in  flower  was  badly  injured. 

6.  -In  general,  the  dates  November  10,  1880,  to  December  15,  1880, 
are  those  indicated  as  most  favorable  for  sowing  wheat  in  that  year, 
and  the  crop  of  1881  may  be  predicted  as  likely  to  be  small,  but  of 
excellent  quality. 


The  grape  and  loine  crop. — In  a  short  study  on  the  relation  between 
the  vine  and  the  weather,  Marie-Davy  (1882,  p.  290)  states  that,  in 
general,  the  annuals,  such  as  the  cereals,  concentrate  all  their  energy 
in  the  formation  of  the  ear  and  the  seed  or  grain.  Their  work  is  then 
finished  and  they  die.  The  next  year's  crop  of  these  annuals  is 
largely  under  the  control  of  the  husbandman,  who  can  obtain  seed 
from  more  favored  regions  if  his  own  crop  was  inferior. 

On  the  other  hand,  the  work  of  the  vine,  like  all  perennials,  is  not 
merely  to  ripen  its  fruit  and  seed,  but  to  preserve  its  own  individual 
self  for  usefulness  in  future  years.  Therefore  it  elaborates  out  of  its 
own  sap  not  merely  leaves  and  fri^t  and  seed,  but  a  store  of  woody 
fiber.  Corresponding  to  this  more  complex  system  of  growth  the 
relations  of  the  perennials  to  the  climate  are  apparently  more  complex 
1  han  the  relations  of  the  annuals,  and,  it  may  also  be  added,  the  range 
of  geographical  distribution,  whether  by  nature  or  by  cultivation,  is 
more  restricted. 

Our  studies  will  be  confined  to  the  data  furnished  by  the  observa- 
tions at  Epernay  (1873-1881),  to  which  Marie-Davy  adds  other  data 
computed  from  the  observations  made  at  Montsouris,  in  which  latter 
computation  certain  laws  of  growth  of  the  vine  as  established  by 
Gasparin  were  adopted. 

In  the  neighborhood  of  Paris  the  leaf  buds  of  the  vine  burst  open 
in  May  when  the  mean  daily  temperature  has  permanently  passed 
above  11°  or  12°  C.  Assuming  that  the  mean  of  twenty  days,  as 
observed  at  Montsouris,  will  give  this  date  (which  was  unfortunately 
not  observed  at  Epernay),  we  obtain  the  figures  in  the  first  three  col- 
umns of  the  following  table.  In  some  of  these  years  the  early  leaf 
buds  were  undoubtedly  killed  by  nocturnal  frosts,  but  they  were  soon 
replaced  by  other  buds,  and  the  dates  here  given  must  be  adopted  in 
the  absence  of  actual  observations,  especially  when  we  remember  that 
the  quantity  and  quality  of  the  final  crop  of  grapes  depend  not  only 


257 


on  the  meteorological  conclitioiis,  but,  equally  or  more,  on  the  condi- 
tion of  the  woody  fiber  of  the  stock  and  stems.  Similarly  the  date  of 
flowering  is  calculated  by  assuming,  with  Gasparin,  that  the  sum  total 
of  the  mean  daily  temperatures  in  the  shade  must  be  466°  C,  count- 
ing from  the  date  of  leafing.  This  number  is  more  especially  appli- 
cable to  the  vineyards  of  Champagne  and  Burgundy,  and  is  not 
necessarily  strictly  applicable  to  P^pernay  or  to  the  vineyards  of 
the  south  of  France.  The  fifth  and  subsequent  columns  of  the 
table  give  the  mean  climatic  conditions  for  a  period  of  sixteen  days, 
in  the  middle  of  which  is  the  calculated  date  of  flowering.  There 
appears  to  be  no  simple  relation  between  this  latter  data  and  the 
resulting  wine  crop,  nor  has  the  crop  any  apparent  relation  with  the 
total  sky  radiation  during  this  period.  In  fact  we  may  conclude  that 
up  to  the  time  of  flowering  the  energy  of  the  vine  has  been  devoted 
to  building  up  its  own  structure  as  a  preparation  for  the  work  that  is 
to  come.  The  development  of  the  grape  does  not  depend  upon  nitrog- 
enous particles  stored  away  in  the  vine,  but  on  the  power  to  elaborate 
the  sap  which  is  to  become  the  juice  of  the  grape,  and  that  power 
depends  upon  the  leaf  surface,  the  roots,  and  the  stock  during  the 
first  stages  of  the  growth  of  the  grape,  but  eventually  upon  changes 
that  go  on  within  the  grape  itself. 

These  facts  are  brought  out  by  the  study  of  the  conditions  prevail- 
ing during  the  last  stages,  viz,  from  flowering  to  maturity : 


Calculated  date  of 
leafing. 

During  80  days. 

During  16  days. 

Average 
tempera- 
ture. 

Total 
rainfall. 

Calculated  date  of  flow- 
ering. 

Average 
tempera- 
ture. 

Average 
radia- 
tion. 

Total 
rain- 
fall. 

May  21,  1873 

°  C. 
12.1 
13.2 
16.0 
14.2 
11.5 
14.1 
12.6 
14.0 
14.6 

mm. 
25.3 
20. 5 
25. 5 

3.0 
.56.8 
.51.7 
a5.9 

0.0 
39.0 

June  22     ..  . 

•a. 

18.7 
16.8 
19.0 
19.4 
20.9 
16.4 
16.6 
16.2 
14.9 

°  Actin. 
46.1 
41.5 
55.2 
49.0 
51.6 
40.3 
43.0 
37.6 
48.7 

mvi. 

May  20,  1874 

June  13 

26  8 

May  9, 1875 

May  28,  1876 

Jiine  25 

52  3 

May  13,  1877 

May  16,  1878 

June  16 

55  1 

May  21,  1879 

June  23 

May  16,  1880 

June  16 

45  5 

May  21,  1881 

15  2 

Average  June  16.. 

Average  May  18  . . . 

13.6 

27.5 

17.7 

45.9 

«.6 

According  to  Gasparin  the  grape  reaches  its  maturity  when  it  has 
received  a  sum  total  of  mean  daily  shade  temperatures  of  1,926°  C, 
counting  from  the  date  of  flowering,  but  the  grape  ceases  to  be 
nourished  or  to  ripen  when  the  mean  daily  temperature  falls  lielow 
12.5°,  If,  now,  we  ascertain  the  date  of  maturity  by  summing  up 
the  daily  temperatures,  as  required  by  Gasparin's  rule,  we  obtain 
the  results  given  in  the  first  column  of  the  following  table.  If  we 
2667—05  >i 17 


258 

lake  the  mean  values  for  the  twenty  days  previous  to  the  date  of 
maturity  we  obtain  the  data  in  the  second,  third,  and  fourth  columns, 
and  we  notice  that  although  in  the  warmer  seasons  there  may  be  a 
great  variety  in  the  value  of  the  crop,  yet  in  the  cold  seasons,  1877 
and  1879,  when  the  mean  temperatures  fell  below  the. limit  (12.5°) 
required  for  ripening,  the  crop  was  very  poor  or  failed  altogether. 
If  noAv  the  total  radiation  from  sun  and  sky  is  computed  according- 
to  Marie-Davy's  method  for  the  period  betAveen  leafing  and  flowering 
and  again  from  flowering  to  maturity  Ave  obtain  the  figures  in  the 
columns  five,  six.  and  seven.  Here  we  see,  as  before,  that  the  variation 
during  the  flowering  period  Avas  of  little  importance,  Avhereas  that 
during  the  ripening  period  has  a  direct  relation  to  the  character  of 
the  wine  crop,  such  that  in  general  the  larger  the  total  radiation  the 
better  the  crop,  provided  the  temperature  of  the  air  has  not  fallen 
too  low. 


During  previous  20    1     Total  radiation  by 
days.                 !               stages. 

General  character  of— 

Calculated  dates  of 
ripening. 

Mean 
daily 
tem- 

tui-e. 

Sum. 

Juice. 

Wine  crop. 

Sugar.    Acid. 

October  7, 187,3 

16.1 
16.0 
17.4 
16.2 
11.9 
13.3 
11.5 
15.2 
15.1 

°Actin. 
30.2 
27.6 
40.6 
27.7 
30.4 
25.5 
36.1 
27.8 
24.2 

mm.    1°  Act  in. 
20.3      1,278 
28.8      1,343 

5.9      1,306 
16.7       1,222 

8.2      1-280 

"Actin. 
4,590 
4,544 
4,322 
4.205 
4,603 
4,165 
•4,033 
3,966 
4,262 

°  Act  in. 
5,868 
5,887 
5,728 
5,427 
5,883 
5,403 

5,301 
5,837 

162          8.2 
179          6. 1 
181          5.4 
174          6.8 
186  ;        8.7 
181  '         6  7 

September  35, 1874 

September  21, 1875 

October  7, 1876 

Finest. 
Good. 

October  2, 1877 

Very  poor. 
Good 

October  2, 1878 

23.8 
6.3 
25.0 
81.2 

1,238 
1,355 
1,305 
1,575 

October  15, 1879... 

September  29, 1880 

September  26, 1881 

154 
188 
180 

9.5 
6.4 
6.1 

Very  poor. 
Excellent. 

Average     Octo- 
ber 2  

14.7 

28.9 

34. 0      1  322 

4,  .302 

5,636 

176          7  1 

In  general,  Marie-DaA-y  concludes  that  the  number  of  grapes  to  the 
bunch  and  the  number  of  bunches  to  the  vine  do  not  seem  to  have  any 
clear  relation  to  meteorological  conditions,  except  in  the  case  of  spring 
frosts,  Avhich  can  destroy  a  crop.  Besides  the  conditions  as  to  pruning 
the  vine  and  dressing  the  soil,  the  number  of  grapes  that  haA^e  set  (on 
which  principally  depends  the  quantity  of  the  tn-op  that  Avill  be  pro- 
duced) is  a  result  primarily  of  the  meteorological  conditions  during 
the  previous  year  and  of  the  state  of  preparation  of  the  Avoody  stock. 
On  the  contrary  the  final  size  of  the  grapes  and  the  quality  of  the 
juice  depends  on  the  meteorological  conditions  of  the  crop  year  and 
those  that  accompany  the  flowering  and  succeed  it  up  to  the  time  of 
maturity.  A  final  sum  total  of  radiation  is  not  ■  sufficient ;  it  is 
necessary  to  take  account  of  its  distribution  Avith  reference  to  the 


259 

phenological  perio  is  and  of  other  accoiiip-uiying-  circumstances. 
Thus  in  1877.  with  a  low  mean  temperature  and  a  high  radiation 
during  maturity,  and  in  1879,  with  a  low  temperature  and  a  low 
radiation  during  the  last  phase,  both  alike  gave  a  poor  crop,  but  the 
sunshine  of  l.'^77  was  able  to  make  a  large  quantity  of  sugar  as 
compared  with  the  small  quantity  of  sugar  in  1871). 


Sugar  heets. — Marie-Davy  (1882)  and  Pagnoul  (1870)  give  the 
data  of  a  research  into  the  relation  of  climate  to  the  development  of 
sugar  beet  as  cultivated  at  Arras,  the  agricultural  station  of  the 
Department  of  Pas  de  Calais.  The  following  table  gives  the  i-esults 
of  meteorological  observations  and  chemical  analyses  of  sample  beets 
taken  up  every  ten  days  during  the  season.  The  beets  were  sown 
April  5,  1879,  averaging  six  plants  to  the  square  meter.  They  were  of 
a  poor  variety,  but  of  the  kind  ordinarily  planted  in  that  section ; 
they  were  of  a  rosy  color,  and  were  planted  a  great  distance  apart  in 
order  that  they  might  grow  more  rapidly. 


Decade  ending 
1879. 


During  the  decade. 


Total 
rain. 


Total 

heat 

(sum  of 

mean 

daily 

shade 

tempera 

tures). 


Total 
sunshine 

(daily 

average 

of  clear 

skyj. 


Total 
radia- 
tion 
(sum  of 
daily 
actino- 
metric 
degrees 
at  Mont- 
souris). 


At  end  of  decade. 


Average 
weight  of— 


Root.    Leaves. 


Aver- 
age 
density 

of 
juice. 


Weight 

of  sugar 

per  100 

beets. 


Weight 
of  sugar 


June  11 

June  21 

Julyl 

July  11 

July  21 

JulySl 

August  10 

August  20 

August  30 

September  9 . . 
September  19 . 
September  29 . 

October  9 

October  19  ... . 
October  29  .... 


Per  cent. 
41 
30 
31 
16 


Actin. 
393 
479 


31 

41 

110 

105 

222 

220 

333 

346 

462 

486 

452 

666 

433 

778 

335 

878 

312 

1,040 

200 

1,048 

126 

1,048 

194 

1,056 

98 

l,a50 

128 

Beau- 
me. 


4.0 
4.2 
4.1 
4.4 
4.3 
4.1 
4.4 
4.1 
4.5 


2.13 

5.18 

.5.:w 

5.88 
6.K5 


7.57 
8.20 
7.46 
7.46 
8.06 
7.46 
7.94 


■.m 

776 
1,422 
1,848 
3,073 
3,534 
4,320 
4,655 
4,691 
5,068 
4,727 
5,002 


The  influence  of  sunshine  is  to  be  found  by  studying  the  fourth  col- 
umn of  the  sum  total  of  daily  average  cloudiness  at  Arras,  as  result- 
ing from  twelve  daily  observations  of  the  amount  of  cloudiness.  The 
clearness  of  the  sky,  as  given  in  the  fourth  column  in  percentages,  is 


260 

the  complement  of  the  cloudiness  and  represents  the  relative  duration 
of  sunshine,  but  owing  to  the  varying  altitude  of  the  sun  can  by 
itself  alone  give  no  idea  of  the  intensity  of  the  radiation  received  by 
the  plant.  To  obtain  this  ^  \st  item  and  as  no  actinometric  observa- 
tions were  made  at  Arras  I  give  in  the  fifth  colunni  the  results  of 
observations  at  Montsouris,  expressed  in  actinometric  degrees; 

The  beets  are  reported  to  have  sprouted  very  late  and  very  un- 
equally ;  this  was  due  not  to  dryness,  since  the  rain  during  March  and 
April  was  in  excess  of  its  normal  value,  but  was  directly  traceable  to 
the  low  temperature,  which  was  especially  low  in  April. 

The  study  of  the  development  of  sugar,  week  by  week,  as  given  in 
the  last  two  columns  of  the  above  table  shows  that  after  September  9 
the  sugar  crop  increased  slowly,  became  stationary,  and  then  fluctu- 
ated very  much  as  the  weight  of  the  leaves  fluctuated.  The  rainfall 
had  at  that  time  become  light  and  the  development  of  the  beet  seemed 
to  depend  mostly  on  the  temperature,  so  that  it  may  be  concluded  that 
the  beet  ceases  to  increase  in  its  quantity  of  sugar  after  the  mean 
daily  temperature  falls  below  13.1°  C,  and  that  there  is  no  probable 
advantage  in  leaving  the  beets  in  the  soil  after  that  date,  which  in 
this  case  is  September  29,  1879. 

Marie-Davy  points  out  that  the  actual  increase  per  decade  of  the 
weight  of  the  roots  coincides  with  the  increase  of  the  rainfall  and 
the  temperature,  but  the  proportion  of  sugar  increases  with  the  degree 
of  radiation  or  total  sunshine;  the  sunshine  precedes  the  formation 
of  sugar,  since  its  action  is  slow  and  indirect,  being  through  the 
assimilation  that  takes  place  within  the  leaves.  It  is  therefore  not 
an  excess  of  water,  but  a  deficiency  of  light  and  heat  that  causes  rainy 
autumns  and  summers  to  give  poor  crops  of  sugar.  Therefore,  if 
during  dry,  clear,  warm  summers  having  large  radiation,  one  could 
irrigate  the  fields  properly  one  would  realize  the  best  conditions  for 
a  good  crop.  Therefore,  every  ray  of  sunshine  that  strikes  the 
ground  instead  of  the  leaf  is  a  loss  to  the  formation  of  sugar  and  by 
helping  to  evaporate  the  moisture  of  the  soil  it  also  causes  further 
great  loss  of  sap  to  the  plant.  These  conclusions  agree  with  other 
experiments  made  by  Pagnoul,  who  raised  beets  both  in  darkness  and 
under  a  transparent  bell  glass,  and  again  in  the  free  air,  and  found 
the  amount  of  sugar  to  increase  with  the  strength  of  the  sunshine. 

The  following  table  gives  a  general  survey  of  the  beet  crops  in  Pas 
de  Calais  and  the  corresponding  climatic  data  at  Montsouris,  which 
is  about  90  miles  south  of  Arras.  The  numbers  given  in  the  columns 
for  quantity  and  quality  of  the  crops  are  the  estimates  obtained  from 
many  planters  and  are  recorded  on  the  following  scale :  1,  very  small 


2(>1 


or  verv  bad ;  2,  small  or  bad ;  ;J,  passable  or  niodiocre ;  4,  fairly  trood ; 
5.  good  ;  0,  ver}'  good. 


Dates  when  mean 
temperature  of 
air  thermome- 
ter in  shade— 


During  the  season. 


General  character  of 
sugar  crop  in  Pas 
de  Calais. 


The  climatic  data  given  in  the  above  table  as  directly  applicable  to 
the  seasons  of  growth  of  the  beet  root  illustrate  what  should  be  given 
for  any  similar  study  of  development  of  any  crop.  But  it  is  com- 
monly the  case  that  the  dates  of  the  various  phenological  epochs  are 
not  exactly  given,  and  that  we  have  to  rely  upon  general  tables  of 
general  climatic  conditions  month  by  month,  such  as  are  recom- 
mended by  the  International  Meteorological  Congress  of  Vienna  and 
by  that  of  Rome.  Therefore,  for  the  sake  of  comparison  with  other 
climates  whose  data  are  given  on  the  so-called  international  forms,  I 
give  in  the  following  table  a  part  of  PagnouFs  tables  of  average  tem- 
perature Centigrade  and  rainfall  in  millimeters  as  observed  at  Arras : 


Mean  daily  shade  temperature. 


1874 
1875 
1876 
1877 
1878 


Apr.  i  May.  June.  July.  Aug.  Sept.  Oct. 


8.6 
11.0 
9.6 
9.3 


19.1 
20.1 
17.4 
19.6 
17.8 
18.0 
15.5 


17.0 
19.1 
19. 15 
17.7 
18.6 
17.6 


Total  monthly  rainfall. 


Apr.  May.  June.  July.  Aug.  Sept.  Oct. 


48.6 
20.7 
8.0 
41.3 
45.0 


45.5  ^.3 
32.9  I  25.7 
m.7  [  H2.0 
1.5.3  32.0 
88.2  23.0 
88.4  60.6 
51.7  138.6 


26.2 
16.0 
6:17 


61.3 
46.7 


40.3  I  33.5 
34.2  1  93.3 


87.3     87.0 
96.5    50.3 


42.9 

;«.5 


56.1 
47.2 
61.6 
24.5 
48.5 
87.3 
4.5.4 


The  preceding  stud}'  gives  n  first  idea  as  to  the  relation  between 
climate  and  the  development  of  the  leaves,  the  roots,  and  the  sugar, 
and  offers  a  first  step  toward  determining  how  suitable  for  the  beet- 
sugar  industry  any  climate  may  be,  and  especially  does  it  suggest  to 


262 

the  planter  how  he  may  early  in  August  begin  to  safely  predict  from 
week  to  week  what  his  jDrobable  crop  will  be  early  in  October.  Thus, 
table  on  page  259  shows,  by  the  samples  taken  August  "20,  that  there 
were  then  in  the  beets  3,073  kilograms  of  suger  per  hectare,  whereas 
on  October  9  there  was  5,068.  or  five-thirds  of  that  present  on  August 
20.  This  factor,  five-thirds  =1.()T.  is.  therefore,  that  by  which  the 
figures  of  August  20  are  to  be  multiplied  in  order  to  obtain  those  of 
October  9.  The  following  table  gives  similar  factors  for  the  succes- 
sive decades  for  the  crop  of  1879,  and  when  a  succession  of  years  has 
been  thus  treated  we  shall  know  something  of  the  accuracy  with  which 
the  harvest  crop  can  be  predicted.  The  regularity  with  which  these 
numbers  run  shows  that  after  the  1st  of  September  the  error  of  pre- 
diction can  only  be  a  small  per  cent. 

ICrop  fac-!  •vrrp;„>,* 
Date  of  sampling  ,  1879).  tor  for  'of  ®'|rr 

'this  date.  °^  sugar. 


AugustlO 2.74  1,848 

August  20 l.&j  3.073 

AugustSO _ 1.43  I  3,534 

Septeinber9 1.17  !  4,320 

September  19 __ 1.09  4,655 

September  29 1.08  4,691 

October  9. 1.00  5,068 

Pagnoul  calls  attention  to  the  fact  that  the  roots  contain  a  consid- 
erable portion  of  nitrates,  although  the  soil  in  which  they  grow  had 
not  received  during  this  or  previous  years  a  trace  of  these  salts. 
This  salt  could  only  have  come  into  existence  by  the  nitrification  of 
organic  nitrogenous  matter,  and  it  is  well  to  insist  upon  this  fact, 
for  we  can  thus  remove  from  the  minds  of  certain  persons  the  idea 
that  if  the  beet  root  contains  nitrates  they  must  have  been  put  into 
the  soil  by  the  cultivator.  This  mistake  has  frequently  caused  un- 
happy contests  between  the  farmer  and  the  sugar  manufacturer. 

If  the  beet  root  had  at  its  -disposal  only  a  proper  proportion  of 
nitrates  that  had  been  formed  in  tlie  soil  before  sowing,  these  salts 
would  be  rapidly  absorbed;  they  would  by  their  decomposition  give 
rise  to  a  large  and  i)rompt  development  of  leaves,  and,  consequently, 
to  an  easier  elaboration  of  sugar,  and  in  proportion  as  vegetation 
advances  we  should  find  smaller  quantities  of  nitrates  in  the  beets. 
This  fact  was  proven  by  Marie-Davy  in  1878. 

If  on  the  contrary  the  nitrogen  is  furnished  by  a  process  of  nitrifi- 
cation that  is  prolonged  during  the  ^hole  season,  then  the  absorp- 
tion of  the  nitrates  goes  on  continuously  and  their  total  weight  per 
hectare  increases  steadily  to  the  end  of  October,  as  shown  in  these 
analyses  for  1879. 


263 

Some  fiii'tlier  experiments  l)y  Pno-noul  (1R70,  p.  4S())  on  the  beet 
as  grown  in  darkness  and  in  sunshine  shows  that  the  former  were 
exceptional!}^  rich  in  alkali,  ash,  and  especially  the  nitrates.  This 
is  explained  as  above,  viz:  The  nitrates  Avill  not  decompose  within 
the  plant  except  under  the  influence  of  sunshine;  if  the  plant  is 
kept  in  darkness  it  stores  up  the  nitrates  within  itself  without  having 
the  power  of  utilizing  its  own  nitrogen,  so  that  the  substances  in  the 
formation  of  which  this  nitrogen  ought  to  be  of  assistance  can  not  be 
formed. 

P'rom  this  one  must  conclude  that  years  that  are  bad  for  the  beet- 
sugar  crop  are  so  not  only  because  of  unfavorable  temperatures  and 
humidities  but  above  all  because  of  a  defect  in  the  insolation.  Lively 
complaints  have  been  made  of  the  quantity  of  nitrates  in  certain 
harvests;  now  these  salts  that  accumulate  in  the  molasses  and  in 
the  inferior  products  and  augment  the  difficulty  of  the  w'ork  occnr 
often  in  beets  cultivated  upon  a  soil  that  has  never  received  a  trace 
of  nitrates  as  a  fertilizer.  It  is  therefore  not  to  the  abuse  of  nitrates 
as  a  fertilizer  that  we  ought  to  attribute  their  presence,  but  rather 
to  a  too  cloudy  sky. 

We  know  that  the  neighborhood  of  large  trees  is  injurious  to  the 
vegetation  aronnd  them.  Ordinarily  we  attribute  this  injurious 
influence  to  their  roots.  It  would  perhaps  be  more  exact  to  attribute 
it  to  the  shade  that  they  cast,  and  the  more  so  because  it  has  been 
demonstrated  b}'  Cailletet  that  green  light  has  no  power  to  bring 
about  the  decomposition  of  carbonic  acid. 

In  the  Annuaire  for  1883  Marie-Davy  studies  the  influence  of  the 
date  of  sowing.  In  order  to  ascertain  the  best  dates  for  sowing  and 
trace  out  the  various  vicissitudes  to  which  the  crop  is  subject,  whether 
resulting  from  the  climate  as  such  or  from  the  ravages  of  insects  or 
fungi,  it  is  necessar}'  to  make  a  rather  detailed  study  of  the  state  of 
development  of  the  plant  under  the  assumption  that  the  seeds  were 
sown  on  successive  dates — for  instance,  on  a  given  series  of  successive 
week  days.  An  elaborate  study  of  this  kind  is  given  for  wheat  by 
Marie- Davy  (pp.  244-285  of  his  ^Vnnuaire  for  1883),  from  which  the 
following  tables  have  been  extracted.  In  general  the  varieties  of 
wheat  cultivated  in  the  south  of  Europe  are  more  sensitive  to  cold 
than  those  of  the  north,  but  the  studies  of  Marie-Davy  for  the  latitude 
Montsouris,  when  paralleled  by  similar  studies  for  localities  in  the 
United  States,  can  but  be  of  the  greatest  value  both  to  the  farmers 
and  the  statisticians  of  this  country.  The  study  of  such  tables  will 
enable  one  to  very  closely  i)redict  the  time  of  harvest,  the  quantity 
and  quality  of  the  cro]),  and  the  range  of  uncertainty.  To  this  end 
it  is,  of  course,  imderstood  that  corresponding  elaborate  tables  of 


264 

meteorological  conditions  must  be  accessible,  samples  of  which  I  have 
prepared  for  twenty  United  States  stations." 

If  we  suppose  some  wheat  to  have  been  sown  on  the  :l2d  of  Septem- 
ber, 1871,  near  Paris,  and  if  we  adopt  the  rule  established  by  Gas- 
parin  that  the  vitality  of  the  seed  is  actively  aroused  as  soon  as  its 
temperature  in  a  moist  earth  exceeds  5°  C,  and  that  it  germinates 
visibly  when  it  has  received  a  sum  total  of  mean  daily  temperatures 
that  is  equal  to  85°  C,  and  that  the  sprout  rises  above  the  surface  of 
the  earth  in  a  few  davs  after  the  seventh,  then  we  obtain  six  days  as 
given  in  the  folloAving  table  for  the  interval  from  sowing  to  germina- 
tion. A  similar  computation  for  every  other  date  of  sowing,  as  given 
in  the  following  table,  shows  at  a  glance  the  effect  of  the  temperature 
of  tJie  soil  on  this  phase  of  plant  life. 

Duration,  in  (Itn/n.  from  aoiriiifi  to  f/rriiiiuation  of  irintrr  irJieat  at  .l/o»f.«oj<r/.s, 
France,  for  the  i/ears  1872-1881. 


1871. 

1872. 

1873. 

1874. 

1875. 

1876. 

1877. 

1878. 

1879. 

1880. 

Germination. 

Date  of  sowing. 

1881. 

Av- 
erage 
dura- 
tion 
for 
the 
years 
1872- 
1881. 

Aver- 
age 
date. 

September  22... 

6 

7 

7 

5 

5 

7 

8 

7 

7 

6 

e 

7 

Sept.  29 

September  29... 

7 

7 

5 

7 

6 

6 

8 

7 

7 

7 

10 

7 

Oct.     6 

October  6 

8 

9 

7 

9 

5 

8 

7 

8 

7 

8 

,8 

Oct.   14 

October  13 

8 

8 

9 

6 

8 

7 

10 

7 

10 

10 

11 

8 

Oct.  21 

October  20 

12 

8 

13 

10 

11 

11 

5 

7 

9 

32 

15 

11 

Oct.  31 

October  27 

70 

8 

13 

9 

11 

16 

8 

29 

14 

18 

13 

20 

Nov.  16 

Novembers 

72 

15 

15 

14 

8 

12 

8 

25 

16 

14 

7 

20 

Nov.  23 

November  10  .  _ . 

77 

15 

17 

32 

8 

8 

14 

48 

98 

9 

10 

33 

Dec.  13 

November  17... 

70 

9 

12 

49 

41 

13 

12 

44 

93 

21 

10 

36 

Dec.  23 

November  24... 

63 

10 

25 

53 

42 

11 

25 

39 

89 

17 

26 

37 

Dec.  31 

December  1.....' 

56 

16 

43 

48 

35 

8 

46 

69 

82 

12 

42 

42 

Jan.   1^ 

Decembers 

49 

16 

36 

42 

28 

22 

67 

62 

75 

11 

6f 

41 

Jan.   18 

December  15.... 

42 

12 

25 

35 

21 

12 

60 

55 

68 

13 

60 

35 

Jan.  19 

December  22.... 

35 

11 

30 

28 

56 

14 

55 

48 

61 

43 

57 

38 

Jan.  29 

December  29 

28 

19 

26 

21 

53 

9 

49 

42 

53 

44 

50 

34 

Feb.    1 

In  studying  the  preceding  table  we  recall  that  the  duration  of 
germination  varies  slightly  with  the  condition  of  the  soil  and  the 
depth  of  the  grain  below  the  surface;  these  two  considerations  will 
be  perfectly  allowed  for  if  we  observe  directly  the  temperature  of 
soil  by  a  buried  thermometer.  Such  observations  are  earnestly  recom- 
mended to  all  agricultural  experiment  stations,  as  they  are,  evidently, 
more  directly  applicable  to  the  growth  of  plants  than  any  crude 


These  tables  are  omitted  in  ttie  present  edition. 


2r)5 

approximations  derived  from  the  observation  of  the  temperatii''e  of 
the  air  only.  If  when  the  grain  has  sprouted  the  soil  continues  very 
dry,  the  nourishment  having  all  been  drawn  from  the  seed,  the  young 
plant  may  droop  and  die.  If,  again,  the  frost  jjenetrates  to  the  seed 
while  it  is  germinating,  many  of  the  seeds  will  perish,  and  the  field 
will  appear  as  if  sparsely  sown,  but  this  latter  mishap  is  generally 
repaired  by  nature  if  the  soil  is  good  and  the  springtime  favorable, 
for  the  sowing  is  generally  in  excess  and  the  extra  heading  will 
supply  the  loss  of  the  seeds  that  have  perished,  but  in  poor  soil  the 
harvest  will  be  notably  diminished,  and  often  it  will  be  i)rofitable  to 
plow  the  soil  for  a  neAV  sowing. 

In  any  case  the  chances  for  a  successful  crop  xarj  very  much  with 
the  date  of  the  sowing,  as  we  shall  see  by  the  study  of  the  following 
table,  which  shows  that  in  each  year  the  season  for  sowing  that  is 
favorable  to  the  crop  of  that  j^ear  is  very  much  restricted  by  the  early 
arrival  of  the  winter  cold.  Thus  in  1871  the  sowing  Avas  stopped  on 
the  '20th  of  October  by  the  cold  weather ;  in  1872  it  continued  through- 
out the  autuuni  until  the  20th  of  December;  in  1880  it  occurred  on  the 
8d  of  November.  Sometimes  heavy  rains  prevent  the  sowing,  but  in 
1881  neither  cold  nor  rain  prevented  field  work  until  the  middle  of 
December.  [In  order  to  save  space  I  have  omitted  the  elaborate 
tables  of  frosts,  low  temperatures,  and  rains  given  by  Marie-Davy  for 
each  of  these  years  and  weeks. — C.  A.] 

The  grain  now  arrives  at  the  epoch  of  heading,  at  which  the  orig- 
inal stalk  becomes  several  branches,  each  of  which  bears  an  immature 
head  on  which  the  rudimentary  seed  can  already  be  counted  under 
the  microscope;  the  number  of  such  seeds  will  not  increase  in  the 
further  development  of  the  plant,  but  many  of  them  may  not  come  to 
maturity;  therefore  a  careful  count  of  these  rudimentary  seeds  over 
a  small  area  of  the  field  would  give  a  first  estimate  of  the  maximum 
possible  crop. 

According  to  Gasparin  the  length  of  time  that  elapses  from  the 
moment  when  the  mean  daily  temperature  of  the  air  in  the  shade  is 
5°  C.  up  to  the  date  of  heading  of  the  wheat  is  such  that  the  sum 
total  of  the  mean  daily  shade  temperatures  is  430°  C,  but  as  the 
initial  date  is  difhcnlt  to  determine  we  shall  in  our  calculations  adopt 
the  rule  of  }Ter\'e  Maugon,  according  to  whom  the  sum  of  the  mean 
daily  temperature  in  the  shade,  rejecting  all  that  are  below  (5°  C 
(at  which  the  wheat  does  not  yegetate),  is  (140°  C.  if  we  count  from 
the  date  of  sowing,  or  5.55°  C.  if  we  count  from  the  date  of  germina- 
tion. The  following  table  is  computed  by  counting  from  the  former 
date;  a  parallel  computation  from  the  latter  date  shows  that  on  the 


266 


Mvorao-o  of  ten  years  there  is  no  appreciable  difference  between  the 
results. 

Duration,  in  dayft,  fmm  sowing  to  heading  of  winter  wheat,  at  Montsouris,  France. 


Date  of  sowing. 

1872. 

1873. 

1874. 

1875. 

1876. 

1877. 

1878. 

1879. 

1880. 

1881. 

1882. 

Average  for 

1872-1881. 

Dura- 
tion. 

Date. 

September  22 . .  - 

152 

67 

87 

58 

91 

57 

61 

167 

160 

85 

154 

99 

Dec.  30 

September  29... 

158 

72 

116 

113 

147 

64 

110 

171 

161 

92 

159 

120 

Jan.  27 

October  6 

161 

80 

161 

155 

153 

84 

1.35 

180 

161 

136 

157 

141 

Feb.  24 

October  13 

168 

90 

164 

172 

164 

140 

173 

164 

147 

155 

147 

Mar.    9 

October  20   

168 

i;« 

163 

175 

163 

107 

138 

178 

164 

148 

150 

154 

Mar.  23 

October  27 

163 

140 

162 

174 

160 

106 

145 

185 

164 

147 

152 

155 

Mar.  31 

Novembers 

162 

141 

158 

172 

156 

107 

156 

182 

162 

141 

146 

154 

Apr.    6 

November  10  ... 

155 

140 

158 

171 

159 

108 

1.t6 

175 

158 

128 

146 

151 

Apr.  10 

November  17  . .  . 

148 

134 

153 

165 

156 

123 

150 

168 

153 

141 

144 

149 

Apr.  15 

November  24... 

141 

134 

148 

159 

160 

125 

147 

162 

147 

135 

141 

145 

Apr.  18 

December  1 

134 

136 

142 

154 

143 

123 

143 

156 

140 

131 

136 

140 

Apr.  20 

Decembers 

127 

132 

135 

148 

136 

120 

138 

149 

133 

127 

129 

135 

Apr.  22 

December  15.-.. 

120 

126 

128 

141 

129 

115 

131 

142 

126 

124 

122 

128 

Apr.  22 

December  22.... 

113 

129 

121 

134 

124 

111 

126 

135 

119 

126 

118 

124 

Apr.  25 

December  29.... 

106 

127 

114 

127 

120 

106 

120 

131 

112 

123 

111 

118 

Apr.  26 

This  table  shows  that  on  the  average  of  ten  years  the  seed  that  was 
sown,  e.  g.,  on  the  27th  of  October  and  required  one  hundred  and 
fifty-five  days  to  head,  is  that  which  took  the  longest  time;  for  sow- 
ings before  that  date,  as  well  as  after  it.  the  durations  steadily 
diminish;  in  other  w^ords,  this  sowing  is  that  whose  development 
was  the  most  retarded  by  the  winter  cold.  If  we  compare  this  table 
with  those  given  by  Marie-Davy,  showing  the  frosts,  we  find  a  com- 
plete inversion  in  the  chances  of  injury  from  frost ;  wheat  as  a  green 
plant  has  as  little  to  fear  from  frost  as  has  the  dry  grain.  But 
during  and  after  the  formation  of  the  embryo  seed,  as  well  as  during 
germination,  on  the  contrary,  frost  is  very  injurious,  and  if  the 
embryo  is  seized  by  frost  it  perishes.  If  this  accident  occurs  it  is 
possible  that  the  progress  of  heading  may  permit  a  new  formation 
of  embryo  to  replace  those  which  have  perished.  Such  accidents 
must  have  occurred  to  the  seed  sown  in  the  hope  of  reaping  an  early 
harvest  in  1874,  1875,  1876,  1877,  1878,  and  1881,  but  did  not  occur 
in  1882.  This  accident  is  not  incompatible  with  an  excellent  harvest, 
as  we  see  in  the  case  of  1874,  but  it  causes  a  decided  retardation  of 
the  harvest,  as  in  1877.  The  mean  of  the  ten  years  shows  that  the 
heading  occurs  at  an  epoch  in  the  spring  when  the  mean  temperature 
of  the  air  is  between  ()°  and  13°  C,  and  when  the  rainfall  is  generally 
iibundant.  so  that  at  this  epoch  damage  does  not  generally  occur  to 
the  grain;  only  in  case  of  the  sowing  of  September  20,  1878,  did  the 


267 

heading  occur  (lurin*)-  the  very  cold  season  likely  to  be  injurious  to 
vegetation. 

We  pass  no-w  to  the  period  from  the  heading  of  the  wheat  to  the 
flowering.  Acconling  to  the  determination  of  Herve  Mangon,  the 
sum  total  of  the  mean  daily  air  temperatures  in  the  shade  necessary 
to  flowering  is  1,500°  C,  counting  from  the  date  of  sowing,  or  8G0° 
if  counted  from  the  date  of  heading.  If  we  consider  the  date  thus 
fixed  for  the  flowering  we  shall  find  that  it  corresponds  to  a  mean 
daily  temperature  at  that  epoch  of  1().5°  C.  on  the  average  of  many 
years;  but  if  we  consider  the  individual  years  we  shall  find  the  actual 
mean  temperatures  of  that  date  to  vary  from  8°  to  22°  C.,  and  also 
that  for  temperatures  below  13°  the  flowering  becomes  uncertain, 
prolonged,  and  detrimental  to  the  crop;  but  as  to  the  upper  limit, 
22°  C,  there  is  no  evidence  that  even  higher  temperatures  wnll  be 
injurious.  The  following  table  gives  the  calculated  number  of  days 
that  elapse  from  the  sowing  to  the  flowering,  together  with  the  aver- 
age duration  and  the  corresponding  average  date.  The  correspond- 
ing tables  of  mean  temj^eratures  and  lowest  temperatures  at  the  date 
and  the  quantity  of  rainfall  are  omitted  for  want  of  space. 

Duration  hi  dans  from   the  soiriii!/  to  the  ffoireriuf/  of  irhiter  irhcat  at  Mont- 
sour  is,  France. 


Date  of  sowing. 

1872. 

September  23... 

244 

September  29..- 

24.S 

Octobere 

a42 

October  13 

241 

October  20 

-m 

October  27 

232 

Novembers 

228 

November  10... 

221 

November  17  .-- 

214 

November  24  . . . 

207 

December  1 

200 

Decembers 

193 

December  15.... 

186 

December  22.... 

179 

December  29.... 

172 

235 

229 

224 

219  ! 

214 

211 

205 

199 

195 

191 

186 

181 


Average  for 
1872-1881. 


Dura 

tion. 


Date. 


May  16 
May  23 
May  29 
June  3 
June  8 
June  12 
June  14 
June  17 
June  19 
June  21 
June  22 
June  23 
June  24 
June  24 
June  26 


The  ripening  of  wheat  is  perfected  when  the  ])lant  has  received  a 
suni  total  of  Tnean  daily  air  temperatures  in  the  shade  of  815°  C.  since 
the  date  of  flowering.  This  result  happens  on  the  average  of  Paris 
forty-four  days  after  flowering,  and  the  individual  irregularities 
scarcely  ever  exceed  four  or  five  days.     Therefore  the  date  of  flower- 


268 

ing  can  be  made  the  basis  of  a  very  close  estimate  of  the  date  of 
i-ipening. 

The  date  of  flowering  occurs  at  the  time  of  the  greatest  vital 
activity  of  the  plant,  which  at  that  time  is  actively  drawing  its 
nourishment  from  the  soil  and  is  transpiring,  assimilating,  and 
increasing  in  Aveight.  But  very  soon  this  work  is  relaxed  and  is 
confined  more  and  more  to  the  interior  of  the  plant,  conveying  into 
the  seed  the  elaborated  materials  formed  within  the  leaves  and  stems. 
It  is  especially  in  this  latter  part  of  the  life  of  the  plant  that  the 
internal  consumption  can  exceed  the  gain  from  without,  and  the 
plant  tends  to  diminish  its  dry  weight. 

This  period  has  a  great  influence  on  the  final  result,  not  only  liecause 
the  plant  can  gain  as  a  whole,  but  especially  because  of  the  distribu- 
tion which  is  made  within  it  of  the  material  which  it  has  brought 
together.  The  straw  has  only  a  secondary  value.  It  is  the  seed 
which  constitutes  nearly  the  whole  value  of  the  harvest.  Therefore 
all  that  passes  from  the  straw  to  the  grain  is  a  benefit,  though  this 
j:)assage  should  be  accompanied  by  a  notable  consumption  of  the 
nutritious  materials  of  the  stalk.  It  is  neither  the  state  of  prepara- 
tion of  the  stalk,  nor  the  heat,  nor  the  radiation,  nor  the  moisture 
which  of  itself  alone  produces  the  best  quality  of  grain.  There  must 
be  a  reunion  of  all  these  various  elements  in  a  proper  proportion,  which 
latter  will  vary  with  the  weather  and  with  the  locality  even  with  the 
same  weather.  The  blighting  of  Avheat  is  an  accident  that  one  dreads 
most  at  this  period.  The  blight,  properly  so  called,  is  due  to  a  tem- 
perature and  a  radiation  that  is  too  intense  for  the  movement  of  the 
sap  in  the  plant ;  the  seed  has  not  time  to  receive  the  sum  total  of  the 
nourishing  particles  that  have  been  prepared  for  it;  therefore  it 
becomes  small,  lean,  and  shriveled  up.  A  greater  sum  total  of 
moisture  in  the  soil  or  a  less  active  transpiration  would  have  given  a 
better  result.  But  we  often  confound  the  blight,  properly  so  called, 
with  the  analogous  result  produced  by  an  insufficient  assimilation  or 
elaboration  of  the  various  materials  that  go  to  make  up  the  wheat 
grain  or  by  a  disproportion  in  the  relative  quantities  of  the  elements 
that  shoidd  make  up  the  seed. 

The  following  table  shows  the  number  of  days  elapsing  from  sow- 
ing to  ripening  for  the  dates  adopted  in  the  previous  tables.  It  is 
calculated  by  first  ascertaining  the  number  of  days  elapsing  from 
flowering  to  ripening  according  to  the  rule  above  given  and  then 
adding  these  intervals  to  those  already  calculated  for  the,flowering. 


269 

Durutio)!.  in  days,  fruin   soirinij  to  ripcniiH),  for  irititrr  ivheat  at  Moiitsotirift, 

France. 


Average  for 

1872-1881. 

Date  of  sowing. 

1872. 

1873. 

1874. 

18V5. 

18V6. 

1877. 

18V8. 

18V9. 

1880. 

1881. 

1882. 

Dura- 
tion. 

Date. 

Days. 

September  22... 

291 

282 

284 

285 

287 

268 

281 

311 

292 

285 

290 

287 

July    6 

September  29... 

290 

279 

287 

285 

287 

264 

379 

308 

393 

284 

289 

286 

July  12 

October  6 

287 

277 

279 

284 

285 

2a3 

275 

306 

286 

281 

285 

282 

July  15 

October  18 

283 

274 

276 

281 

281 

2m 

272 

399 

282 

277 

281 

279 

July  19 

October  20 

279 

271 

272 

280 

277 

362 

268 

396 

279 

273 

276 

276 

July  23 

October  27. 

272 

287 

269 

276 

272 

258 

265 

296 

275 

267 

271 

272 

July  36 

November  3 

289 

263 

365 

272 

266 

255 

261 

290 

271 

261 

264 

367 

July  28 

November  10... 

262 

260 

259 

369 

262 

249 

258 

283 

266 

2i)5 

363 

362 

July  :30 

November  17  . . . 

255 

254 

255 

263 

257 

245 

3;>2 

276 

260 

252 

259 

257     Aug.    1 

November  24  . . . 

248 

249 

249 

257 

250 

240 

248 

270 

254 

247 

254 

251 

Aug.    2 

December  1 

241 

244 

242 

251 

243 

234 

243 

263 

247 

241 

258 

245 

Aug.    3 

Decembers 

234 

240 

235 

245 

236 

232 

234 

256 

240 

235 

241 

239 

Aug.    4 

December  15 

227 

234 

228 

238 

229 

231 

2:« 

249 

233 

231 

234 

233 

Aug.    5 

December  22.... 

220 

229 

221 

231 

225 

226 

225 

242 

226 

226 

329 

227     Aug.    6 

December  29 

213 

226 

217 

224 

219 

220 

218 

236 

219 

220 

222 

221     Aug.    7 

In  the  following  table  I  present  a  summary  of  the  iDreceding  de- 
tails, showing  the  average  duration  and  dates  for  the  ten  years  from 
1872  to  18S1,  inclusive.  To  this  I  have  added  the  average  total  daily 
radiation  for  crops  sown  in  1873  to  1880,  as  computed  by  Marie-Davy 
in  actinometric  degrees  for  two  phases,  viz,  from  heading  to  flower- 
ing, and  for  thirty  days  after  flowering,  which  brings  us  through  the 
greater  and  more  important  part  of  the  ripening  phase. 

Summary  of  dates  and  radiation  for  icinter  ivheat  during  ten  years,  1872-1881, 
at  Moiitsouris,  France. 


Date  of  sowing. 


Average  interval  from  sowing  to—    Average    Aver- 

date  of    age  date 

Ripen-    germina-  of  head- 
ing,    i     tion.         ing. 


Germi- 


Flower- 

ing. 

Days. 

Days. 

99 

236 

120 

236 

141 

2;i5 

147 

233 

154 

zn 

1.55 

227 

154 

2£i 

151 

219 

149 

214 

145 

2(H) 

140 

2(« 

i:« 

197 

128 

191 

134 

184 

118 

179 

September  22. 
September  29. 

October  6 

October  13.... 
October  2(J..-. 
October  27.... 
November  3.. 
November  10. 
November  17. 
November  34. 
Decern  V)er  1  .. 
December  8  . . 
December  15  . 
December  22  . 
December  29  . 


Days 


Days. 


Sept.  29 
Oct.  6 
Oct.  14 
Oct.  21 
Oct.  31 
272  '  Nov.  16 
Nov.  23 
Dec.  13 
Dec.  23 
Dec.  31 
Jan.  12 
.Tan.  18 
Jan.  19 
Jan.  29 
Feb.    1 


Dec. 
Jan. 
Feb. 
Mar. 
Mar. 
Mar. 
Apr. 
Apr. 
Apr. 
Apr. 
Apr. 
Apr. 
Apr. 
Apr. 
Apr. 


270 

Summuri/  of  dates  and  radiaiioii  for  iriiitrr  a-heut  diiriitf/  ten  years.  1872-1881, 
at  Moi'tsouris,  France — Continued. 


Date  of  sowing. 


Average  total  radiation,  in 
acfinometric  degrees,  1874- 
Average '    1^81. 
date  of 


Flower-     Ripen- 
ing ing 
stage.       stage. 


September  22 . 
September  2ft . 

Octobers 

October  13  — 
October  20.... 
October  27  .... 
Novembers... 
November  10. . 
November  17. . 
November  24-. 
De(.:eniber  1 . . . 
December  8... 
December  1.5.. 
December  22. . 
December  29. . 


3,906 
3,989 
4,116 
4,1.W 
4,131 

4.i2n 

4.127 
4.131 
4. 131 
4,131 
4,lft6 
4,121) 
4,128 
4,04.5 
4,018 


On  the  average  the  Avheat  sown  October  IH  and  ripening  July  V.) 
received  the  most  sunsliine  during  the  hist  two  stages  and  shoukl  give 
the  best  crop. 

The  preceding  study  gives  the  details  of  the  weather  and  the 
development  of  the  wheat  from  1872  to  1882.  Marie-Davy  compares 
these  figures  with  the  annual  reports  of  the  total  crops  actually 
gathered  in  the  Department  of  Seine-et-Oise,  immediately  surround- 
ing Montsouris,  as  shown  in  the  folloAving  table,  assuming  that  the 
crop  ripened  at  any  time  between  July  6  and  August  7  during  those 
years. 

Wlieat  crops  and  sunshine  at  Montsouris. 


Year  of  harvesting. 

hectoli- 
ters per 
hectare. 

Total  ac- 
tinometric 
degrees 
during 
flowering 
and  ripen- 
ing stages. 

Year  of  harvesting. 

Total  a<-- 
rs.  ^r^      tinomctric 
y.     1%        degrees 
terfper      ^"""K 
Wta^re     Aowering 
hectaie.  and  ripen- 
ing stages. 

1872 

31.0 
17.3 
28.9 
21.9 
25.0 
23.0 
19.4 
17.9 

1880* 

24.4               4,1.54 

1873 

1881* 

24.6               4.a51 

4,494 
3,892 
4,416 
4,140 
3,584 
3,703 

26.8 

3,941 

*  Average  of  5  good 
years 

+  Average  of  4  poor 

25.9 
20.4 

1876* 

4,284 

1877t     --- 

3,827 

1879t 

If  we  summarize  the  five  years  of  crops  above  the  mean  and  the 
four  years  of  crops  below  the  average,  as  ijidicated  in  the  preceding 


271 

table,  there  results  an  apparent  continnation  of  our  view  tliat  the 
radiation  during  the  flo>vering  and  ripeniiiii:  phases  has  an  important, 
direct  influence;  in  fact,  the  diminution  of  the  average  sunshine  from 
4,284  to  3,827  actinometric  degrees  has  been  accompanied  by  a 
diminution  of  the  crop  from  '2'k^^  to  '20A  hectoHters  per  hectare 
This  diminution  of  25  per  cent  of  the  crop  corresponds  to  a  h)ss  of 
about  1.2  hectoliters  per  hectare,  or  4  per  cent  of  tlie  normal  crop, 
for  every  100  actinometric  degrees. 

We  have  already  seen  that  if  we  suppose  the  same  number  of  stalks 
to  the  hectare  and  the  same  relative  total  simi  of  solid  nutriment 
taken  from  the  soil  by  each  stalk,  then,  according  to  theory,  the  radia- 
tion can  serve  as  a  measure  of  the  possible  work  of  assimilation  by  the 
plant,  and  consequently  of  the  actual  sum  total  of  the  assimilated 
material.  These  conditions  are  never  completely  realized  for  many 
reasons,  and  one  can  not  hope  for  an  exact  relation  between  the  crop 
and  the  radiation,  but  it  is  interesting  to  see  that  the  above-reported 
crops,  both  in  detail  and  general  averages,  confirm  the  theory. 

Some  of  the  minor  departures  from  perfect  agreement  are  ex- 
plained by  a  detailed  examination  of  the  conditions  during  the  suc- 
cessive phases  of  germination,  heading,  flowering,  and  ripening 
during  the  good  years  and  the  poor  years.  The  following  table  gives 
the  average  climatic  conditions  during  the  first  three  phases  and 
shows  that  as  between  the  good  and  bad  years  there  can  have  been 
but  slight  average  differences  in  the  condition  of  the  stalks  and  the 
embryo  seeds  up  to  the  beginning  of  the  ripening  stage,  as  far  as  it 
depends  on  climatic  conditions. 


Compurifson  of  cliinateK  during  five  ijood  and  four  poor  yean 


Stage. 

Germiuating  period: 

Duration days.. 

Freezing  weather days.. 

Average  minimum  temperatures "C. 

Rainfall  during  the  period millimeters.. 

Heading  ijeriod: 

Duration • days.. 

Freezing  weather days.. 

Average  of  the  minimum  temperatures °C.. 

A vert-ge  temperature  at  the  epoch  of  heading "C. 

Average  rainfall  at  the  epoch  of  heading millimeters.. 

Flowering  period: 

Duration days . . 

Mean  daily  temperature  at  the  epoch  of  flowering °  C. . 

Average  rainfall  at  the  epoch  of  flowering millimeters.. 

Average  radiation  during  this  period Actinometric-  degrees. . 

Ripening  period: 

Average  radiation  during  this  period Actiuometri<-  degrees.. 


Good 
yeai's. 


ll.fi 

-  4.66 
9.4 

114 
5.7 

-  1.7 
10.1 
14.8 

75 
16.3 
ii6.3 
2,826 

1,45H 


'.t.O 

-  a.  7 
11.6 

113 
6.1 

-  2.1 
9.7 

22.1 

80 
16.3 
31.6 
2,525 


272 

The  preceding  table  shows  that  the  only  important  difference 
between  these  good  and  poor  years  consists  in  the  fact  that  the  latter 
have  more  rain  and  less  sunshine.  The  influence  of  the  tempera- 
ture of  the  air  as  such  and  of  the  number  of  days  of  freezing  weather 
does  not  seem  to  be  important,  so  that  we  must  conclude  that  the 
cloudy  weather  which  accompanies  the  rain  and  cuts  off  the  sunshine, 
affects  the  plant  unfavorably  only  by  this  loss  of  radiation.  xV  defi- 
ciency of  light  is  more  unfavorable  than  excessive  moisture  in  the 
soil.  In  general  in  France,  and  especially  in  dry  countries  such  as  the 
arid  regions  of  America,  it  is  the  deficiency  of  Avater  in  the  soil  that 
affects  the  crops  unfavorably.  Where  an  abundance  of  sunshine 
exists  the  wheat  plant  can  utilize  more  water  than  ordinary  soils 
possess;  hence  the  great  advantage  of  irrigation,  as  long  since  prac- 
ticed in  Mesopotamia,  Egypt,  China,  India,  Arizona,  and  South 
Africa.  The  numerical  data  with  regard  to  the  quantity  of  water 
and  the  times  of  irrigation  have  been  approximately  determined  at 
agricultural  experiment  stations,  Avitli  results  given  in  the  next  sec- 
tion of  this  present  report. 


In  the  Annuaire  for  1890  Marie-Davy  gives  climatic  tables  espe- 
cially adapted  for  phenological  study. 

In  order  that  meteorological  data  may  he  presented  in  form  con- 
venient for  the  comparison  of  crop  reports  or  for  the  prediction  of 
the  future  development  of  the  current  crop  or  for  other  studies  in 
the  growth  of  plants  it  is  necessary  that  the  data  should  be  compiled 
in  a  manner  very  different  from  that  ordinarily  given  in  climato- 
logical  tables.  The  monthly  means  and  other  data  given  in  the 
so-called  international  form  recommended  and  urged  by  the  recent 
international  conferences  of  Europe  have  much  more  regard  to 
dynamic  meteorology  and  to  questions  in  hygiene  than  to  questions 
in  agriculture.  For  our  agricultural  studies  a  continuous  sunnna- 
tion  must  be  made  from  the  beginning  to  the  end  of  the  year,  either 
by  decades,  by  weeks,  by  pentads,  or  even  by  days  for  each  succes- 
sive year.  From  such  tables  we  can  calculate  the  total  work  that 
has  been  done  upon  the  plant  bj  the  sunshine  and  the  work  that 
remains  to  be  done  before  the  harvest.  Such  tables  can  be  compiled 
in  an  empirical  approximate  way  from  the  data  furnished  by  the 
international  forms,  as  I  have  attempted  to  do  in  table — ."  But  it 
is  far  better  to  prepare  them  from  the  original  records,  and  they 
nuist  be  prepared  for  every  agricultural  experiment  station  in  the 
United  States  before  we  can  profitably  study  the  influences  of  our 

a  Tliis  table  is  omitted  iu  the  present  edition. 


273 

climates   upon   our   crops.     Those   tables   must    include   at    least  the 
following  data  : 

1.  The  mean  temperature  of  the  air  in  the  shade.  This  may  be 
deduced  most  simply  from  the  average  of  the  daily  maximum  and 
minimum  temperatures. 

2.  The  mean  temperature  of  a  thermometer,  preferably  a  black 
bulb,  but  not  in  vacuo,  exposed  to  the  full  sunshine  and  wind  and 
placed  amid  the  foliage  of  the  trees  or  the  blades  of  the  grain  that 
is  to  be  studied,  so  that  its  temperature  may  be  ap])roximately  that 
of  the  plant.  This  should  also  preferably  be  obtained  by  using 
maximum  and  minimum  thermometers. 

3.  The  temperature  of  the  soil  at  depths  of  1  inch  and  6  inches, 
corresponding  to  the  depths  of  the  roots  of  the  plants. 

4.  The  hygrometric  condition  of  the  free  air,  which  may  be 
expressed  either  as  relative  humidity  or  as  dew  point  or  as  vapor 
tension.     The  latter  Avill  be  most  convenient  in  all  our  calculations. 

5.  The  velocit}^  of  the  w^ind  or  its  daily  movement. 

6.  The  cloudiness  of  the  sky.  This  may  be  obtained  from  the 
ordinary  estimates  of  cloudiness  if  these  are  made  very  frequently, 
but  with  more  ease  and  accuracy  from  some  form  of  sunshine  recorder. 

7.  The  total  effective  radiation  from  sun  and  sky.  This  may  be 
obtained  from  frequent  observations  of  the  Marie-Davy  actinometer 
or  the  so-called  Arago-Davy  conjugate  thermometer,  or  Violle's  conju- 
gate bulbs,  but  still  better  when  these  are  made  self-recording,  and 
better  yet  from  such  forms  of  apparatus  as  the  photantitupimeter  or 
phantupimeter  of  Marchand,  or  the  radiometer  of  Bellani,  which 
Marie-Dav}^  has  improved  uj^on  in  the  form  described  by  him  as  the 
vaporization  lucimeter.  (See  Annuaire  de  Montsouris,  1888,  p.  207, 
or  1890,  p.  61.)  The  methods  of  using  these  instruments  are  doubt- 
less subject  to  improvement,  but  these  or  some  more  delicate  sub- 
stitutes are  absolutely  necessary  in  order  to  enable  us  to  appreciate 
the  w^ork  done  by  solar  radiation.  In  the  absence  of  instruments 
we  may  use  the  maximum  sunshine  as  diminished  by  the  estimated 
cloudiness. 

8.  The  actual  evaporation  from  plants  and  soils,  or  in  lieu  of  this 
the  evaporation  recorded  by  the  Piche  or  even  older  forms  of  evapo- 
rimeters  whose  records  are  doubtless  closely  parallel  to  those  of  the 
plants  in  the  soil,  but  usually  largely  in  excess  of  these. 

9.  The  total  rainfall  as  measured  by  the  ordinary  rain  gauges  in 
the  experimental  field. 

As  an  illustration  of  the  convenience  of  such  tables  I  have  com- 
piled the  following  table  for  Montsouris  by  pentads  in  so  far  as  the 
data  is  given  by  pentads  by  Descroix  in  the  Annuaire  for  1890. 
Some  of  the  data  is  obtained  by  interpolation  from  monthly  values 

2667—05  M 18 


274 

and  some  columns  are  left  blank  to  show  that  they  are  still  desirable." 
The  pentads  or  decades  to  be  used  in  such  a  table  as  this  should 
always  be  those  introduced  by  Dove,  the  limiting  dates  of  which  are 
as  given  in  this  table;  the  twelfth  pentad  of  the  ordinaiy  year  has 
five  days,  but  that  of  the  leap  year  has  six  days,  so  that  the  limiting 
dates  are  alw^ays  as  here  given,  viz,  from  February  25  to  March  1, 
inclusive.  The  data  given  by  Descroix  in  the  Annuaire  for  1 890  con- 
sist of  the  mean  values  for  the  respective  pentads.  From  these  I  have 
constructed  the  sum  totals  from  January  1  to  date,  which  are  needed 
in  agriculture,  and  which  are  still  more  easily  obtained  when  we  have 
the  original  tables  of  observations  at  hand,  by  simply  taking  the 
sums  in  a  continuous  series  and  avoiding  the  labor  of  computing  the 
means.  From  such  a  table  of  sum  totals  w'e  obtain  the  sum  between 
any  two  dates  by  subtracting  the  sum  for  the  earlier  from  that  for  the 
later  date. 

a  The  omitted  columns  are:  (1)  Sunshine;  actual  duration.  (2)  Actino- 
metric  degrees;  actual  daily  average.  (3)  Ratio  of  actual  actinometric  degrees 
to  the  maximum  possible  daily  average.  (4)  Soil  temperature  at  the  surface. 
(5)   Soil  moisture.     (U)   Percentage  of  saturation. 


275 


C 

^ 

-i> 

3 

t- 

X. 

ri 

-N 

c 

3 

r 

0 

c    t- 

0- 

,- 

- 

AT     S 

,> 

CD 

Baq 

o; 

.r; 

^ 

■M   in 

c: 

— 

? 

cc   ^ 

CC     = 

2  =  2^  =  28'-  =  '-^'"* 

^2^ 

= 

s^ii 

C 

g 

§ 

a 

3^ 

S? 

i 

^1 

g  ^ 

s|igisSSS5!SS8S 

&m 

iJ 

U 

^ 

k 

OS      L 

i  £ 

fo    P^    (x.    ^ 

P^ 

b 

|x. 

b 

fc 

fc 

fe  &. 

^^6   . 

■<t 

..': 

i- 

w 

X    t- 

-t 

„ 

_ 

ri   ^ 

OS    o- 

M(,   ^N-H(Mi-eos^   =    -»>in 

|lr- 

n   N 

s 

rr 

;c    c 

^     3- 

?jss22;:-d2ii=:-d 

|i| 

* 

s 

8  3!  S 

3 

s 

cc    U5    -1 

ccoiiriccin^irioocDuscococoi-'os 

• 

Rela- 
tive 
humid- 
ity. 

o 

CD 

t- 

^ 

>-H  ec 

o 

cc  c 

OS   V 

ososi-iniooNajxxinoscc 

ft; 

g 

^ 

s 

S 

gE= 

& 

t~ 

?: 

l^  ^ 

g   g 

rigSSggSSSSSSd 

Sun 
tem- 

ture 
(daily 
maxi- 
mum). 

ci 

® 

OC 

OS   t- 

X 

X 

3  ^ 

X     ^ 

-^e*-#^cc<^J050cD(3soscsos 
^  S  ^  S  ^  2  S  §j  SJ  g  Si  53  ^ 

'k 

fsi 

in 

^. 

c 
cc 

05     -« 

CC  !d 

t- 

in 

cc 
cc 

rH      C 

X    o- 

os^oxoccxinxcD^io-* 
o   t-^   5ci   OS   C5   o   ■*   i-J   cc   in   CO   x   OS 

ig 

-f 

Qsa 

1^ 

li 

« 

5^1 

o 

cc     r-l 

•* 

^ 

cc 

in   ^- 

^    CD 

•-IX^SOSCOX'-^CD'NXXX 

t^    :c    X    ..c    t^    1-    =;•    x"    x"    -    -^    a>j    ^" 

1 

-1- 

4 

1 

.•^i 

>. ' 

j> 

U5 

-* 

>-■: 

S5     X 

c 

cc 

m    ;d 

X      r- 

=    t-    -.    C:    t-    =    I-    X    X    m    o    ^    cc 

^^.a 

'3  >^ 

5: 

Sig?55gS^§§§ 

q)  §  SS  ^ 

^3fSSSSSS£§p:?if2 

B    1    §. 

pgo3 

tk 

g 

t- 

l^ 

••i' 

<N 

■* 

-*     1!" 

NOcoccos-^t-rHinxci-^in 

g 

i 

s 

g 

g 

gs 

s 

^ 

k: 

gf: 

gggasggssjsssggs 

^a 

iz; 

1 

iiji 

.s: 

"* 

O 

'' 

t-    cc 

X 

'~ 

tr 

X     « 

t-   cr 

OS     t-     OS    I-     OS     X     X     OS     -XI     I-     X     CD     t- 

s 

im 

cc 

^ 

<o 

« 

O    OJ 

t. 

c 

CC   cc 

00    (N 

-*aOO-*eDOCClOOO<NTX5DO» 

-n 

rfS 

00 

00 

X 

c»   o5 

o: 

a 

= 

s  = 

S    - 

SS^SS22S?2  3  33S 

gS|-B 

PJ 

-  .  ® 

oc 

= 

<= 

05    :D 

IT 

OS 

cc 

CO   X 

o  c 

rtrH<N(N!MCC-*eOXi-l»nOCO 

1 

m 

" 

'^ 

g 

g 

i 

£S 

S 

S 

ss? 

&SSSS^«55!S!cl?S?SS 

o 

(N 

« 

r-<     OC 

1- 

r-. 

ir 

X    c 

C^    (N 

ccco^coeoin-*<NOt-ccoO(Si 

fl 

s 

o 

ss 

53 

s 

s  s 

s 

cc 

s  s 

X     CD 

^0JrHrHCCint>:o»'rHej-*U5t^ 

^i        « 

1 

' 

1 

1 

1    1 

1 

1 

! 

1    1 

1         1 

1    1    1  +  -f  + 

6 

!N 

cc 

-* 

O     CD 

oo 

OS 

g     rH 

S  2 

3S2SS2S53§JSS;SS 

^ 

1 

1 
S 

1 

a 

"-• 

1 

> 

r-i 

® 

s 

,d 

(■ 

^ 

;2 
> 

a 

2 

S 

1 

3 

^ 

? 

a 

1^ 

cc 
ei 

1 

5 

> 

5 

1 

1 
.  > 

e 
3 

•7 

— 

1 

1 

C£ 

1 

5? 

a 

1 

< 

1 

1 

2 

5 

>> 

1 

276 


I  03  eS  3 


o   m   00   c 


111 

s: 

^ 

i.~^-^'!i^air^c6docc^^^ai:i<£<6d^t~aT^cici 

g 

» 

l~^ 

9.1 
9.0 
12.4 
9.5 
11.8 
13.8 
14.7 
11.4 
10.6 
14.4 
14.4 
11.4 
12.8 
14.3 
14.3 
9.9 
11.0 
14.2 
14.7 
21.9 
9.3 
6.1 
9.0 
4.9 
13.1 

III 

1 

S:SSSgeggS3gS^^'g8g3S8^SS3^Si 

^S^jdi^'^SSSSSS^^'^^'SSSSpi^^^SSS* 

iiF 

ai 

s 

ssssssSsssssssssssiS^SSSs 

OC'-KtOOOiOCOCO-* 


5^S;5g^^^^§?5J5S 


O    1-H     IN    05     5D     lO     «0 


CO^CCiO(NOOOOOT«DT-linCO-*ieiN 


IM    IN    IN    i-H    IN 


>-l    lO    ■*     -*     CO 


OsOl-COiOOOtO>Ot-OS 


■Sift 


-*  -*  o  in  CO  «o  to 


■^t-t-t-COOSOlNCOi-lO 


05  O  N  IN 


CO  CO 


IN   rH   rH 


t-«omcoot-coo>o^ec 
i(ji5ioin>ri^-*'*cococ.i 

CCaoOOODCOODODOOODGOOO 


nil 


^CO»na0t-00O5lO«Ot-t-COlOINir-IN-* 


i-H     -*(     IC 


05     O     O     i-H     T-H     r-H 


^•»o»c>o»cifr?D:ocDcocD:o»c 


lNOOOinCOOl--*rHOO 

>oio-*^'-*-*cococooj 


.-H  CO  in  o  CD  -* 


N"*^ 


QO     IN     OS    t~     CO 

^  g  ^  ^  s 


OJINCDNODiOCOi-lOOS 


S3§SSS53g?S^5SISfeSS§S:S^95!^^^§SaS 


s  s  ;s 


s  ?^ 


^     ... 


-H.— (ClC-l07_(r-i-:r-(r-(r-l(na)(V) 


>>>>>,>>** 


S     d     ;3     S     S     3     3 

t-5    1-5    l-S    1-5    l-S    l-S    »-5 


277 


X 

X 

«5 

« 

iC 

» 

05 

r: 

X 

:= 

^ 

— 

CO 

-4- 

3: 

= 

00 

o 

TC 

t- 

= 

n-' 

— ■ 

->i 

^ 

?. 

_ 

„ 

), 

1- 

^ 

— 

— 

— 

•r 

:- 

r,~ 

■<«< 

— 

— 

— ■      , 

S  Sg 

s 

S  ^  S  g  g 

«n 

S  :g 

s 

g 

s 

C! 

8 

§ 

a 

§ 

g 

§ 

nn 

« 

fO 

fi 

t- 

rn 

fn 

IX 

h. 

rp 

S 

|z< 

b 

b 

[>< 

tb 

[i< 

[^ 

fe 

t<H 

t- 

Tf 

^ 

t- 

»o 

CO 

rt 

CO 

00 

^ 

CO 

C5 

a> 

CO 

^ 

CO 

CO 

w 

^ 

CO 

« 

s 

s 

05 

s 

^ 

^ 

?; 

3 

'^^ 

2 

OC 

e 

KO 

2 

s 

3 

2 

X 

CO 

s 

2 

^ 

g 

SSSgSSSS§3S8§ 

3 

8 

§ 

S! 

g  s 

'" 

CO 

'^ 

*" 

*~ 

OC 

'" 

i- 

'" 

* 

^ 

® 

«5 

lO 

CO 

CO 

"T 

CO 

-* 

CO 

CO 

^ 

» 

00 

00 

(33 

(M 

05 

i- 

CO 

-J3 

CO 

,- 

» 

« 

OS 

-^ 

^ 

c: 

OS 

l^ 

CO 

ggggj 

?i 

S 

fS 

S 

''' 

•"^ 

^ 

{= 

§g 

s 

s 

s 

SS 

ss 

s 

s 

» 

so 

« 

>o 

^ 

CO 

CO 

00 

09 

00 

CO 

05 

>o 

o 

^ 

CO 

CO 

CO 

OM 

^ 

OS 

^^ 

5^ 

s 

^  ^  s 

2 

53 

s 

s 

s 

*" 

^ 

'~ 

-M 

-* 

CO 

!N 

o 

'^ 

^ 

5D 

■>*< 

CO 

^ 

N 

o 

00 

SI 

^ 

00 

c» 

CS 

^ 

CO 

CO 

X 

t- 

I, 

CO 

CO 

s 

2 

s 

s 

s 

s 

s 

2 

^ 

2h 

2 

2 

as 

s 

'^ 

o 

rj 

•N 

■N 

OS 

" 

t- 

^ 

^ 

c: 

^ 

?r 

_ 

s: 

u- 

« 

JT 

CO 

w 

t- 

CQ 

CO 

o 

N 

o 

^ 

^ 

^ 

^ 

^ 

— 

_ 

— 

_ 

— 

H 

— 

— 

,, 

-f 

'N 

^ 

^ 

— 

^ 

o 

1 

+ 

i 

(N 

OS 

lO 

CO 

•* 

<M 

CO 

»* 

„ 

ao 

^ 

s^ 

CO 

co 

»1 

-*. 

CD 

« 

OS 

- 

CO    t- 

g 

S 

5.5 

3 

" 

$ 

5 

o 

JS  S  g  JS  s 

?§ 

g? 

CO 

5? 

s 

CO 

^  JS 

o 

^ 

t. 

o 

84 

(N 

«4 

rt 

o 

o 

00 

CD 

CO 

o 

^ 

^ 

t- 

(M 

OS 

o 

91    l- 

s 

s 

g8 

g 

g 

I: 

g 

g 

2^ 

?2 

"" 

g 

§ 

s 

fe 

ssssss 

CD    •*    05    t- 


ic   00   i~   >n   b-   X    »i   X    in 


t-    o    X    X 


xxt-cDiacoi-tt-co 


osoooixi->oeoo»iooeocDt-cecoosco-*->><N 
d^co^cd«>3jicg«3j^«c5g5H^g^gjgjgjm 
+    I      I      I      I      I      I      I I      I      I      I      I      I 


ioioin»ftiOiciococo5bti5co 


SI 


S  S  jt  i  s 

O     (B     3) 


«  £:  8  ^  I  S  ^ 

ci 


53  ^  Q 
i^  ?^  V3 


—  s  53  CM  S 


u  u  u  -^  ^ 

©  0)  a>  o  . 

^    „   ^   ^   fi  ^  fi  J2  h 

3  i  a  a  s  a  s  '  " 


u     :j     O     i^ 


I     § 


278 

THE  REStriiTS  OF  RECENT  STUDIES  BY  ANGOT. 

In  1880  the  Central  Meteorological  Bureau  of  France,  under  the 
minister  of  public  instruction,  organized  a  system  of  phenological 
observations;  the  resulting  data  have  been  studied  by  Angot  in  a 
series  of  memoirs. 


In  his  first  paper  (1882)  Angot  grouped  the  dates  of  the  wheat 
harvest  as  observed  during  1880  and  1881  at  several  hundred  stations 
in  France  in  groups  of  four  or  five  stations  and  plotted  these  upon 
maps  showing  the  elevations  of  the  stations.  By  a  careful  comparison 
of  neighboring  stations  he  shows  that  the  date  of  ihe  harvest  is 
everywhere  quite  uniformly  retarded  with  increase  of  elevation,  and 
at  the  rate  of  four  days  in  time  for  every  hundred  meters  of  ascent. 
Apparently  this  retardation  is  the  general  result  of  a  complex  sys- 
tem of  influences  in  which  rainfall,  drainage,  soil,  sunshine,  tempera- 
ture, and  other  local  peculiarities  combine.  It  is  evident  that  the  spe- 
cial influence  of  any  local  climate  on  the  crop  can  not  be  successfully 
studied  until  the  observations  have  been  corrected  for  the  general 
influence  of  elevation.  He  therefore  reduces  all  the  dates  of  harvest 
to  sea  level  by  applying  the  preceding  correction. 

A  similar  calculation  showed  him  that  the  phenomena  of  flowering 
are  also  retarded  at  precisely  the  same  rate  of  four  days  per  100  meters 
of  elevation  and  these  dates  also  are  thus  reducible  to  sea  level. 

Angot's  charts,  showing  the  dates  of  flowering  and  harvesting  thus, 
reduced  to  sea  level,  show  great  regularity  and  the  isanthesic  lines 
show  the  perfect  regularity  with  which  the  reduced  epoch  of  flow- 
ering begins  in  southern  France  on  the  11th  of  May  and  advances 
nortliward  until  it  reaches  the  northern  boundary  of  France  on  the 
25th  of  June ;  in  a  similar  way  the  harvesting  of  winter  Avheat  begins 
in  southern  France  on  the  10th  of  June  (reduced  epoch)  and  in 
northern  France  on  the  9th  of  August.  The  variations  of  these 
isanthesic  lines  from  year  to  year  may  be  compared  Avith  the  ordi- 
nary charts  of  temperature  reduced  to  sea  level  or  with  other  mete- 
orological data  in  a  very  simple  manner. 

Angot  has  modified  and  apparently  improved  the  methods  of 
determining  the  influence  of  temperature  on  the  date  of  flowering 
and  harvesting.  He  says  that  since  1837  Boussingault's  idea  that 
the  ripening  demands  a  certain  sum  total  of  heat,  which  is  constant 
for  each  species  of  plant,  has  been  generally  adopted.  At  first  this 
sum  total  w^as  calculated  by  adding  together  all  mean  daily  tem- 
peratures from  the  germination  of  the  seed  or  the  beginning  of 
vegetation  after  rejecting  such  means  as  were  below  freezing  point. 
Then,  as  C.  H.  Martins,  De  Gasparin,  and  A.  de  Candolle  had  shown 


279 

that  the  temperatures  useful  to  the  phmt  vary  with  the  species  and 
are  decidedly  above  freezing,  therefore  students  have  taken  other 
limits.  Thus  Gasparin  and  ITerve  Mangon  adopt  0°  C.  for  the 
initial  temperature  in  the  growth  of  wheat.  In  order  to  ascertain 
the  proper  method  of  counting  temperatures  Angot  has  accomplished 
the  labor  of  prosecuting  three  parallel  computations  by  tliree  difi'erent 
methods,  as  follows: 

(A)  First  method. — By  observations  of  daily  maximum  and  mini- 
mum temperatures.  In  this  method  Angot  has  examined  separately  the 
observed  maxima  and  minima  of  the  thermometer  in  the  shade.  After 
rejecting  all  observations  below  6°  C.,  he  subtracts  6°  C.  from  all  the 
others  and  takes,  the  separate  sums  of  the  remaining  maxima  and 
minima  for  each  month  and  then  the  average  of  these  two  sums, 
which  consequently  represents  a  sum  total  of  heat  received  during 
the  month  in  excess  of  ()°  C. 

(B)  Second  method. — By  the  daily  means.  In  this  method  the 
mean  of  each  day  is  first  computed  by  taking  the  average  of  the 
maxinunn  and  minimum;  6°  C.  is  then  subtracted  from  each  of 
these  daily  means  and  all  negative  remainders  are  rejected.  The 
sum  of  the  positive  remainders  represents  the  sum  total  of  heat 
received  in  excess  of  6°  C. 

(C)  Third  method. — By  maximum  temperatures  alone.  In  this 
method,  which  is  a  modification  of  that  proposed  by  Hoffmann,  a  max- 
imum thermometer  is  exposed  to  the  direct  rays  of  the  sun  and  the 
sum  total  of  the  maximum  temperatures  is  used  by  Hoffmann.  But 
Angot  prefers  to  use  the  maximum  thermometer  in  the  shade,  as  in 
the  first  method,  and,  as  before,  takes  the  sum  total  of  all  the  posi- 
tive remainders  after  subtracting  0°  C. 

In  all  these  methods  the  principal  difficulty  is  to  fix  the  epoch 
from  which  the  summation  should  begin.  Sometimes  the  date  of 
sowing  has  been  adopted  as  this  epoch,  but  from  the  date  of  sowing 
up  to  the  date  of  sprouting  the  seed  and  the  young  plant  are  sub- 
jected only  to  the  temperature  of  the  soil,  and  not  to  that  of  the  air, 
which  often  differ  considerably.  It  would  perhaps  be  better  to 
start  with  the  date  at  which  the  plant  appears  above  the  earth,  but 
the  date  of  sprouting  is  not  generally  given  by  observers.  He  there- 
fore provisionally  adopts  the  1st  of  December  as  the  point  of  depar- 
ture and  calculates  the  sum  total  of  temperatures  for  the  nine  stations 
in  France  for  which  the  dates  of  flowering  and  harvesting  of  winter 
wheat  have  been  best  determined  for  the  years  1880  and  1881.  The 
agreement  among  themselves  of  the  numbers  calculated  by  these 
three  methods  for  nine  stations  and  two  different  years  is  such  that 
no  decision  can  be  arrived  at  as  to  which  method  is  the  best,  and 
such  decision  is  reserved  for  a  future  study  of  other  harvests. 


280 

A  similar  elaborate  study  of  the  harvest  of  rye  gave  the  following 
results : 

(1)  Retardation  for  altitude  is  approximately  four  days  per  100 
meters,  with  some  indication  that  the  correct  figure  is  rather  less 
than  this. 

(2)  The  date  of  harvest  reduced  to  sea  level  begins  with  the  5th  of 
June  in  southern  France  and  ends  with  the  25th  of  July  on  the 
northern  border. 

(3)  The  sum  total  of  temperatures  computed  by  the  three  methods 
A,  B,  C,  above  mentioned,  shows  that  whatever  method  be  finally 
adopted  as  the  best,  these  sums  are  less  for  rye  than  for  winter  wheat. 

A  similar  study  for  spring  barley  shows  the  following  results: 

(1)  A  retardation  of  four  days  per  100  meters  of  altitude  suf- 
ficiently harmonizes  the  observations. 

(2)  A  retardation  of  thirty  or  forty  days  in  the  date  of  sowing 
has  no  appreciable  effect  on  the  date  of  harvest,  which  varies  from 
the  20th  of  June  in  southern  France  to  the  14th  of  August  on  the 
northern  boundary. 

(3)  The  sum  total  of  temperatures  from  sowing  to  harvest  is  too 
variable  to  be  determined. 

A  similar  study  of  the  flowering  of  the  narcissus  {Narcissus 
fseudonarcissus)  shows  that  the  retardation  of  the  date  of  flowering 
is  at  the  rate  of  four  to  five  days  per  100  meters,  and  four  days  can  be 
adopted  without  notable  error. 

A  study  of  the  currant  {Rihes  ruhrum)  shows  that  the  retarda- 
tion is  between  three  and  four  days  per  100  meters.  The  sum  total 
of  heat  from  December  1  up  to  the  date  of  flowering,  as  deduced  by 
the  second  and  third  methods,  but  under  three  different  assumptions — 
i.  e.,  that  the  initial  temperature  is  4°,  6°,  8°,  respectively,  seems  to 
show  that  4  is  the  proper  figure  for  this  plant. 

A  study  of  the  flowering  of  the  lilac  shows  that  a  retardation  of 
four  days  per  100  meters  best  satisfies  the  observations  of  both  leafing 
and  flowering.  The  latter  begins  in  southern  France  on  the  22d  of 
March  and  ends  in  northern  and  eastern  France  on  the  Oth  of  May. 
The  calculation  of  the  heat  required  for  leafing  shows  that  the  most 
accordant  results  are  obtained  when  we  take  the  sum  of  maximum 
daily  temperatures  above  4°  C.  and  count  from  the  date  of  the  last 
heavy  frost,  w^hich  sum  is  about  360°  C.  For  the  flowering,  on  the 
contrary,  we  have  to  take  the  sums  of  the  mean  daily  temperatures, 
counting  from  4°  C.  and  from  the  same  date  of  frost,  which  sum  is 
then  350°  C,  while  the  sum  of  the  maximum  daily  temperatures 
would  have  given  695°  C. 

A  study  of  the  leafing  and  flowering  of  the  horse-chestnut  (.^s- 
eulus  hippocastanvm)  shows  that  the  retardation  of  four  days  per  100 
meters   also   satisfies   these  observations.     The   dates   of  leafing,   as 


281 

reduced  to  sea  level,  begin  with  March  12  in  southern  France  and 
extend  to  April  '21  in  northern  France.  The  dates  of  fiowerinij;  begin 
with  April  G  in  southern  France  and  extend  to  May  10  in  northern 
France. 

The  smns  of  temperatures  are  counted  from  the  last  severe  frost, 
and  the  most  accordant  results  are  obtained  when  the  sums  of  daily 
maxima  are  taken,  counting  from  2°  C.  The  sum  total  is  715°  to 
(late  of  leahng,  and  from  leafing  to  flowering  1,070". 

The  leafing  of  the  birch  is  found  by  Angot  to  have  the  same  rate 
of  retardation — very  little  less  than  four  days  per  100  meters — and 
the  reduced  epochs  of  leafing  begin  the  9th  of  March  at  the  southeast 
corner  of  France  and  extend  to  the  16th  of  April  at  the  northern 
border.  The  sums  of  temperatures  up  to  the  time  of  leafing  are 
best  computed  by  taking  the  sums  of  daily  maxima  above  2°  C,  but 
are  very  uncertain. 

The  leafing  of  the  common  oak  {Quercus  peduncidata)  has  ^ 
retardation  of  four  days  per  ascent  of  100  meters,  and  the  reduced 
epochs  begin  with  the  (Jth  of  April  in  southern  France  and  end  with 
the  6th  of  May  in  northern  France.  We  can  .provisionally  admit 
that  the  leafing  of  the  oak  occurs  when  the  sum  of  the  maximum 
daily  temperatures  has  attained  910°  C,  counting  above  2°  C.  and 
from  the  date  of  the  last  heavy  frost. 

The  flowering  of  the  elder  {Samhucus  nigra)  has  an  approximate 
retardation  of  four  days  per  100  meters.  The  reduced  dates  begin  on 
the  6th  of  April  in  southern  France  and  end  on  the  10th  of  June  in 
northern  France.  The  flowering  of  the  elder  occurs  when  the  sum 
of  the  mean  daily  temperatures  since  the  date  of  the  last  frost  has 
attained  840°  C.  if  we  count  from  2°,  or  630°  if  we  count  from  4°  C. 

The  flow^ering  of  the  common  linden  {Tilia  euroj)oea)  or  the  Tilia 
silvestris  is  retarded  three  days  per  100  meters'  ascent  for  the  moun- 
tainous countries,  but  four  days  is  adopted  for  the  whole  of  France, 
and  the  reduced  dates  of  flowering  begin  with  the  1st  of  May  in 
southeastern  France  and  extend  to  the  20th  of  June  in  northern 
France.  The  flowering  of  the  linden  occurs  when  the  sum  of  the 
mean  daily  temperatures,  counting  from  the  last  heavy  frost  and 
r.bove  2°  C.,  has  attained  1,090°  C. 

It  would  seem  to  result  from  all  this  that  the  leafing  of  the  trees 
and  shrubs  occurs  when  the  sum  total  of  the  maximum  daily  tem- 
peratures, counting  above  a  certain  limiting  value  and  from  the  date 
of  the  last  heavy  frost,  has  attained  a  certain  value  characteristic  of 
each  plant.  But  for  a  certain  number  of  plants  the  flowering  seems 
rather  to  depend  on  the  sum  of  the  mean  daily  temperatures. 


282 

In  his  second  memoir  Angot  (1886)  studied  the  additional  data 
for  the  years  1882  and  1888.  A  new  determination  of  the  influence 
of  altitude  on  the  epoch  of  leafing  again  gave  an  average  retardation 
of  four  days  for  each  100  meters  of  altitude  for  the  lilac,  the  chest- 
nut, the  birch,  and  the  oak.  The  average  mean  daily  temperature 
of  the  air  at  the  date  of  leafing  varies  between  5°  and  12°  C.  for  the 
lilac,  with  an  average  of  9.1° ;  from  4°  to  14°  C.,  with  an  average  of 
10.1°,  for  the  chestnut;  from  7°  to  15°  C.,  with  an  average  of  10.7°, 
for  the  birch;  from  5°  to  16°,  with  an  average  of  11.3°,  for  the  oak. 
These  ranges  are  so  large  that  it  is  impossible  to  indicate  any  simple 
relation  between  the  leafing  of  these  plants  and  the  mean  daily  tem- 
perature at  this  epoch.  The  mean  of  the  daily  maxima  were  also 
computed  for  the  epoch  of  leafing,  and  were  14.6°  for  the  lilac,  15.7° 
for  the  chestnut,  16.1°  for  the  birch,  and  16.4°  for  the  oak.  But 
again  the  variations  were  too  large  to  attach  any  phenological  impor- 
tance to  these  numbers. 

As  to  the  sum  total  of  temperatures  Angot  adopts,  not  a  constant 
date,  as  December  1  or  January  1,  but  dates  that  are  variable  for  each 
station  and  each  year  and  approximately  represent  the  close  of  the 
last  period  of  freezing  weather.  They  vary  in  this  case  between  the 
18th  of  January  and  the  13th  of  February.  After  laborious  calcu- 
lations by  different  methods  and  starting  from  different  initial  tem- 
peratures he  concludes  that  the  leafing  of  the  four  plants  under  con- 
sideration occurs  when  the  sum  of  the  mean  daily  temperatures, 
counted  from  0°  C,  or  the  sums  of  the  maximum  daily  temperatures, 
counting  from  0°  C.  and  beginning  at  the  date  of  the  commencement 
of  vegetable  growth  as  above  defined,  attains  the  values  given  in  the 
following  table : 


Plant. 

Sums  of 
daily 
means. 

Sums  of 

daily 
maxima. 

Lilac 

°  C. 
333 
523 
517 

077 

"  C. 
550 

845 

Birch 

838 

Oak 

1,082 

In  order  to  decide  which  of  these  two  modes  of  calculation,  daily 
mean  or  daily  maxima,  are  most  proper  it  will  be  necessary  to  oper- 
ate upon  a  much  longer  series  of  observations. 

The  flowering  of  the  narcissus,  the  lilac,  the  chestnut,  the  elder,  and 
the  linden  was  studied  in  a  manner  similar  to  that  of  the  leafing.  The 
retardation  for  altitude  is,  as  before,  four  days  to  the  100  meters. 
The  man  daily  temperature  at  the  date  of  flowering  is:  For  the  nar- 
cissus, 6°  to  14°  C,  average  9.4° ;  for  the  lilac,  from  8°  to  15°  C, 


283 

average  12.2° ;  for  the  chestnut,  8°  to  16°  C,  average  12.0° ;  for  the 
elder,  9°  to  20^  C,  average  13.9° ;  for  the  linden,  12°  to  21°  C,  aver- 
age 1().4°.  The  mean  daily  maximum  temperatures  at  the  date  of 
flowering  for  these  same  plants  is  as  follows : 


Plant. 

Daily  maxima. 

Daily  mean. 

Range. 

Mean. 

Range. 

Mean. 

"  C. 
9.. 20 
13.. 21 
13.. 25 
14.. 26 
17..29 

"  a 

14.9 
IB.G 
17.6 
19.7 
22.5 

"C. 
6. .14 
8. .15 
8.. 16 
9.. 20 

12.. 21 

"C. 
9.4 

Lilac 

11.2 

12.0 

Elder 

13.9 

16.4 

Evidently  the  maximum  temperatures  have  no  clearer  connection 
with  the  date  of  flowering  than  have  the  mean  daily  temperatures. 

The  sums  of  temperatures  from  the  beginning  of  vegetation  to  the 
date  of  flowering  have  also  been  computed  by  different  methods  and 
from  different  initial  temperatures.  The  following  are  the  results 
when  the  initial  temperature  is  0°  C. : 


Plant. 

Sums  of 

positive 

daily 

means. 

Sums  of 
positive 

daily 
maxima. 

Narcissus                                                                                 

°  C. 
359 
613 
771 
990 
1,277 

°  C. 
591 

Lilac 

983 

1,217 

Elder 

1.542 

1,938 

Here,  again,  as  in  previous  cases,  the  relative  value  of  the  different 
methods  of  taking  account  of  the  temperature  is  determined  numer- 
ically by  taking  the  sums  of  the  departures  from  the  average  for  the 
individual  stations  and  years.  In  the  present  case  the  mean  depart- 
ures as  thus  determined  are  exactly  the  same  for  both  methods,  so 
that  four  years  of  observations,  1880-1883,  have  not  sufficed  to  decide 
a.s  to  which  mode  of  calculation  it  is  proper  to  adopt  lus  the  best.  .V 
similar  calculation  as  to  the  amount  of  heat  received  by  the  lilac  and 
the  chestnut  between  the  epochs  of  leafing  and  flowering  leads  to  the 
same  indecision  as  to  the  methods  of  calculation.  The  actual  sums 
between  the  leafing  and  the  flowering  are  as  follows : 


Plant. 

Sums  of  1  Hums  of 

positive    positive 

daily         daily 

means,    maxima. 

Lilac                                                                                   

280             4:« 

Chestnut                                                                                          -     -- 

250               372 

284 

The  flowering  and  ripening  of  winter  wheat  during  1882  and  1883 
has  been  studied  on  the  basis  of  data  from  about  500  stations,  com- 
bined with  the  previous  data  for  1880  and  1881. 

The  mean  daily  temperature  at  the  time  of  flowering  is  for  rye 
13.3°  ;  but  the  individual  numbers  range  from  9°  to  18°  ;  similarly  for 
winter  wheat  the  mean  is  16.2°  and  the  range  from  10°  to  21°.  The 
commencement  of  vegetation  for  winter  wheat  is  uniformly  adopted 
as  December  1.  The  sums  of  the  mean  daily  temperatures  have  been 
calculated  from  several  points  of  departure  and  seem  to  prove  that 
the  lower  limit  of  useful  temperatures  is  very  nearly  .5°  C,  so  that 
we  can  take  ()°  C.  as  the  point  of  departure,  as  has  been  done  by 
many  authors. 

The  sums  of  the  mean  daily  temperatures,  less  6°  C,  rejecting  the 
negative  remainders  and  counting  from  the  1st  of  December,  are  as 
follows : 


Periods  for  winter  grain. 


Bye. 


From  December  1  to  flowering  . 
From  December  1  to  harvest. . . 
From  flowering  to  tiarvest 


c. 

"  C. 

420 

596 

ft55 

1,099 

535 

503 

The  harvest  date  for  spring  barley  is  shown  to  depend  in  1882  and 
1883  quite  as  little  on  the  date  of  soAving  as  it  did  in  1881. 

The  retardation  due  to  altitude  is  as  before,  four  days  per  100 
meters.  Adopting  the  20th  of  March  as  an  average  date  of  sowing, 
the  sums  of  the  mean  daily  temperatures  have  been  considered  up  to 
the  date  of  harvest,  with  different  assumptions  as  to  the  fundamental 
temperature.  As  before,  the  best  result  is  given  when  the  sums  are 
taken  of  the  excess  of  the  mean  daily  temperatures  above  0°  C,  and 
the  resulting  figure,  984,  is  seen  to  be  between  the  two  figures  for  rye 
and  winter  wheat. 


In  his  third  memoir  Angot  (1888)  studies  the  phenomena  of  1884 
and  1885  in  combination  with  the  preceding.  The  same  allowance 
is  made  for  rates  of  retardation.  The  relation  between  the  times  of 
leafing,  the  mean  daily  temperature  at  that  date,  and  the  maximum 


285 


((•iii|H'r;i(iii('  ;it  thai  dalo,  is  r()iH|)iitod  by  llu'  saiue  process  as 
with  the  following  results  for  the  years  1884  and  1885 : 


hefori 


Plant. 

Daily  mean  tem- 
perature. 

Daily  maximum 
temperature. 

Meah. 

Range. 

Mean. 

Range. 

Lilac. 

"  C. 
9.1 
9.6 
10.1 
10.3 

"  C. 
5.7..U.2 
6. 3.. 13. 7 
5. 8.. 14.3 
6.0.-15.1 

"C. 

,14.7 
15.3 
15.9 

"  C. 
4  7    20  8 

Birch 

9  7    22  7 

Oak • 

The  mean  values  here  given  agree  well  with  those  of  the  j^revioiis 
years,  but  the  individual  numbers  have  such  a  wide  range  that  w^e  can 
not  conclude  any  simple  relation  between  the  leafing  and  the  mean 
temperatures. 

The  relation  between  the  leafing  and  the  sums  of  temperatures  is 
found,  as  before,  by  assuming  the  end  of  the  last  period  of  frost  as 
the  commencement  of  vegetation ;  for  these  years  this  corresponds 
with  the  last  few  days  of  January.  The  useful  temperatures  are 
considered  to  be  those  above  0°  C,  and  Angot  has  computed  both  the 
sums  of  the  mean  daily  temperatures  and  also  the  sums  of  the 
maxima  alone  with  the  following  results : 


Plant. 

Sums  of  daily 
means. 

Sums  of  daily 
maxima. 

1884. 

1885. 

1884. 

1885. 

Lilac 

"  C. 
428 
568 
609 
709 

°  C. 
414 
575 

587 
717 

"C. 
686 
924 
988 

1,149 

"  a 
666 

Chestnut 

925 

Birch 

944 

Oak 

1,146 

The  reliability  of  these  sums  is,  as  before,  determined  by  examin- 
ing the  departures,  although  not  according  to  the  strict  rules  of  the 
law  of  probabilities  of  errors,  but  sufficiently  so  to  show  that  the 
uncertainties  of  each  of  these  figures  is  larger  than  the  differences 
for  successive  years.  The  average  of  the  two  years,  1884  and  1885, 
are  considerably  higher  than  those  for  the  previous  four  years. 

The  flowering  of  the  lilac,  chestnut,  elder,  and  linden  is  again  inves- 
tigated by  using  the  observations  at  some  1,200  stations  or  less.  The 
reduction  for  altitude  is  as  before.    The  mean  daily  temperatures 


286 

and  the  maximum  daily  temperatures  for  the  dates  of  flowering  give 
the  results  in  the  following  table : 


Plant. 

Daily  mean  tem- 
perature. 

Daily  maximum 
temperature. 

Mean. 

Range. 

Mean. 

Range. 

Lilac ^ 

°  C. 
10.1 
U.7 
15.3 
46.3 

"C. 
4. 7.. 15. 4 
6. 7.. 17.1 
10. 7.. 19. 6 
12. 9.. 20. 8 

"  C. 
15.6 
17.9 
22.2 

23.0 

9.1. .23.0 
13. 5..  26. 3 

Elder 

Linden :.... 

15.0.. 29. 5 
16. 9.. 29. 9 

Again  the  accord  with  the  results  of  previous  years  is  satisfactory, 
but  the  individual  variations  are  so  large  as  to  show  that  there  is  no 
clear  connection  between  the  epochs  of  flowering  and  the  mean  tem- 
peratures. Next  the  sums  of  temperatures  received  by  these  plants 
since  the  last  severe  cold  is  computed,  assuming  0°  C.  as  the  initial 
temperature,  with  the  following  results : 


Plant. 

Sums  of  daily 
mean  tem- 
peratures. 

Sums  of  daily 

maximum 
temperatures. 

1884. 

1885. 

1884.    1    1885. 

Lilac 

"C. 

689 

846 

1,033 

1,366 

672 

841 
1,108 
1,354 

°C.          °C. 
1.097  '      1,070 

Chestnut 

1,345        1,304 

Elder.. 

1,619        1,685 

Linden 

2,091        2,022 

• 

These -sums  agree  well  among  themselves  for  the  two  years,  but  are 
notably  higher  than  the  sums  for  the  four  previous  years,  the  excess 
being  so  much  larger  than  the  uncertainty,  as  deduced  from  the  agree- 
ment of  the  numbers  among  themselves,  that  we  can  scarcely  con- 
sider that  such  sums  as  these  represent  the  true  influence  of  climate 
on  these  plants. 

The  dates  of  flowering  and  harvest  of  rye  and  winter  wdieat  at  700 
or  800  stations  give  the  following  results : 

The  mean  temperatures  at  the  date  of  flowering  are,  for  rye,  in  1884, 
14°  C,  and  1885,  12.2°  C;  for  winter  wheat,"in  1884,  15.1°  C,  in 
1885,  16.4°  C.  These  figures  agree  well  with  the  previous  four  years, 
but  the  individual  discrepancies  show  that  there  is  no  simple  relation 
between  the  flowering  of  these  plants  and  the  mean  temperature. 

Again,  the  sums  of  temperatures  are  computed  from  the  1st  of 
December ;  5°  C.  is  subtracted  from  all  the  mean  daily  temperatures 
and  the  sums  of  the  positive  remainders  are  given.  Since  in  previous 
years  ()°  C.  has  been  adopted,  whereas  the  evidence  points  toward  a 
lower  figure,  therefore  Angot  now  gives  the  results  of  a  recomputa- 


287 

tion  of  the  live  years,  adoptiiij;-  5^  C.  as  the  h)\ver  limit  of  useful 
temperatures,  with  the  following  results : 

Sums  of  mean  daUy  temperatures,  less  5°  C.  and  rejecting  neoalivc  remainder.^, 
from  December  1  up  to  the  dates  of  fioicering  and  of  harvest inf/. 


Rye. 

Winter  wheat. 

Year. 

Flower- 
ing. 

Harvest- 
ing. 

Flower- 
ing. 

Harvest- 
ing. 

1880             ....             .  

537 

6()2 
496 
460 
527 
468 

1,113 

1,180 
1,075 
1,076 
1,089 
1,047 

730 
793 

720 
K38 

727 
686 

1,235 

1881 

1,311 

1882 

1,271 

1883                                                                  

1,248 

1884 

1,268 

1885                                                        

1,245 

Mean 

515 

1,096 

716 

1,263 

The  differences  between  the  numbers  for  flowering  and  harvesting 
show,  as  in  previous  years,  that  although  winter  wheat  requires  more 
heat  (716°  C.)  to  bring  it  up  to  the  flowering  point  than  does  rye 
(515°  C),  yet  after  having  attained  that  point  the  wheat  requires 
less  heat  (547°  C.)  than  does  the  rye  (581°  C.)  in  order  to  ripen  the 
grain  to  the  harvest.  This  fact,  wdiich  has  shown  itself  in  each  of 
the  six  years,  can  be  considered  as  well  established. 

The  harvest  of  spring  harley. — The  dates  of  harvest  are,  as  before, 
reduced  to  sea  level  by  allowing  for  retardation  at  the  rate  of  four 
days  per  100  meters.  The  sums  of  mean  daily  temperatures,  less 
5°  C.,  counting  from  the  21st  of  Maich,  wdiich  is  the  mean  date  of 
sowing,  and  up  to  the  date  of  harvest,  are  given  for  each  year  in  the 
following  table : 


Year. 

Spring 
barley 
harvest- 
sums  of 
tempera- 
tures. 

Year. 

Spring 
barley 
harvest- 
sums  of 
tempera- 
tures. 

1880 

°  C. 
1,071 
1,110 
1,128 

1883 

1,083 

1881 

1884                                              

1,049 

1882                 .              

1885 

1,042 

The  general  mean  for  these  six  years  is  (within  the  range  of 
its  probable  error)  the  same  as  the  corresponding  figures  for 
winter  rye. 


In  a  fourth  memoir,  Angot  (1890)  gives  similar  computations 
for  the  harvests  of  1886  and  1887  in  France,  the  number  of  stations 
being  now  appreciably  larger  than  in  the  preceding  years.  A  new 
computation  of  the  retardation  due  to  altitude  gives  him  8.7  days 
per  100  meters  for  the  lilac,  4.0  for  the  chestnut,  3.7  for  the  elder, 


288 


and  3.5  for  the  oak.     For  all  these  he  adopts  4  days,  as  in  previo,as 
years. 

Lea-fing. — The  mean  temperatures  at  the  dates  of  leafing  for  1886 
and  1887  are  given,  as  follows : 

Data  for  1886  and  1887. 


Plant. 

Mean  of 
daily  tem- 
perature. 

Mean  of 
daily  max- 
imum 
tempera- 
ture. 

Plant. 

Mean  of 
daily  tem- 
perature. 

Mean  of 
daily  max- 
imum 
tempera- 
ture. 

Lilac 

"  C. 
9.4 

°  C. 
14.8 
16.2 

Birch 

<•  C. 
9.9 

n.7 

"  C. 
15.3 

'  Oak    

17.6 

1 

The  sums  of  temperatures  received  by  these  plants  from  the  last 
freezing  period  up  to  the  time  of  leafing,  and  counting  from  0°  C.  as 
the  initial  temperature,  are  as  follows : 


Plant. 

Sums  of  daily 
means. 

Sums  of  daily 
maxima. 

1886. 

1887. 

1886. 

1887. 

Lilac       - 

°  C. 
356 
469 
465 
622 

402 
531 
531 
682 

°  C. 

622 

788 

796 

1,016 

°  C. 

772 

Chestnut                                     --   - 

983 

Birch                                                                                    

981 

Oak - 

1,208 

The  -flowering  of  the  lilac,  chestnut.,  elder.,  and  linden. — A  new 
determination  of  the  rate  of  retardation  of  flowering  for  these  plants 
gives  4.7,  4.2,  4.4,  and  3.8  days  per  100  meters,  respectively,  for 
which,  as  before,  4  days  is  adopted.  The  mean  temperatures  at  the 
times  of  flowering  for  the  years  1886  and  1887  are  as  follows : 


Plant. 

DaUy 
means. 

Daily 
maxima. 

Lilac                                                                                                - 

°  C. 
12.2 
12.8 
15.2 
16.4 

17.8 

18.7 

21.0 

Linden                                                                                                                   -     -  - 

22.5 

The  sums  of  temperatures  above  6°  C,  counting  from  the  last  freez- 
ing period  and  up  to  the  date  of  flowering,  for  the  years  1886  and 
1887  are  as  follows: 


Plant. 

Sums  of  daily 
means. 

Sums  of  daily 
maxima. 

1886. 

1887. 

1886. 

1887. 

Lilac                                                                                              

°  C. 
621 
704 
975 

1,269 

°  C. 

661 

773 

1,001 

1,245 

°  C. 

1,020 

1,147 

1,543 

1,949 

"  a 

1,184 

1,351 

Elder                                                                                          

2,014 

289 


The  probable  errors  of  these  sums,  considered  individually,  arc 
quite  large,  and  their  agreement  from  year  to  year  is  not  sufficient 
to  justify  the  belief  that  we  have  attained  to  a  satisfactory  expression 
for  the  connection  between  the  temperature  and  the  date  of  flowering. 

Flowering  of  rye  and  winter  wheat — Harvest  of  rye,  winter  wheat, 
and  spring  barley. — A  new  investigation,  based  on  an  increased  number 
of  stations  for  the  vears  1886  and  1887,  gives  for  the  rate  of  retarda- 
tion of  these  epochs  the  following  figures :  Flowering  of  rye,  -1.2  days 
per  100  meters;  flowering  of  winter  wheat,  4;  harvest  of  rye,  4.5; 
harvest  of  winter  wheat,  4.3;  harvest  of  spring  barley,  4.2.  We  can, 
therefore,  as  before,  take  4  days  as  an  approximate  value  for  all  these 
phenomena. 

The  mean  temperature  at  the  time  of  flowering  is  determined,  both 
for  daily  means  and  for  daily  maxima,  as  follows: 


Flowering  of  plant. 

Daily  mean. 

Daily  maxima. 

1886. 

1887. 

1886. 

1887. 

Rye                  

15.4 
16.2 

°  C. 
12.3 
17.3 

°  C. 
22.1 
22.0 

°  C. 
18.3 

Wheat 

24  3 

Again,  the  average  numbers  agree  well  from  year  to  year,  but  the 
individuals  from  which  they  are  derived  have  a  wide  range. 

The  sums  of  the  mean  daily  temperatures,  less  5°  C,  counting  from 
December  1  for  the  winter  rye  and  wheat,  but  from  March  21,  for  the 
spring  barley,  are  as  follows : 

/S'w»i.s-  of  tcjiipcrature. 


Plant  and  stage. 

1886. 

1887. 

Aver- 
age. 

°  C. 
313 
735 
1,080 
1,286 
1,214 

415 

630 

1,017 

1,185 

1,120 

0  C. 
364 

Flowering  of  winter  wheat 

682 

1,048 

Harvest  of  winter  wheat 

1  21% 

1, 167 

From  the  flowering  to  the  harvest,  on  the  average  of  these  two 
years,  rye  has  received  1,048 — 364=684°  C.,  and  winter  wheat  1,236 — 
682=554°  C,  but  on  the  average  of  eight  years,  1880-1887,  the  sums 
of  temepratures,  less  5°  C.,  have  been,  for  rye,  from  December  1  to 
the  flowering,  477°  C,  and  from  flowering  to  harvest,  607°  C. ;  for 
winter  wheat  the  numbers  are,  respectively,  708°  to  549°  C.  From 
the  beginning  of  vegetation  up  to  harvest  the  numbers  are:  For  rye, 
1,084°  C;  winter  wheat,  1,256°  C;  spring  barley,  1,103°  C.  The.se 
results  can  be  considered  as  having  definitely  established  the  fact  tlmt 
2667—05  M 19 


'      290 

in  France  rye  requires  less  heat  to  bring  it  to  the  harvest  and  winter 
wheat  more ;  but,  on  tlie  other  hand,  from  the  flowering  to  the  harvest 
rye  requires  more  and  winter  wheat  less. 

The  following  table  gives  a  resume  of  Angofs  general  average 
dates  and  temperatures  for  sea  level  for  the  whole  of  France  for  the 
vears  1880-1887 : 


Plant. 

Mean  daily  tempera- 
ture when— 

Leafing 
occurs. 

Flowering 
occurs. 

Lilac 

°  C. 
9.1 
10.1 
10.4 

n.i 

°  C. 
11.2 

Indian  chestnut 

14  6 

Oali 

Elder 

17.1 

Linden               

18  9 

13.4 

Winter  wheat 

16.2 

As  to  the  sums  of  the  mean  daily  temperatures  above  5°  C..  count- 
ing from  December  1 : 


Plant. 

Sums  of  temperature 
at  time  of— 

Flower- 
ing. 

Harvest. 

Eye .     ...                   ...      .                  

°  C. 

477 
707 

°  C. 
1,085 

Winter  wheat 

1  256 

The  harvest  of  spring  barley  occurs  when  the  sum  of  the  mean  daily  temperatures, 
less  5°  C.  and  counting  from  March  21  or  the  average  date  of  sowing,  amounts  to  1,102°  C. 

The  large  variations  of  the  individual  numbers  whose  means  are 
given  above  are  probably  due  to  special  meteorological  conditions,  and 
Angot  states  that  he  will  report  upon  these  if  it  is  possible  to  take 
them  into  account  when  ten  whole  years  of  observations  have  accumu- 
lated. 

REQUESTS  FOR  PHENOLOGICAL  OBSERVATIONS. 

The  influence  of  a  climate  upon  cultivated  crops  is  parallel  to  its 
influence  upon  uncultivated  plants,  and  the  comparative  study  of 
climates  in  their  relations  to  plants  can  be  attained  by  careful  obser- 
vations of  the  general  features  of  the  natural  life  of  special  plants 
that  are  widely  distributed  over  the  earth.  To  this  end  several 
special  invitations  have  been  issued  urging  the  observation  of  certain 
phenological  stages. 


291 

(A)  Hoti'mann  and  Ihiie  have  published  a  special  list  of  plants 
selected  by  them  as  a  result  of  many  years'  experience  in  Europe.  The 
following  calendar,  copied  from  the  appeal  for  "  phenological  obser- 
vations," contained  in  their  ''  Beitrage,  1884,"  shows  the  names  of 
the  plants  and  the  approximate  date  in.  Europe  of  the  phenomena 
that  they  wjsh  to  have  observed.  Corresponding  observations  in 
America  are  desirable  and  should  be  communicated  either  to  tliem 
directly  or  to  the  journals  of  botan3%  climatology,  or  general  science, 
or  to  the  botanist  of  the  Department  of  Agriculture. 

CALENDAR   FOR   PHENOLOGICAL   OBSERVATIONS. 

Instructions. — Plants  should  be  examined  daily.  The  object  is  to 
obtain  for  individual  stations  average  data  characteristic  of  the  cli- 
mate; therefore  plants  that  are  known  to  be  exceptionally  early  or 
late,  and  those  that  are  forced  by  special  treatment,  or  those  that  are 
artificially  trained  on  walls  are  not  to  be  considered.  It  is  not  neces- 
sary to  confine  the  observations  to  the  same  plant  year  after  year, 
but  to  those  individuals  that  represent  the  average  conditions  of  the 
plant  in  nature. 

For  brevity  the  following  notation  may  be  used : 

(P)   Pollen  disseminated  {Pollen  effunditur.  Linne). 

(1)  Leaf,  or  the  first  visible  surfaces  of  the  leaves,  or  beginning  of 
the  leafing  out  or  of  the  foliage  {frondescentia :  prima  folia  expli- 
cantur  lAnxiQ ;  erste  Blattoher-fldche  Hoffmann;  feuiUaixon  Quetelet). 

(F)  Full  foliage:  All  leaves  have  appeared  {folatio  perf.  Linne; 
allgemeine  Blatt  Hoffmann). 

(2).  Flower,  or  the  first  opening  of  the  flower  buds  {e-fflorescentia : 
primi  fores  ostenduntur  Linne;  erste  Bliithe  off  en  Hoffmann;  fiorai- 
son  Quetelet). 

(3)  Ripe  fruit  {Prima  fructas  matura;  haccm  definite  coloratm 
Linne;  erste  Frucht  reif  Hoffmann;  maturation  des  fruits  Quetelet). 

(H)  Harvest,  or  first  date  of  cutting  cereals  {Ernte  Anfang  Hoff- 
mann: Messis  initium  Linne). 

(4)  Leaves  color  or  fall  {foliorum  pars  major  decolorata  Linne)  ; 
allgemeine  Lanhrerfarhung  Hoffmann;  rolhtdndlge  Entlauhung 
Karl  Fritsch ;  Effeuillaison^  chute  des  feuilles  Quetelet) . 


292 


Pheiiological  calendar  for  Giessen. 
[Lat.  50°  35'  N. ;  long.  8°  12'  east  of  Greenwich  ;  altitude,  160  meters.] 


Date. 

Plant. 

Phase  of  veg- 
etation. 

Date. 

Plant. 

Phase  of  veg- 
etation. 

Feb.  10 

Apr.  10 

13 

Corylus  avellana 

JEsculus  hippocast 

Pollen. 

Leaf. 

Flower. 

Do. 
Pollen. 
Flower. 

Do. 
Leaf. 
Flower. 

Do. 

Do. 
Leaf. 
Flower. 
Leaf. 
Flower. 

Do. 
Full  foliage. 
Flower. 

Do. 

Do. 

Do. 
Foliage. 
Flower. 

Do. 

Do. 

Do. 

Do. 

May  28 
Junel 

2 

2 
5 
14 
20 
21 
22 
26 
30 
July  4 
5 
19 
30 
30 

Aug.  1 
11 
24 

Sept.  9 
16 

Oct.  10 
13 
15 
20 

Atropa  belladonna 

Symphoricarpos  race- 

mosa. 
Rubus  idseus 

Flower. 
Do. 

17 

Do. 

Salva  officinalis 

Cor nus  sangu  inea 

Do. 

18 

PriTniiR  avium 

Do. 

Prunus  spinosa 

Betula  alba 

Do. 

Rihfis  rnbriTm 

Fruit. 

Ligustrum  vulgare  — 

Tilia  grandif  olia 

Lonicera  tatarica 

Lilium  candidum 

Rubusidaeus 

Ribes  aureum 

Secale  cereale  hibern. . 

Sorbus  aucuparia 

Symphoricarpos  race- 
mosa. 

Atropa  belladonna 

Sambucus  nigra 

Cornus  sanguinea 

Ligustrum  vulgare .... 
^sculus  hippocast.  ... 
.  —  .do 

22 
33 

Prunus  cerasus 

Prunus  padus 

Flower. 
Do. 

23 
25 

28 

Pyrus  communis  ...... 

Fagus  sylvatica 

Fruit. 

Flower. 

Fruit. 

May    1 

3 
4 
4 

Quercus  pedunculata  . 

Lonicera  tatarica 

Syringa  vulgaris 

Fagus  silv 

Do. 

Harvest. 
Fruit. 
Do. 

i 

9 
12 
14 
14 
16 

Narcissus  poeticus 

^sculus  hippocast.  .  _ . 
Cratagus  oxyacantha . 
Spartium  scoparium  - . 
Quercus  pedunculata  . 

Cy tisiis  laburnum 

Cydonia  vulgaris 

Sorbus  aucuparia 

Sambucus  nigra 

Secale  cereale  hibern. . 

Do. 
Do. 
Do. 
Do. 
Do. 
Fall. 
Do. 

16 

28 

28 

Fagus  sylvatica 

Quercus  pedunculata.. 

Do. 
Do. 

(B)  Smithsonian  list. — In  the  United  States  calls  for  phenological 
observations  were  issued  by  the  New  York  Agricultural  Society  in 
1807  and  by  the  Regents  of  the  University  of  New  York  about  1820, 
also  by  Jo.siah  Meigs  as  Commissioner  of  the  General  Land  Office  in 
1817,  but  the  principal  work  has  been  that  undertaken  by  Prof. 
Joseph  Henry,  who  as  Secretary  of  the  Smithsonian  Institution  estab- 
lished in  1818  a  system  of  phenological  observations  undoubtedly 
arranged  by  Dr.  Asa  Gray  or  Dr.  Arnold  Guyot,  and  subsequently 
published  a  revised  list  of  plants  and  epochs. 

This  system  was  also  promulgated  by  the  Department  of  the 
Interior  on  behalf  of  the  Patent  Office  and  its  Bureau  of  Agriculture 
requesting  accurate  observations.  The  following  is  an  abstract  of 
Doctor  Gray's  schedule,  which  is  here  produced,  because  we  shall 
have  occasion  to  quote  observations  made  on  this  plan,  which  was  a 
slight  modification  of  Quetelet's  plan. 

The  observations  thus  collected  by  the  Smithsonian,  1854-1859, 
were  used  by  Fritsch  in  his  memoir  and  list  quoted  on  page  191. 

The  following  observations  were  requested  by  the  Smithsonian 
Institution : 


293 

(1)  Frondescence,  or  leafing:  When  the  buds  first  open  and  exhibit 
tlie  green  leaf. 

(2)  Flowering:    When  the  anther  is  first  exhibited — {a)   in  the 
most  favorable  location;    {b)  general  flowering  of  the  species. 

(3)  Fnictification :    \^'^len   the   pericarp   splits   spontaneously   in 
dehiscent  fruits  or  the  indehiscent  fruit  is  fully  ripe. 

(4)  Fall  or  leaf:  WTien  the  leaves  have  nearly  all  fallen. 

List  uf  plants  recommended  for  ohservation  hy  the  Smithsonian  Institution. 


Pages  of 
Gray's  Man- 
ual of  Botany. 


Edi-       Edi- 
tion VI.  tion  V. 


46 
31.5 
341 

50 


479 
46K 
147 
153 

S37 
47 
91 
322 
214 


Acerrubrum  L 

Acer  dasycarpum  Ehrh 

Acer  saccharinum  L 

Achillea  millef oliuni  L  _ 

Actea  rubra  Willd 

Actea  alba  Bigelow 

Aesculus  hippocastanum  L 

Aesculus  glabra  Willd 

Aesculus  flava  Ait 

Ailantus  glandulosa 

Amelanchier  canadensis 

Amorpha  fruticosa  L 

Amygdalus  nana  La 

Anemone  nemorosa  L 

AquUegia  canadensis  L 

Arctostaphylos  uva-ursa  (Spreng)  - 

Asclepias  cornuti  Decaisne 

Asimina  triloba  Dunal 

Azalea  nudiflora  L 

Bignonia  (Tecoma)  radicans  (Juss) 

Castanea  vesca  L x -- 

Carya  alba 

Cercis  canadensis  L 

Cerasus  virginiana  D.  C 

Cerasus  serotina  D.  C 

Chionanthus  virginica  L 

Cimicif  uga  racemosa  Ell 

Claytonia  virginica  L 

Clethra  alnif  olia 

Cornus  florida  L 


Crataegus  crus-galli  L 

Crataegus  coccinea  L 

Crataegus  oxycantha  L 

Epigsea  repens  L 

Epilobium  angusti  folium  L 

Erythronium  amt-ricanum  Smith 

Fraxinus  americana  L 

Qaylussacia  resinosa  Torrey  and  Gray. 

Gerardia  flava  L 

Geranium  maculatum  L 


103 
a  This  genus  of  Rosacese  is  not  in  Gray's  Manual  of 


Common  names. 


Red  or  soft  maple. 

White  or  silver  maple. 

Sugar  maple. 

Millefoil  or  yarrow. 

Red  baneberry. 

White  baneberry;  necklace  weed. 

Horse-chestnut. 

Ohio  buckeye. 

Yellow  buckeye. 

Tree  of  heaven;  ailanthua. 

Shad  bush;  service  berry. 

False  indigo. 

Flowering  almond. 

Wind  flower;  wood  anemone. 

Wild  columbine. 

Bearben-y. 

Milkweed. 

Papaw. 

Common  red  honeysuckle. 

Trumpet  creeper. 

Chestnut. 

Shagbark  or  shellbark  hickory. 

Redbud;  Judas  tree. 

Chokeborry  or  (-hokecheiTy. 

Wild  black  cherry. 

Fringe  tree. 

Black-snake  root;  rattlesnake  root. 

Spring  beauty. 

White  alder  or  sweet  pepper  bush-. 

Flowering  dogwood.    (The  real  flower, 

not  the  white  involucre. ) 
Cockspur  thorn. 
Scarlet- fruited  thorn. 
English  hawthorn. 
Trailing  arbutus;  ground  laun-l. 
Willow  herb. 

Dogtooth  violet  or  adder's-tongue. 
White  ash. 
Black  huckleberry. 
Yellow  false  foxglove. 
Crane's  bill. 
Plants  Indigenous  to  United  States. 


294 

List  of  plants  recommended  for  observation  by  the  Smithsonian  Institution — Con. 


Pages  of 
Gray's  Man- 
ual of  Botany. 


Edi-    i    Edi- 
tion VI.  tionV. 


Common  names. 


Halesia  tetraptera  "Willd. . . 

Hepatica  triloba  Chaix 

Houstonia  caerulea  Hook. .. 
Hypericiun  perforatum  L  . 

Iris  versicolor  L 

Kalmia  latif olia  L 


53 
536 

54 
545 

505 

507 

164 

161 

164 

161 

475 

450 

321 

300 

Laurus  benzoin  L  (Benzoin  odorif erum 
Nees.) 

Leucanthemum  vulgare  Lam 

Linnaea  borealis  (Gronov)  (Linnaeus). 

Lobelia  cardinalis  L 

Lonicera  tartarica  L 

Lupinus  perennis  L 

Liriodendron  tulipif era  L 

Magnolia  glauca  L 

Mitchella  repens  L 

Morus  rubra  L 

Nymphaea  odorata  Ait 

Persica  vulgarisL.n 

Podophyllum  peltatum  L 

Pontederia  cordata  L 

Pogonia  ophioglos-soides  Nutt 

Pyrus  communis  L 

Pyrus  malusL. 

Quercusalba  L 

Rhododendron  maximum  L 


Snowdrop  tree. 

Round-lobed  liverwort. 

Bluets;  innocence,  etc. 

St.  John's  wort. 

Large  blue  flag. 

Mountain  laurel. 

Spice  bush;  Benjamin  bush. 

Ox-eye  daisy;  white  weed. 

Twin  flower. 

Red  cardinal  flower. 

Foreign  spurs. 

Wild  lupine. 

Tulip  tree;  American  poplar. 

Small  or  laurel  magnolia;  sweet 

Partridge  berry. 

Red  mulberry. 

Sweet-scented  water  lily. 

Peach. 

Mandrake;  May  apple. 

Pickerel  weed. 

Adder's-tongue. 

Common  pear  tree. 

Common  apple  tree. 

White  oak. 

Great  laurel. 


176 

165 

Ribes  rubrum  L. 

Red  currant. 

134 

131 

Robinia  pseud-acacia  L 

Common  locust. 

134 

131 

Clammy  locust. 

155 

157 

Rubus  villosus  Ait 

Blackberry. 
Common  elder. 

217 

2a5 

Sambucus  canadensis  L  — 

217 

205 

Sam hn ens  Tiigra  Ti 

Black  elder. 

58 

60 

Sanguinaria  canadensis  L 

Bloodroot. 

57 

58 

Side-saddle  flower. 

170 

168 

Saxifraga  virginiensis  Michx 

Early  saxifrage. 
Two-leaved  Solomon-seal. 

526 

530 

Smilacina  bifolia  Ker.  (Maianthemum 
canadense  Gray.) 

174 

166 

Syringa    vulgaris     L.    (Philadelphus 
coronarius  Gray.) 

Lilac. 

308 

280 

Taraxacum  dens-leonis  Desf 

Dandelion. 

101 

103 

Tilia  americana  L 

Bass  wood;  American  lime  or  linden. 

462 

442 

219 

206 

Viburnum  lentago  L 

Sweet  viburnum. 

«  This  genus  of  the  order  Rosaceae  is  not  in  Gray's  Manual  of  Plants  Indigenous  to  the 
United  States. 


Chapter  XI. 

ACCLIMATIZATION  AND  HEREDITY. 

Scientific  literature  is  full  of  illustrations  of  the  natural  and  arti- 
ficial acclimatization  of  i)lants  and  the  influence  of  the  annual  varia- 
tions of  climate  on  the  crops,  all  of  which  exemplify  Linsser's  general 
laws. 

GRAPEVINE. 

The  following  remarks  and  data  relative  to  the  changes  of  climate 
during  the  historical  period,  as  given  by  Fritz  (1889,  pp.  206-269), 
will  be  valuable  for  further  study  and  are  referred  to  in  another  part 
of  this  work : 

The  northern  boundary  of  vine  culture  in  Europe  extends  from 
somewhat  north  of  the  mouth  of  the  Loire,  where  the  Marne  empties 
into  the  Seine,  to  the  junction  of  the  Aar  and  the  Rhine,  north  of  the 
Erzgebirge,  to  about  the  fifty-second  degree  of  latitude,  descends 
along  the  Carpathians  to  the  forty-ninth  degree,  extends  on  this 
parallel  eastward,  and  near  the  Volga  turns  southward  to  its  mouth, 
on  the  Caspian  Sea.  In  the  middle  ages  wine  was  made  in  the  south 
of  England,  in  Gloucester  and  Windsor;  in  the  Netherlands;  in 
Namur,  Liege,  Louvain;  in  northern  Germany,  in  the  Eifel  range  of 
hills  in  Sauerland  (a  division  of  Rhenish  Prussia),  on  the  slopes  of 
the  Ruhr  Mountains,  on  the  Weser  as  far  as  Raddesdorf,  in  lesser 
Waldeck  (or  Pyrmont)  ;  in  Hesse  as  far  as  Fritzlar;  in  Thuringia,  in 
Brandenburg,  and  in  lower  Lusatia;  in  Berlin,  Brandenburg,  Oder- 
berg,  Guben ;  in  Prussia,  at  Kulm,  Neuenburg,  Thorn,  Marienburg, 
even  beyond  Konigsberg;  in  Kurland  (Courland),  and  even  in 
Seeland  (Zealand)  the  vine  has  been  cultivated  in  great  quantities. 
Although,  we  have  very  favorable  accounts  of  many  harvests  in  those 
times,  even  for  the  highest  of  the  latitudes  mentioned  above,  still 
one  must  not  generalize  too  far.  The  sensation  of  taste  is  very  vari- 
able and  often  peculiar.  We  frequently  at  the  present  time  obtain 
a  very  sour  beverage  from  countries  reputed  to  produce  good  wine, 
and  in  the  north  we  eat  grapes  which  farther  south  are  considered 
very  sour.  It  must  be  taken  for  granted  that  in  those  times  when 
there  was  no  communication  over  long  distances  they  were  not  very 
exacting  in  regard  to  wine,  particularly  as  the  best  wines  were 
unknown,  as  must  have  been  the  case  in  northern  Germany,  the 
Netherlands,  and  England.  If  the  wine  was  harsh  and  sour,  it  was 
still  wine,  which  in  favorable  years,  and  even  in  those  latitudes  where 
the  crop  did  excellently  well,  could  be  made  into  a  very  drinkable 
beverage.     In  later  times,  and  when  better  wines  became  known,  when 

(295) 


296 

the  culture  of  the  vine  was  carried  to  greater  perfection  in  southern 
Germany  and  wine  could  more  easily  be  carried  into  northern  Ger- 
many, the  cultivation  of  the  vine  must  have  been  given  up  in  regions 
where  favorable  years  were  only  the  exception.  "When  the  first  decade 
of  the  nineteenth  century  proved  very  unfavorable  to  vine  cultivation. 
a  number  of  vineyards  were  suppressed  even  in  the  best  situations, 
such  as  Rhenish  Hesse  and  Rheingau,  which  were  afterwards  re- 
stored with  the  return  of  better  times,  namely,  after  1834  and  1835. 
With  the  present  facilities  for  communication  and  the  competition  in 
the  wine  business  resulting  therefrom  vine  culture  is  no  longer 
profitable  in  many  places  where  thirty  years  ago  it  was  so;  in  many 
places  even  grain  cultivation  is  declining,  because  the  grain  can  be 
procured  from  a  distance  cheaper  than  the  cost  of  cultivation,  as  is 
especially  the  case  in  Alpine  countries.  Xo  one  would  conclude  that 
this  is  owing  to  the  deterioration  of  the  climate,  and  with  equal  right 
one  can  not  attribute  the  decline  of  vine  culture  in  high  latitudes, 
where  it  is  now  no  longer  profitable,  to  change  of  climate. 

Herodotus  describes  the  fertility  of  Assyria,  notwithstanding  that 
it  seldom  rains  there.  Xo  one,  he  says,  could  bring  himself  to  believe 
in  its  productiveness  who  was  not  convinced  of  it  by  seeing  for  him- 
self. At  present  the  fruitfulness  of  that  region  is  very  limited. 
But  Herodotus  also  describes  the  excellent  irrigation  of  that  country 
in  his  time,  and  Alexander  the  Great  is  said  to  have  found  on  the 
Scythian  frontier  an  inscriiDtion  dedicated  to  Semiramis  (2000  B.  C.)  : 
"  I  forced  the  streams  to  flow  where  I  willed,  and  I  willed  only  what 
was  useful;  I  made  the  dry  earth  fruitful  by  watering  it  with  my 
streams."  At  the  present  day  the  countries  in  question  produce  only 
very  meager  crops,  with  the  exception  of  the  regions  on  the  Tigris, 
near  Bagdad;  in  Mesopotamia,  near  Urfa;  in  northern  Syria,  near 
Aintab,  and  Messir  and  other  places,  where  recently  irrigation  canals 
have  again  been  laid  and  magnificent  cultivation  thereby  revived. 
Xo  change  of  climate  has  taken  place;  human  energy  alone  has 
altered.  Similar  changes  are  seen  in  Palestine,  in  Arabia,  in  Sicily, 
and  many  other  countries.  Should  the  Chinese  in  many  portions 
of  their  country  neglect  irrigation  for  even  short  periods  they  would 
quickly  see  only  deserts  where  now  garden  cultivation  reigns,  while 
the  climate  would  not  change  in  the  least.  Xo  one  acquainted  with 
the  true  cause  would  attribute  to  change  of  climate  the  increased 
productiveness  of  Lombard}'  since  the  restoration  of  its  excellent 
system  of  canals  and  irrigation,  or  the  gi'eat  decrease  of  grain  culture 
in  Switzerland.  Without  this  knowledge  only  perverted  and  false 
conclusions  would  be  derived. 

The  diminution  of  forests  in  the  extreme  north  of  Europe,  in  Ice- 
land, and  in  the  high  Alpine  regions  is  more  simply  to  be  explained 
by  the  partial  deforestation  done  by  the  hand  of  man,  rendering  the 
remainder  sparser  and  less  capable  of  resistance  to  wind  and  weather 
than  by  hypothesis  of  change  of  climatic  conditions. 

At  the  same  time  it  will  not  be  denied  that  by  irrigation  and  drain- 
age, by  important  changes  in  the  system  of  cultivation,  by  various 
natural  phenomena  of  nature,  etc.,  many  changes  of  a"  climatic 
character  take  place.  These  changes,  however,  are  only  local  and 
disappear  as  soon  as  the  causes  which  produced  them  are  removed. 

Besides,  there  is  in  climatic  conditions  only  a  moderate  stability, 


297 


subject  to  steady  and  in  all  probability  periodic  variations  and  inter- 
chano^es,  Avhicli  aiv  difficult  to  recognize  in  consequence  of  the  mani- 
fold combinations  of  the  numerous  effective  factors.  Climatic 
changes,  extending  over  long  periods  of  time,  are  indicated  by 
geological  periods,  which  latter  themselves  demonstrate  again  only 
the  gradual  and  not  any  sudden  alterations  of  climate.  Sudden, 
and  even  very  moderate  slow  changes  of  climate  cause  the  destruc- 
tion of  the  vital  organism. 

The  comparison  of  the  climatic  conditions  of  individual  years,  the 
differences  in  the  yield  of  fruits  of  various  kinds,  as  already  men- 
tioned above,  the  unfavorable  years  in  central  Europe  at  the  end  of 
the  sixteenth  and  eighteenth  and  beginning  of  the  nineteenth  cen- 
turies, and  the  very  favorable  seasons  for  grain  and  wine  in  the  last 
quarter  of  the  seventeenth  and  at  the  beginning  of  the  eighteenth 
century  and  in  the  first  third  of  the  nineteenth  century,  together  with 
the  recurring  failure  inider  similar  conditions  of  crops,  particularly 
of  wine,  in  1847  and  1881,  caused  by  the  cool  weather  at  the  end  of 
summer  and  beginning  of  autumn,  in  spite  of  the  hot  summer  which 
had  preceded  it,  etc.,  and  furthermore  the  exact  numerical  researches 
based  on  results  of  observations  of  the  meteorological  elements,  all 
show  a  variability  of  climate  such  as  is  accomplished  within  a  century, 
or  even  Avithin  the  lifetime  of  a  man,  and  which  can  be  most  positively 
recognized  from  year  to  year,  from  decade  to  decade.  To  find  the 
causes  of  these  changes  belongs  to  those  who  have  devoted  themselves 
to  researches  in  the  laws  of  meteorolog:y,  and  particularly  to  discov- 
ering the  methods  by  which  to  prognosticate  the  conditions  of  weather 
for  long  periods  in  advance. 

Distribution  of  good  and  poor  wine  crops,  hy  decades,  since  1600. 
[From  Fritz   (1889),  p.  301.] 


Germany 
(Rhine). 

Switzerland 
(Zurich). 

Decade. 

Germany 
(Rhine). 

Switzerland 
(Zurich). 

Decade. 

Above 
aver- 
age. 

Below 
aver- 
age. 

Above 
'aver- 
age. 

Below 
aver- 
age. 

Above 
aver- 
age. 

Below 
aver- 
age. 

Above 
aver- 
age. 

Below 
aver- 
age. 

1600-1609 

1 
4 
2 
4 
2 
3 

5 

7 

6 
4 

: 

3 
5 

9 
6 

8 
6 

8 

5 
5 
3 
9 
4 
6 

7 
5 

1760-1769 

1770-1779 

1780-1789 

1790-1799 

1800-1809 

1810-1819 

1820-1829 

1830-1839 

1840-1849 

1850-1859 

1860  lHfi9 

lSTU-1879 

1880-1887 

General 
average. 

4 
5 

: 

4 

i 

4 
4 
2 

6 
5 
5 
8 
5 
6 
6 
4 
7 
6 
6 
6 

5 

8 
8 
5 

6 
5 
6 
4 
6 
2 
2 

5 

1610-1619... 

3 

1620-1629 

1630-1639 

1640-1649 

1650-1659 

1 
2 
2 
3 
4 
3 
5 
5 
6 
3 
6 
5 

9 

8 
8 
7 
6 

7 

' 
5 

4 

7 

4 

5 

5 

1660-1669. 

1670-1679 

5 

1680-1689  ... 

1690-1699 

e 

1700-1709...      . 

4 

1710-1719 

8 

1720-1729 

6 

1740  1749 

3.9 

6.0 

4.5 

5.4 

1750-1759 

298 


Good  and  poor  wine  crops,  by  years,  since  1820. 
[From  Fritz   (1889),  pp.  293,  295,  296.] 


Year. 

i 

1 

pi 

.as 
II 

§1 
§^ 

1 

II 

If 

si 

8. 

0  ^ 

II 

M 

1 
1 

Year. 

I 

t 
.So 

1? 

If 

go 

h 
il 

If 
l\ 

II 

i 

w 

o 

} 

1 

K 

m 
§ 

o 

1820 

2.03 
0.69 
11.19 
5.70 
5.35 
8.20 
15.65 
4.55 
16.45 
5.16 
0.80 
3.67 
5.28 
10.35 
15.43 
12.65 

7 
7 
16 

7 

6 
32 
22 
29 
16 
5 
8 
10 
19 
29 
33 
18 
20 
12 
17 
19 
6 
17 
9 
9 
9 
21 
22 
22 
13 
11 
11 
13 
10 

1854 

1855 

1856 

1857 

1858. 

1859 

1860 

1861 

1862 

1863 

1864 

1865 

3.82 
3.13 
9.95 
10.75 
9.07 
5.94 
4.62 
8.92 
7.14 
5.40 

2 

8 

26 

17 
10 

6 
15 
17 
15 
17 
13 
16 
27 
15 
18 
17 

7 

7 

15 
27 
15 
10 
10 

3 

2 

22 
12 

8 
19 
10 

4 
11 

2 

4 
3 
4 
64 
27 
12 
6 

1821 

1822 

34 
56 
14 
55 
92 

1 

52 
33 

4 



1824 

12.88 
12.88 
13.17 
8.78 
9.66 
9.08 
11.00 
6.10 
13.21 
15.23 
24.59 
28.99 
13.76 
16.46 

1825 

1826 

1828 

1829 

1830 

18.7 
28.0 
44.3 
28.4 
46.5 
31.7 
23.6 
8.8 
3.7 
10.0 
32.4 
51.8 
27.8 
19.8 
31.2 
9.3 
3.9 
36.7 
13.5 
33.3 

1831 

41.8 

1832 

26 
55 
■  45 
55 
28 
14 
13 
18 
35 
2 
24 
15 
11 

1866 

21.4 

1833 

1867 

39.8 

1834 

1868 

19.1 

1835 

1869 

14.9 

1836 

1870. 

236.7 

1837 

4.51 
2.74 
7.06 
4.24 
3.25 
8.05 
2.33 
3.93 
5.-36 
13.53 
10.09 
7.95 
6.90 
6.68 
5.57 
7.64 

7.07 

1 

1871 

91.7 

1838 

1872. 

24.4 

1873 

10.7 

1840 

1874..^.. 
1875  .... 

106.9 

24.6 

1842 

1876 

63.8 

1843 

1877 

59.1 

1844 

1878 

80.0 

1879 

90.3 

1846 

23 
45 
32 
19 

13 
15 
34 

1880 

126.0 

1847 

1881 

83.0 

1882 

121.0 

1849 

1883 

28.0 

1884 

1851 

1885 

1852 

1886 

1887 

1    1 

1 

299 

Wheat  crop  in  Ohio,  by  years,  since  1850. 

[From  P'ritz  (ISSO),  p.  303.  The  figures  for  1850-1877  refer  to  the  average  of  two  coun- 
ties, viz,  Belmont  in  the  southeast  and  Erie  on  the  north  border  of  the  State.  The  fig- 
ures for  1878-1883  are  averages  for  the  whole  State.] 


Bushels 
per  acre. 

Bushels 
per  acre. 

Bushels 
per  acre. 

1850 

17.0 
14.7 
14.6 
11.8 

9.1 
15.6 
11.4 
10.7 

9.7 
17.0 
13.8 
13.4 

1862 

13.8 
12.8 
6.7 
6.8 
10.5 
13.0 
12.9 

1874 

17.8 

1851 

1863 

1875 

187(i 

13.3 

1852 

1864 

14.5 

1853 

1865 

1866 

18(57.. _ 

1868 

1869 

1877 

11.6 

1854 

1878 

16.9 

ia55 

1879 

17.7 

1856 

1&«0           

17.1 

1857 

1881 

1882.- 

13.8 

1858 

1870 

15.6 

1859 

1871 

14.3 
8.5 
14.4 

1883 

16.6 

1860 

1872 

1873 

""" 

1861 

GRASSES. 


Relative  to  the  acclimatization  of  the  grasses  Sporer  (1867)  says: 

As  in  the  Alps  and  Himalayas  up  to  altitudes  of  15,000  to  16,000 
feet,  so  also  in  the  farthest  north,  beyond  the  limit  of  trees,  the 
grasses  flourish.  The  varieties  that  compose  the  grassy  carpet  of 
Taimyr  are  still  somewhat  numerous.  They  embrace  10  families 
and- 21  species;  about  one-half  belong  to  *the  sour-grass  family, 
the  binse  or  rushes,  ried  (reed),  woold  or  cotton  grass.  But  fully 
one-half  are  the  sweet  grasses,  such  as  in  central  Europe  are  esteemed 
the  best  fodder,  and  not  less  so  in  Taimyr  Land,  where  they  extend  to 
the  shores  of  the  icy  Arctic  Ocean  beyond  latitude  7.5°  30'  north, 
including  among  them  the  ''  wiesen  "  or  meadow  ^ass,  the  rispen  or 
ray  grass  (Poa  pratensis),  and  the  "  rasen  schmiele  "  or  turfy  hair 
grass,  Ahri  desc/unnpsia  ea'spitosa.  It  is  not  surprising,  therefore, 
that  the  best  milch  cattle,  the  so-called  "  cholmogor  breed,'"  the  suc- 
cessors of  the  cattle  transported  thither  from  the  Netherlands  by  the 
care  of  Peter  the  Great,  should  flourish  in  the  desert  polar  regions  at 
Mesenja. 

The  sour  grasses,  as  genuine  earl}^  spring  plants,  form  their  floAvers 
in  the  previous  summer  season,  and  at  the  beginning  of  the  northern 
summer  (July  10  to  20)  are  in  the  fullest  bloom  and  have  already 
turned  brown  when  the  sweet  grasses  begin  to  show  their  flower  buds. 

In  general  the  ground  thaws  only  to  the  depth  of  a  few  inches  and 
the  roots  do  not  penetrate  into  the  frozen  soil.  The  tundra  of  north- 
ern Russia  and  Siberia  rests  on  such  a  frozen  soil ;  the  steppe  or 
prairie  or  llano  rests  on  unfrozen,  deeper,  and  dryer  soil. 

The  modest  circle  of  plants  that  surrounds  our  Arctic  Circle  is 
not  so  complexly  constituted  under  different  longitudes  as  are  those 
of  the  warmer  phenological  girdles  of  the  globe;  everywhere  we 
have  the  same  species  of  plants  and  the  same  families;  everywhere 
the  gramineae,  the  crucifera?,  the  caryophyllea%  and  the  saxifra- 
gacea^,  are  the  dominating  families,  and  among  the  genera  the  Draha 
Saxifj^aya.,  Ranunculus^  Carex^  and  the  meadow  grasses;  all  these 


300 

high  northern  varieties  are  enduring;  only  a  few  of  them  fail  annu- 
ally to  set  their  fruit  and  ripen  their  seed.  An  annual  plant  disap- 
pears when  for  a  single  season  it  fails  to  ripen  its  seed. 

A  comparison  of  the  flora  of  Spitzbergen  and  the  high  portions  of 
the  Alps  and  Pyrenees  shows  that  the  former  are  the  lost  children  of 
Euroi^ean  flowers  that  have  since  the  Glacial  epoch  survived  at  great 
altitudes  in  the  mountains  as  well  as  in  the  damp,  cold  morasses  of 
central  Europe. 

A  comparison  of  the  flora  of  Taimyr  and  the  mountains  of  southern 
Siberia  shows  that  the  northern  flora  has  wandered  thither  and  be- 
come acclimatized  from  the  southern,  and  that  this  process  is  still 
going  on. 

CEBEAIiS. 

The  elaborate  report  of  Brewer  on  cereals,  in  the  Tenth  Census 
of  the  United  States,  contains  the  fullest  information  as  to  the  rela- 
tion of  climate  and  soil  to  our  cereals.  From  pages  10  to  27  of  this 
volume  I  quote  the  following  general  remarks : 

We  may  say  that,  as  a  rule,  in  all  former  times,  and  until  modern 
means  of  transportation  came  into  use,  the  grain  most  largely  con- 
sumed for  bread  in  any  country  or  region  was  the  one  most  easily 
and  most  surely  grown  at  home,  or  at  least  at  no  great  distance  away ; 
the  bread,  of  necessity,  had  to  be  made  of  such  grain  as  could  be 
grown  or  procured  with  the  facilities  then  enjoyed.  Rye,  buckwheat, 
oats,  barley,  and  millet  had  among  our  ancestors  an  imi3ortance  as 
bread  plants  that  they  have  now  lost  and  will  probably  never  regain. 
This  fact,  apparently  so  obvious  and  yet  so  hard  to  realize  in  prac- 
tice, lies  at  the  bottom  of  that  agricultural  revolution  already 
alluded  to,  which  is  now  going  on  every^^here  among  nations  and 
peoples  of  our  civilization,  and  most  notably  in  western  Europe. 

Seven  species  (calling  buckwheat  a  cereal)  are  cultivated  in  Amer- 
ica in  sufficient  abundance  to  be  returned  in  the  census  tables,  and 
three  or  four  more  are  occasionally  cultivated  in  a  few  localities. 
Taken  altogether,  these  include  all  the  more  important  cereals  of  the 
world. 

Of  the  seven  species  we  have  to  deal  w4th,  six  are  natives  of  the 
Eastern  Hemisphere  and  one  of  the  western.  No  cultivated  grain  has 
originated  on  an  island,  if  we  except  canary  grass,  and  none  in 
southern  Africa  or  Australia,  regions  otherwise  very  rich,  botanically, 
in  species.  Hmnboldt  called  it  a  striking  phenomenon  "  to  find  on 
one  side  of  our  planet  nations  to  whom  flour  and  meal  from  small- 
eared  grasses,  and  the  use  of  milk,  were  completely  unknown;  while 
the  nations  of  almost  all  parts  of  the  other  hemisphere  cultivated  the 
cereals  and  reared  milk-yielding  animals.  The  culture  of  the  differ- 
ent kinds  of  grasses  may  be  said  to  afford  a  characteristic  distinction 
between  the  two  parts  of  the  world." 

The  genera  to  which  the  principal  cereals  belong  are:  Oryza,  or 
rice;  Triticum^  which  includes  all  the  varieties  of  wheat  and  spelt; 
Avena,  oats  of  various  kinds;  Hordeum^  the  various  kinds  of  barley; 
Secale^  rye,  and  Zea,  Indian  corn.  Among  the  true  cereals — that  is, 
belonging  to  the  grass  family — there  are  various  species  of  millet, 
belonging  to  several  different  genera  {Panicum,  Pennicillaria,  Emil- 
ium,  Setaria^  Holcus^  and  Sorghum)  ;  durra,  a  species  of  Sorghum 


301 

(called  also  Indian  millet  and  Guinea  corn,  and  spelled  in  various 
ways,  as  "dura,"  "  dliura."  "doura"');  canary  grass,  FhaUois,  and 
a  few  other  species  holontjing  to  the  grasses.  In  addition  to  these 
botanical  cereals  are  the  buckwheats,  which,  for  convenience  in  this 
report,  are  classed  among  the  true  cereals.  They  belong  to  the  genus 
FoJyyonum^  two  species  of  which  are  cultivated  in  this  country, 
and  perhaps  others  elsewhere.  Several  species  belonging  to  the 
genus  Chenopodium  have  been  cultivated  in  various  parts  of  the 
world,  particularly  in  India  and  central  Asia,  but  none  are  of  impor- 
tance to  European  nations  as  grains.  Of  a  considerable  list  that 
might  be  made,  wheat,  rice,  and  Indian  corn  are  the  first  three  in 
importance;  oats,  barley,  and  rye  next;  then  durra,  the  millets,  and 
buckwheats  next ;  all  the  remainder  being  of  insignificant  importance 
to  the  world  at  large. 

However  defined  and  classified,  and  however  used,  all  the  cereals 
are  agricultural  grains,  all  are  starchy,  all  are  breadstulfs,  and  all  are 
annual  plants. 

Being  annuals,  they  are  adapted  to  almost  universal  cultivation 
where  the  summer  climate  admits,  for  ''  an  annual  plant  may  be  said 
to  belong  to  no  country  in  particular,  because  it  completes  its  exist- 
ence during  the  summer  months,  and  in  every  part  of  the  world  there 
is  a  summer." 

This  fact  underlies  the  agricultural  importance  of  the  cereals. 
Every  gardener  knows  that  annuals  may  be  brought  from  almost  any 
country  and  be  made  to  flourish  in  cultivation  in  any  other  country 
in  which  they  can  complete  their  life  in  one  summer,  and  that,  even  if 
the  summer  is  too  short,  varieties  may  be  produced  by  art  which  w^ill 
mature  quicker,  and  then  their  cultivation  may  be  extended  to  cli- 
mates unlike  that  of  their  original  home.  This  may  be  continued  up 
to  certain  limits  set  by  nature  for  each  species,  which  limits  can  be 
determined  only  by  experiment.  Not  so  Avith  perennials.  They 
must  have  not  only  a  favorable  summer  climate,  but  also  a  favorable 
winter  climate  and  a  favorable  average  climate,  and,  moreover,  be 
able  to  stand  occasional  wide  deviations  from  the  average  climate. 
The  exceptional  heat  of  one  year  or  cold  of  another,  a  too  wet  season 
or  a  too  dry  one,  may  kill  the  tree  or  perennial  which  has  lived  and 
thrived  for  many  years.  Hence  all  perennials  are  restricted  in  their 
growth  to  very  much  narrower  limits  than  annuals.  Moreo\'er, 
annual  plants  are  believed  to  be  nnich  more  varial)le  under  ditl'erent 
external  conditions  than  perennials  are.  They  vary  more  in  nature, 
and  it  is  among  the  cultivated  annual  species  that  we  have  the  widest 
variation  known  to  science.  They  can  adapt  themselves  more  readily 
to  changes  of  soil,  climate,  and  other  variable  conditions  than  peren- 
nials. Thus  it  is  that  the  plains  of  Dakota  and  Manitoba,  with  their 
genial  summers  and  fertile  soil,  even  though  the  winters  be  of  Arctic 
severity,  and  California,  .wnth  its  rainless  summer,  bnt  genial  winter, 
can  alike  send  wheat  to  the  mild-wintered  and  moist-summered 
British  islands. 

Illustrating  the  first  point  regarding  excellence  of  seed,  both  as  to 
its  actual  condition  and  its  pedigree,  there  are  numerous  illustrations 
recorded;  but  the  famous  experiments  of  Mr.  Frederick  Hallett,  of 
Brighton,  England,  may  be  taken  as  a  good  illustration.  The  experi- 
ments were  planned  with  so  much  intelligence,  conducted  with  such 


302 

patience  and  care,  were  so  profitable  in  their  results — the  essential 
results  have  been  confirmed  in  so  many  other  ways  and  by  so  many 
practical  men — that  they  are  worthy  of  being  quoted  in  this  con- 
nection. 

He  began  with  a  single  head  of  wheat,  chosen  irrespective  of  ^ize 
or  vigor,  but  of  a  variety  producing  a  good  quality  of  grain.  The 
head  was  4f  inches  long  and  had  47  gi-ains,  which  were  carefully 
planted  in  rows,  1  grain  in  a  place,  12  inches  apart  each  way.  At 
harvest  the  plants  were  carefully  compared,  and  the  one  with  the 
largest  number  of  heads  was  chosen,  and  the  grains  from  the  best 
head  of  this  best  plant  were  planted  the  next  year  in  the  same  wa}"; 
and  this  was  continued  year  after  year,  choosing  each  time  for  seed 
the  best  head  from  the  most  prolific  plant.  At  the  first  harvest  the 
best  plant  bore  10  heads,  at  the  second  22,  at  the  third  39,  at  the  fourth 
52,  the  best  head  of  which  was  8f  inches  long  and  bore  123  grains. 
.  (Jour.  Roy.  Agi-.  Soc,  Vol.  XXII,  p.  371,  and  plate.) 

This  was  the  origin  of  the  famous  "  Pedigree  wheat.''  Later,  and 
in  a  similar  way,  he  made  the  varieties  of  "  Pedigree  oats  "  and 
"  Pedigree  barley,"  all  very  prolific,  and  each  becoming  famous.  He 
gave  the  name  ''  Pedigree  "  to  these  varieties  because  his  process  was 
precisely  analogous  to  that  of  improving  live  stock  by  breeding  to 
points  and  strengthening  the  heredity  of  the  good  points  by  pedigree. 
vStill  later  he  gave  his  riper  conclusions  (Trans.  Brit.  Assoc.  Adv. 
Sci.,  1869,  p.  113)  drawn  from  his  long  series  of  experiments,  in  sub- 
stance as  follows:  That  every  fully  developed  plant,  whether  of 
wheat,  oats,  or  barley,  has  one  ear  su^Derior  in  reproductive  power  to 
any  of  the  others  on  the  plant;  that  every  such  plant  has  one  gnxin 
more  productive  than  any  other,  and  that  this  best  grain  grows  on 
the  best  ear;  that  the  superior  vigor  of  this  grain  is  transmissible  to 
its  progeny ;  that  by  selection  this  superiority  is  accumulated ;  that 
the  improvement  is  at  first  very  rapid,  but  that  in  successive  years  it 
gradually  grows  less;  that  an  improved  type  is  the  result,  and  that 
by  careful  selection  the  improvement  can  be  kept  up.  Another  paper 
on  his  pedigree  system,  read  before  the  Farmers'  Club  at  Birming- 
ham in  1874,  giving  many  interesting  facts,  is  republished  in  sub- 
stance in  the  monthly  reports  of  the  United  States  Department  of 
Agriculture  for  August  and  September,  1874,  page  381. 

The  practical  fact  underlying  this  relates  to  selection.  "  Natural 
selection  "  is  undoubtedly  the  principle  by  which  species  are  pre- 
served, whether  it  accounts  for  their  origin  or  not,  and  artificial 
selection  of  seed  is  the  only  method  by  which  any  variety  of  grain 
can  be  improved  or  even  maintained.  Without  it  the  variet}^  alwaj^s 
either  runs  out  or  changes;  how  rapidly  this  takes  place  depends 
upon  various  circumstances. 

It  is  unnecessary  to  multiply  further  proofs,  because  all  experi- 
ment points  the  same  way,  and  the  law  is  universally  recognized.  I 
have  merely  cited  a  few  out  of  many  scientific  experiments.  The 
principle  is  never  denied ;  it  is  simply  too  often  neglected  in  practice. 
In  this  connection  it  is  well  to  remember  that  it  is  easier  to  deteriorate 
a  crop  by  using  bad  seed,  or  even  by  simply  neglecting  the  selection  of 
the  good,  than  it  is  to  improve  an  already  good  variety;  the  down- 
hill road  is  the  easiest  traveled.  The  selection  of  seed  to  keep  up 
the  vigor  and  the  fruitfulness  of  the  varieties  cultivated  are  more 


303 

important  than  fertility  of  the  soil  as  factors  in  permanent  ijrain 
growing.  The  matter  of  soil  exhaustion  is  so  well  known  that  it  is 
the  staple  argument  with  the  majority  of  popular  writers  and 
speakers  on  agriculture;  but.  so  far  as  I  have  i)ersonally  seen  or  have 
been  able  to  learn  from  the  observations  or  the  experience  of  others, 
in  every  locality  in  this  countrv  where  wheat  growing  has  suddenly 
risen  to  large  tigures  the  quality  and  the  yield  have  diminished  more 
rapidly  from  carelessness  in  the  selection  of  the  seed  and  in  the  care 
of  the  crop  than  from  mere  soil  exhaustion. 

"While  there  is  no  absolute  proof  that  any  variety  of  cereal  has  ever 
originated  in  a  "  sport,"  nevertheless  the  indications  are  that  soniie  have 
so  originated.  The  new  variety  of  Baniia  cotton  originated  in  a 
single  plant,  entirely  unlike  its  fellows,  found  in  a  cotton  field  in  the 
Nile  Valley  in  1873,  and  the  variety  has  already  nearly  revolutionized 
cotton  culture  in  Egypt.  (McCoan,  Egypt  as  it  Is,  p.  187,  and  Kew 
Rept.  for  1877,  p.  26,  fig.  7.)  Cotton  is  propagated  from  the  seed 
as  the  cereals  are,  but  the  plant  being  a  more  conspicuous  one,  a  sport 
would  be  more  liable  to  be  noticed.  A  single  cereal  plant,  unlike  its 
fellows,  in  a  great  field  of  grain  w^ould  be  gathered  unnoticed  unless 
some  very  unusual  accident  secured  its  preservation. 

It  is  well  known,  however,  that  many  varieties  of  grain  have  origi- 
nated in  some  single  plant  differing  from  its  fellows  found  growing 
in  some  exceptional  place,  but  how  that  plant  acquired  its  special 
characters,  whether  suddenly,  as  sports  do,  or  not,  we  have  no  knowl- 
edge. We  simply  and  only  know  that  here  and  there  some  single 
plant  has  been  found  that  represents  to  us  a  new  variety  ready  made, 
and  varieties  have  been  perpetuated  from  such  plants  which  have 
grown  true  to  the  seed  and  which  have  been  valuable  and  enduring. 
The  variety  of  oats  known  as  ''  potato  oats  "  is  said  to  have  originated 
in  a  single  plant  found  growing  in  a  potato  patch  (hence  the  name) 
in  Cumberland,  England,  in  1778  (Allen,  New  America  Farm  Book, 
p.  163),  or,  as  some  say,  in  1789  (Stephen's  Farmers'  Guide,  I,  4-19). 
This  variety,  after  nearly  a  hundred  years'  existence,  is  still  one  of 
the  best  and  brings,  it  is  said,  the  highest  price  in  the  English  markets. 
Its  excellence  has  been  proved  throughout  Europe  and  entirely  across 
the  continent  of  America,  for  it  is  in  common  cultivation  from  Maine 
to  Oregon  and  "Washington. 

The  Clawson  wheat  originated  in  a  single  plant  found  growing  by 
a  stump  in  the  State  of  New  York.  Darwin  says  that  the  Fenton 
wheat  was  found  growing  on  a  pile  of  detritus  in  a  (luarry  in  Eng- 
land. The  Chidham  wheat  originated  from  an  ear  found  growing 
in  a  hedge  in  the  same  countrv,  and  numerous  other  examples  are 
recorded  in  the  agricultural  literature  of  this  century.  It  is  only 
fair  to  say,  however,  that  many  varieties  of  such  origin  have  been 
rejected  on  trial  as  of  no  value,  just  as  numerous  varieties  of  seedling 
apples  and  potatoes  are  rejected.  It  is  only  the  few^  that  are  actual 
improvements  on  what  we  had  before.  In  ornamental  and  otlier 
garden  jDlants  the  tendency  to  "  sport "  is  much  increased  by  cross- 
ing varieties,  and  this  is  probably  also  true  of  all  classes  of  cultivated 
plants. 

Using  seed  which  has  been  grown  in  some  other  locality,  or,  as 
farmers  say.  "  a  change  of  seed,"  has  been  practiced  by  grain  growers 
m  all  ages;  and  that  this  is  very  often  attended  with  an  increase  of 


304 

crop  has  been  proved  by  the  experience  of  centuries.  Sometimes  this 
change  of  seed  means  bringing  in  a  variety  previously  cultivated 
there  by  bringing  it  from  some  other  place  more  or  less  distant. 

To  illustrate:  Potatoes  grow  well  as  far  south  as  Louisiana,  the 
Bermudas,  and  other  warm  climates,  if  the  seed  is  yearly  brought 
from  a  cooler  region.  The  same  fact  is  true  of  peas,  and  there  are 
large  importations  of  seed  peas  from  Canada  to  the  United  States 
every  year.  Most  garden  vegetables  behave  in  a  similar  way,  and  on 
this  fact  the  modern  business  of  growing  garden  seeds  is  largely 
founded.  In  Connecticut,  onion  seed  is  imported  from  Tripoli.  The 
first  crop  grown  from  this  seed  is  of  such  excellent  quality  that  the 
trouble  and  expense  oi  the  importation  are  justified;  but  if  the  cul- 
tivation is  continued  from  seed  produced  by  the  American  crop,  in  a 
few  years  the  onions  degenerate  to  the  size  of  acorns.  The  constant 
sending  of  the  seeds  of  squashes  and  other  garden  vines  from  the 
New  England  States  and  other  places  east  of  the  Appalachians  to 
the  fertile  prairie  soils  of  the  West  is  another  familiar  illustration, 
and  similar  facts  have  been  observed  all  over  the  world.  Melon  seeds 
from  Tibet  are  taken  every  year  to  Kashmir,  and  produce  fine  fruit 
weighing  from  4  to  10  pounds;  but  vines  growing  from  the  seed 
of  melons  produced  thus  in  Kashmir  yield  the  next  year  fruit 
weighing  but  2  or  3  pounds.  Seed  of  the  sea -island  cotton  have 
been  carried  to  every  cotton-producing  country  of  the  world,  but  the 
variety  rapidly  degenerates  in  every  place  yet  tried  distant  from  its 
original  home,  and  if  the  excellency  of  the  fiber  is  kept  up  elsewhere 
it  is  only  done  by  the  use  of  fresh  seed. 

Now,  it  often  happens  that  such  a  variety,  specially  prepared  for 
a  region  by  a  long  process  of  adaptation,  may  be  better  suited  to  it 
than  any  new  one,  and  in  such  cases  no  increase  of  crop  follows  a 
change  of  seed.  For  example,  heavy  oats  taken  from  the  cool,  moist 
climates  of  Canada  or  northern  Europe,  used  as  seed  in  the  north- 
ern or  middle  United  States,  usually  produce  at  first  a  crop  weigh- 
ing more  per  bushel  than  that  produced  from  home-grown  seed. 
But  in  various  places,  notably  so  on  Long  Island,  where  special 
varieties  have  long  been  grown  from  seed  carefully  selected  as  to 
weight  until  this  weight  reaches  that  which  is  produced  from  foreign 
seed,  no  increase  of  weight  is  obtained  by  any  change  of  seed. 
This  appears  to  be  the  case  in  several  localities  reported.  Another 
example  to  the  point  is  in  the  local  varieties  of  corn  sometimes  culti- 
vated on  farms  in  New  England  and  the  Middle  States.  Where  a 
single  variety  has  been  cultivated  for  a  man's  lifetime  in  the  same 
neighborhood,  or  even  on  the  same  farm  each  year,  the  seed  having 
been  carefully  selected  and  prepared  until  no  further  improvement  is 
reached  by  such  selection,  here  it  often  happens  that  such  home-bred 
local  variety  yields  better  than  any  variety  introduced  from  without. 
But  it  also  happens  that,  having' been  so  long  purely  bred,  it  is  of 
especial  value  in  mixed  planting,  as  already  described". 


305 

COTTON. 

H.  Hammond,  in  his  report  to  K.  AV.  Hilgard  on  the  cotton  produc- 
tion of  the  State  of  South  Carolina  (Tenth  Census  U.  S.,  1880,  Vol. 
VI,  p.  475),  says: 

In  a  handful  of  ordinary  cotton  seed  three  varieties  may  often  be 
recognized,  j) resenting  well-marked  differences.  The  largest  of  these 
is  covered  with  a  green  down;  another  smaller  and  much  more 
numerous  seed  is  covered  Avith  a  white  or  grayish  down;  the  third 
variet}'  is  naked,  smooth,  and  black.  It  may  not  be  possible  to  say 
whether  these  three  sorts  of  seeds  correspond  to  three  classes  under 
Avhich  the  numerous  varieties  of  cotton  are  arranged.  These  are, 
first,  the  ''green  seed,'  corresponding  with  the  GoHsypbtvi  hlrsKtnm, 
or  shrub  cotton,  attaining  a  height  of  from  10  to  12  feet,  a  native  of 
Mexico,  and  varying  as  an  annual,  biennial,  or  perennial,  according  to 
the  climate  in  which  it  is  grown ;  second,  the  "  wdiite  seed,"  corre- 
sponding with  the  Gossypiirm  herhaceum^  or  herbaceous  cotton,  an 
annual,  attaining  a  height  of  2  feet,  native  of  the  Coromandel  coast 
and  the  Xilgherries;  third,  the  ''black  seed,"  corresponding  w^ith 
Gossypium  arhorexm^  or  tree  cotton,  a  native  of  the  Indian  peninsula, 
but  attaining  a  height  of  100  feet  on  the  Guinea  coast,  and  producing 
a  silky  cotton.  The  black  seed,  how^ever,  is  not  distinguishable  from 
the  seed  of  the  long-staple  or  sea-island  cotton. 

HISTORY   OF   THE    LONG-STAPLE    COTTON. 

It  would  be  a  matter  of  much  interest  to  determine  the  origin  and 
history  of  the  varieties  of  cotton  now  in  cultivation.  The  difficul- 
ties of  doing  this  are  much  increased  by  the  very  wide  geographical 
range  occupied  b}^  the  plant.  The  earliest  explorers,  Columbus, 
Magellan,  Drake,  Captain  Cook,  and  others,  seem  to  have  found  it 
almost  everywhere  in  the  broad  belt  extending  from  the  equator  to  30° 
south  and  to  40°  and  45°  north  latitude,  w here  it  now  grows.  Although 
it  is  not  found  among  those  oldest  of  vestments,  the  wrappings  of 
Egyptian  mummies,  its  use  was  known  to  man  in  Europe,  Asia,  Africa, 
America,  and  the  outlying  islands  of  the  sea  in  the  remote  past,  far 
beyond  the  historic  age.  Its  very  name  itself  bears  evidence  to  this, 
occurring,  as  it  does,  in  many  and  in  the  most  ancient  languages. 

Xevertheless  nothing  can  show  more  clearly  the  importance  of 
tracing  and  understanding  the  history  of  plants  under  cultivation 
than  the  variation  and  improvements  in  black  seed  cotton  since  its 
introduction  on  the  Carolina  coast.  It  is  known  that  the  first  bale  of 
long-staple  cotton,  exported  from  America  in  1788,  wa^f  grown  on  St. 
Simons  Island,  Georgia,  by  a  Mr.  Bissell,  from  seed  that  came  from 
cither  the  Bahamas  or  the  Barbadoes  Islands."  Singularly  enough, 
the  authorities  leave  this  matter  in  doubt,  the  Hon.  William  Elliott 
saying  it  came  from  Anguilla,  one  of  the  Bahamas,"  and  Signor 
Filipino  Partatori  (Florence,  180(5),  saying  it  came  from  Cat  Island, 
one  of  the  Barbadoes."  But  as  Anguilla  is  one  of  the  Barbadoes"  and 
Cat  Island  one  of  the  Bahamas"  it  would  seem  difficult  to  decide  to 
which  group  of  islands  we  are  indebted  for  these  seed.  However,  as 
Mr.  Thomas  Spalding,  of  Sapelo  Island,  says,  in  a  letter  to  Governor 

tt  Sic. 
2667—05  M 20 


306 

Seabrook,  in  1844,  that  three  parcels  of  long-stapled  cotton  seed  were, 
to  his  knowledge,  brought  in  1785-86  from  the  Bahamas  to  a  gentle- 
man in  Georgia,  it  would  seem  certain  that  the  seed  reached  our  coast 
from  those  islands.  There  it  was  known  as  Gossypium  harhadense,  as 
coming  from  the  Barbadoes.  In  the  Barbadoes  it  was  called  Persian 
cotton,  the  seed  having  been  brought  from  that  countr3\  In  this 
manner  its  descent  from  the  G.  arhoreum  of  India  is  traced. 

Be  this  as  it  may,  Mrs.  Kinsey  Burden,  Burden  Island,  Colleton 
Covmty,  S.  C,  obtained  some  of  these  seeds  from  Georgia  and  planted 
them.  This  crop  failed  to  mature,  and  the  first  successful  crop  of 
long-staple  cotton  grow^n  in  South  Carolina  was  planted  in  1790  by 
William  Elliott,  on  the  northwest  corner  of  Hilton  Head,  on  the 
exact  spot  wdiere  Jean  Eibault  landed  the  first  colonists  and  erected 
a  column  of  stone,  claiming  the  territory  for  France  a  century  before 
the  English  settled  on  the  coast.  Mr.  Elliott's  crop  sold  for  lOid. 
per  pound.  Other  planters  made  use  of  this  seed,  but  it  was  not  until 
Kinsey  Burden,  sr.,  of  Colleton  County,  began  his  selections  of  seed, 
about  the  year  1805,  that  attention  was  strongly  called  to  the  long- 
staple.  Mr.  Burden  sold  his  crop  of  that  year  for  25  cents  per  pound 
more  than  did  any  of  his  neighbors.  He  continued  to  make  selections 
of  seed  and  to  improve  his  staple,  and  in  1825  he  sold  a  crop  of  60 
bales  at  $1.16  per  pound.  The  year  subsequent  his  crop  sold  for 
$1,255  and  in  1828  he  sold  2  bales  of  extra  fine  cotton  at  $2  per  pound, 
a  price  not  often  exceeded  since.  The  legislature  was  on  the  point  of 
offering  Mr.  Burden  $200,000  for  his  method  of  improving  the  staple 
of  cotton,  and  Mr.  William  Seabrook,  of  Edisto,  w^as  prepared  to  pay 
him  $50,000  for  his  secret,  when  it  w^as  discovered  that  the  fine  cotton 
was  due  wholly  to  improvements  made  in  the  seed  b}^  careful  and 
skillful  selection.  Since  then  the  greatest  care  has  been  bestowed 
upon  the  selection  of  the  seed,  and  to  such  perfection  was  the  staple 
brought  by  this  means  that  the  crops  of  some  planters  were  sold  not 
by  sample,  but  by  the  brand  on  the  bale,  as  are  the  finest  wines. 

During  the  war  of  1861-1865,  the  cultivation  of  the  finest  varie- 
ties being  abandoned  on  the  islands,  the  seed  removed  to  the  interior 
greatly  deteriorated  in  quality.  So  scarce,  on  this  account,  was  good 
seed  directly  after  the  war  that  J.  T.  Dill,  a  cotton  merchant  in 
Charleston,  at  one  time  had,  in  an  ordinary  letter  envelope,  the  seed 
from  which  are  derived  all  the  better  qualities  of  long  staple  now  cul- 
tivated. Nor  have  the  improvements  made  by  careful  selection  of 
the  seed  ceased  in  later  years.  The  staple  has  kept  fully  up  to  the 
best  grades  of  former  days,  and  the  proportion  of  lint  to  seed  cotton 
has  been  increased.  Formerly  1  pound  of  lint  cotton  from  5  pounds 
of  seed  cott(5n  of  the  fine  varieties  was  considered  satisfactor3\ 
Thanks  to  the  efforts  of  Mr.  E.  M.  Clark,  a  cotton  has  been  recently 
found  which  yields  1  pound  of  lint  to  3^  of  seed  cotton,  preserving 
at  the  same  time  the  lenglh,  strength,  and  evenness  of  fiber  charac- 
teristic of  the  best  varieties. 

BEANS. 

The  history  of  the  derivation  of  the  bean  ( Vicia  sativa,  Vicia  faha, 
and  Ervum  lens)  is  given  by  A.  de  Candolle  (see  Agr.  Sci.,  Vol.  I, 
p.  58),  who  shows  that  its  cultivation  began  in  Persia,  and  that  the 
common  white  bean,  which  has  been  cultivated  since  prehistoric  times 


307 

in  Europe,  has  some  similarity  to  a  bean  cultivated  in  India  since 
the  earliest  times.  The  characteristic  peculiarities  of  the  cultivated 
bean  and  its  uncultivated  relatives  have  probably  existed  for  at 
least  five  or  six  thousand  years,  and  the  original  stock  from  which  the 
cultivated  bean  was  derived  has  long  since  become  extinct. 

PEPPER. 

The  derivation  and  varieties  of  peppers  from  all  parts  of  the  world 
(genus  Capsicum)  are  described  by  E.  L.  Sturtevant  (Agr.  Sci., 
Vol.  II,  p.  1).  The  general  effect  of  climate  is  to  diminish  the  size 
of  the  fruit  when  the  seeds  are  planted  in  higher  latitudes — that  is' to 
say,  with  a  diminution  of  temperature.  Similarly,  the  effect  of  cold 
nights  is  to  check  the  growth,  diminish  the  size,  and  promote  early 
ripening. 

KENTUCKY  BLUE  GRASS. 

The  germination  of  Kentucky  blue-grass  seed  {Pon  ptrtteHKh),  as 
also  that  of  red  top  and  timothy,  has  been  studied  by  Thomas  F, 
Hunt  at  the  agricultural  experiment  station,  Champaign.  111.  Al- 
though the  object  of  the  experiment  was  primarily  to  determine 
the  relative  vitality  or  honesty  of  the  seeds  and  samples  from  differ- 
ent sources,  yet  the  results  have  some  bearing  upon  the  question  as 
to  the  best  temperature  for  germination  and  the  possibility  of  accli- 
matization, Kentucky  blue  grass,  raised  in  Kentucky,  wdien  sown 
in  the  Geneva  sprouting  apparatus,  would  not  germinate  in  thirteen 
weeks  at  temperatures  from  70°  to  80°  F.,  wdiereas  80  per  cent  of 
meadow  fescue  and  95  per  cent  of  mammoth  red  clover  sprouted 
during  the  first  w^eek  in  June,  1888.  xVgain,  in  1889  a  specimen  of 
blue  grass  from  the  same  locality  would  not  sprout  in  sixty  days  at 
an  average  temperature  of  67°  F.,  whereas  during  the  first  eight 
days  98  per  cent  of  both  timothy  and  red  clover  and  85  per  cent  of 
meadow^  fescue  sprouted.  Again,  a  sample  from  another  dealer  in 
Kentucky,  tested  for  thirty  days  under  similar  conditions  as  the  last, 
gave  one  sprout  to  a  hundred  seeds.  Another  sample  w^as  sent  from 
Chicago  to  Manitoba  and  thence  to  Champaign  for  testing.  Out  of 
500  seeds  not  one  sprouted,  but  in  the  best  of  subsequent  samples  7 
per  cent  sprouted. 

Finally,  samples  were  obtained  from  19  different  sources,  mostly 
in  Kentucky,  and  were  all  tested  uniformly  in  the  Geneva  apparatus 
at  Champaign,  111.,  from  July  23  to  August  31,  1889.  The  range  of 
temperature  in  the  apparatus  was  from  63.5°  to  73.5°  F.     Out  of  all 


308 

the  samples  the  maximum  and  the  minimmn  percentages  of  sprouting 
were  as  shown  in  the  following  table : 


Variety. 


Kentucky  blue 

Red  top 

Timothy 


Per  cent.    Per  cent. 

ol 

4  \  25 

42  76 


These  are  not  likely  to  be  abnormal  percentages,  since,  according 
to  Professor  Himt's  calculation,  with  an  ordinary  seeding  of  30 
pounds  to  the  acre,  if  only  2  per  cent  germinates  there  would  be  40 
plants  to  the  square  foot.  But  the  question  may  still  remain  as  to 
whether  the  soil  or  the  temperature  were  unfavorable  or  whether  the 
seed  of  the  Kentucky  blue  grass  was  in  some  abnormal  condition. 
(Agr.  Sci.,  Vol.  IV,  p.  4.) 


Chapter  XII.« 

RELATIONS  OF  SPECIAL  CROPS    TO    SPECIAL    FEATURES  OF 
CLIMATE  AND  OTHER  INFLUENCES. 

The  preceding  chapter  on  phenology  has  given  several  illustrations 
of  the  influence  of  the  date  of  planting  upon  the  dates  of  the  resulting 
phases  and  on  the  amounts  of  the  harvest  for  special  plants.  The  exper- 
iments at  experiment  stations  now  about  to  be  quoted  were  under- 
taken with  a  view  to  the  further  direct  elucidation  of  this  relation. 
From  such  experiments  we  obtain  definite  data  by  which  to  decide  as 
to  the  best  date  for  planting  and  the  probable  resulting  crop  both  in 
normal  and  abnormal  seasons.  We  "see  to  what  extent  the  seed  and 
plant  have  acquired  habits  suitable  to  the  prevailing  climate,  and 
furthermore,  what  climatic  influences  the  plants  were  not  able  to 
withstand  when  the  seeds  were  planted  too  early  or  too  late.  It  is, 
of  course,  of  prime  importance  in  each  case  to  know  where  the  seeds 
were  grown  or  to  what  climate  they  were  acclimatized  before  being 
planted  at  the  experiment  station. 

By  measuring  the  weight  and  nutritious  value  of  a  sample  of  a 
crop  at  various  stages  of  development  we  are  able  to  form  tables 
showing  the  relation  of  the  mature  ultimate  harvest  to  the  immature 
plant,  and  this  relation  is  found  to  be  sufficiently  constant  to  justify 
one  in  predicting  the  harvest  per  acre  from  its  condition  on  any  given 
day  several  months  before  harvesting.  Examples  of  this  process  have 
already  been  given  and  others  now  follow. 

BEETS   AND   POTATOES. 
DATE   OF    PLANTING. 

Briem  finds  the  crops  of  beets  and  potatoes  that  have  become  accli- 
matized in  Austria-Hungary  varv  with  date  of  planting,  as  given  in 
the  table  following. 

a  A  chapter  on  "  Forests  and  climate."  which  was  originally  intended  to  pre- 
cede this  chapter,  is  omitted. 

(309) 


310 


Date  of  sowing. 


From  sowing  to  harvest.^ 


Number 
of  days. 


Sums 
of  mean 

daily 
temper- 
atures. 


Number 

of  days 

when 

rain  fell. 


Average 

weight  of  one 

tuber. 


March  1 . . 
March  16  . 

Aprill 

Aprilie... 

Mayl 

May  16. .  - . 

June  1 

June  16  _ . . 

Julyl 

July  16.... 
August  1  - . 
August  16- 


"  C. 
3,271 
3,209 
3,151 
3,020 
2,881 
2,726 
2,469 
3,197 
1,890 
1,627 
1,331 
1,026 


mm. 
519 
506 
496 
453 
417 
373 
294 
169 
154 
122 


222 

272 
257 
302 


217 
173 
158 


Harvest  October  20. 


SUGAB  BEETS. 

Durin  has  shown  that  the  sugar  beet  loses  the  sugar  in  the  root  by 
its  consumption  in  forming  stalks  and  leaves  as  well  as  seeds.  The 
roots  die  when  all  the  sugar  is  used  up,  from  which  I  infer  that  the 
best  time  for  gathering  the  beets  must  be  at  that  period  of  ripeness 
in  which  the  formation  of  leaves  ceases,  and  possibly  this  formation 
of  leaf  and  loss  of  sugar  can  be  checked  artificially  by  cutting  the 
young  leaves.     (Agi*.  Sci.,  Vol.  IV,  p.  326.) 

6BASSES. 

The  changes  in  the  chemical  composition  of  grass  and  in  the 
nutritious  quality  of  the  dried  hay  have  been  determined  by  E.  F. 
Ladd  (Agr.  Sci.,  Vol.  I,  p.  221)  by  experiments  on  timothy  {Phleum 
'pratense)^  who  concludes  as  follows: 

(1)  The  amount  of  water  in  timothy  diminishes  rapidly. 

(2)  There  was  a  large  increase  in  crude  fiber  in  late-cut  timothy 
over  that  cut  at  the  period  of  full  bloom. 

(3)  As  the  grass  approached  maturity  there  was  a  considerable 
diminution  in  the  percentage  of  sugar  and  an  increase  of  the  starch. 

(4)  After  the  period  of  full  bloom  the  proportion  of  albuminoids 

to  the  other  organic  constituents  diminished. 

******* 

(8)  Finally,  from  a  chemical  point  of  view,  it  seems  preferable  to 
cut  timothy  for  feeding  at  the  period  of  full  bloom,  rather  than  after 
the  seeds  have  formed.     (Agr.  Sci.,  Vol.  I,  p.  223.) 

The  effect  of  climate  on  the  yield  and  chemical  composition  of 


311 


grasses,  especially  the  pasture  grass,  has  been  studied  at  the  Pennsyl- 
vania State  College  Agricultural  Experiment  Station,  by  G.  L.  Holter 
(Agr.  Sci.,  Vol.  Ill,  p.  285),  in  connection  with  studies  on  the 
yield  per  acre.  Samples  of  grass  were  cut  every  few  days  during  the 
season  (of  1887),  but  the  comparisons  with  rainfall  and  temperature 
showed  no  definite  relation,  except,  perhaps,  that  the  percentage  of 
ash  increased  as  the  temperature  diminished.  The  following  table 
gives  the  figures  showing  the  average  rainfall  and  temperature  from 
the  middle  of  one  period  to  the  middle  of  the  next,  and  for  the  average 
of  seven  plats  of  ground : 


Period. 

Rain- 
faU. 

Tem- 
pera- 
ture. 

Yield  per  acre, 
in  pounds. 

Period. 

Rain- 
fall. 

Tern- 

Yield  per  acre, 
in  pounds. 

Fresh     Dry 
grass,      hay. 

Fresh 
grass. 

Dry 
hay. 

May  5-22 

Inches. 

'F. 

1,300 
525 
325 
140 
229 
171 
247 
170 
101 
105 
145 

339 
130 
91 
41 
65 
50 
67 
45 
34 
23 
43 

Aug.  29-Sept.5- 

Sept.  10-14 

Sept.  18-21 

Sept.22-29 

Sept.  29-Oct.  2 - 

Oct.  15-17 

Oct.  17-22 

Oct.  30-Nov.  5.- 

Inches. 
0.88 
1.56 
1.50 
0.41 
0.39 
0.85 
1.42 
1.37 

"F. 

66.5 

60.2 

60.4 

60.2 

55.9 

45.2 

46.1 

45.6 

147 
216 
202 
84 
85 
32 
43 
9 

May  2o-June  4  . . 

June  6-12 

June  13-22-- 

June  25-July  2-. 

July  3-11 

July  13-20 

July  21-29 - 

2.62 
0.52 
0.23 
1.75 
0.51 
1.74 
0.72 
0.25 
1.48 
3.24 

61.0 

70.0 
75.3 
67.2 
67.9 
69.2 
75.2 
72.6 
68.6 

52 
53 
24 
21 
11 
16 
3 

July30-Aug.  7.- 

Total 

4,277  !      1.145 

Aug.  8-20 

Aug.  22-28 

1 

If  we  assume  that  the  whole  season  extended  from  May  10  to  Sep- 
tember 29,  we  may  compute  the  average  daily  growth,  which  will  be 
found  to  be  very  large  at  first,  but  rather  uniform  from  June  13  to 
September  16,  after  which  it  steadily  diminishes.  The  irregularities 
in  the  growth  from  one  week  to  the  next  have  no  simple  connection 
with  rainfall  or  temperature,  but  there  is  no  evidence  to  show  that 
other  climatic  elements,  such  as  sunshine  and  evaporation,  would  not 
have  thrown  some  light  upon  the  subject. 

•  Mr.  Holter  has  also  experimented  on  the  yield  per  acre  of  pasture 
grass,  as  measured  week  by  week  during  the  growing  season  of 
1888  and  1889  at  the  Pennsylvania  State  College  Agricultural 
Experiment  Station.  (See  Agr.  Sci.,  Vol.  V,  p.  52.)  The  plat 
experimented  upon  represents  an  average  of  the  uplands  of  the  Alle- 
gheny Mountains.  The  weather  of  the  season  was  most  favorable 
for  the  growth  of  grass,  having  a  heavy,  evenly  distributed  rainfall. 
The  following  table  shows  the  dates  of  cutting  and  the  average  daily 
growth  between  these  dates,  expressed  in  pounds  of  dried  grass  per 
acre.  It  will  be  seen  that  there  was  a  rapid  increase  in  growth  up 
to  May  21,  after  which  there  was  a  steady  decline.  The  daily 
average  for  the  whole  season  of  one  hundred  and  seventy-eight  days 


S12 

is  32.1  o  pounds  of  fresh  matter  and  9.06  of  dry  matter.  ,  Evidently 
a  pasture  that  is  fairly  well  stocked  Avith  cattle  in  May  and  June 
will  be  overstocked  in  August  and  September. 


Date  of  cutting. 


April  2() 
May  1  - . 
May  9 . . 
May  15  . 
May  21 . 
May  24  _ 
May  29. 
June  5  . 
June  11 


Weight 
of  dry 
matter. 


Pounds. 
0.00 
4.86 

15.93 
20.01 
15.29 
12.48 
12.81 
13.49 


Date  of  cutting. 


June  IT  . 
June  22  . . 
June  28  . . 
July  5.... 
July  11.. 
July  17.. 
July  23.. 
July  29.. 
August  3 


Weight 
of  dry 
matter. 


Pounds 
13.26 
13.04 

9.78 
13.41 

8.77 

9.74 
11.46 

9.79 
13.91 


Date  of  cutting. 


August  9 

August  16 

August  23 

August  29 

September  9 . 
September  23 

October  4 

October  15... 


Weight 
of  dry 
matter. 


Pounds. 
8.53 
7.95 
8.48 
5.78 
4.65 
.5.-35 
4.32 
1.78 


CEREALS. 

C.  Richardson  (Agr.  Sci.  Vol.  I,  p.  125)  states  that  the  quality  of 
the  grain  produced  in  any  locality  is  dependent  principally  on  three 
conditions — the  climate,  the  soil,  and  the  cultivation.  Wheat  is  most 
susceptible  to  its  environments;  thus  the  Atlantic  slope  produces  a 
wheat  grain  of  medium  size  and  with  less  than  the  average  amount 
of  nitrogenous  constituents.  In  this  part  of  the  country  latitude 
exerts  a  minor  influence. 

In  the  Central  States — Tennessee,  Kentucky,  Arkansas — the  grain 
is  larger  and  contains  more  nitrogen. 

In  the  Xorthwest  a  grain  is  harvested  smaller  than  anywhere 
and  richer  in  nitrogen. 

In  Colorado,  where  irrigation  is  practiced,  a  large  grain  is  grown 
which  is  rich  in  nitrogen. 

On  the  northwest  Pacific  slope  the  grain  is  large,  very  starchy,  and 
with  less  nitrogen  than  anj^where  else. 

The  above  conditions,  as  at  present  existing,  are  probably  in  a 
state  of  transition. 

The  following  table  shows  the  difference  in  the  composition  of  the 
crops  of  standard  varieties  of  wheat  in  Minnesota  and  Dakota  : 


Crop. 

Albumi- 
.    noids. 

Crop. 

Albumi- 
noids. 

Per  cent. 
13.21 
15. 14 

1884        

Pei-  cent. 
14.28 

15.99 

313 

The  followino;  table  shows  the  diflferences  for  the  varieties  raised 
in  the  respective  States : 


Weight 

of  100 

kernels. 

Albumi- 
noids. 

kernels. 

Albumi- 
noids. 

Grams. 
3.644 
3.489 
3.684 
3.205 
4.091 
3.325 
3.969 

Per  cent. 
12.15 
11.35 
12.66 
14.07 
9.73 
10.87 
11.67 

Ohio 

Grams. 
3.476 
3.150 
3.454 
3.43:^ 
3.579 
3.424 

Per  cent. 

12.  K^ 

12.50 

Central  States 

Kentucky 

13  15 

12. 10 

North  Pacific 

Georgia 

11  78 

11. 2S) 

Michigan 

The  effect  of  climate  and  soil  on  wheat  is  strikingly  shown  in  that  a 
soft  plump  yellow  wheat  from  Oregon  and  a  small  hard  red  variety 
from  Minnesota,  when  used  as  seed  in  Colorado,  in  three  years'  time 
had  lost  nearly  all  their  differences,  so  as  to  look  more  like  Colorado 
grain  than  like  their  own  originals." 

A  study  of  38  varieties  grown  during  seven  years  on  one  farm  in 
Colorado  shows  a  progressive  change,  as  in  the  following  table : 


Year. 

Weight 
of  100 
grains. 

Albumi- 
noids. 

Weight 
bushel. 

Year. 

Weight 
of  100 
grains. 

Albumi- 
noids. 

Weight 

per 
bushel. 

1881    .  ... 

Grams. 
4.865 
4.283 
3.941 

Per  cent. 
13.40 
13.04 
11.74 

Pounds. 

1884 

Grams. 
4.222 
3.810 

Per  cent. 
12.53 
11.34 

Pounds. 
65.2 

1882 

1885 

62  2 

1883 

These  determinations  show  plainly  that  the  soil  and  other  condi- 
tions in  1885  would  not  produce  as  good  a  crop  from  introduced  seed 
as  in  1881,  and  that  the  drop  in  character  of  the  crops  as  a  whole  is 
due  as  much  or  more  to  soil  than  to  season.  The  seven  varieties 
grown  for  several  years  in  Colorado  which  showed  no  signs  of  deteri- 
oration are  on  this  account  worth  considering,  since  they  are  perhaps 
the  varieties  to  select  for  the  locality,  because  they  may  be  more 
suited  to  the  conditions  there  existing  than  any  others.  Attention 
is  called  to  the  fact  that  deterioration  in  quality,  as  evidenced  by 
diminution  of  albuminoids,  is  shown  by  the  loss  of  weight  per  bushel. 
In  the  present  case  a  drop  of  1,2  per  cent  in  albuminoids  was  accom- 
panied by  a  loss  in  weight  of  3  pounds  per  bushel.  No  other  cereal 
seems  to  be  influenced  by  its  environment  in  the  same  way  as  wheat. 
Oats  are  more  changed,  by  climate  and  soil,  in  the  outward  physical 
appearance  and  properties  of  the  grain;  barley  is  modified  in  its 


a  There  is  nothing  to  show  how  nmch  this  may  have  been  due  to  spread  of 
pollen  from  one  field  to  the  other. — C.  A. 


314 

chemical  composition;  maize  is  modified  as  to  its  size;  rye  varies 
very  little  with  change  of  conditions,  except  as  to  the  effect  upon  the 
htraw ;  but,  as  we  have  seen,  wheat  changes  both  its  external  appear- 
ance and  its  chemical  constituents. 

With  regard  to  maize,  the  high  ripening  temperature  of  the  South- 
ern States  appears  to  diminish  the  size  of  the  kernel  and  prevent  a 
large  formation  of  starch.  But  the  variations  in  size  peculiar  to  the 
varieties  are  much  smaller  than  variations  that  are  due  to  the  climate 
and  soil,  thus  Dent  varieties  of  corn  from  Tennessee  and  Indiana  have 
been  found  weighing,  respectively,  64.1  and  13.9  grams  per  100  ker- 
nels, or  a  ratio  of  5  to  1  in  the  weights  of  the  kernels.  Hence  a 
comparison  of  the  yield  per  acre  by  the  weights  of  the  crops  would 
differ  very  much  from  a  comparison  by  volumes  in  bushels.  The  per- 
centage of  albuminoids  varies  very  much  less  in  the  large  and  small 
kernels  of  maize. 

As  to  oats,  the  climatic  surroundings  cause  a  ver}"  large  variation 
in  their  physical  appearance.  The  extreme  weights  per  bushel  are 
48.8  and  24.7  pounds;  the  extreme  ratios  in  the  weight  of  the  kernel, 
with  reference  to  the  weight  of  the  kernel  plus  the  hull,  are  79  and  55 
per  cent.  The  average  composition  all  over  the  country  as  to  the 
percentage  of  albuminoids  is  between  12  and  10  per  cent,  except  in  a 
few  extreme  cases  of  9  and  19  per  cents,  which  are  as  liable  to  occur 
in  one  locality  as  in  another. 

Barley  is  not  as  variable  in  composition  and  aj)pearance  as  wheat 
and  oats;  the  extreme  weights  per  bushel  are  00.2  and  50.4  pounds, 
and  the  extreme  weights  of  100  kernels  are  4.900  and  2.630  grams; 
the  extreme  percentages  of  albuminoids  are  14.88  and  8.75.  For 
malting  purposes  the  large  quantity  of  albuminoid  is  not  desirable, 
while  starch  is  desirable. 

WHEAT— GENERAL  RELATIONS  TO  CLIMATE  AND  SOIL. 

In  his  tenth  census  report  Professor  Brewer  says : 

While  the  cultivation  of  wheat  in  a  commercial  sense  is  determined 
by  a  complicated  set  of  conditions,  in  an  agricultural  sense  the  matter 
is  very  much  simpler.  The  yield  and  quality  of  the  crop  practically 
depends  upon  but  five  conditions — the  climate,  the  soil,  the  variety 
cultivated,  the  method  of  cultivation,  and  the  liability  to  destruction 
by  insects.  Even  under  poor  cultivation  and  exemption  from  insect 
depredations,  if  the  other  three  conditions  are  favorable  good  crops 
of  wheat  of  good  quality  may  be  very  often  grown,  and  in  a  good 
climate  and  with  a  good  variety  of  wheat  an  excellent  quality  may  be 
grown  even  where  the  soil  is  comparatively  poor.  The  yield  may 
be  small,  but  the  grain  itself  will  be  good. 

As  regards  soils,  we  nvAj  say  in  a  general  way  that  light  clays  and 
heavy  loams  are  the  best  for  wheat.     On  the  one  hand,  very  heavy 


315 

clays  often  procluco  o-ood  crops,  both  as  to  yield  and  as  to  quality, 
and  on  the  other  hantl  the  liohter  soils  may  yield  a  good  quality.  It 
is  simply  smaller  in  quantity.  The  best  crops,  however,  come  from 
moderately  stitf  soils,  but  any  fertile  soil  will  produce  good  wheat 
if  all  the  other  conditions  are  favorable. 

Geologically  considered,  the  most  of  the  wheat  grown  in  the  United 
States  is  over  the  region  of  drift,  but  much  of  the  wheat  soil  has  been 
so  modified  by  other  geological  influences  that  the  geological  factor 
is  not  an  important  one,  the  essential  character  which  gives  it  its 
value  being  as  largely  physical  as  chemical.  Good  wheat  lands 
agree  in  this,  that  they  are  sufficiently  rolling  for  natural  drainage; 
are  at  the  same  time  level  enough  to  admit  of  the  use  of  field  ma- 
chinery, and  are  easily  tilled,  admitting  the  use  of  light  field  imple- 
ments in  their  tillage  and  thus  allowing  of  a  very  large  production 
of  grain  in  proportion  to  the  amount  of  human  labor  emplo^yed. 
The  facility  of  putting  in  the  crop  and  harvesting  it  is  really  the 
controlling  condition  in  many  localities,  so  much  so  that  the  very 
important  wheat  regions,  where  some  of  the  most  speculative  farm- 
ing of  the  United  States  is  practiced,  are  in  regions  where  the  cli- 
matic conditions  are  such  that  the  average  yield  one  year  with 
another  may  be  as  low  as  10  bushels  per  acre.  In  such  cases  this 
low  average  is  usually  due  to  climatic  reasons  rather  than  to  a  lack 
of  fertility  in  the  soil,  and  in  favorable  years  the  yield  may  be  very 
much  larger.  The  ease  of  cultivation,  the  facilities  for  gathering  the 
crop,  and  its  good  qualities  in  favorable  years  incite  to  the  hope  that 
all  years  will  be  favorable,  and  in  good  years  the  profits  are  large. 
In  color,  in  the  amount  of  clay  contained,  in  physical  and  in  chemical 
characters,  there  is  much  diflference  in  the  different  soils  of  the  coun- 
try. Some  contain  much  vegetable  matter,  others  but  little.  We 
may  say  that  the  soils  of  all  the  more  important  wheat  regions  (so 
far  as  we  have  chemical  analyses)  are  rich  in  lime,  as  well  as  in  those 
other  elements  of  fertility,  such  as  potash  and  phosphoric  acid,  which 
are  necessarv  for  a  good  crop  and  a  good  quality  of  grain. 

For  commercial  as  well  as  for  agricultural  success  climate  is  an 
all-controlling  condition.  AMieat  is  normally  a  winter  annual.  For 
a  good  crop  the  seed  must  germinate  and  the  young  plant  grow  dur- 
ing the  cool  and  moist  part  of  the  year,  which  season  determines  the" 
ultimate  density'  of  growth  on  the  ground  and,  consequently,  mostly 
determines  the  yield.  "\Alieat  ripens  in  the  warmer  and  drier  parts 
of  the  3'ear,  which  season  more  largely  determines  the  quality,  phunp- 
ness,  and  color  of  the  grain.  In  climates  with  winters  so  cold  that  all 
vegetable  growth  is  suspended-  we  have  tAvo  distinct  classes  of 
varieties,  known,  respectively,  as  spring  and  winter  wheats.  Through- 
out all  the  Northern  States,  from  ocean  to  ocean,  and  to  some  extent 
in  those  Southern  States  which  lie  east  of  the  Great  Plains,  these  two 
classes  of  varieties  are  very  distinct  as  regards  their  cultivation  and 
to  scmie  extent  also  as  regards  their  characters.  In  California  and 
in  similar  climates,  as  in  Egypt,  this  distinction  does  not  exist  in 
respect  to  their  cultivation,  although  the  varieties  partake  more  of 
the  character  of  winter  wheats  than  of  spri ug,  both  in  their  mode  of 
growth  and  in  the  character  of  the  flour  made  from  them. 

But  in  all  climates  and  whatever  variety  may  be  grown,  the  crop 
must  be  sown  and  have  its  early  growth  in  a  cool  part  of  the  year. 


316 

AYheat  branches  only  at  the  ground,  and  produces  no  more  heads  than 
stalks.  It  only  sends  out  these  branches  early  in  its  growth  or  dur- 
ing cool  weather  and  when  the  growth  is  comparatively  slow.  The 
branching  of  wheat  (called  ''  tillering  "'  in  the  Old  World,  and  ''  stock- 
ing," "  stooling,"  and  "  tillering  "  in  different  sections  of  this)  must 
take  place  before  the  plant  attains  any  considerable  height  or  it  does 
not  occur  at  all.  Hence,  in  climates  like  those  of  the  Northern  and 
Eastern  States  this  takes  place  mostly  in  the  spring,  and  a  cool,  pro- 
longed, and  rather  wet  spring  is  therefore  best  for  the  ultimate  yield 
of  the  crop;  the  grain  then  stands  heavier  on  the  ground.  On  the 
contrary,  a  warm,  rather  dry,  rapidly  growing,  and  early  spring  in 
those  parts  of  the  country  diminishes  the  yield  of  wheat,  because  of 
this  habit  of  growth;  there  are  then  fewer  stalks,  and  the  heads  are 
fewer.  Consequently,  when  from  the  nature  of  the  season  or  the 
general  climate  of  *the  region  there  is  an  undue  tendeuc}^  for  the 
Avheat  to  shoot  up  without  sufficient  branching  it  is  common  to  check 
the  growth  by  pasturing  off  the  grain  in  the  early  spring,  as  is  a 
common  practice  in  many  of  the  Southern  States. 

In  a  countrj"  of  cold  winters,  for  good  crops  it  is  better  that  the 
ground  bo  continuously  covered  with  snow.  Bare  ground,  freezing 
and  thawing,  now  exposed  to  cold  and  dry  winds  and  now  to  warm 
sunshine,  is  exceedingly  destructive  to  wheat.  It  "  Avinter-kills "'  in 
two  ways — what  may  be  frozen  to  death  by  cold,  dry  winds,  or,  as  is 
more  often  the  case,  particularly  on  soils  rich  in  vegetable  matter,  it 
"heaves  out,"  and  by  the  alternate  freezing  and  thaAving  of  the  sur- 
face soil  the  roots  are  lifted  out  of  the  soil  and  the  young  plant 
perishes.  The  means  of  guarding  against  this  or  of  lessening  the 
danger  will  be  spoken  of  later. 

After  the  wheat  comes  in  head  more  sun  is  needed  and  less  rain. 
Too  much  rain,  particularly  if  accompanied  with  heat,  induces  rust, 
juildew,  and  other  diseases,  and,  on  the  other  hand,  too  dry  Avinds 
shrink  the  grain. 

The  ideal  climate  for  Avheat  is  one  with  a  long  and  rather  wet 
winter,  with  little  or  no  frost,  prolonged  into  a  cool  and  rather  Avet 
spring,  Avhich  gradually  fades  into  a  Avarmer  summer,  the  Aveatlier 
groAving  gradually  drier  as  it  grows  warmer,  Avith  only  comparatiA^ely 
light  rains  after  the  blossoming  of  the  crop,  just  enough  to  bring  the 
grain  to  maturity,  with  abundant  sunshine  and  rather  dry  air  toAvard 
liie  harA^est,  but  Avithout  dry  and  scorching  Avinds  until  the  grain  is 
fulh^  ripe,  and  then  hot,  dry.  rainless  Aveather  until  the  harAx^st  is 
gathered.  This  ideal  is  nearer  realized  in  the  better  years  in  Cali- 
fornia than  in  any  part  of  the  United  States,  and  it  is  there  in  such 
years  that  Ave  find  the  greatest  yields  knoAvn  to  tlie  country. 

The  quality  of  the  grain  is  largely  determined  by  the  climate,  a 
liot,  dry,  and  sunny  harA^est  time  being  best  for  wheat  of  the  first 
grade.  The  berry  is  then  brighter,  and  millers  say  the  quality  is  bet- 
ter if  the  climate  has  been  hot  and  dry  before  the  harA^est.  •  The 
wheat  of  sunny  climates — those  of  California,  Egypt,  northern  Africa, 
and  similar  countries — has  ahvays  ranked  high  for  quality,  and 
the  statement  is  often  made  that  the  Avheat  of  such  climates  is  also 
richer  in  gluten — that  is.  makes  stronger  flour — than  the  Avheat  of 
cooler  climates.  Of  this  latter  assertion  T  find  no  proof  from  the  mod- 
ern and  fuller  chemical  analyses.     The  chemical  composition  depends 


317 

more  upon  the  variety  cultivated  than  upon  either  soil  or  climate. 
The  spring  wheat  of  Dakota  and  ^linnesota  produces  as  strong  flour 
as  does  grain  from  a  sunnier  climate.  It  is  true  that  certain  varieties 
of  very  hard  wheats  only  grow  in  hot,  dry  climates.  Such  is  said  to 
be  the'  case  with  the  best  macaroni  wheats.  It  is  claimed  that  the 
macaroni  wheats  of  California  are  equal  to  the  best  of  northern 
Africa  or  of  southern  Europe  and  that  the  macaroni  made  from  it  in 
San  Francisco  is  equal  to  the  best  Italian.  But  while,  as  a  whole, 
the  quantity  of  gluten  and  the  strength  of  the  flour  is  determined  more 
by  the  variety  of  wheat  than  by  the  climate  or  the  soil,  yet  both  of  the 
latter  have  their  influence  on  chemical  composition.  Although  direct 
chemical  evidence  is  lacking,  derived  from  a  large  numl)er  of  chem- 
ical analyses  from  samples  chosen  with  this  special  object  in  view, 
it  is  claimed  that  abundance  of  phosphates  in  the  soil  increases  the 
quantity  of  gluten  in  the  crop.  The  millers  of  western  New  York 
say  that  the  flour  has  grown  stronger  with  the  increase  in  the  use  of 
superphosphates  in  growing  wheat  in  that  region,  and  that  the  same 
has  often  been  stated  as  a  fact  in  English  experience. 

The  particularly  bright  character  of  American  grain,  however, 
depends  upon  the  climate  rather  than  upon  the  soil.  The  sunny 
climate  of  the  whole  United  States  south  and  west  of  New  England 
is  favorable  for  this,  and  from  the  time  of  the  first  settlement  of 
the  colonies  the  bright  color  of  American  grain,  as  compared  with 
that  of  northern  Europe,  particularly  that  of  Great  Britain,  has  been 
remarked. 

The  table  of  distribution  according  to  annual  temperature  (Tenth 
Census,  Cereals,  Table  XIX,  p.  14)  shows  that  the  greatest  produc- 
tion is  where  the  mean  annual  temperature  is  between  50°  and  55°, 
173,895,149  bushels,  or  37.8  per  cent,  being  grown  in  this  belt,  and 
136,401,822,  or  29.7  per  cent,  where  the  mean  annual  temperature  is 
between  45°  and  50°.  Adding  these  two,  we  see  that  310,296,971 
bushels,  or  67.5  per  cent,  is  grown  where  the  mean  annual  tempera- 
ture is  between  45°  and  55°.  Considered  in  respect  to  the  mid- 
summer or  July  temperature  (Table  XX,  p.  14),  which  has  much  to 
do  with  the  ripening  of  the  gi^ain,  our  figures  are  of  less  interest  in 
this  crop,  because  over  considerable  regions  of  the  country  the  crop 
is  already  ripe  before  July  begins,  notably  in  California ;  but  we 
find  that  223,852,371  bushels,  or  48.7  per  cent,  grows  where  the  mean 
temperature  of  July  is  between  70°  and  75°,  and  178,530,037  bushels, 
or  38.9  per  cent,  where  the  midsummer  temperature  is  between  75° 
and  80°,  or  an  aggregate  of  87.6  per  cent  wdiere  the  July  temperature 
is  between  70°  and  80°  and  97.3  per  cent  where  it  is  between  65°  and 
85°.  AMiile  the  ideal  climate  for  wheat  is  one  of  mild  winters,  and 
some  of  the  most  noted  wheat  regions  of  the  world  are  where  snow 
and  frozen  ground  are  unknown  or  very  rare  (as  in  Egypt,  India, 
and  California),  nevertheless  most  of  the  wheat  of  the  world  grows 
in  regions  of  cold  winters. 

The  table  of  distribution  according  to  mean  winter  temperature 
(Tenth  Census,  Cereals,  Table  XXI,  p.  15)  shows  that  in  this  country 
46.6  per  cent  grows  wdiere  the  mean  January  temperature  is  between 
20°  and  30°,  68.9  per  cent  where  it  is  below "30°,  and  it  is  safe  to  say 
that  70  per  cent  of  the  wheat  crop  of  the  country  is  grown  where  the 


318 

average  January  temperature  is  below  the  freezing  point.  This  same 
condition  marks  most  of  the  great  wheat  regions  of  the  world. 

The  wheat  countries  (which  are  also  the  countries  of  oats,  barley, 
and  rye)  are  where  the  summer  season  only  is  the  growing  season, 
and  the  comforts  of  winter  must  be  provided  for  by  forethought  and 
labor;  and  hence  they  are  also  the  countries  of  labor,  industry,  and 
enterprise,  and  wdiere  the  highest  civilization  has  been  developed,  the 
result  being  correlated  to  these  climatic  conditions. 

The  table  of  distribution  according  to  rainfall  (Table  XXII,  p.  16) 
shows  that  132,152,234  bushels,  or  28.8  per  cent  of  the  crop,  grows 
with  an  annual  rainfall  of  between  40  and  45  inches,  62.7  per  cent 
Avhere  it  is  between  35  and  50  inches,  and  92.4  per  cent  where  the 
annual  rainfall  is  above  25  inches,  although  some  important  wheat 
regions,  notably  those  of  California,  are  where  the  mean  annual 
rainfall  is  less  than  25  inches.  We  have  an  explanation  of  this  in 
the  seasons  at  which  the  rain  falls.  The  table  of  distribution  accord- 
ing to  the  rainfall  of  the  growing  season  (Table  XXIII,  p.  16)  shows 
that  220,656,637  bushels,  or  48  per  cent  of  the  crop,  grows  where 
from  20  to  25  inches  of  rain  falls  during  this  season,  and  366,381,658 
bushels,  or  79.7  per  cent,  where  the  rainfall  during  the  growing 
season  is  from  15  to  25  inches,  6.4  per  cent  wdiere  it  is  below  15  inches, 
and  only  1  per  cent  where  it  is  less  than  10  inches — a  fact  of  much 
significance  for  great  tracts  of  our  country. 

CULTIVATION   OF   CEREALS— EXPERIMENTS   AT    BROOKINGS, 
S.  DAK. 


The  first  annual  report  of  this  station,  for  the  year  ending  June  30, 
1888,  gives  following  table  of  results  of  experiments  on  different 
varieties  of  wheat,  at  Brookings,  S.  Dak.  (lat.  44.3°  N.;  long.  98.5° 
W.),  in  April  and  May,  1887,  on  plats  of  ground  that  had  already 
borne  one  crop  of  wheat  or  flax  or  oats.  Some  were  soAvn  broadcast 
and  had  no  subsequent  cultivation;  others  were  "drilled  by  hand" 
and  subsequently  hoed  twice  or  thrice. 

The  columns  giving  the  calculated  sums  of  degrees  of  temperature 
are  based  upon  observations  at  the  Signal  Service  station  at  Huron, 
some  distance  to  the  westward,  because  the  special  station  at  Brook- 
ings was  not  then  established.  The  meteorological  table  for  Huron 
follows  the  agricultural  tables,  so  that  the  student  may  make  such 
further  studies  as  he  desires.  A  fragment  of  the  meteorological 
record  at  Brookings  for  1888  is  given  in  the  station  Bulletin  No.  5, 
which  I  have  compared  with  the  record  for  Huron  and  find  that  no 
important  error  will  result  from  using  the  Huron  records. 


319 


Variety. 


Date  of  t  Date  of 
sowing,    ^'^r;^^^- 


Sums  of 
positive 
tempera- 
tures 
(T-43°F.). 


Sown  broadcast: 

Saskatchewan  Fife 

French  Imperial 

Hand  drilled: 

Blount,  Colorado 

Wellman's  Saskatchewan. . 

Pure  Scotch  Fife 

Russian  Fife 

China  Tea 

Velvet  Chafif  or  Blue  Stem . 

BlouHt's  Hybrid,  No.  15.... 

Blounfs  Hybrid,  No.  IT.... 

Champlain.. _. _. 

Golden  Drop 

Blount's  Rustproof 

Peerless  or  Black  Bearded . 

Pringle's  Grandee 


1887. 
Apr.  25 
...do... 


Apr.  30 


...do... 
May  3 
...do... 
...do. 
Apr.  30 
May  3 
May  8 
May  3 
...do.. 
...do.. 
...do... 


Aug.  1 
July  29 

Aug.  10 
Aug.  9 
Aug.  6 
Aug.  11 
....do... 
July  29 
Aug.  9 
Aug.  6 
Aug.  8 
Aug.  4 
Aug.  8 
Aug.  20 
Aug.  12 


2,279 

2,513 
2,484 
2,397 
2,514 
2,514 
2,168 
2,484 
2,373 
2,311 
2,326 
2,437 
2,728 
2,534 


The  following  table  gives  the  results  of  experiments  on  different 
varieties  of  barlej-  at  Brookings,  S.  Dak.,  as  given  in  the  first  annual 
report  of  that  station.  For  further  details  see  the  preceding  section 
on  wheat  experiments. 


Variety. 

Date  of 
sowing. 

Date  of 

harvest 

ing. 

Sums  of 
positive 

tempera- 
tures 

(T-43°  F.) 

Sown  broadcast: 

Scotch 

1887. 
Apr.  25 
....do 

1887. 
July  18 
July  23 
July  18 
....do... 

July  23 
July  22 
July  20 
July  25 
....do... 
July  20 
July  28 

°  F. 
1,977 

Chevalier 

2,095 

....do... 

1,977 

....do 

1.977 

Hand  drilled: 

May    5 
do 

1,946 

Two-Rowed 

1  922 

Melow 

....do.  . 

1,880 

Imperial 

do 

2,010 

....do... 

2,010 

Barley  No.  3 

do 

1,880 

Black  Hulless 

do 

2,099 

320 


OATS. 


The  following  table  gives  the  results  of  experiments  on  different 
varieties  of  oats  at  Brookings,  S.  Dak.,  as  given  in  the  first  annual 
report  of  that  station.  For  further  details  see  the  preceding  section 
on  wheat  experiments. 


Variety. 


Datp  of     ^^^®  °^ 


Sums  of 
positive 
tempera- 
tures 
T-43°F.). 


Sown  broadcast: 

Probstier 

Welcome 

White  Belgium 

Wide  Awake 

White  Bonanza 

Hargett's  White  Seizure. 
Hand  drilled: 

White  Victoria 

Black  Norway 

Black  Tartarian 

Dakota  Chieftain 

No  Name 

Golden  Eussian 

White  Surprise 

Holstein 


Apr.  23 
Apr.  25 
....do... 


Apr.  5 
...do. 


May 
....do. 
....do. 
....do. 


.do-. 


1887. 
July  29 
....do... 
Aug.  1 
Aug.  3 
Aug.  1 
July  22 

Aug.  3 
Aug.   8 

....do... 
Aug.   1 

....do... 
July  28 
Aug.   1 

.-..do... 


2,279 
2,279 
2,:3ti7 
2,319 
2,365 
2,069 

2,270 
2,389 
2,399 
2,218 
2,218 
2,099 
2,218 
2,218 


The  meteorological  record  for  the  "  growing  season  "  of  1887  at 
Huron  is  now  given  for  detailed  comparisons.  The  last  three  columns 
give  the  temperatures  computed  by  the  two  methods  of  Boussingault 
and  Angot,  respectively. 

Meteorological  data  for  Huron,  Dak.,  in  1887. 


Mean 
daily 
tem- 
pei-a- 
ture. 


Rela- 

Dew     ^ 

P°i°t-   mid- 

'  ity. 


Posi- 
tive 
tem- 
pera- 
ture 
(T 
-43° 
¥.). 


Sum  of  daily  tem- 
perature. 


All 
above 

43°  F. 


All 
posi- 
tive 
(tem- 
pera- 
ture 
above 
43°F.). 


Apr.  1 
2 
3 
4 
5 


15 

64 

17 

64 

22 

52 

29 

54 

33 

53 

36 

32 

47 

57 

30 

72 

44 

76 

Per  ct.  Miles. 
55  127 
151 
437 
250 
222 
187 
354 
514 
476 


Per  ct.      In. 

67  1 

83  ,    0.03 
100        .03 


Date.       °F. 
1  4 

.!         5 


321 


Mrtvorolof/iiitl  (Ititn  for  II uron.  Dak.,  in  /,S.S7— Contiiiuod. 


1887. 
Apr.  12 
13 
14 
15 
16 
17 
18 


Mean 
daily 
tem- 
pera- 
ture. 


May  1 
2 
3 
4 
5 


Rela- 
T-.„™  tive 
D?w  Yxn- 
POii^t-   mid- 

ity. 


F.  \Perct. 
43  72 
47  93 

37  89 

30  75 


25 


59 
50 

26  53 

27  54 
40  81 


46 

45  \ 

31 

26 

35  I 
34! 

43  I 

49 

40 

44 
48 
51  1 


Clouds.  Rain.  Frosts 


58 


Perct. 

67 

100 

67 

100 

100 

70 

0 

33 

10 

70 

50 

67 

80 

0 

17 


Posi- 
tive 
tem- 
pera- 
ture 
(T 
-43° 
F.). 


Sum  of  daily  tem- 
perature. 


°F. 
11 
6 


All 
above 
43°  F. 


874 
921 
967 
1,002 
1,034 
1,068 
1,109 
1,154 
1,310 
1,268 
1,338 
1,411 
1,468 
1,507 
1,560 
1,621 
1,684 
1,756 
1,831 
1,901 
1,973 
2,047 
2,118 
2,186 
2,251 

2,:»8 

2,370 
2,414 
2,465 

2,601 
2,676 
2,7;« 
2,792 
2,852 
2,908 
2,970 
3,(K36 
3,102 


971 
1,028  I 
1,028  j 
1,081 
1,142 
1,205 
1,277 
1,352 
1,422 
1,494 
1,568 
1,639 
1,707 
1,772  \ 

1,891 
1,935 
1,986 
2,049 
2,122 
2,197 
2,256 
2,313 
2,373 
2,429 
2,491 
2,657 
2,623 
2,684 


All 
posi- 
tive 
(tem- 
pera- 
ture 
above 
43°F.). 

'F. 
94 
100 
100 
100 
100 
100 
UOl 
103 
107 
110 
110 
110 
110 
110 
112 
125 
140 
167 
197 
211 
211 


347 
376 
407 
435 


496 
515 
516 
524 
544 
574 
600 


T08 
731 
749 


2667—05  M- 


-21 


Light. 


322 


Meteorological  data  for  Huron,  Dak.,  in  1887 — Continued. 


daily 
tem- 
pera- 
ture. 


Dew 

point. 


Rela- 
tive 
hix- 

mid- 
ity. 


Posi- 
tive 
tem- 
pera- 
ture 
(T 
-43° 
F.). 


Sum  of  daily  tem- 
peratures. 


All 
above 
43°  F. 


All 
posi- 
tive 
(tem- 
pera- 
ture 
above 
43°F.). 


May  29 
30 
31 
June  1 
2 
3 
4 
5 


29 
30 
July  1 
2 
3 
4 
6 


Per  ct 
46 


Miles. 
421 
469 
237 
212 
316 
360 
190 
371 
441 
234 
119 
141 
276 
183 
160 
196 
340 
461 
301 
280 
211 
249 


Per  ct. 
40 
67 
53 
43 
100 
57 
0 
0 
7 


In. 
Tr. 


1.13 

.17 

Tr. 


Tr. 
.92 


Tr. 
.03 


°F. 
3,226 
3,279 
3,335 
3,396 
3,461 
3,520 
3,576 
3,646 
3,729 
3,799 
3,866 

4,005 
4,079 
4,151 
4,225 
4,305 
4,386 
4,463 
4,538 
4,611 
4,682 
4,747 
4,810 
4,870 
4,929 
4,994 
5,063 
5,136 
5,213 

5,356 
5,429 
5,501 
5,564 
5,628 
5,698 
5,770 
5,843 
5,919 
5,995 
6,066 
6,148 
6,216 

6,367 
6,453 


"F. 
2,747 
2,800 
2,856 
2,917 
2,982 
3,041 
3,097 
3,167 
3,250 
3,320 
3,387 
3,457 
3,526 
3,600 
3,672 
3,746 
3,826 
3,907 
3,984 
4,059 
4,132 
4,203 
4,268 
4,331 
4,391 
4,450 
4,515 
4,584 
4,657 
4,734 
4,804 
4,877 
4,950 
5,022 
5,085 
5,149 
5,219 
5,291 
5,364 
5,440 
5,516 
5,587 

5,737 
5.807 

5,974 
6,054 


779 
792 
810 


1,012 

1,043 

1,072 

1,103 

1,140 

1,178 

1,212 

1,244 

1,274 

1,302 

1,324 

1,344 

1,361 

1,377 

hi 

1,425 

1,455 

1,' 

1,516 

1,546 

1,576 

1,605 

hi 

l,t 

1,( 

hi 

1,722 

1,755 

l,' 

1,^ 

1,855 

1,880 

1,907 

1,945 


323 


MctcorohHjicul  data  for  Huron,  Dale,  in  1SS7 — Continued. 


July  16 
1" 
18 
19 


30 
31 
Aug.  1 
2 
3 
4 
5 


Mean 
daily 


Dew 
point. 


Rela- 
tive 
hu- 
mil- 
ity. 


Miles. 
276 
167 
174 


139 

100 

332 

93 

423 

0 

381 

67 

248 

50 

196 

73 

.48 
1.49 


Posi- 
tive 
tem- 
pera- 
ture 
(T 
-43° 
F.). 


Sum  of  daily  tem- 
perature. 


06,772 
6,844 
6,911 


7,110 
7,177 
7,249 
7,327 
7,400 
7,471 
7,545 
7,619 


7,836 
7,906 
7,976 


8,170 
8,249 


8,386 
8,458 
8,526 
8,589 
8,654 
8,724 
8,790 
8,856 


9,062 
9,127 
9,195 
9,252 
9,303 
9,356 
9,408 
9,463 
9,526 
9,595 
9,659 
9,726 
9.793 


All 
above 
43°  F. 


6,aS2 
6,403 
6,470 
6,531 
6,598 
6,670 
6,748 
6,831 
6,892 
6,966 
7,040 
7,109 
7,181 
7,357 
7,327 
7,395 
7,457 
7,521 
7,589 
7,668 
7,739 
7,805 
7,877 
7,945 
8,008 
8,073 
8,143 
8,209 
8,275 
8,345 
8,412 
8,481 
8,546 
8,614 
8,671 
8,722 
8,775 
8,827 


All 
posi- 
tive 
(tem- 
pera- 
ture 
above 
43°F.). 


2,061 
2,068 
2,087 
2,111 
2,139 
2,163 
2,181 
3,205 
2,234 
2,269 
2,299 
2,327 
2,358 

2,415 
3,444 
3,477 
2,504 
2,539 
2,548 
2,569 
2,594 
2,638 
2,658 
2,681 
2,710 
2,735 
2,755 
2,777 
2,804 
2,827 
2,850 
2,877 
2,901 
2,927 
2,949 
2,974 
2,988 
2,996 
3,006 
3,015 


8,945 

3,047 

9,014 

3,073 

9,078 

3,094 

9,145 

3,118 

9,212 

3,142 

a  On  and  after  July  17  the  numbers  in  the  column  "  Sums  of  all  temperatures  "  must  be  dimin- 
ished by  lOO. 


324 


Meteoroloffical  data  for  Huron,  Dak.,  in  1887 — Continued. 


1887. 
Sept.  1 
2 
3 
4 
5 
6 


Mean 
daily 
tem- 
pera- 
ture. 


Dew 

point. 


Rela- 
tive 
hu- 
mid- 
ity. 


Perct 

80 
79 


Miles. 
119 
171 


tive 
tem- 
pera- 
ture 
(T 
—43° 
F.). 


Sum  of  daily  tem- 
perature. 


"F. 
9,861 
9,931 
9,998 
10,065 
10,139 
10,207 
10,266 

10,391 
10,441 
10,503 
10,565 
10,620 
10,675 
10,728 
10,^91 
10,855 
10,921 
10,991 
11,058 
11,111 
11,157 
11,202 
11,260 
11,314 
11,374 
11,423 
11,472 
11,525 
11,578 


All 
above 
43^  F. 


"F. 
9,280 
9,350 
9,417 
9,484 
9,558 

9,685 
9,758 
9,810 
9,860 
9,922 
9,984 
10,039 
10,094 
10,147 
10,210 
10,274 
10,340 
10,410 
10,477 
10,530 
10,576 
10,621 
10,679 
10,73:3 
10,793 
10,842 
10,891 
10,944 
10,997 


All 
posi- 
tive 
(tem- 
pera- 
ture 
above 
43°F.). 


°F. 
3,167 
3,194 
3,218 
3,242 
3,273 
3,298 
3,314 
3,344 
3,353 
3,360 
3,379 

3,410 
3,422 
3,432 
3,452 
3,473 
3,496 
3,513 
3,537 
3,547 
3,550 
3,552 
3,567 
3,578 
3,595 
3,601 
3,607 
3,617 


MAIZE. 

The  record  of  the  plantings  and  general  condition  of  the  corn  for 
the  season  of  1888  is  taken  from  the  station  Bulletin  No.  d  by  Prof. 
Luther  Foster,  director  and  agriculturist,  and  is  as  folloAvs: 

The  corn  experiment  embraced  a  set  of  39  plats,  each  containing 
60  rows  24  hills  in  length.  Thirty-three  of  these  plats  Avere  planted 
Avith  different  varieties  of  corn,  18  of  Dent  and  15  of  Flint,  the  rest 
being  used  for  experiments  in  deep  and  shallow  cultivation. 

On  the  first  33  plats  the  planting  began  on  the  7th  and  8th  days  of 
May.  Two  rows  of  each  plat  were  planted  every  day  for  thirty  con- 
secutive working  days. 

It  may.  perhaps,  be  unnecessary  to  state  that  these  daily  plantings 
were  made  with  the  object  of  determining  the  corn  growing  season, 
when  germination  begins,  and  the  extreme  length  of  planting  time. 


325 

Preparation  of  soil. — The  land  nsed  is  a  sandy  loam,  with  a  sub- 
soil of  clay,  and  slopes  slifjhtly  to  the  northwest.  It  was  plowed  the 
jjrevious  August  to  a  depth  of  (>  inches,  and  thoroughly  harrowed  in 
the  spring  just  before  planting.  It  had  produced  two  crops  of  small 
grain,  and  luul  never  been  manured. 

FlantiiKj. — The  rows  were  made  with  a  marker  8  feet  0  inches  each 
way.  Part  of  the  corn  was  droi)})ed  by  hand  and  covered  with  the 
hoe,  the  rest  being  put  in  with  hand  planters.  Of  the  Dent  corn, 
the  hills  contained  8  and  4  grains;  of  the  Plint,  4  and  5. 

The  stand. — The  early  part  of  the  season  was  not  favorable  for 
corn  growing,  being  cold  and  wet.  The  coming  up  W'as  quite  irregu- 
lar, from  six  to  ten  days  frequently  elapsing  between  the  appearance 
of  the  first  and  last  hills  in  a  row.  This  was  especially  true  of  the 
iirst  fifteen  days'  planting. 

The  stand  in  general  was  poor,  resulting  in  part  from  unfavorable 
weather  and  bad  seed,  but  principally  from  the  w^ork  of  ground 
squirrels.  This  latter  evil  Avas  the  most  persistent  and  damaging  one 
with  which  the  corn  experiment  had  to  contend.  The  per  cent  taken 
depended  upon  location  of  the  variety,  whether  more  or  less  remote 
from  the  unbroken  j:)rairie.  Notwithstanding  all  efforts  to  destroy 
the  squirrels,  the  damage  done  was  very  great.  For  several  succes- 
sive days  previous  to  })lanting  poisoned  corn  was  placed  in  every 
squirrel  hole  that  could  be  found.  This  was  done  not  only  on  the 
experiment  ground,  but  also  on  the  whole  80  acres  and  on  the  edges 
of  the  land  immediatel}^  surrounding  it.  This  work,  reenforced  with 
the  trap  and  shotgun,  was  continued  throughout  the  whole  plant- 
ing season. 

Cultivation. — All  the  plats  were  given  four  different  cultivations, 
a  six-shovel  corn  \Ao\t  and  a  double  spring-tooth  cultivator  being 
used  for  the  purpose.  In  addition  to  this  they  were  twice  hoed. 
Cultivation  began  on  the  11th  day  of  June  and  ended  on  the  ITth 
day  of  July. 

General  remarks. — It  was  observed  in  all  the  plats  that  the  earlier 
plantings  grew  larger  and  stronger  than  the  after  ones  and  that  the 
silks  and  tassels  made  their  appearance  more  regularly. 

The  ears  of  nearly,  all  varieties  of  the  Flint  corn  were  infested 
with  a  species  of  worm.  These  did  but  little  damage  beyond  mar- 
ring the  appearance  of  the  ears.  The  Dents  were  not  disturbed  by 
the  worms. 

Immediately  after  the  killing  frost  on  the  night  of  September  11 
the  corn  on  all  the  plats  was  cut  and  shocked.  It  was  allowed  to 
^tand  a  few  weeks  before  husking. 

The  results  of  a  single  season's  work  are  only  entitled  to  the  pub- 
lic attention  as  showing  the  scope  of  the  experiment  undertaken. 

Definite  results  of  any  practical  value  to  the  farmer  can  only  be 
obtained  by  a  continuance  of  the  same  experiment  under  a  system 
of  careful  observations  extending  through  a  number  of  years.  Of 
this  a  beginning  has  been  made. 

Tahuhited  statement. — In  the  following  table  that  date  of  plant- 
ing is  taken  which  shows  the  least  number  of  days  from  time  of 
})lanting  to  maturity.  The  first  seven  to  ten  days  planting  came  up 
and  matured  at  the  same  time,  while  the  coming  up  of  the  rest  varied 
quite  regularly  with  the  time  of  jdanting. 

The  items  in  the  columns  headed  "  Up,"  "  In  tassel,"  "  In  silk," 


326 

"  Matured,"  and  "  Days  to  mature  "  apply  only  to  the  planting  up  to 
and  including  the  date  in  the  first  column.  The  items  in  the  other 
columns  apply  to  the  whole  piece. 

The  per  cent  of  corn  standing  and  that  taken  by  squirrels  was 
made  from  actual  daily  counts  of  hills. 

In  computing  the  yield  the  corn  was  weighed  instead  of  measured.^ 

Experiments  of  1888  in  pJanting  corn  at  Brookings,  *S'.  Dak. 
[First  killing  frost,  1888,  September  12,  a.  m.] 


Variety. 

Dat*»of 
plant- 
ing. 

Date  of 
sprout- 
ing. 

Date  of 

tassel- 
ing. 

Date  of 
silking. 

Date  of 
matur- 
ing. 

Days 
to  ma- 
ture _ 

Sums 

°'tFvT- 

(T-43° 

F.). 
plant- 
ing to 
matur- 
ing. 

Yield 

per 

acre  of 

shelled 

corn. 

Dents: 

White  Rustler 

Austin's  Calico 

Dakota  Yellow.- 

Davis-s  White 

Hickory  King 

May  14 
....do..- 
May  13 
May  14 
do 

June   5 
....do... 
June   4 
June   6 
June   5 

June    4 
June   5 
June   6 

....do... 
June   8 
June   4 
June   5 
June   6 

....do... 
June   7 

-...do.-- 

June   6 
June   5 

June   4 
June   6 

....do... 

....do--. 

...-do..- 

June   5 
June   7 
....do--. 
June   6 
....do-.- 
do 

July  20 
July  21 
July  18 
July  23 
Aug.  16 

July  20 
Aug.    1 
July  25 
July  21 
July  25 
July  18 
July  24 
July  28 
Aug.   1 
July  23 
Aug.  13 
July  20 
July  24 

July  14 
July  17 
July  19 
July  23 
July  16 
July  19 
July  16 
July  11 
July  23 
....do... 
July  16 
July  20 
....do--. 
July  26 
July  23 

July  30 
July  31 
..-do... 
July  30 
Sept.  11 

Aug.  11 
Aug.  10 
Aug.   1 

....do... 
Aug.    4 
July  27 
Aug.  10  • 

....do--. 

....do... 
July  31 
Aug.  22 
Aug.    4 
Aug.    1 

July  26 
July  31 
Aug.    2 

-...do-.- 
July  27 
July  26 

.--.do.-- 
July  18 
Aug.    2 

....do.- 
July  26 
July  31 
July  30 
Aug.   2 
July  30 

Sept.  4 
Sept.  10 
....do... 
Sept.  11 

113 
119 
120 
121 

Silk. 

Milk. 
Soft. 

118 

115 
Soft. 

118 
Soft. 
Pair. 
Poor. 

113 
Milk. 

118 

n3 

107 
106 
113 
117 
109 

96 
105 

90 
118 
113 
103 

li- 
tis 

118 
111 

"  F. 

2,556 

2,692 

2,696 

2,711 

Bush. 

m 
m 

24 
42 

Chester     County 

....do-.- 

....do... 

May  16 

do 

Austin's  Yellow. 

Davis's  Yellow 

Sept.  11 
Sept.  8 

2,703 
2,641 

2,703 

29 
24 

....do... 

....do... 
May  12 
May  16 
May  15 
May  16 
May  15 
May  16 
May  18 

May  15 
May  14 
May  12 
May  17 
May  16 
May  15 
May  17 

....do.-- 

May  15 

May  16 

do 

31  j^ 

Pride  of  the  North. -- 

Sept.  11 

21i 

Sept.  6 

Improved  Learning- - 
Dakota  Gold  Coin.... 

Golden  Beauty- 

Bloody  Butcher 

North  Star 

2,601 

27 

Sept.  11 
Sept.  8 

Aug.  20 
Aug.  28 
Sept.  3 
Sept.  11 
Sept.  2 
Aug.  19 
Aug.  30 
Aug.  15 
Sept.  10 
Sept.  6 
Aug.  27 
Sept.  11 
....do... 
....do.-- 
Sept.  1 

2,703 
2,640 

2,187 
2,410 
2,527 
2,703 
2,505 
2,162 
2,453 
2,071 
2,689 
2,601 
2,371 
2,703 
2,703 
2,703 
2,504 

15 

214 

Flints: 

STTint  Nosfi 

37i 

Compton's  Early 

Top  Over 

27 
28 

Early  Canada- - 

Self  Husking         .    . 

17 
45 

Early  Six  Weeks 

15i 

24i 

Mandan  Indian 

20 
18 

Minnesota  White.... 

271 
37 

Waushakum 

May  17 
May  16 
....do... 
May  13 

....do... 
June   4 
June    8 
June    7 

36 

Silver  White 

27 

King  Philip 

Angel  of  Midnight. -- 

9^ 

m 

I   regret  not  to  be  able  to  state  the  source  whence  the  seed   was  obtained   an( 
Qatic  peculiarities  under  which  it  was  raised.     According  to  Linsser's  laws  this 


ind  the 
climatic  peculiarities  under  which  it  was  raised.  According  to  Linsser's  laws  this  must 
decide  as  to  the  behavior  of  the  seed  and  plant  in  a  new  climate.  I  know,  however,  tbat 
some  of  the  varieties  had  been  raised  in  previous  years  in  the  neighborhood  of  Brookings, 
S.  Dak.— C.  A. 


327 

In  comparing  the  maize  experiments  at  Brookings  with  the  climate 
of  that  region,  I  shall  use  the  record  of  the  Signal  Service  station  at 
Hm-on,  S.  Dak.  (lat.  44.3°  N.;  long.  98.1°  AV.;  altitude  above  sea 
level,  1,800  feet),  which  is  70  miles  west  of  Brookings,  and  the  gen- 
eral meteorological  tables  for  Huron  as  calculated  for  this  agricul- 
tural usage  are  appended  to  this  table  of  agricultural  experiments. 

Meteorolcgical  data  for  Huron,  Dak.,  in  18S8. 


Mean 
daily 
tem- 
pera- 
ture. 


Dew 

point 


Rela- 
tive 
hu- 
mid- 
ity. 


Tem- 
pera- 
ture 
-43° 
F. 


Sums  of  tempera- 
tures. 


Re- 
ject- 
ing all 
below 
43°  F. 


Apr.    1 
2 


30 

May    1 

2 

3 

4 
5 
6 
7 
8 
9 


P.ct. 

73 
73 

68 
74 


P.  ct. 

80 


In. 
0.0 
Tr. 

.02 

.50 

.0 

.0 

.0 

.0 

.04 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 

.0 
Tr. 

.16 

.16 

.0 


.44 
.22 
Tr. 
.0 
.34 
.06 
.0 
.0 


984 
1,028 
1,085 
1,141 
1,198 
1,240 
1,272 
1,306 
1,343 
1,383 
1,425 
1,465 
1,510 
1,561 
1,607 
1,655 
1,708 
1,765 


913 

913 

913 

913 

913 

913 

913 

913 

958 

1,009 

1,055 

1,103 

1,156 

1,213 


328 


Mctcorulogicnl  data  for  Huron,  Dak.,  in  1SS8 — Coutiiuied. 


May  10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
30 
21 
23 
23 
24 
25 
26 
27 


31 

June   1 

2 


Mean  Rela- 

daily  I  Dew  ^^^^ 

tern-    JifZ  ^^^'- 

pera-  P°i°*-  mid- 

ture.  ity. 


P.ct. 
54 
54 
57 

44 


Wind. 

Clouds. 

Miles. 

P.ct. 

261 

90 

416 

30 

352 

3 

295 

33 

155 

50 

331 

47 

106 

50 

139 

100 

155 

37 

430 

73 

317 

63 

388 

100 

400 

100 

391 

100 

207 

67 

79 

33 

244 

100 

375 

77 

290 

33 

156 

53 

316 

50 

109 

47 

206 

0 

130 

7 

439 

67 

573 

77 

378 

70 

166 

50 

541 

30 

496 

67 

508 

100 

234 

17 

176 

70 

183 

40 

228 

37 

153 

37 

382 

40 

393 

3 

180 

33 

355 

0 

465 

40 

533 

73 

615 

57 

538 

90 

436 

93 

299 

90 

108 

87 

389 

100 

104 

97 

In. 
.43 
.0 
Tr. 
Tr. 
Tr. 
.0 
Tr. 

12 
.04 

32 

0 

84 

93 

0 
Tr. 
Tr. 


0 

0 

60 
Tr. 
Tr. 
Tr. 
.0 
.0 


Tem- 
pera- 
ture 

F. 


Sums  of  tempera- 
tures. 


°  F. 
1,821 

1,909 
1,952 
1,999 
2,047 
2,095 
2,137 
2,181 

2,296 
2,354 
2,409 
2,461 
2,514 
3,572 

3,685 
3,743 
3,797 
3,852 
2,906 


14  I  3,014 


21  3,144 

7  3,194 

13  3,349 

30  3,333 

36  3,391 

11  3,445 

20  3,508 


18  3,569 

27  3,639 

32  3,714 

31  3,788 

37  3,868 

38  3,949 
36  4,038 
35  4,106 

4,180 

35  4,348 

16  4,307 

18  4,368 

18  4,429 

19  4,491 
19  4,553 
14  4,610 
19  4,673 


31 


Re- 
ject- 
ing all 
below 
43°  F. 


°  F. 
1,269 
1,316 
1,316 
1,316 
1,363 
1,409 
1,457 
1,457 
1,501 
1,553 
1,616 
1,674 
1,729 
1,781 
1,834 
1,893 
1,946 
2,005 
2,062 
2,117 
2,172 
2,226 
2,277 
2,291 
2,314 
2,335 
2,342 
2,354 
3,384 
2,410 
2,531 
3,641 
3,559 
3,  .586 
3,618 
3,649 
2,686 
3,734 
3,760 
2,795 


2,851 
3,867 
2,885 
2,903 
2,922 
3,941 
3,955 
2,974 


All 
posi- 
tive 
(tem- 
pei-a- 
ture 
-43" 
F.). 


329 


Mctcoroloninn  data  for  Huron.  Dah:,  in  7888— Continued. 


Mean 

tem^    Dew 
ture. 


June  38         05 

29  !        70 


July    la] 
2 
3 


4 

72 

5 

76 

6 

70 

7 

70 

8 

70 

9 

66 

10 

75 

11 

82 

12 

76 

13 

67 

14 

72 

15 

68 

16 

66 

17 

69 

18 

68 

Rela- 
tive 


mid- 
ity. 


P.ct. 

84 


Clouds. 


P.  ft. 
53 

70 


In. 
.0 
.03 
.0 
.0 
.0 
.34 

Tr. 

Tr. 


Tr. 

Tr. 
.0 
.0 

Tr. 
.0 
.26 

Tr. 
.0 
.01 
.19 
.07 

Tr. 

Tr. 
.70 
.0 
.76 

Tr. 
.01 

Tr. 

1.50 
.48 
.0 
.01 


Tem- 
pera- 
ture 
—43° 
F. 


Sums  of  tempera- 
tures. 


All 

ieX      *'^'« 
.^'"Jii  (tem- 

5fJo,^    ture 
43°  F.    _43o 

F.). 


°F. 
4,737 
4,807 
4,889 
4,969 
5,043 
5,109 
5,181 
5,357 


5,467 
5,5a3 
5,608 
5,690 
5,766 
5,833 
5,905 
5,973 
6,039 
6,108 
6,176 
6,245 
6,323 
6,400 
6,468 
6,5:38 
6,606 
6,680 
6,753 
6,831 
6,907 
6,984 
7,062 
7,127 
7,197 
7,268 
7,342 
7,410 
7,475 
7,539 
7,603 
7,658 
7,714 
7,770 
7,828 
7,887 


op 

2,996 
3,023 
3,062 
3,142 
3,216 
3,282 
3,354 
3,430 
,3,500 
3,570 
3,640 
'3,706 
3,781 
3,863 

4,006 
4,078 
4,146 
4,212 
4,281 
4,349 
4,418 
4,496 
4,573 
4,641 
4,711 
4,779 
4,8,53 
4,926 
5,004 
5,080 
.5,155 
5,233 
5,298 

,5,4:39 
5,513 
5,, 581 
5,046 
5,710 
5,774 
5,829 
5,885 
5,941 
5,999 
6,058 


ojr, 
1,002 
1,029 
1,068 
1,105 
1,136 
1,1,59 
1,188 
1,221 
1,248 
1,275 
1,;302 

l,a57 
1,396 
1,439 
1,4.53 
1,482 
1,507 
1,5:30 
1,5,56 
1,.581 
1,607 
1,642 
1,676 
1,701 
1,728 
1,7.53 
1,784 
1,814 
1,849 
1,882 
1,910 
1,9,51 
1,973 
2,(XK) 
2,(t'8 
2,0.59 
2,084 
2,106 
2,127 
2,148 
2, 160 
2,173 
2,186 
2,201 
2,217 


»  Hours  of  observation  changed  July  15,  from 
and  8  p.  m.     ilean  D.  P.  and  R.  II.  not  known. 


a.  m.,  3  p.  m.,  and  10  p.  m.  to  8  a.  m. 


330 


Meteorological  data  for  Huron,  Dak.,  in  1888 — Continued. 


daily 
tern 
pera- 
ture. 


Dew 
point. 


Rela- 
tive 

hu-    I  Wind. 
mid- 

ity. 


Tem- 
pera- 
ture 
-43° 
F. 


Sums  of  tempera- 
tures. 


Re- 
ject- 


All 
posi- 
tive 
ing  all  (**^^- 

bel«^  ?url" 
43°  F.  ^^^o 

F.). 


Aug.  13 
14 
15 
16 
17 
18 
19 
20 
81 
22 
23 
24 


31 
Sept.  1 
2 
3 
4 
5 


Miles. 
407 


In. 
Tr. 


.10 
Tr. 
Tr. 
Tr. 

.02 
Tr. 
Tr. 

.0 

.0 
Tr. 
Tr. 
Tr. 
Tr. 

.0 

.0 

.0 

.0 

.0 
Tr. 
Tr. 

.0 

.01 

.04 

.0 

.0 

.0 

.0 
Tr. 

.0 

.06 

.06 
Tr. 
Tr. 
Tr. 
Tr. 

.02 
Tr. 

Tr. 

Tr. 

Tr. 

Tr. 

.0 

.0 

.0 
Tr. 
Tr. 


7,955 
8,021 
8,080 
8,144 
8,208 
8,271 
8,338 
8,406 
8,472 


3,7.54 


8,970 
9,042 
9,107 
9,161 
9,222 


9,407 
9,475 
9,546 
9,610 
9,672 
9,735 
9,801 
9,853 
9,901 
9,966 
10,024 
10,076 
10,122 

4  10,169 

5  10,217 

17  ;10,277 
21  10,341 

18  10,402 

14  10,4.59 
17   10,519 

15  10,. 577 
7   10,627 


6,252 
6,316 
6,380 
6,443 
6,510 
6,578 
6,644 
6,710 
6,781 
6,855 


7,142 
7,214 
7,279 
7,333 
7,394 
7,460 
7,523 
7,579 
7,647 
7,718 
7,784 
7,846 
7,909 
7,975 
8,027 
8,075 
8,140 
8,198 
8,250 
8,296 
8,343 
8,491 
8,551 
8,615 


8,851 
8,901 


9  10,679 

8,953 

0  10,722 

8,996 

0  10,765 

9,039 

2  10,810 

9,084 

11  10,864 

9,138 

°F. 
2,242 
2,265 
2,282 
2,3a3 
2,324 
2,344 
2,368 
2,393 
2.416 
2,' 
2,467 
2,498- 
2,; 
2,555 
2,582 
2,613 
2,642 
2,664 
2,685 
2,' 
2,726 
2,746 

2,: 

2,784 

2,812 

2,833 

2,852 

2,872 

2,) 

2,914 

2,919 

2,941 

2,1 

2,965 

2,! 

2,972 

2,977 

2,994 

3,015 

3,033 

3,047 

3,064 

3,079 

3,( 

3,095 

3,095 

3,095 

3,097 

3,108 


331 

Ej-pcriiiicntfi  in  1S90  in  i)la)iting  corn  at  Brookings,  8.  Dak. 
[Experiment  Station  Bulletin  No.  24.] 


Variety. 


Dents: 

Lovelaud 

Hughsou 

Davis  White 

Queen  of  the  North 

Dakota  Dent 

Dakota  King 

Gold  Coin 

Flints: 

Squaw. 

Pride  of  Dakota 

Mandan  Indian 

Hudson  Bay 

Mercer 

King  Philip 

Compton's  Early 

Early  Six  Weeks. 

Landreth's  Extra  Early. 

Early  Canada 

Blue  Blade 

Smut  Nose 

SeK-Husking 

Chadwick 


Dates  of      Dates 
planting,  matured 


May  IT 
...do... 
...do... 
...do... 
...do... 
May  19 
...do... 


May  17 
...do... 
May  23 
...do... 
June  3 
May  IT 
May  23 
...do... 
May  17 
May  23 
May  17 
...do... 
May  23 
May  16 


Aug.  24 
Sept.  10 

(«) 

W 

(«) 
Sept.  12 
....do.. 


Sept.  5 
...do... 
Sept.  1 

Sept.  16 
Sept.  12 
Sept.  3 
...do... 
Sept.  12 
...do... 
...do... 
Sept.  5 
Sept.  6 
Sept.  1 


Yield 
Days  to   per  acre 
mature,    shelled 


Bushels. 
33.5 
29.2 
32.4 
■  30.8 
21.8 
33.6 
34.2 

35.4 
26.2 
26.4 
24.1 
22.1 
24.1 
20.0 
24.3 
*2.  t! 
a).  5 
22.3 
25.8 
23.8 
25.3 


n  Some  frosted. 
Notes. — First  killing  frost  1890,  September  13,  a.  m. 

The  data  for  1890  given  in  this  table  came  to  hand  too  late  to  allow  of  preparing  the 
corresponding  meteorological  table. — C.  A.     June  30,  1891. 

MAIZE. 


From  experiments  in  planting  maize,  made  at  the  Indiana  Agri- 
cultural Experiment  Station  (see  Agr.  Sci.,  Vol.  Ill,  p.  192),  the 
following  results  were  deduced  : 

Planting  on  May  1  gave  a  loss  at  harvest  of  5.47  bushels  per  acre: 
planting  on  May  21  gave  a  gain  of  0.31  bushels  per  acre. 

Deep  plowing  in  1880  and  1888  gave  an  increase  over  shallow 
plowing  of  2.4  bushels  per  acre,  and  0.1  bushel  in  1888. 

Deep  culture  with  a  cultivator  of  3  to  4  inches  gave  better  results 
than  a  shallow  culture  of  from  2  to  3  inches. 

As  to  rate  of  planting  or  density  of  stand,  two  kernels  every 
28  inches  apart  and  three  kernels  every  36  inches  apart  seem  to  give 
the  best  results  for  hand  planting.  For  machine  planting,  the  best 
results  were  given  with  stalks  12  and  14  inches  apart. 


332 


NEW    YORK. 

Prof.  C.  S.  Plumb  states,  as  the  result  of  a  research  made  by  him- 
self during  the  summer  of  1886  at  the  New  York  Agricultural 
Experiment  Station,  on  the  growth  of  maize  and  its  dependence  upon 
climate,  the  following  conclusions  : 

(1)  That  maize  makes  a  positive  daily  growth  upward  from  the 
appearance  of  the  plant  above  ground  till  the  plant  has  reached  its 
maximum  height. 

(2)  That  the  variation  in  the  development  of  the  plant  from  day 
to  day  and  week  to  week  is  not  controlled  by  meteorological  condi- 
tions, for  of  two  plants  that  one  which  is  the  most  backward  at  the 
beginning  of  the  season  may  eventually  become  the  stronger,  larger, 
and  more  vigorous  of  the  two. 

The  measures  on  which  these  conclusions  are  based  (see  Agr.  Sci., 
Vol.  Ill,  p.  1)  were  made  day  by  day  upon  seven  individual  plants, 
and  the  aA^erages  are  given  in  the  folio Aving  table ;  the  date  of  plant- 
ing was  May  21,  1886,  and  the  dates  of  sprouting  extended  from  May 
31  for  plant  No.  1  to  June  4  for  plant  No.  7. 


Date  of  observation. 


height 

of  7 
plants. 


Sums  for  preced- 
ing 7  days. 


Air 
temper- 
atures. 


Soil 
temper- 
atures. 


Sunshine 
dura- 
tion. 


June  6 

June  13 

June  20 

June  27 

July  4- 

Julyll 

July  18 

July  25 

Total. 


Inches. 
3 
8 

14 
23 
35 
41 
47 


F. 
452 
475 
494 
466 


Days. 
28 
60 
50 
46 
84 
50 
53 
50 


Inches. 
0.76 
.0 
■0 
.40 
.0 
.71 
.73 


4,678 


The  unsteadiness  of  the  growth  is  very  notable.  There  was  a 
steady  increase  up  to  July  4  and  then  a  drop  for  fourteen  days,  but 
growing  more  rapidly  during  the  last  period.  AVhen  the  greatest 
growth  was  made  in  the  eighth  or  last  period,  the  total  air  and 
soil  temperatures  were  less  than  in  the  fifth  period,  when  great 
growth  was  also  made.  During  this  last  period  of  greatest  growth 
the  rainfall  was  large,  while  during  the  previous  period  of  great 
growth  the  rainfall  was  zero.  Evidently  it  needs  a  peculiar  combi- 
nation of  rainfall,  temperature,  and  sunshine  to  bring  about  the 
rapid  growth.  According  to  Frear,  the  very  rapid  growth  of  plants 
observed  immediately  after  rainfall  is  largely  due  to  a  simple  expan- 
sion of  the  cells  with  water. 

Although  a  soil  gains  some  nitrogen  from  the  air  as  brought  down 


333 

by  the  rain  wvter,  yet  it  loses  a  large  quantity  by  the  drainage  water, 
whicli  is,  of  course,  richer  in  nitrogen  than  the  rain.  In  188()  and 
JS87  Bertlelot  determined  by  measurement  that  the  nitrogen  carried 
from  th<'  soil  by  drainage  water  is  nearly  ten  times  that  brought  to 
the  soil  by  rain  water.  It  is  therefore  economical  to  return  this 
tlraiuage  water  to  the  field,  as  far  as  possible,  and  thus  return 
with  it  the  nitrogen  which  has  at  great  expense  been  given,  in  the 
shape  of  fertilizers,  to  the  field  by  the  farmer.  (Agr.  Sci.,  VoL  III, 
p.  35.) 

MISSOURI. 

Dr.  P.  Schweitzer,  of  the  Missouri  Agricultural  Experiment  Sta- 
tion, publishes  in  Bulletin  No.  IX  an  elaborate  study  of  the  chemical 
changes  that  go  on  in  the  various  parts  of  the  maize  plant  at  differ- 
ent stages  of  growth.  The  plant  takes  up  nearly  all  the  ash  ingre- 
dients during  the  first  stages  of  growth.  The  more  ash  constituents 
a  plant  takes  up  over  and  above  its  needs  the  quicker  is  its  develop- 
ment finished  and  the  smaller  is  the  crop.  The  young  plant  takes  up 
nitrogen  with  extraordinary  avidity,  and  contains  a  considerable 
quantity  of  it.  The  crop  of  corn  from  an  acre  of  land  removes  there- 
from 219  pounds  of  ash  and  135  pounds  of  nitrogen.  The  ears  in 
this  crop  alone  contain  52  pounds  of  ash  and  86  pounds  of  nitrogen. 
(Agr.  Sci.,  Vol.  IV,  p.  84.) 

PENNSYLVANIA. 

The  relation  between  meteorological  conditions  and  the  develop- 
ment of  corn  is  elaborately  presented  by  Messrs.  Frear  and  Caldwell 
in  the  annual  report  for  1888  of  the  Pennsylvania  State  College 
Agricultural  Experiment  Station,  at  Harrisburg,  Pa.  By  testing 
samples  of  corn  at  various  stages  of  its  growth  we  obtain  not  only 
some  idea  of  the  nature  of  the  changes  going  on  in  the  plant  under  the 
influence  of  the  climate  and  soil,  but  the  records  of  past  seasons  on  a 
given  variety  at  a  given  locality  should  give  us  the  means  of  approxi- 
mately estimating  what  will  be  the  crop  of  the  present  year.  For 
instance,  the  loss  or  gain  of  dry  matter  is  shown  in  the  following 
table  for  one  variety  of  corn  out  of  many  that  were  tested  at  the 
Pennsylvania  Station. 

Dry  ircif/ht  in  1  acre  of  several  varieties  of  corn  at  diffrmit  stafjrs  of  proicth. 


Variety. 

Fully 
tasseled. 

Ears 
filling 
out. 

Kernels 

begin  to 

glaze. 

Mature 
ears. 

Blount's  Prolific 

Pounds. 
2,7a5 
3.392 
2,499 
2,846 
2,63:^ 

Pounds. 
5,289 
4,337 
3,950 
3,443 
3,825 

Pounds. 
4,695 
5,690 
4,619 
4,636 
5,344 

Pounds. 
2  310 

3,073 
2  835 

Golden  Beauty . 

Do. 

3,077 
2  529 

Golden  Dent 

334 

Such  tables  as  these  show  that  the  weight  of  the  rKatiire  ears  at 
harvest  will  not  differ  much  from  the  weight  of  the  yhole  plant 
when  dried  at  the  stage  of  full  tasseling,  the  variations  froixi  this  rule 
being  about  10  per  cent  above  or  below  for  these  varieties. 


The  closeness  with  which  corn  or  maize  or  other  cereals  may  be 
planted  depends  not  only  upon  the  quantity  of  moisture  available  in 
the  soil,  but  also  upon  the  ultimate  proposed  nature  of  the  croj:). 
Thus  in  experiments  made  by  the  Illinois  Agricultural  Experiment 
Station,  when  corn  is  planted  for  ensilage  one  plant  to  every  3  inches 
gave  the  best  result.  When  planting  for  the  grain  the  thinnest 
planted  plats  gave  5,664  and  the  thickest  planted  gave  18,932  ears  per 
acre.  As  to  the  date  of  planting,  May  4  to  May  19  gave  the  best 
harvest. 

As  to  mode  of  planting,  hills  nor  drills  nor  fertilizers  gave  any 
strongly  marked  differences. 

As  to  pruning  the  roots,  the  pruned  and  unpruned  showed  no  spe- 
cial difference  in  regard  to  size,  vigor,  date,  or  yield  of  harvest. 
(Agr.  Sci.,  Vol.  II,  p.  162.) 

The  development  of  corn  from  week  to  week  during  the  growing 
season  has  been  studied  by  Thomas  F.  Hunt  at  the  University  of 
Illinois  Agricultural  Experiment  Station,  at  Champaign.  He  states 
that  the  same  18  varieties  of  corn  have  been  grown  at  this  institution 
during  each  of  the  years  1887,  1888,  and  1889,  the  same  varieties 
being  always  grown  on  the  same  plats  and  the  seed  obtained  from  the 
same  source.  The  average  yield  of  air-dried  corn  per  acre  for  the  18 
varieties  was  29.4  bushels  in  1887,  83.2  bushels  in  1888,  and  66  bushels 
in  1889.  Meteorological  conditions  appear  to  have  been  largely,  if  not 
solely,  the  causes  of  these  differences  in  the  yield.  In  1889  measures 
were  made  weekly  on  three  plants  on  each  hill  of  Edmund's  Golden 
Dent,  which  is  usually  an  early  variety,  but  this  year  matured  late, 
owing  to  the  low  temperature.  The  corn  was  planted  four  kernels  to  a 
hill  on  the  4th  of  May ;  it  sprouted  on  the  20th  of  May,  the  soil  hav- 
ing been  very  dry,  and  made  slow  growth  to  June  10,  on  account  of 
the  low  temperature.  The  following  table  shows  the  weight  of  dried 
substance  in  a  hill  of  three  plants  of  uniform  character : 


Dato  of  cutting. 


335 


Average 
weight. 


June  10 

June  17 

June  25 

Julyl 

Julys 

July  15 

July  22 

July  30 

Augusts 

August  12 

August  19 

August  26 

September  2. . 
September  10. 
September  16. 


Orams. 
0.51 


1,034. 
1,176. 


Tassels  showing;  not  in  bloom;  no  silk. 
All  in  tassel;  in  bloom;  in  silk. 

Silks  dead  or  partly  so. 

Soft  milk  stage. 

Milk  stage  or  passed. 

Mostly  glazed. 

Varies  from  milk  stage  to  ripe. 

All  ripe  except  1  ear. 


Professor  Hunt  finds  that  the  varieties  of  corn  that  mature  about 
September  25  give  the  Largest  3'ields ;  date  of  planting  has  little  influ- 
ence on  the  j'ield.  Depth  of  planting  and  drilling  versus  hill  planting 
did  not  affect  the  yield  in  1888  or  1889.  The  quantity  of  seed  planted 
was  more  important  than  the  allotment  of  the  kernels  to  the  hills; 
preventing  the  growth  of  weeds  was  more  important  than  stirring 
the  soil;  pruning  of  roots  injured  the  crops;  shallow-working  cul- 
tivators gave  better  results  than  deep-working;  commercial  ferti- 
lizers did  not  materially  increase  the  yield,  but  stable  manures  did 
so.     (Agr.  Sci.,  Vol.  IV,  p.  184.) 


MAIZE  AND  PEAS. 


Xir\V    YORK. 


Sturtevant  (ISS-t)  gives  the  results  of  two  years'  observations 
(1883  and  1884)  at  the  experiment  station,  Geneva,  N.  Y.,  on  the 
thermal  constants*  of  many  varieties  of  maize  and  peas.  He  observed 
both  the  temperature  of  the  soil  and  the  air,  and  takes  for  his  com- 
putations always  the  first  plant  which  sprouted,  bloomed,  or  ripened. 
Observations  of  128  varieties  of  maize,  four  hills  to  each  variety, 
gave  an  extreme  variation  of  19  days  between  the  blooming  of  the 
first  and  last  hill,  the  average  interval  being  4.92  days.  As  Sachs 
adoj^ts  49.1°  F.  as  the  lowest  temperature  at  which  maize  will  ger- 
minate, and  Koppen  gives  49.2°  F.,  therefore  Sturtevant  adopts 
50°  F.,  and  considers  that  any  observed  temperature,  less  50°  F., 
leaves  a  remainder  that  is  nearly  proportional  to  the  growth  of  maize 
at  that  temperature.  A  similar  lower  limit  of  44°  F.  is  adopted  for 
the  groAvth  of  the  pea.  He  notes  that  in  1885,  by  trial  at  this  exper- 
iment station,  the  ''  Chester  Countv  Mammoth   Corn  "  germinated 


336 

in  430  hours  at  a  temperature  which  Avas  between  37°  and  42°.  averag- 
ing above  40°  F.,  while  the  AVaushakum  variety  required  4(30  hours 
at  the  same  temperature. 

Sturtevant  calculates  the  sum  total  of  temperatures  by  three  meth- 
ods, a  comparison  of  w^iich  is  instructive.  His  results  are  in  the 
following  table : 

Thermal  constants  for  maize  at  Genera,  N.  Y.,  from  ijermination  to  blooming. 


Variety  and  subvariety. 

Sums  of 
all  mean 
daily  air 
temper- 
atures. 

Sums  of 
all  posi- 
tive 
mean 
daily  air 
temper- 
atures, 
less  50°  F. 

Sums  of 
all  posi- 
tive 
daily 
means  of 
temper- 
ature of 
air,  and 
soil  at  1 
foot 
lepth. 
le«s50°F. 

Sweet  corn: 

Crosby's  Early 

"  F. 
3,595 
3,181 
4,342 
4.400 

3,328 
3,751 

4,668 

3,589 
4,187 
4,737 
5,192 

3,818 

°ir. 

845 

756 

1,042 

1,050 

803 

901 

1,118 

893 

839 
1,012 
1,162 
1,842 

943 

°  F. 
937 

&59 

Egyptian 

1  132 

1,147 

Flint  corn: 
Forty  Days 

854 

9ti5 

Rural  Thoroughbred 

1,210 
956 

Dent  corn: 

978 

1,086 

Blount's  Prolific 

1,235 

1,319 

Sibley's  Pride  of  the  North 

987 

The  dates  were  :  Corn  planted  May  16.  1883,  and  May  19,  1884 ;  sprouted  May  28, 
1883,  and  May  26,  1884  ;  bloomed  July  16  to  August  8,  1883,  and  July  16  to  August  26, 
1884. 

Thermal  constants  for  peas  from  sprouting  to  maturity  at  Geneva,  V.  Y. 


Variety.' 

• 
Sums  of 
all  mean 
daily  air 
temper- 
atures. 

Sums  of 
all  posi- 
tive 
mean 
daily  air 
temper- 
atures, 
less  44°  F. 

Sums  of 
all  posi- 
tive 
means  of 
air  and 
soil  tem- 
peratures 
at  1  foot 
depth, 
less  44°  F. 

°F. 

3,516 

4,516 

3,674 

4,515 

3,836 

4,576 

-F. 

1,150 

1,377 

1,176 

1,376 

1,152 

1,408 

"F. 
1,236 

1,506 

1,501 

McLean's  Advance - - 

Premium  Gem 

1,520 
1,250 

1,524 

Peas  planted  April  21  and  May  12,  1883;  April  28,  1884 
6,  1883  ;  July  2  to  28,  1884. 


ripened  July  10  to  August 


337 

These  figures  show  eccentricities  from  year  to  year  in  the  same  vari- 
ety, but  the  peculiarities  of  the  varieties  are  nnicli  hirger  than  these 
eccentricities,  Sturtevant  suggests  that  actinism  has  an  influence 
scarcely  second  to  temperature. 

SOBGHXTM. 

UNITED  «TATES. 

^y.  E.  Stone  (Agr.  Sci.,  Vol.  IV,  p.  160)  siinunarlzes  the  results 
of  the  experiments  on  sorghum  published  by  Wiley  in  Bulletins  Nos. 
20  and  26,  Division  of  Chemistry,  United  States  Department  of 
Agi'iculture.  He  says  the  controlling  conditions  of  success  are  suit- 
able soil  and  climate,  proximity  of  cane  fields  to  the  factorj^,  supply 
of  water  and  fuel,  cost  of  the  factory,  and  careful  control  of  its 
operations.  All  experience  points  to  southern  central  Kansas  as  the 
region  best  adapted  to  the  growth  of  the  sorghum.  In  New  Jersey 
the  plant,  which  at  one  time  gave  hopeful  results,  has  deteriorated 
until  it  has  become  a  worthless  variety  for  sugar  making,  or  even  for 
the  production  of  sirui3.  In  Louisiana  the  results  were  disappoint- 
ing in  seasons  which  were  the  most  favorable  for  the  sugar  cane.  At 
Conway  Springs,  Kans.,  the  average  percentage  of  cane  sugar  was 
12.42  in  1888  and  11.98  in  1889,  being  the  best  record  of  all. 

In  general,  with  a  normal  amount  of  moisture,  and  other  things 
being  equal,  the  percentage  of  sugar  depends  upon  the  amount  of 
sunshine  received;  excessive  moisture  is  detrimental,  as  it  directly 
interferes  with  nutrition  and  indirectlj'^  as  being  accompanied  by 
cloudiness. 

A  mean  temperature  of  70°  F.  is  the  minimum  necessary  to  mature 
early  varieties.  The  semiarid  region  south  of  the  isotherm  of  70°  F. 
in  the  southwest  central  portion  of  the  United  States  is  best  adapted 
to  the  groAvth  of  sorghum.  East  of  the  Mississippi  the  recurrence  of 
wet  seasons  renders  the  crop  uncertain.  A  pernuinently  improved 
plant  can  certainly  be  developed  from  existing  varieties  by  selection, 

OATS. 


During  the  drought  of  1890  the  Kansas  Agricultural  Experiment 
Station  secured  the  following  comparative  observations:  On  un- 
plowed  land  the  yield  of  listed  oats  was  2.4  bushels  per  acre  better 
than  on  plowed  land;  the  yield  of  drilled  oats  was  1  bushel  per  acre 
better  on  unplowed  land;  the  yield  of  oats  cultivated  into  the  soil 
was  5  bushels  jjer  acre  better  on  the  unplowed  land ;  the  oats  sown 
broadcast  on  plowed  land  gave  the  same  results  as  the  oats  cultivated 
into  unplowed  land ;  the  oats  jilowed  under  gave  the  least  harvest  of 
2667—05  M 22 


338 

all  the  five  methods  of  seeding,  while  the  drilled  oats  gave  the  best. 
This  superiority  of  the  drilled  oats  is  probably  due  to  the  fact  that 
the  instrument  pressing  firmly  upon  the  soil  makes  a  firm  bed  at  the 
bottom  of  the  drill,  into  which  the  seed  is  dropped.  In  a  loose  soil 
oats  run  to  straw,  but  in  a  firm  soil  they  give  a  larger  percentage  of 
grain.  In  the  present  case  oats  drilled  into  Unplowed  land  gave  34.5 
bushels  per  acre,  but  when  plowed  under  gave  21.6  bushels,  or  a  loss 
of  35  per  cent. 

As  to  the  time  of  harvesting  oats,  they  should  be  cut  early,  viz,  in 
the  dough  stage,  if  the  straw  is  wanted  for  feed;  but  if  the  grain 
alone  is  wanted  they  should  be  allowed  to  mature,  notwithstanding 
the  fact  that  there  is  then  a  greater  loss  due  to  the  beating  out  or 
dropping  of  the  grain  in  harvesting.  (Agr.  Dept.  Exp.  Sta.  Record, 
Vol.  II,  p.  222.) 

OHIO. 

In  Bulletin  No.  3  of  Volume  III  of  the  Ohio  xigricultural  Experi- 
ment Station  it  is  shown  that  the  experiments  of  1889  indicate  that 
more  cultivation  should  be  given  in  dry  seasons  than  in  wet  seasons. 

FREEZING  OF  PLANTS  AND  SEEDS. 

Detmer  (1887),  with  reference  to  the  effect  of  low  temperatures  on 
plants,  finds : 

(1)  Fruits  and  seeds  that  have  been  dried  in  the  air  can  be  exposed 
for  a  long  time  without  injury  to  very  low  temperatures,  but  if  they 
have  first  been  swollen  with  moisture  they  are  destroyed  by  low  tem- 
peratures. In  the  case  of  wdieat  exposed  to  a  temperature  of  — 10°  C, 
although  it  will  germinate,  still  its  power  of  growth  is  decidedly  less 
than  before. 

(2)  Many  plants  and  parts  of  plants  withstand  temperatures  below 
freezing,  and  many  bacteria  withstand  much  lower  temperatures: 
those  experimented  on  by  him  w^ere  not  killed  by  an  exposure  to 
temperatures  of— 17°  C. 

(3)  In  accordance  with  Sach's  experiments,  he  finds  many  plants 
which  after  being  frozen  survive  if  they  are  thawed  out  in  water  at 
low^  temperatures  (6°  C),  but  not  when  thawed  out  in  water  at 
-f  17°  C,  thus  showing  the  manner  in  which  a  warm  rain  may  act 
injuriously  upon  a  forest. 

(4)  Certain  plants  are  definitely  destroyed  by  freezing  independ- 
ently of  the  subsequent  thawing,  such  as  the  leaves  of  the  begonia. 

(5)  Experiments  have  given  a  negative  result  as  to  the  question 
whether  any  plant,  although  accustomed  to  the  warmest  climate,  can 
be  killed  by  a  short  exposure  to  a  low  temperature  which  is,  however, 
still  above  freezing.     (See  Wollny,  X,  p.  236.) 


339 


xV  tletailod  s;tiuly  of  the  relation  of  low  teniporatiiros  to  the  growing: 
of  wheat  has  been  made  by  S.  G.  Wright,  of  Indiana,  from  which  I 
take  the  following  conclusions : 

SIcef. — When  the  winter  wheat  has  its  blades  covered  with  ice  that 
has  fallen  as  sleet,  and  after  the  ice  has  melted  otf  a  microscopic  exam- 
ination shows  the  cellular  structure  to  be  altered,  the  epidermis  is 
separated  from  the  underlying  cells  and  there  is  a  general  disunion  of 
tiie  cells,  and  when  the  growing  season  comes  the  plants  are  found  to 
be  entirely  dead. 

Sudden  thawing. — '\Mieat  plants  exposed  to  a  very  low  freezing 
temperature  in  dry  air  if  thawed  out  slowly  are  not  much  injured, 
but  if  thawed  out  rapidly  the  younger  sprouts  are  completely  killed 
and  the  older  ones  subsequently  die.  The  similar  rule  obtains  for  the 
germination  of  seeds.  ^^Tien  frozen  seeds  were  quickly  thawed  out 
only  18  per  cent  germinated,  but  when  slowly  thawed  out  86  per  cent 
germinated. 

Freezing  temperature  of  the  juices  of  the  ivheat. — The  juice  ex- 
tracted by  pressure  from  the  wheat  has  a  lower  freezing  point  than 
that  of  pure  '\\'ater  when  contained  in  its  original  living  tissues,  but 
after  being  extracted  by  pressure  it  freezes  at  an  intermediate  point 
below  that  of  pure  water.  Again,  the  juice  extracted  from  plants 
that  have  been  exposed  to  a  low  winter  temperature  withstands  freez- 
ing better  than  the  juice  from  plants  that  have  not  had  such  exposure. 
For  example,  the  juice  within  the  cells  was  not  frozen  at  — 13°  C, 
while  that  thrust  out  of  the  cells  froze  at  — 6°  C.,  and  in  general  the 
power  to  resist  freezing  is  increased  by  exposing  plants  to  the  ordinary 
winter  temperatures  of  the  open  air. 

Method  of  sowing. — The  best  method  of  sowing  wheat  in  order 
that  it  may  withstand  severe  winter  weather  is  (1)  to  avoid  mulching 
or  having  any  layer  of  porous  material  about  the  roots  of  the  wheat, 
as  experiment  shows  that  this  is  a  decided  injury  both  to  the  winter- 
ing, the  after  growth,  and  the  harvest.  An  average  depth  of  seed 
jolanting  of  1.5  inches  is  much  better  than  three-fourths  inch  or  3 
inches. 

Range  of  temperature  for  germination. — According  to  Sachs,  the 
minimum  temperature  is  5°  C.  and  the  maximum  37°  or  38°  C. 
According  to  Haberlandt,  the  temperature  for  germination  ranges 
between  0°  and  —4.8°  C.  at  the  lower  limit  and  31°  to  37°  C.  at  the 
upper  limit.  Wright's  experiments,  at  a  constant  temperature  of 
39°  C,  gave  germination  successful  in  forty-eight  hours;  at  a  tem- 
perature of  42.5°  C.  only  a  very  few  seeds  could  be  made  to  germinate. 
At  a  temperature  of  0°  C.  the  seeds  germinated  in  ten  days ;  hence  the 
extreme  range  of  germinating  temperatures  for  winter  wheat  of  the 
varieties  thus  tested  in  Indiana  is  from  0°  to  42.5°  C.     As  to  the  effect 


340 

oi)  germination  of  freezing  the  seeds  just  before  they  were  ready  to  ger- 
]ninate,  it  was  found  that  seeds  soaked  until  ready  to  germinate  and 
then  kept  frozen  for  a  length  of  time  required  a  longer  time  to  com- 
plete, the  germination  than  did  those  that  had  not  been  frozen;  the 
I'etardation  increased  in  proportion  to  the  duration  of  the  freezing, 
amounting  to  about  twelve  daj's  for  a  freezing  of  twenty-four  days. 
The  percentage  of  thawed-out  seeds  that  germinated  was  also  smaller 
in  proportion  as  the  duration  of  the  freezing  increased,  being  -t-t  per 
cent  for  a  duration  of  tw^enty-four  daj'^s. 

Changes  in  the  seeds  produced  hy  frost. — After  the  seeds  had 
remained  frozen  for  ten  to  twelve  days  a  white,  glutinous  material 
oozed  out  at  every  slight  break  in  the  coat  of  the  seed.  A  micro- 
scopic examination  showed  that  the  cell  w^all  and  starchy  protoplasm 
was  almost  entirely  disorganized,  but  the  starch  granules  themselves 
were  entirely  unaffected.  Strange  to  say,  the  power  of  the  seeds  to 
germinate  was  not  destroyed  by  this.     (Agr.  Sci.,  Vol.  IV,  p.  337.) 

Protection  from  frosts. — The  formation  of  artificial  clouds  of 
smoke  for  the  protection  of  plants  from  frost  is  generally  successful, 
and  should  be  resorted  to  in  critical  cases;  thus,  in  a  vineyard  at 
Pagn}'  about  3  a.  m.  of  May  13,  1887,  wdien  the  temperature  was  3°  F. 
below  freezing,  liquid  t^'  was  ignited,  which  had  been  poured  into 
tin  boxes,  as  also  pieces  of  solid  tar.  Large  clouds  of  smoke  quickly 
enveloped  the  vineyard ;  the  fires  lasted  for  about  two  hours,  but  the 
smoke  lasted  considerabl}^  longer.  All  injury  to  the  plants  by  frost 
was  entirely  prevented.     (Agr.  Sci.,  Vol.  1,  p.  172.) 

INJURIES  AND  BENEFITS  DUE  TO  WIND-BREAKS. 

Protection  against  the  injurious  effects  of  wind  may  be  obtained 
by  the  use  of  wind-breaks,  which  are  usually  made  b}^  planting  a 
couple  of  rows  of  trees  on  the  windAvard  side  of  the  field,  or  by  so 
arranging  the  plantation  that  the  hardiest  and  most  vigorous  decidu- 
ous trees  are  on  the  windward  side.  According  to  Bulletin  No.  IX 
issued  by  the  Cornell  University  Agricultural  Experiment  Station, 
the  benefits  derived  from  Avind-breaks  are  the  following:  Protection 
from  cold,  diminution  of  evajjoration  from  soil  and  plants,  diminu 
tion  of  the  number  of  windfalls,  diminution  of  liability  to  mechanical 
injury  to  trees,  retention  of  snow  and  leaves,  facilitation  of  outdo(n- 
labor,  protection  of  blossoms  from  severe  winds,  protection  of  trees 
from  deformity  of  shape,  diminution  of  evaporation  and  drying  up 
of  small  fruits,  diminution  of  the  encroachment  of  sand  or  the  loss 
of  dry  soil  or  the  scattering  of  rubbish,,  increased  rapidity  of  m.atur- 
ity  of  fruits,  and  encouragement  of  birds  that  are  beneficial  to 
agriculture. 

Among  the  organisms  arrested  by  wind-l)reaks  and  usually  reckoned 
as  an  injurious  climatic  influence  are  the  fungi  or  the  spores  of  fungi. 


341 

Joiisen  h;!--.  however,  shown  that  bunt  in  wheat  and  smnt  in  oats  or 
barley  or  rye  can  be  ahnost  wholly  prevented  by  washing  the  seed 
))ef()re  sowing,  in  water  whose  tenij)erature  is  not  lower  than  130°  F. 
nor  higher  than  135°  F.  The  sacks  to  receive  the  seeds  should  also 
be  disinfected.  Professor  Kellernian  shows  that  if  the  seeds  are 
Ijreviously  soaked  in  cold  w^ater  for  eight  hours  the  hot-water  wash 
may  have  a  temperature  of  12J:°  to  128°.  I  infer  that  the  spores  of 
the  smut,  having  been  by  the  winds  blown  over  the  field  in  the  ripen- 
ing period,  have  stuck  to  the  grains  from  that  time  on  to  the  next 
sowing  season.     (Agr.  Sci.J  Vol.  IV,  p.  100.) 

THUNDERSTORMS  AND  OZONE. 

A.  L.  Treadwell  seems  to  have  shown  that  the  souring  of  milk 
during  thunderstorms  can  not  be  attributed  to  any  formation  of 
ozone,  and  is  more  likely  to  be  due  to  the  fact  that  the  bacteria  caus- 
ing this  souring  multiply  with  unusual  rapidity  during  the  warm 
sultry  Aveather  that  precedes  and  accompanies  thunderstorms. 
(Agr.  Sci.,  Vol.  V,  p.  108.) 

PRUNING  VERSUS  CLIMATE. 

Kraus  (188G)  in  some  experiments  on  pruning  hop  vines  shows  first 
that  those  that  w^ere  not  pruned  had  lui  advantage  in  the  early 
growth,  especially  in  the  cold  and  wet  of  June,  1886,  in  Germany,  but 
in  consequence  of  this  precocity  the  early  ones  suffered  from  frost. 
Those  that  were  early  pruned  surpassed  them  in  the  harvest. 

Those  that  were  pruned  late  gave  the  smallest  harvest,  but  of 
the  highest  quality,  the  leaA^es  remaining  a  beautiful  green  up  to  the 
harvest  time,  while  those  that  were  not  pruned  or  those  that  were  late 
pruned  turned  dark  and  soon  yellowed. 

This  explains  why  for  a  long  time  it  has  been  impossible  to  define 
exactly  the  climate  that  is  best  for  the  cultivation  of  hops,  since  it  is 
now  evident  that  changes  in  the  pruning,  harmonizing  with  pecu- 
liarities of  weather  or  locality,  have  so  great  an  influence  upon  the 
successful  cultivation.     (See  WoUny,  X,  p.  230.) 

WHEAT,  TEMPERATURE,  AND  RAIN  IN  ENGLAND. 

The  wheat  harvest  of  England  has  been  studied  by  an  anonymous 
writer.  (Nature,  1891,  vol.  43,  p.  569.)  I  do  not  know  the  authori- 
ties for  his  statements  as  to  the  character  of  the  harvests  from  year 
to  year,  but  reproduce  in  the  following  tables  the  figures  given  by  him 
as  to  the  general  character  of  tlu;  wheat  harvests  for  each  year  and  the 
corresponding  mean  temperatures  and  total  rainfall  for  the  months 
of  June,  July,  and  August  as  observed  at  the  Royal  Observatory,  at 
Greenwich.  Certain  deductions  are  given  by  him  as  to  the  connection 
between  the  harvests  and  these  items  of  the  weather,  but  a  more  care- 
ful study  of  the  figures  convinces  me  that  taken  as  they  stand  no  infer- 


342 


ence  can  be  safely  drawn  from  them  which  will  endure  the  test  of 
critical  examination.  Any  small  selection  of  years  may  be  made 
Avhich  will  seem  to  support  some  suggested  relation  between  tempera- 
ture, rainfall,  and  crop,  but  other  years  will  be  found  to  contradict  this. 
In  a  general  way  good  crops  result  from  hot  and  dry  summers  and 
bad  harvests  depend  upon  the  large  rainfalls  rather  than  on  the  low 
temperatures.  I  have  added  the  column  of  departures  and  have  com- 
puted the  probable  errors  of  the  averages,  the  study  of  which  shoAvs 
that  the  temperatures  of  the  good  harvest  seasons  are  not  sufficiently 
above  those  of  the  poor  harvest  seasons  to  'justify  the  conclusion  that 
warm  seasons  are  intimately  connected  with  good  harvests.  If,  how- 
ever, we  go  into  more  detail  and  examine  all  of  the  fifty-three  years 
from  1816  to  1888,  inclusive,  and  arrange  them  by  the  character  of 
the  harvests,  we  find  innumerable  contradictions.  The  study  of  the 
rainfall  with  its  probable  errors,  or  rather  its  probable  variability, 
shows  a  somewhat  stronger  argument  in  favor  of  the  idea  that  large 
rainfalls  accompany  poor  harvests,  and  yet  here  again  the  contradic- 
tions are  too  numerous  to  allow  us  to  suppose  that  this  simple  state- 
ment expresses  exactly  any  law  of  nature.  Thus  the  largest  rainfall 
of  1888  and  the  small  rainfall  of  1886  both  contradict  this  law.  In 
the  notes  a  few  statements  are  made  by  the  author  as  to  special  occur- 
rences which  seem  to  him  to  explain  these  anomalous  cases,  and  by 
hunting  through  the  records  a  few  more  notes  might  have  been  added 
so  that  after  leaving  out  the  anomalous  cases  one  might  say  that  the 
remainder  accords  well  with  the  idea  that  dry  hot  summers  give  large 
crops  and  that  heavj"  rains  give  poor  crops.  In  general,  however,  it 
seems  more  proper  to  conclude  that  we  are  far  from  having  attained 
the  expression  or  formula  connecting  the  crops  and  the  weather,  and 
that  even  if  we  knew  this  it  would  be  improper  to  study  the  crops 
of  England  with  reference  to  the  temperature  and  rainfall  at  Green- 
wich, or,  indeed,  any  other  single  station. 

English  irlieat  liarvests  and  Greemcich  iceather. 

[Weather  in  June,  July,  and  August.] 

I.  SUPERIOR  WHEAT  HARVESTS. 


Character  of  harvest. 

Temperature. 

Rainfall. 

Year. 

Ob- 
served. 

Dep. 

Ob- 
served. 

Dep. 

1775 
1779 
1791 
1818 

■plentiful 

-  F. 
62.0 
62.3 
59.5 
64.3 
60.3 
58.0 
62.0 
64.0 
60.0 

"  F. 
+0.8 
+1.1 
-1.7 
+3.1 
-1.9 
-3.2 
+0.8 
+2.8 
-1.2 

Inches. 

(?) 

(■') 

Dry. 
1.4 
4.6 
8.2 
3.3 
.5.1 
2.9 

do 

-4.3 

-1.1 

1820 

+2.5 

-2.4 

-0.6 

1827 

Good -- 

-8.8 

343 


Eiifflifih   trhrat  harvcftts  and  Greciiicich  weather — Contirmed. 
I.   SUPERIOR  WHEAT  HARVESTS— Continued. 


1834b 

isai 

1840 
1849 
1851 
1854 
1857 
1858 
1863 
1864 
1868 
1874 


Character  of  harvest. 


Abundant 

Early;  very  productive . 

Good 

Fine  yield 

Above  the  avei*age 

....do.. 

Extremely  good 

Above  the  average 

...-do. 

Abundant 

Good 

Productive 

Very  good 

Above  the  average 


Mean  of  23  and  20,  respectively . 
Probable  errors  of  these  means 


Temperature. 
Dep. 


Ob- 
served 


61.2 
±0.37 


Ob- 
served. 


11.3 
4.5 
3.9 
3.8 
7.2 
5.6 
6.0 
5.7 
6.6 
2.5 
4.1 
6.4 

13.8 


Dpp. 


5.68 
±0.65 


II.  INFERIOR  WHEAT  HARVESTS. 


1795 
1800 
1810 
1811 
1812 
1816 
1817 
1821 
1823 
1828 
1829 


1860 
1867 
1873d 
1875 
1876e 
1877* 


Very  deficient  . 

Inferior 

Very  defective. 


Scanty  

Very  scanty 

Vei-y  defective 

Very  great  deficiency . 

Deficient 

Inferior 

Deficient 


Inferior. 

Late;  unproductive 

Damaged 

Very  bad 

Below  the  average.. 


Very  deficient 

Deficient 

Very  deficient 

Very  unsatisfactory. 

Unsatisfactory 

do 

Worst  known 

Deficient 

do 

do 


Mean  of  28  and  of  21,  respectively  . 
Probable  errors  of  the  means 


59.7 

+0.3 

Wet. 

58.3 

-1.1 

Wet. 

57.8 

-1.6 

(?) 

60.7 

+1.3 

Wet. 

60.0 

+0.6 

CO 

59.0 

-0.4 

(?) 

56.0 

-3.4 

(?) 

55.2 

-4.2 

8.4 

57.4 

-2.0 

7.9 

57.8 

-1.6 

7.0 

57.8 

-1.6 

7.1 

60.3 

+0.9 

12.0 

59.0 

-0.4 

9.4 

59.1 

-0.3 

7.3 

59.3 

-0.1 

7.6 

59.5 

+0.1 

10.6 

61.7 

+2.3 

11.4 

60.1 

+0.7 

11.0 

56.7 

-2.7 

11.6 

59.8 

+0.4 

10.2 

61.7 

+2.3 

7.6 

60.3 

+0.9 

9.8 

62.7 

+3.3 

3.7 

62.0 

+2.6 

6.0 

.58.5 

-0.9 

13.3 

60.6 

+1.2 

7.1 

61.1 

+1.7 

7.9 

61.0 

+1.6 

4.1 

58 

.4 

8 

±0 

.33 

±0 

"  May  was  very  dry. 

»  The  winter  was  very  mild  ;  the  spring  very  dry. 

"  The  winter  and  early  spring  were  very  cold  ;  May  was  very  dry,  with  much  sunshine. 

d  Frost  occurred  at  blooming  time. 

eThe  spring  was  cold. 

/The  winter  and  early  spring  were  very  cold:  May  was  very  wet. 


344 

SUGAR   CROP   AND   RAIN   IN   BARBADOS. 

Sir  R.  AV.  Eaw'son,  as  governor  of  the  British  colonies  at  Barba- 
dos, published  (1874)  a  colonial  report,  printed  by  the  house  of 
assembly,  giving  an  elaborate  study  of  the  dependence  of  the  cane- 
sugar  crop  upon  the  monthly  and  annual  rainfall.  Barbados  offers 
an  exceptional  opjDortunity  for  such  study,  since  the  cane  is  the  only 
staple  and  is  nearly  all  exported,  so  that  the  records  of  the  crop  are 
accessible  in  the  customs'  returns.  Moreover,  the  number  of  rainfall 
records  averaged  more  than  1  to  a  square  mile,  being  178  for  the 
whole  island  and  for  a  period  of  about  twenty-five  years,  this  re- 
markable system  of  observations  being  due  largely  to  the  labors  of 
Dr.  R.  Bowie  Walcott,  who  still  resides  in  the  parish  of  St.  Joseph, 
and  was,  in  May,  1890,  on  the  occasion  of  my  recent  visit  to  him, 
still  active  in  collecting  rainfall  data.  To  his  devotion  and  Governor 
Rawson's  assistance  we  owe  this  unique  study  of  rainfall  and  sugar 
crop.  It  is  impossible  for  me  at  present  to  do  more  than  give  the 
accompanying  Tables  I,  II,  and  III  of  monthly  rainfalls  and  annual 
crops.  The  crops,  as  given  in  Tables  II  and  III,  iix  hogsheads,  are 
credited  to  the  years  in  which  they  passed  thrOugh  the  custom-house. 
The  cane  is  usually  gathered  and  the  sugar  and  molasses  shipped 
between  January  and  May;  after  the  latter  date  the  fields  are  newly 
planted  and  in  eighteen  months  are  again  ready  for  cutting,  so  that 
the  crop  of  any  year  has  been  grown  under  the  influence  of  the  rain 
of  the  preceding  year  and  the  latter  half  of  the  year  preceding  that. 
In  the  second  table  I  give  the  dates  of  the  first  shipment  of  sugar 
each  year,  thus  showing  whether  the  crop  was  gathered  early  or  late, 
and  also  the  general  character  of  the  croi?  as  credited  to  that  year. 

Table  III  illustrates  Governor  Rawson's  conclusion  that  the  crop 
of  any  year  is  influenced  only  in  a  slight  degree  by  the  rainfall  of 
that  year,  but  depends  upon  the  rainfall  of  the  jjreceding  year.  Thus 
it  is  arranged  according  to  the  quantity  of  rainfall,  and  the  crop  of 
the  following  year  is  compared  with  the  rain  of  the  ciirrent  year ;  the 
wet  years  are  followed  by  large  crops  the  next  year,  while  the  dry 
years  are  followed  by  small  crops;  the  increase  being  10  per  cent 
after  a  wet  year  and  the  decrease  being  12  per  cent  after  a  dry  year. 

The  general  development  of  the  sugar  plant  is  illustrated  in  the 
following  extract  (see  p.  ?>3,  Rawson's  Report)  : 

The  influence  of  the  rainfall  in  particular  months  and  seasons 
y'.'jon  the  coming  crop  is  generally  felt  and  admitted,  but  not  known 
\vith  any  certainty.  It  is  believed,  writes  an  experienced  agricul- 
turist, that  any  marked  excess  of  rain  during  the  first  six  months  of 
the  year  is  injurious  both  to  the  crop  that  is  being  reaped  and  to 
that  which  is  to  follow.  The  cane  plant  during  the  early  stages  of 
its  growth  is  very  hardy  and  requires  but  little  moisture;  the  small 


345 

early  shoots  are  hard  and  fibrous,  and  very  different  from  the  large 
succulent  shoots  which  are  afterwards  produced  and  which  lengthen 
into  the  juicy  reed  whence  the  crop  is  made.  In  ordinary  and  favor- 
able years,  with  light  showers  during  the  first  six  months,  the  young 
canes  make  no  marked  progress,  but  the  roots  are  increasing  in 
length  and  strength,  and  in  the  months  of  July  and  August  the  i)lant 
begins  to  sucker,  as  it  is  called,  and  to  put  out  the  shoots  which  form 
ihe  canes,  but  these  make  no  great  progress  in  length  before  the  end 
of  August  and  in  September  and  October,  when  the  rains  usually 
come  to  their  aid  at  the  critical  time.  They  then  grow  with  extreme 
rapidity,  are  extremely  tender  and  succulent,  and  a  short  spell  of  dry 
weather  at  that  time  usually  does  serious  mischief.  If,  however, 
the  first  six  months  of  the  year  are  wet,  and  the  young  canes  are 
excited  to  an  abnormal  rapidity  of  growth,  they  are  liable  to  be  seri- 
ously aifected  by  any  interval  of  dry  weather  in  the  middle  of  the 
year.  Moreover,  rainy  weather  in  the  reaping  season  retards  the 
nuinufacture,  and,  especially  in  the  black  soils  which  contain  an 
excess  of  iron  variously  combined,  causes  a  great  loss  from  the 
rotting  of  the  canes  at  the  roots. 

An  illustration  of  this  is  afforded  by  the  rainfall  and  crops  of 
18G0  and  the  two  following  years.  1860  was  a  model  year;  the  rain 
fell  at  the  right  time,  and  in  exactly  the  average  quantity,  57.01 
inches,  of  which  12.46  fell  during  the  first  six  months.  The  crop  of 
1861  would  undoubtedly  have  reached  55,000  hogsheads  but  for  the 
w^et  reaping  season  of  that  year,  in  which  the  rainfall  of  the  first 
six  months  was  31.93  inches — 6,35  in  April,  8.01  in  May,  and  8.01 
in  June.  The  consequence  was  that  the  crop  only  reached  49,745 
hogsheads,  and  although  so  much  rain  fell  throughout  the  year 
(73.82  inches),  the  following  crop  of  1862  was  only  46,120  hogsheads. 

In  the  same  manner  the  heavy  rainfall  of  1855  (77.31  inches,  of 
which  30.68  fell  in  the  first  six  months)  Avas  followed  in  1856  by 
only  a  moderate  crop  (43,077  hogsheads),  although  the  reaping 
season  of  that  year  was  most  favorable.  The  result,  however,  is  by 
no  means  constant. 

The  sugar-crop  records  go  back  to  the  year  1806,  but  the  returns 
are  only  interesting  since  1847,  which  was  "the  first  in  which  the  crop 
recovered  from  the  effects  of  emancipaticm  in  1839.  Since  1847 
there  has  been  a  steady  increase  until  the  crop  has  attained  nearly 
twice  what  it  was  before  emancipation.  There  has  also  been  a  slow 
increase  in  acreage  of  canebrake;  the  size  of  the  hogsheads  has  been 
gradually  increasing  since  1806;  there  has  been  a  decided  increase 
in  the  usage  of  guanos  and  other  foreign  manures;  there  has  also 
been  a  very  decided  improvement  in  the  machinery  and  processes 
for  crushing  the  cane  and  manufacturing  the  sugar."' 

« Although  Governor  Rawsoii  was  evidently  consc-ious  of  these  progressive 
c-hanges,  and  in  fact,  niejitions  most  of  tlieni,  yet  he  docs  not  aijproxiniat  'v 
eliminate  their  effects  by  taking  the  difference  JK'tweon  the  individual  cr< 
and  a  progressively  increasing  ideal  normal,  but  takes  the  difference  between 
the  simple  average  and  the  individual  years;  his  results,  therefore,  need  to 
be  computed  and  all  the  data  for  this  puriwse  are  given  In  the  tables  here- 
with.—C,  A. 


346 

The  average  crop  divided  by  the  average  rainfall  of  the  preceding 
year  shows  that  each  inch  of  rain  corresponds  to  about  800  hogs- 
heads in  the  resulting  crop;  the  extreme  limits  of  variations  are  713 
and  877  hogsheads,  so  that  in  general  Governor  Rawson  proposes 
to  predict  the  crop  that  will  be  gathered  during  the  dry  season, 
February  to  May,  each  year  by  simply  multiplying  the  ramfall 
of  the  preceding  calendar  year  by  800.  The  average  uncertainties  of 
the  crop  thus  predicted  is  very  small,  the  extreme  error  being  28 
per  cent  positive  following  the  wet  year  1861  and  4  per  cent  negative 
for  a  certain  dry  year;  therefore  as  an  improvement  on  this  method 
he  adopts  the  rule  of  adding  7  per  cent  for  wet  years  and  subtracting 
7  per  cent  for  dry  years,  the  average  year  being  that  which  corre- 
sponds to  55  inches  of  rainfall. 

In  supplementary  calculations  Rawson  and  Walcott  show  the 
chances  of  a  good  crop  as  calculated  from  a  large,  small,  or  average 
rainfall,  respectively,  for  each  month  of  the  year,  but  I  do  not  find 
that  they  have  at  any  time  compared  the  crop  with  the  total  rainfall 
for  the  whole  eighteen  months  or  growing  period  that  immediately 
preceded  the  crop,  which  comparison  I  have  therefore  made  and 
give  in  Table  III. 

From  all  which  it  appears  that  large  rains  gives  large  crops,  but 
occasionally  much  smaller  rains  do  also,  so  that  it  may  reasonably 
be  suspected  that  here,  as  elsewhere,  the  sunshine  must  be  considered ; 
probably  large  rains  are  only  of  advantage  when  they  occur  at  such 
a  time  that  they  do  not  diminish  the  sunshine  and  in  such  a  manner 
that  they  do  not  wash  the  soil  too  severely. 

It  would  have  been  desirable  to  have  stated  these  crops  as  yields 
per  acre  rather  than  as  total  crops,  but  I  find  no  stateihent  of  the 
actual  acreage  in  cane.  Rawson  gives  only  the  total  areas  of  the 
six  divisions  of  the  island,  Avhich  sum  up  107,000  acres;  probably 
two-thirds  of  this  is  planted  in  sugar  cane,  so  that  an  inch  of  annual 
rainfall  corresponds  to  touott?  oi'  one-ninetieth  of  a  hogshead  of 
sugar  per  acre. 

It  is,  however,  more  proper  to  reason  upon  this  matter  as  follows : 
Eleven  j^oor  crops- gave,  according  to  Table  I,  an  average  deficit  of 
15  per  cent;  12  good  crops  gave  an  average  excess  of  14  per  cent; 
the  average  rainfalls  were  55.15  and  58.18,  respectively.  Therefore 
an  increase  of  1  inch  in  rainfall  corresponds  to  a  gain  of  ^,  or  10 
per  cent  of  an  average  crop. 


347 


Table  I. — Barbados  sugar  crop  and  monthly  rainfall. 


Excess 

of  sugar 

crop. 


Jan. 


Apr. 


May. 


June. 


July. 


1852. 
1871. 
1854. 
1867. 


855. 
851. 


'60. 


.TO. 
18a7. 
1849 . 
1847. 


Average  of  12  positive . . 

Average  of  11  negative 

All  (25).. 


Percent. 
+29 
+27 
+21 
+20 
+17 
+14 
+13 
+11 
+10 
+  2 
+  2 
+  1 
0 
0 

-  5 

-  6 

-  8 
-12 
-13 
-14 
-15 
-16 
-17 
-27 


nclies. 
4.29 
3.76 
3.30 
4.13 
2.64 
2.68 
1.62 
1.73 
3.49 
7.60 
2.36 
6.96 
1.62 
4.04 
2.28 
1.19 
1.14 
2.10 
3.96 
2.63 
3.61 

.2.83 
2.74 
4.76 
1.63 


Inches. 
1.74 
2.75 
1.58 
2.29 
1.95 
4.49 
1.28 
2.18 
1.96 
1.12 
2.19 
2.95 
3.01 
3.94 
2.85 
3.88 
2.52 
2.64 
1.35 
5.78 
2.72 
0.96 
2.47 
2.04 
1.47 


3.70 
2.43 


Inches. 
1.93 
1.57 
1.53 
1.07 
1.43 
0.88 
1.40 
1.19 
2.76 
0.31 
1.39 
1.86 
1.99 
2.38 
1.13 
2.26 
0.78 
1.22 
0.90 
2.02 
3.90 
1.20 
0.77 
2.66 
1.03 


Inches. 
0.97 
1.26 
2.17 
0.56 
1.20 
1.64 
0.96 
0.81 
6.36 
1.12 
4.13 
5.49 
1.58 
3.38 
2.41 
2.26 
2.96 
1.24 
0.93 
1.64 
2.69 
2.98 
0.63 
1.58 


Inches. 
1.68 
2.74 
7.11 
0.98 
1.33 
2.66 
2.23 
2.94 
8.01 
3.63 
6.89 

6.13 
9.26 
0.66 
0.56 
4.70 
3.56 


2.34 
1.02 
3.07 
6.74 
4.32 


Inches. 
3.46 
2.63 
2.17 
2.71 
5.56 
10.94 
4.64 
5.49 
9.31 
7.18 
9.19 
6.61 
5.31 
6.21 
3.13 

10.48 
5.68 

10.15 
5.43 
6.63 
2.10 
2.17 
2.21 
3.05 


Inches. 
6.26 
6.23 
2.49 
3.65 
5.68 
7.50 


7.35 
8.00 
6.63 
3.89 
3.90 
3.66 
9.01 
5.72 
5.62 
7.14 
5.64 
2.27 
7.51 
6.25 
4.42 


2.21 
2.42 

2.58 


1.44 
1.62 
1.47 


2.05 
1.99 


2.76 
3.64 


6.80 
4.78 
6.45 


5.62 
6.56 
5.70 


348 


Table  I. — Barbados  sugar  crop  and  montlili/  rainfall — Continued. 


Aug. 


Sept. 


Oct. 


Annual- 


Rain.    I    Crop. 


1871 

1854 

1867 

1858. 

1856 _._ 

1861 

1862 _. 

1865 

1855 ..-. 

1851 

1853 - 

1860 

1863 __. 

1850 .__ _.. 

1859 _. 

1870 

1857... 

1849 

1847 _ 

1864 

1848 - 

1869.. 

Average  of  12  positive. 

Average  of  11  negative 
All  (25) 


Inches. 

11.89 
7.36 
5.37 
5.11 
9.62 
4.24 
7.80 
4.65 
7.23 
8.91 

12.84 
7.00 
8.08 
7.93 
9.34 
6.82 
3.21 
5.61 


5.26 
7.37 
7.53 
6.95 


.55 


Inches. 
4.63 
4.22 

6.70 
3.97 
8.54 
3.54 
5.98 
6.77 
4.74 
5.07 
9.27 
9.25 
7.75 
7.31 
4.99 
3.34 
4.80 
5.03 
7.93 
4.74 
10.20 
10.77 
5.41 
4.  .56 
5.59 


Inches. 
8.20 
8.99 


7.03 
12.74 
10.46 
6.15 
7.60 
11.18 
11.00 
5.12 
6.53 
10.43 
13.30 
2.89 
10.17 
10.13 
11.24 
6.58 
8.53 
7.11 
9.14 
11.78 
6.99 


Inches. 
4.42 
7.85 

14.15 
4.03 

11.19 
4.30 
6.13 
7.25 
7.50 
7.40 
4.53 
5.98 
4.29 
8.36 
7.97 
6.45 
9.61 

10.18 
8.37 
9.74 
1.43 
8.45 
6.31 
5.79 
5.13 
7.06 


Inches. 
1.40 


4.08 
3.79 
3.89 
5.22 
4.21 
7.11 


6.58 
5.41 
6.05 
2.20 
5.09 
3.37 
6.36 
3.74 

3.10 
3.73 
3.73 
6.16 
7.04 
5.73 

4.71 
4.66 
4.50 


Inches. 
44.60 
59.68 
58.77 
41.46 
50.88 
69.93 
45.22 
48.49 
73.82 
59.27 
68.64 
77.31 
59.40 
68.84 
57.91 
42.38 
67.88 
54.22 
60.17 
60.90 
52.77 
48.10 
59.19 
&3.77 
48.52 
58.18 
55.15 
57.74 


Hhds 
58,  &5:! 
57,1KH 
48,€i: 
53,907 
4.5, 1.-! 
51,30J 
50,7.'« 
43,077 
49, 74.-. 
46,12'! 
46,0(vs 

.  39,2-.'. 
38, 7:,  i 
38,:  ' 
42,(^- 
42,2--: 
35, 311-: 
39,  &i. 
39, 2;  c 


5,l;^!i 
B,l()li 


349 


Table  II. — Barhados  sufjar  crop  and  rainfall  of  the  growing  period. 


1S47. 
1848. 
1849. 
1850. 
1851. 
1853. 
185:5. 
1854. 
ia55. 


1861. 
1862- 
1863. 
1864. 
1865- 
1866. 
1867. 


1870. 
1871. 
1872. 


Total 
rainfall 
of  cur- 
rent 
year. 


Inches. 
48.10 
63.77 
52.77 
67.88 
59.40 
58.77 
68.84 
50.88 
77.31 
48.49 
60.90 
45.22 
54.22 
57.91 
73.82 
59.27 
42.38 
59.19 
68.64 
59.68 
69.93 
44.60 
48.52 
00.17 
41.46 
48.36 


Crop. 


28,169 
33,077 
35,302 
38,731 
48,611 
38,719 
4.5,181 
39,290 
43,077 
38,798 
50,788 
39,666 
42,684 
49,745 
46,120 
42,281 
36,199 
46,068 
57,188 
51,304 
58,250 
33,150 
39,370 
53,907 
39,167 


Date  of 

first 
ship- 
ment. 


Jan. 
Feb. 
Jan. 
Jan. 
Jan. 
Jan. 
Feb. 
Jan. 
Feb. 
Jan. 
Feb. 
Feb. 
Mar. 
Feb. 
Feb. 


Feb. 
Mar. 
Mar. 
Feb. 
Feb. 
Feb. 
Mar. 
Feb. 
Feb. 
Mar. 


Total  rainfall  during  growing  sei 
son  of  the  crop  of  current  year. 


.11  of    I  Latter 
mgyear.   ^lf^^^_ 


48.10 
63.77 
52.77 
67.88 
59.40 
58.77 
68.84 
50.88 
77.31 
48.49 
60.90 
4.5.22 
54.32 
57. 91 
73.82 
59.27 
42.38 


44.60 
48.52 
60.17 
41.46 
48.36 


37.02 
43.80 
30.88 
45.31 

40.81 
40.71 
36.77 
46.62 
34.25 
40.82 
33. 28 
37.78 
45.50 
41.91 
38.30 
30.  .59 
47. 26 
43. 44 
44.98 
46.59 
30.53 
33.78 
39.25 


100.79 
96.57 
98.76 
104.71 
98.52 
109.65 
91.. 59 
114.08 
95.11 
95.15 
86.04 
87.  .50 
9.5.69 
118.  »2 
101. 18 
80.68 
89.78 
11.5.90 
K)4. 12 
114.91 
91.19 
79.05 
93.95 
80. 71 
78.55 


First 
half  of 
year  be- 
fore. 


11.08 
19.97 
31.89 

22.  .57 
19.65 
17.% 
28.13 

u.n 

30. 69 
14.24 
2(J.(I8 
11.94 
16.  44 
13.41 
31.91 
30.97 
11.79 
11.93 
25.20 

14. 70 

23.  :w 
14.07 
14.74 
30.92 
11.30 


350 


Table  III. — Barha(l0)<  siifjar  crop  and  rainfall  of  preceding  yen) 


Year. 

Above 

(-)the 
Rainfall,  average 
of  crop 
of  fol- 
[  lowing 
year. 

Year. 

Rainfall. 

1855 

Inches.   ^  Per  cent. 

77.81  :         +11 

73.82  I          4-  2 

1864 

Inches. 
59.19 
58.77 
57.91 
54.22 
52.77 
50.88 
48.52 
48.49 
48  10 

■+  2 
Q 

1861 

1852 

1867 _ 

69.93 
.    68.84 
68.64 
67.88 
63.77 
60.90 
60.17 
59.68 
59.40 
59.27 

+29 
+17 
+27 
0 
-15 
+13 
+20 
+14 
+25 
+  6 

1860. 

1853 

1859 

5 

1865 

1849 

9 

1850 

1854 

1848  . 

1869 

13 

1857 

1856 

1847 

1870 

27 

1866 .- 

1858 

45.72 
44.60 

42.38 

12 

1851 

1868 

28 

1862 

1863          .      . 

-19 

Note. — In  calculating  the  average  crop  and  the  respective  annual  excesses  or  deficits 
given  in  Tables  I  and  III  Governor  Rawson  says  that  "  he  has  made  an  arbitrary  division 
of  the  whole  period  into  two  sections  marked  by  the  introduction  of  the  use  of  guano 
as  a  fertilizer."  For  the  first  section,  1847-1856,  inclusive,  he  considers  38,795  hogsheads 
as  the  average,  but  for  the  second  section,  1857-1872,  inclusive,  he  takes  45,036  hogsheads 
as  the  average.  He  states  that  this  is  virtually  assuming  that  duriug  the  whole  period 
climatic  and  other  conditions  were  nearly  constant  and  that  the  principal  difference  was 
in  the  introduction  of  the  use  of  guano  and  the  great  increase  of  crops  was  due  to  that. 
During  the  first  interval  an  inch  of  rain  corresponded  to  642  hogsheads  of  sugar  in  the 
crop  of  the  next  year,  but  during  the  second  interval  it  corresponded  to  800  hogsheac"^. 


353 

f'vr-  T.  to  which  we  can  rely  upon  them  for  further  instruction,  can 
', .  '  5  estimated  by  a  study  of  such  exact  experiments  as  have  been 
made  at  the  experiment  stations  throughout  this  country  and  Europe. 
Some  ilhistrations  of  this  matter  are  given  by  C.  S.  Plumb,  under  the 
title  of  the  "  Fallacies  of  plat  experimentation  "  (Agr.  Sci.,  Vol.  II, 
p.  4),  to  which  I  will  add  the  following  remarks.  Two  sets  of  meas- 
ures are  taken  from  the  results  of  the  year  1887  at  Geneva,  N.  Y. 
The  plats  were  arranged  in  two  series,  or  two  fields,  but  were  in  every 
respect  as  much  alike  as  possible  and  supposed  to  be  identical.  The 
harvests  from  the  respective  plats  were  as  follows : 


Plat. 

Weight  of  good 
ears. 

Plat. 

Weight  of  good 
ears. 

Series  C. 

Series  E. 

Series  C. 

Series  E. 

Pounds. 
237.2 
224.2 
222.7 
242.0 
264.2 

155.3 
107.3 
222.2 
243.8 
224.6 
209.0 
191.7 

Pounds. 
223.8 
216.9 
199.0 
222.2 
/ 196.1 
174.2 
182.7 
213.6 
197.6 
186.0 
168.1 
169.1 
177.6 

14 

Pounds. 

172.8 
171.8 
172.6 
183.4 

Pounds. 

2 

15 

167  1 

3.. 

16 

4 

17 

150  1 

18   . 

6  .      . 

19 

128  2 

7 

Average 

204.6 

182  7 

8 

Yield  per  acre bushels. . 

9 

51.1 
12,380 
12,180 

45.7 
12,320 
11,400 

10 

11 

Number  of  good  ears 

12 

13.. 

The  individual  differences  between  these  36  plats  simply  show  that 
the  conditions  were  not  so  uniform  as  the  author  supposed ;  in  fact, 
the  regular  gradations  from  the  high  numbers  at  the  top  of  the  column 
to  the  low  ones  at  the  bottom  show  that  there  was  a  slight  systematic 
difference  among  the  plats  in  each  series.  On  the  other  hand,  the 
decided  apparent  differences  between  the  two  series,  as  well  as  between 
the  plats,  is  very  largely  of  the  nature  of  those  differences  that  are 
called  accidental  in  the  theory  of  exact  measurements.  Similar  dif- 
erences  in  a  long  series  of  observations  of  the  temperature  or  the  rain- 
fall of  any  locality  are  spoken  of  not  as  accidental  error  but  as  the 
variability  of  the  climate,  and  these  differences  in  the  present  case 
may  properly  be  treated  as  variability  in  the  productive  power  of  any 
plat  compared  with  the  neighboring  plat  without  for  the  moment 
inquiring  as  to  the  cause  of  this  variability.  But  the  mathematical 
theory  of  probabilities,  or  chance,  or  errors  of  observation,  is  equally 
applicable  to  this  question  of  variability  due  to  unknown  influences. 
According  to  that  theory  we  obtain  the  index  of  variability  if  we  take 
the  difference  betAvcen  the  average  of  a  series  and  the  individual  num- 
2667—05  M 23 


354 

bers  in  the  series  and  treat  these  departures  according  to  the  following 
formula : 

Index  of  variability  of  the  plats  equals 

I  ,-)  op ,  /  Sum  of  all  the  (Departures)^ 
\  Number  of  departures  less  1, 
which  formula  may  be  interpreted  as  meaning  that  from  the  squares 
of  the  departures  added  together  and  divided  by  the  number  of  plats 
less  1  we  derive  an  index  called  the  ''  probable  uncertainty  of  1  meas- 
ure," or  "  the  probable  variability  of  1  plat  as  compared  with  all  the 
plats  of  the  series."  Again,  knowing  this  uncertainty  of  any  one 
measure,  we  find  the  "  probable  uncertaint}^  of  the  average  of  n  meas- 
ures "  by  the  following  formula  : 

Index 
Probable  nncertaintv  of  the  average  =  ±  — 7^. 

vn 

This  latter  formula  is  to  be  interpreted  as  meaning  that  there  is 
an  even  chance  that  the  computed  average  is  too  large  or  too  small 
by  this  probable  uncertainty.  Applying  these  principles  to  the  meas- 
ures of  plats  C  and  E,  I  obtain  the  figures  31.3  and  22.9  as  the  indices 
of  variability  and  8.33  and  5.26  as  the  probable  errors  of  the  two 
averages.  That  is  to  say,  so  far  as  any  internal  evidence  is  given 
l\y  the  discrepancies  between  the  measurements  of  the  plats  them- 
selves, there  is  an  even  chance  that  the  crop  from  a  plat  in  series  C  is 
betw^een  the  limits  212.9  and  196.3  or  outside  of  these  limits;  simi- 
larly, for  series  E  there  is  an  even  chance  that  the  crop  from  any 
plat  is  within  the  limits  188.9  and  177.4  or  outside  of  these  limits. 
But  the  numbers  within  each  of  these  two  series  overlap  each  other  so 
much  that  it  is  perfectly  possible  that  if  we  could  increase  the  number 
of  plats  in  each  series  sufficiently,  all  other  conditions  remaining  the 
same,  we  should  eventually  arrive  at  very  nearly  the  same  average 
value  for  each.  In  other  words,  the  mere  difference  of  the  two  aver- 
ages 201.6  and  182.7  is  no  evidence  that  in  this  particular  case  there 
was  any  important  constant  difference  between  the  plats  of  series  C 
and  those  of  series  E,  but  that,  on  the  contrary,  unknown  sources  of 
influence  are  at  w^ork  in  each  series  and  in  all  the  plats  that  are  more 
important  than  any  that  were  thought  of  when  the  experimenter 
endeavored  to  make  these  36  plats  perfect  duplicates  of  each  other. 

Professor  Plumb  shows  that  this  difference  did  not  depend  upon  the 
previous  crops  or  treatment  of  the  j^lats  during  the  previous  five 
years.  It  certainly  did  not  depend  on  the  meteorological  climate, 
the  mechanical  condition  of  the  soil,  nor  on  the  seeds,  nor  on  injury 
by  insects  and  animals.  We  may  possibly  fiiKl  a  partial  explanation 
in  the  irregular  distribution  of  microbic  life  in  the  soil,  but  it  is 
more  likely  that  it  depended  upon  the  inherent  variability  of  the 


355 

vitality  of  the  seed,  due  to  unknown  causes,  and  which  we  have  no 
means  of  measuring  except  by  just  such  experiments  as  these.  The 
elaborate  measurements  made  by  Lawes  and  Gilbert  at  Rothamsted, 
England,  since  1850,  furnish  innumerable  illustrations  of  this  same 
principle;  so,  also,  do  those  of  ^Y.  R.  Lazenby,  at  Columbus,  Ohio, 
and  many  others. 

"We  shall  therefore  hope  to  derive  more  reliable  results  from  the 
study  of  farming  operations  on  a  large  scale,  taking  the  averages  by 
counties  and  States  where  the  crops  have  been  carefully  measured. 
We  may  possibly  eliminate  irregularities  in  many  disturbing  ele- 
ments, and  be  able  to  clearly  set  forth  that  small  percentage  by  which 
the  crops  of  the  United  States  as  a  whole  are  influenced  by  purely 
climatic  conditions.  Such  influences  may  in  extreme  cases  be  very 
large,  but,  on  the  average,  they  are  not  so  large  as  those  which  depend 
upon  seed,  cultivation,  rotation,  and  fertilizers. 

EFFECT   OF   VARIATIONS    IN  METHOD  OF   CULTIVATION  AND  IN 
aUALITY  OF  SEED  FOR  DIFFERENT  REGIONS  AND  YEARS. 

Among  the  modes  of  cultivation  that  materially  affect  the  devel- 
opment of  the  plant  and  the  quantity  of  the  harvest  must  be  consid- 
ered the  practice  of  sowing  seed  broadcast  with  the  hand  as  con- 
trasted with  that  of  putting  it  in  wdth  the  drilling  machine.  The 
drilling  requires  less  seed,  the  saving  being  about  one-half  bushel 
per  acre;  the  grain  is  buried  more  evenly,  starts  more  uniformly,  and 
stands  the  droughts  better.  Moreover,  the  drilled  wheat  fields  are 
considered  to  yield  more  per  acre,  although  it  is  difficult  to  state  how 
much  is  due  to  the  drilling  independent  of  the  character  of  the  soil, 
because  in  general  the  fields  that  are  drilled  are  most  apt  to  be  those 
free  from  stumps,  stones,  and  steep  slopes,  while  the  broadcast  sow- 
ing is  especially  adapted  to  this  latter  character  of  field.  The  census 
of  1879  shows  that  the  drilled  fields  of  winter  wheat  in  Ohio  yielded 
50  per  cent  more  than  the  broadcast  fields  of  sunnner  wheat  in  the 
Northwest ;  but  it  is  not  plain  w^hat  proportion  of  this  is  respectively 
due  to  the  drilling  and  to  the  soil. 

In  the  report  for  1875  of  the  Department  of  Agriculture  (p.  42) 
the  follow^ing  statistics  are  given  as  to  the  percentage  of  area  drilled, 
the  quantity  of  seed  per  acre,  and  the  increase  of  harvest  in  drilled 
fields  over  that  in  broadcasted  fields : 

The  following  table  omits  the  New  England  States,  which  produce 
little  wheat,  neai'ly  all  of  which  is  sown  broadcast.  The  wheat  area 
of  New  York  is  divided  efjually  between  the  two  methods.  In  New 
Jersey,  Pennsylvania,  Delaware,  and  Maryland  the  drill  greatly 
predominates.  Tn  the  Soutliern  States  the  area  is  small,  particu- 
larly in  the  cotton  States,  and  the  drill  is  comparatively  unknown. 
North  of  the  Ohio  River,  in  the  winter-wheat  States,  the  drill  is  very 


356 

generally  used,  the  proportion  rising  to  76  per  cent  in  Illinois.  In 
the  spring-wheat  region  there  are  several  reasons  for  prominence  of 
broadcasting.  One  comes  from  a  prevalent  practice  of  sowing  wheat 
on  the  irregular  surface  of  a  cornfield  without  plowing;  another  is 
found  in  the  use  of  the  combined  cultivator  and  broadcast  seeder, 
which  destroys  many  of  the  weeds  that  would  otherwise  be  left 
between  the  drills.  *  *  *  The  result  of  the  investigation  shows 
that  47  per  cent  of  the  winter  wheat  and  30  of  the  spring,  or  37  of 
both,  represent  the  proportion  seeded  by  the  drill.  The  improvement 
by  drilling  is  made  to  average  10  per  cent.  The  average  quantity  of 
seed  used  for  seeding  winter  wheat  is  1.35  bushels  per  acre;  1.24  for 
drilled,  1.44  for  the  sown.     The  details  are  as  follows : 

Percentages  for  1875. 


Relative  area- 


Sown.     Drilled 


Seed  per  acre. 


Increase 

of  prod- 1 

uct  by      Broad-    Ti-..;ni 
drilling,   casting.    DriUmg 


New  York 

New  Jersey 

Pennsylvania... 

Delaware 

Maryland 

Virginia 

North  Carolina 
South  Carolina 

Georgia 

Alabama 

Mississippi 

Texas 

Arkansas 

Tennessee 

West  Virginia . 

Kentucky 

Ohio 

Michigan 

niinois- 

Indiana 

Missouri 

Kansas 

Nebraska 

California. 

Oregon 


Per  cent. 
50 
45 


Per  cent. 
50 
55 

70 
74 


Per  cent. 
13 
6 
12 
10 


Btishels. 
1.80 
1.95 
1.74 
1.75 
1.70 
1.44 
1.07 
1.00 
1.00 
1.00 
1.25 
1.18 
1.10 
1.20 
1.53 
1.36 
1.57 
1.62 
1.52 
1.48 
1.52 
1.49 
1.56 
1.33 
1.50 


Bushels. 
1.60 
1.60 
1.49 
1.50 
1.43 
1.21 
0.83 
0.70 
0.90 


0.90 


1.10 
1.33 
1.11 
1.33 
1.40 
1.24 
1.21 
1.21 
1.23 
1.25 


1.21 


857 


The  following  table,  from  the  Agricultural  Report  for  1882  (p. 
G36),  gives  the  proportion  of  winter  wheat  that  was  drilled  and 
broadcasted  in  the  autumn  and  winter  of  1881  and  1882  for  each 
State : 


Connecticut  ... 

New  York 

New  Jersey 

Pennsylvania . . 

Delaware 

Maryland 

Virginia 

North  Carolina 
South  Carolina 

Georgia 

Alabama 

Mississippi 


Drilled. 

Broad- 
casted. 

Percent. 

Per  cent. 

5 

ml 

53 

48 

56 

U 

70 

30 

75 

25 

63 

37 

30 

70 

8 

92 

1 

99 

2 

98 

6 

94 

• 

99 

Louisiana 

Texas 

Arkansas 

Tennessee 

West  Virginia 

Kentucky  

Ohio 

Michigan 

Indiana 

niinois 

Missouri 

Kansas 


Percent. 

1 
II 

2 
15 
40 
31 
78 
52 
81 
71 
58 
73 


Broad- 
casted. 


As  it  has  not  been  practicable  to  obtain  data  that  will  accurately 
present  the  effect  on  the  crop  of  the  diverse  features  of  cultivation 
that  are  independent  of  climate,  I  give,  in  addition  to  the  preceding, 
the  following  general  statements  bearing  on  the  annual  crop  statistics 
.kindly  communicated  by  Mr.  J.  E.  Dodge,  Statistician  to  the  Depart- 
ment of  Agriculture.  Relative  to  the  seeding  and  the  stand  of  the 
crop  and  other  matters,  he  says : 

The  practice  varies  with  the  kinds  of  corn.  The  small  northern 
corn  is  planted  closer  than  the  larger  more  southern  varieties.  In 
the  South  corn  is  given  greater  distances  than  in  the  AVest.  It  grows 
larger  there  and  makes  more  stalk  growth  and  fewer  ears.  Only 
one  or  two  stalks  are  planted  in  the  hill  there,  while  two  or  three  in 
the  middle,  and  three  and  even  four  in  the  extreme  northern  latitudes, 
are  sometimes  left  in  the  hill.  We  have  allowed  one-third  of  a  bushel 
per  acre. 

The  individual  differences  in  yield  per  acre  in  the  States  of 
highest,  as  well  as  of  the  lowest  yield,  are  far  greater  than  the  dif- 
ferences in  these  State  averages,  as  produced  by  differences  in  soil,  in 
the  effects  of  the  various  vicissitudes  on  different  soils,  in  fertility  or 
lack  of  it,  in  thoroughness  of  cultivation. 

In  the  extreme  West,  beyond  the  Mississippi,  where  land  is  plenty 
and  labor  scarce,  the  cultivation  is  reduced  to  the  minimum.  Satis- 
factory results  are  now  produced  in  southern  Iowa  in  winter-wheat 
growing  by  simply  "  cultivating ''  between  corn  rows  and  sowing 
wheat  at  a  labor  expense  of  00  cents  per  acre.  The  rough  surface  is 
favorable  for  exemption  from  Avinter  killing,  and  some  records  of 
experiment  show  an  increase  of  25  i)er  cent  in  yield  over  |)lanting 
after  clover  on  a  smooth  surface.  This  is  so  notwithstanding  the 
clover  soil  might  be  expected  to  have  something  like  as  great  aii 
advantage  in  real  fertility  over  the  .soil  that  had  grown  a  crop  of 
maize.     The  corn  exhausts,  the  clover  enriches,  and  still  the  yield  is 


358 

the  greater  after  the  corn,  because  the  plants  are  not  much  injured  by 
frost. 

EFFECT  OF  VARIATIONS  IN  DATES  OF  SEEDING  AND 
HARVESTING. 

The  injurious  effects  of  late  frosts  on  early  vegetables  and  on 
grains  sown  in  the  spring  is  generally  annulled  in  part  by  a  second 
sowing,  so  that  the  crop  reports  for  the  year  do  not  show  the  full 
extent  of  the  injury  done  to  the  plant  by  the  climate. 

In  a  general  comparison  between  the  climate  and  the  crops  accu- 
racy would  require  that  we  know  the  date  of  last  planting,  but  in  the 
absence  of  this  fundamental  datum  w^e  are  obliged  to  use  the  average 
dates  between  which  the  planting  is  done  in  any  given  State,  and 
such  dates  are  given  in  the  following  table  and  are  assumed  to  refer 
to  the  dates  of  planting  the  seed  which  actually  brought  forth  the 
subsequent  harvest,  whose  yield  per  acre  is  given  in  the  tables  pub- 
lished by  the  statistician  of  the  Department  of  Agriculture. 

These  tables  are  also  necessary  in  order  to  compute  the  thermal 
constants  and  to  anticipate  the  dates  of  bloom  and  harvest.  The 
following  tables,  for  1882  and  1889,  as  published  in  the  Annual 
Reports  of  the  Department  of  Agriculture  (pp.  409  and  636,  respec- 
tively), give  the  dates  of  seeding  for  wheat: 


Date  of  seeding. 


Fro  in- 


seeding. 


Date  of  seeding. 


From- 


Aver- 

age 
date  of 
seeding. 


Connecticut 

New  York 

New  Jersey 

Pennsylvania  .. 

Delaware 

Maryland 

Virginia 

North  Carolina 
South  Carolina. 

Georgia 

Alabama 

Mississippi 

Louisiana 

Texas... 

Arkansas 

Tennessee 

West  Virginia  . 

Kentucky  

Ohio 

Michigan 

Indiana 

niinois 

Missouri.. 

Kansas 

California 

Oregon 


Sept.  1 
Aug.  15 
Aug.  28 
Aug.  20 
Sept.  20 
Sept.  1 
Aug.  20 
Sept.  1 
Oct.  1 
Sept.  1 
....do... 
....do... 
....do... 
....do... 
....do... 
Aug.  1 
Aug.  20 
Aug.  25 
Aug.  1 
Aug.  20 
Aug.  15 
Aug.  20 
Aug.  15 
Aug.    1 


Nov.  1 
Oct.  30 
Nov.  10 
Oct.  20 
Oct.  10 
Dec.  1 
Nov.  25 
Jan.  10 
Jan.  1 
Jan.  10 
Dec.  20 
Dec.  1 
Nov.  20 
Mar.  15 
Jan.  15 
Dec.  15 
Nov.  15 
Dec.  20 
Nov.  20 
Nov.  15 
....do.. 
Nov.  10 
Dec.  1 
Jan.     1 


Sept.  25 
Sept.  16 
Sept.  28 
Sept.  20 
Oct.  1 
Oct.  13 
Oct.  15 
Oct.  29 
Nov.  1 
Nov.  2 
Nov.  3 
...do... 
Nov.  5 
Nov.  7 
Oct.  26 
Oct.  15 
Sept.  30 
Oct.  7 
Sept.  20 
Sept.  17 
Sept.  10 
Sept.  20 
Sept.  25 
Sept.  23 


Sept.  1 
Aug.  15 
Aug.  25 
Aug.  10 
Sept.  15 
Aug.  20 
Sept.  5 
Sept.  1 
Oct.  1 
Sept.  1 
Sept.  15 
....do... 


Oct.  25 
Oct.  15 
Oct.  25 
Oct.  30 
Nov.  1 
Nov.  20 
Dec.  1 
Dec.  15 
Dec.  10 
Dec.  25 
Jan.  1 
Dec.  30 


Sept.  25 
Sept.  15 
Sept.  25 
Sept.  19 
Oct.  10 
Oct.  13 
Oct.  19 
Nov.  5 
Nov.  13 
Nov.  14 
Nov.  7 
Nov.   5 


Sept.  1 
...do... 
...do... 
...do... 
...do... 
Aug.  25 
Aug.  20 
...do... 
Aug.  25 
Aug.  15 
...do... 
Sept.  1 
Sept.  15 


Feb.  1 
Jan.  10 
Dec.  20 
Nov.  15 
Dec.  10 
Nov.  15 
Nov.  1 
Nov.  20 
Nov.  13 
Dec.  1 
...-do... 
May  1 
Apr.    1 


Nov.  6 
Nov.  1 
Oct.  22 
Oct.  2 
Oct.  12 
Sept.  24 
Sept.  15 
Kv-  •■ 
Bopt.23 
Sopt.:.-^! 
St'.pt  3* 
D<M  .  37 
Nov.  25 


859 

'  le  folloAving  table  gives  dates  of  sowing  and  ripening,  especially 
in  America  additional  to  those  given  by  Lippincott  (18G;i),  and  in 
many  cases  will  give  nseful  indications  of  the  progressive  change  that 
has  gone  on  since  1860  in  methods  of  cultivation  and  in  the  habits  of 
the  wheat  itself : 


Locality. 


Deltaof  Egypt ... 

Europe. 
Malta 

Palermo,  Sicily . . . 

Naples 

Rome 

Alps: 

3,000  feet 

4,000  feet 

Central  Germany 

South  of  England. 

Middle  of  Sweden 

United  States. 

Aroostook  Coun- 
ty, Me. 

Franklin  Countv, 
Me. 

Penobscot  Coun- 
ty, Me. 

Somerset  Coimty, 
Me. 

Washing  ton 
County,  Me. 

St.  Lawrence 
County,  N.  Y. 

Do 


tude 
north. 


Windsor  County, 
Vt. 

Oshkosh  County, 


Walworth  Coun- 
ty, Wis. 

Hillsdale  County, 
Mich. 

Wayne  County, 
Mich. 

Washtenaw 
County,  Mich. 

Genesee  County, 
N.Y. 

Livingston  Coun- 
ty, N.  Y. 

Ontario  County, 
N.Y. 

Monroe  County, 
N.Y. 


Seneca 
N.Y. 


Do 


County, 


Utet^r    County, 


Stfuix^n  County, 

N.Y 
Hainp.saire  Conn- 


ty,>ilf 


46  47 
45  00 
45  00 
45  00 
45  00 
44  40 

44  40 

43  30 

44  00 
43  00 
42  00 
42  15 

42  15 

43  00 
42  45 

42  45 

43  00 
42  45 

42  45 

41  45 

42  15 

42  00 


Date  of  sowing.       Date  of  reaping. 


Dec.  1  . 
....do. 
Nov.  16 
Nov.  1. 


May  —  . 

May  13 . 
May  20. 
June  2  . 
July  2.. 


Dura- 
tion. 


Days. 
ISO 


Sept.  12 Aug.  7. 

Sept.  8 Aug.  14. 

Nov.  1.. July  16. 

Aug.  4.. 

....do.. 


May  15 

May  20 

May  21  to  June  1 . 
May  25  to  June  1  . 
Apr.  10  to  May  10 
Apr.  to  June 


Sept.  1  

Sept.  20 

Aug.  15 -. 

Aug.  20  to  Sept.  20. 

Sept.  10-20 

August- 


Sept.  to  Nov 
Sept.  18 


^ept.  1 

Sept.  1-15 

Sept.  10-25 

Sept.  5-25 

Sept.  1-20 

Aug.  15  to  Sept.  15 

Sept.  15 

Aug.  20  to  Sept.  25. 

Sept.25 

Sept.10-20 


July. 
July: 


Sept.  2.... 
Sept.  1-20. 


Aug.  25  to  Sept.  10. . 
Sept.6 


Aug.  15 

July  20 

July  10-20 

July  5-15 

July  8-20 

July  25 

July  20  to  Aug.  20 
July  15  to  Aug.  1  . 

Julys 

July  20 


July  13.... 
July  10-20  . 


July  25 . 


Variety  of  wheat 
and  remarks. 


May. 


Dayton. 
Mediterranean. 


360 


Locality. 

Lati- 
tude 
north. 

Date  of  sowing. 

Date  of  reaping. 

Dura- 
tion. 

"Variety  of  whea*^ 
and  remarks. 

o        , 

Days. 

43  00 

Iowa. 
Scott     County, 

43  00 

April 

July 

Iowa. 
Henry  County, 

41  00 

September 

Julyl 

Iowa. 

41  00 

Apr.  1  20  _ 

July  15 

Da 

Iowa. 
Do 

41  (X) 

July  4     . 

Lee  County,  Iowa. 

40  45 

September 

July  5-12 

40  00 

Oct.1-15 

111. 
St.  Clair  County, 

38  30 

Sept.  28  to  Oct  18 

m.               ^' 

39  00 

Sept.  1  to  Oct.  30.  _. 
Sept.  15 

June  30 

Mo. 

40  15 

Julyl  15 

ty,  Ind. 

Rusli     County, 

3St  30 

September 

Sept.  1  to  Oct.  15 

June  25  to  July  5 

Ind. 
"Wayne    County, 

39  45 

June  25  to  July  7 

Ind. 
Han-ison  County, 

40  15 

Sept.  1-20 

July  1-10 

Soule. 

Ohio. 

39  30 

Sept.3 

Julyl 

Ohio. 

Clinton    County, 
Ohio. 

39  20 

July  4 

Rock. 

Lawrence   Coun- 

38 40 

October 

May  30 

May. 

ty,  Ohio. 

41  00 

July  15 

ty,  Ohio. 

39  45 

Do. 

Ohio. 

40  30 

Sept.  10  to  Oct.  15.. 

Julys 

County,  Pa. 

Fayette   County, 
Mifflin   fiouTltv. 

40  fX) 

Sept  1  20 

July  7 

Do.    ' 

40  30 

Sept.  10  to  Oct  1 

July  1     . 

Pa. 

Dauphin  County, 
Pa. 

Berks   County, 

Pa. 
Philadelphia 

County,  Pa. 

40  30 

Sept.  1  to  Oct.  1  .... 
Sept  10-15 

July  4:-15 

40  30 

July  4-20 

Blue  Stem. 

40  00 

Sept.  15  to  Oct.  15.. 

July  15 

Mediterranean. 

Bergen    County, 

41  00 

Oct.  1 

July  5  15 

39  45 

do 

July  1-10 

ty,N.J. 

Salem    County, 
N.J. 

Newcastle  Coun- 

39 30 

Sept.  30  to  Oct.  7... 
Sept.  20  to  Oct.  10 

June  25  to  July  1 

Do. 

39  00 

Do. 

ty,  Del. 

Dover  County, 
Del. 

39  00 

do 

June  15  23 

Sussex     County, 
Del. 

Harford  County, 
Md. 

Jefferson  County, 
Do 

Sept.  28  to  Oct.  15.. 
Sept.  1  until  frost.. 
Sept.  25  to  Oct.  15  . . 
Sept  4-23 

39  45 

39  15 

June  25  to  July  1 

39  15 

July  22                .  . 

Do. 

Richmond  Coun- 

37 50 

Sept.  16, 1859 

Junel4,1860 

Japan. 

ty,  Va. 
Do 

37  50 

June  2 

Early  Conner. 

Do 

37  50 

May  26,1842 

May. 

861 


Lati- 
tude 
north. 


Date  of  sowing. 


Date  of  reaping. 


Dura- 
tion. 


Variety  of  wheat 
and  remarks. 


Franklin  County, 

Va. 
Bxickingham 

County,  Va. 
Mason  County,  Ky 
Clark  County ,  Ky  . 
Logan  County,  Ky 


CabarrasCounty, 
N.  C. 

Bedford  County, 
Tenn. 

Habersham 
County,  Ga. 

Cherokee  Coun- 
ty, Ala. 

Montgomery 
County,  Ala. 

Gaudalupe  Coun- 
ty, Tex. 

Santa  Fe,  N.  Max 

Albuquerque, 
N.  Mex. 

Donna  Ana  Coun- 
ty, N.  Mex. 

Utah  Territory. . . 

Stanislaus  Coun- 
ty, Cal. 

British  North 

America. 

PortFraser 


Cumberland 
House,  on  Sas- 
katchewan 
River. 

Red  River  settle- 
ment. 

Fort  Francis, 
Rainy  Lake  dis- 
trict. 

Quebec,  Canada . . 
Prince     Edward 

Island. 
Fredericton.  New 

Brunswick. 
Pictou,    Nova 

Scotia. 

Beyond  north 
polar  limit  of 
successful  icheat 
culture. 

Sitka,  Alaska 


Fort     York,    on 

Hudson  Bay. 
Edmonton,  on 

Saskatchewan 

River. 
Carlton  House,  on 

Saskatchewan 

River. 

Fort   Liard,   Mc- 
Kenzies  River. 

St.   Johns,  New- 
foundland. 


37  40 

38  30 
38  00 
37  (X) 


35  30 
34  45 

34  15 

32  30 

30  m 

35  40 
35  10 

33  30 
43  00 


54  30 
53  57 


50  00 
48  36 


46  49 
46  12 


46  00 
45  34 


57  00 
.-.3  40 


60  00 
47  33 


Days. 


Oct.l  to  Dec.  15.... 

Oct.  1  to  Nov.  15.... 

Sept.  1  to  Oct.  15  . . . 
Sept.  15  to  Oct.  30  . 
October   and   No- 
vember. 
November 

Sept.  15  to  Nov.  15.. 

Sept.  15  to  Dec.  I . . 

Oct.  1  to  December. 


June  20  to  July  10. 
June  15  to  July  4. . 


June2 

June  and  July . 
June  10-30 


June  1-10 

June  1-14 

June  15  to  July  15. 

June  1-15.. 

May  31.. 

Junel. 


April. 


February    and 
March. 


August. 
July  31 . 


August. 


Sept.l  toMay  1. 
November 


June  to  September 
Junel 


Early  May. 


West  of  the  Rocky 
Mountains. 


Sown  May  8;  reaped 
in  August. 


Wheat  grows  luxu- 
riantly. 

Sown  May  1:  reaped 
in  August  (120 
days). 

Wheat  succeeds. 
Extensively  grown. 

Wheat  succeeds. 

August  mean,  63; 
wheat  succeeds. 


Wheat  does   not 
ripen. 

Do. 


Often  destroyed  by 
frost. 


Do. 


Grows  occasionally. 


Wheat  does   not 
ripen. 


362 

BRIEF   SUMMARY    OF    CONCLUSIONS. 

Some  of  the  principal  points  that  have  been  brought  out  in  this 
collection  of  data  will  seem  like  the  expression  of  ideas  that  have 
long  been  known,  yet  whose  importance  has  probably  been  under- 
rated by  those  who  desired  to  deduce  definite  numerical  relations 
between  the  climate  and  the  crops  of  any  locality. 

(1)  We  have  seen  that  in  a  general  way  the  plant,  like  every  other 
living  being,  adapts  itself,  when  possible,  to  its  climatic  surroundings, 
and  therefore  will  produce  some  crop,  if  possible,  the  first  year  and 
will  do  better  and  better  in  the  next  few  succeeding  years  if  the 
seasons  are  not  too  severe. 

So  sensitive  is  the  plant  to  a  change  of  environment  that  the  ordi- 
nary seasonal  irregularities  from  year  to  year  have  a  strong  influence 
upon  it,  so  that  the  general  disposition  acquired  by  the  seed  in  a 
single  dry  or  wet,  or  cold,  or  early,  or  late  season  prepares  it  for  a 
corresponding  dry  or  wet,  cold,  early,  or  late  season  next  year.  Or, 
again,  a  "  sport "  that  has  unexpectedly  developed  under  the  special 
influence  of  a  given  season  and  soil,  and  has  acquired  to  a  high  degree 
characteristics  which  make  it  harmonize  with  that  season,  becomes 
the  progenitor  of  some  important  variety  whose  adoption  may,  in  a 
few  years,  revolutionize  the  agriculture  of  that  region.  The  weather 
of  any  growing  season  affects  the  crops  of  future  years  by  modifying 
the  seeds  of  the  current  crop.  The  current  season  and  the  resulting 
seeds  must  harmonize  together. 

(2)  If,  instead  of  adapting  the  plant  to  the  climate,  we,  for 
instance,  plant  the  seeds  proper  for  a  moist  climate  in  an  arid  region, 
and  if  we  must  therefore  artificially  irrigate  in  order  to  secure  a 
crop,  such  irrigation  should  be  looked  upon,  not  as  establishing  an 
expensive  custom  to  be  adhered  to  in  future  ages,  but  as  simply  a 
temporary  device  to  be  managed  in  the  interests  of  the  evolution  of 
new  varieties  that  can  eventually  be  cultivated  in  that  soil  and  cli- 
mate without  irrigation.  This  is  the  result  that  nature  has  herself 
frequently  achieved  by  the  slow  process  of  carrying  seeds,  step  by 
step,  from  moist  to  arid  regions,  and  which  man  endeavors  to  hasten 
when  he  carries  seeds  by  railroad  and  steamship  from  England  to 
our  arid  region. 

(3)  Inasmuch  as  the  cultivation  of  the  cereals  cotton,  tobacco, 
sugar,  and  other  important  crops  will  hardly  be  attempted  except  in 
regions  where  the  climate  is  known  to  be  reasonably  in  harmony  with 
the  seed  that  is  planted,  therefore  we  may  assume  that  an  average 
crop  is  certain  under  the  average  climatic  conditions.  The  departure 
of  any  special  season  as  to  climate  will  produce  a  corresponding 
departure  as  to  crop,  but  the  latter  must  be  expressed  as  a  percentage 
of  the  average  ordinary  crop,  and  not  simply  in  absolute  measure, 


363 

as  bushels  or  pounds,  since  the  absohite  crop  depends  so  much  upon 
the  soil,  the  manuring,  the  cultivation,  the  thickness  of  seeding,  and 
other  details.  On  the  other  hand,  the  crop  of  one  season  must  have 
some  relation  to  the  crop  of  the  preceding  season  by  reason  of  the 
inherited  tendencies  of  the  seed  from  which  it  was  raised.  The  cli- 
,,     „  rainfall  or  useful  moisture        ,  rainfall  or  nutriment 

matic  factors  te.,,perature^.Fh^ ^"^  ^iTH^hi^  " 

are,  as  shown  by  Linsser,  the  data  that  must  be  compared  with  the 
resulting  harvests. 

(4)  It  is  evident  that  the  (juestion  of  the  effect  of  climate  on  a 
given  crop  in  the  past  is  not  so  important  as  the  prediction  of  what 
crop  will  be  harvested  from  a  given  field  already  planted.  On  this 
point  I  have  given  all  the  illustrations  that  I  could  find,  especially 
in  Chapter  XII,  showing  how  from  an  analysis  of  a  sample  at  any 
given  date  one  should  be  able  to  predict  the  resulting  crop.  The 
result  can  be  made  correct  to  within  10  per  cent,  if  we  allow  for  the 
ordinary  average  irregularities  of  the  clitnate,  a  statement  of  whose 
extent  can  easily  be  made  up  from  meteorological  records.  As  to 
extraordinary  irregularities  of  climate  w^hich  can  not  be  foreseen,  I 
remark : 

(a)  First  of  all  the  effects  of  excessive  droughts  at  each  stage  of  the 
plant  can  be  estimated  from  the  experimental  data  given  in  Part  I, 
and  will  be  found  to  harmonize  as  well  as  could  be  expected  with  the 
results  of  actual  experience  as  given  in  Part  II : 

(h)  The  effect  of  severe  unusual  droughts,  or  heat,  or  cold,  or  mois- 
ture are  ordinarily  felt  over  relatively  small  portions  of  the  country, 
so  that  the  average  result  is  small  in  comparison  with  the  whole 
crop  available  in  the  country;  for  instance,  in  1890,  in  Kansas 
and  Nebraska  the  corn  harvest  was  one-half  of  its  usual  amount  and 
almost  the  same  in  1887,  reckoning,  of  course,  the  yield  per  acre, 
but  this  and  the  corresponding  small  yields  in  a  few  other  States 
represent  only  an  inapiireciable  percentage  of  loss  to  the  country  at 
large. 

(5)  The  studies  of  the  effect  of  climate  on  the  daily  development 
of  sugar  in  beets,  sugar  cane,  or  sorghum,  or  on  the  nutritious  harvest 
of  grass  and  cereals  has  shown  the  approximate  best  dates  for  harvest- 
ing these  crops. 

(6)  The  studies  of  the  j^hysiological  importance  of  the  leaves  of 
beets  will  eventually  show  whether  these  should  be  trinnned  or  how 
they  should  be  treated  in  order  to  stimulate  the  production  of  sugar. 
As  the  pruning  of  hop  vines  and  grapevines  stimulates  the  ripen- 
ing and  increases  the  amount  of  the  crops,  and  as  the  plucking  of 
the  tassels  from  the  maize  apparently  increases  that  crop,  and  as  the 
plucking  of  the  flowers  and  balls  from  the  potato  vines  increases  the 
growth  of  the  tubers,  so  doubtless  in  many  other  ways  the  methods  of 


564 

cultivation  may  be  made  to  simulate  the  effects  of  a  favorable  climate, 
so  that  in  general  we  are  justified  in  the  conCltisiori  tMt-'^thile  unculti- 
vated plants  and  their  fruits  are  wholly'd't^ii^n'cWn^'dn  the  weather, 
yet  methods  will  be  found  by  which  we  ma}"  r^td'^r  the  harvests  from 
cultivated  j^lants  largely  independent  of  the  weather. 

(7)  The  data  here  collected  demonstrate  that  the  richness  of  the 
soil  determines  the  amount  of  the  annual  cereal  crop  more  than  does 
the  climate.  The  latter  determines  principally  the  dates  of  sowing, 
ripening,  and  the  immunity  from  early  or  late  frosts  or  the  possi- 
bility of  bringing  the  plant  to  maturity. 

(8)  We  see  that  rain  or  irrigation  water,  so  necessary  as  the 
medium  for  bringing  the  nitrogenous  molecules  from  the  soil  up 
into  the  seed  cells  of  the  plant,  also  by  drainage  and  seepage  carries 
away  any  such  molecules  if  these  are  present  as  earths  or  manures, 
whereas  if  these  are  present  in  living  microbic  or  rotting  leguminous 
cells  they  are  far  more  available  for  plant  use.  The  best  method  by 
which  the  nitrogen  of  the  free  air  is  thus  made  available  for  agricul- 
ture is  elaborated  in  chapters  VIII  and  IX. 

(9)  From  the  data  now  at  hand  I  should  say  that  the  yield  per 
acre  for  any  one  of  the  ten  principal  crops  whose  statistics  are  here 
given  has  probably  never  been  either  increased  or  diminished  by  50 
per  cent  of  the  normal  yield  per  acre  by  climatic  influences  alone 
over  any  large  region,  such  as  100  square  miles,  and,  further,  that  the 
total  annual  harvest  for  any  given  crop  in  the  United  States  is  not 
likely  to  be  diminished  5  per  cent  by  the  occurrence  of  an  inclement 
season  in  some  one  portion  of  the  country. 

The  detailed  comparison  of  the  climate  for  each  season  with  the 
crop  for  that  season  has  become  practicable  to  me  only  since  complet- 
ing the  table  of  statistics  in  this  chapter,  and  it  is  as  yet  too  soon  to 
anticipate  all  the  results  that  will  follow  therefrom. 

Note. — As  these  statistical  tables  are  very  voluminous  and  only 
extend  to  the  year  1890  their  publication  has  been  deferred  until  they 
can  be  brought  up  to  date.  They  will  probably  form  a  continuation 
of  this  present  text. — C.  A. 


PART  IV. 


Chapter  XIV. 

CATALOGUE  OF  PERIODICALS  AND  AUTHORS  REFERRED  TO  IN 
THIS  REPORT  BY  MERELY  aUOTING  THE  AUTHORS'  NAMES 
AND  THE  DATE  OF  PUBLICATION. 

Abbott.  Helen  C.  De  S.     Plant  analysis  as  an  applied  science.     Journal  of  the 

Franklin  Institute,  1887.     Vol.  CXXIV.  pp.  1-33. 
The  chemical  basis  of  plant  forms.     Journal  of  the  Franklin  Institute, 

1887.     Vol.  CXXIV.  pp.  161-185. 
Agricultural  Experiment  Station,  Amherst,  Mass.     Eighth  Annual  Report  of 

the  Board  of  Control.     Boston,  1890. 
Agricultural  Science.     A  monthly  periodical.     Charles  S.  Plumb,  ed.     Vol.  I, 

Geneva,  N.  Y.,  1887;  Vol.  II.  Kuoxville,  1888;  Vol.  Ill,  Knoxville,  1889;  Vol. 

IV,  Knoxville,  1890 ;  Vol.  V,  Lafayette,  Ind.,  1891. 
Andre,  Ch.     Influence  de  I'altitude  sur  la  temperature.     Lyon,  1880? 
•Ingot,  Alfred.     Etude  sur  la  luarche  des  phenomenes  de  la  vegetation  en  France 

pendant  les  annees   1880  et   1881.     Annales  du   Bur.   Cent   Met.   de  France, 

annee  1882,  Tome  I.     Paris,  1884. 
Etude  sur  la  marche  des  phenomenes  de  la  vegetation  et  la  migration 

des  oiseaux  en  France  pendant  les  annees  1882  et  1883.     Annales  du  Bur. 

Cent.  Met  de  France,  annee  1884,  Tome  I.     Paris,  1886. 
fitude  sur  la  marche  des  phenomenes  de  la  vegetation  et  la  migration 

des  oiseaux  en  France  pendant  les  annees  1884  et  1885.     Annales  du  Bur. 

Cent.  Met  de  France,  annee  1880.  Tome  I.     Paris,  1888. 
Etude  sur  la  marche  des  phenomenes  de  la  vegetation  et  la  migration 

des  oiseaux  en  France  pendant  les  annees  1886  et  1887.     Annales  du  Bur. 

Cent  Met  de  France,  annee  1888.  Tome  I.     Paris.  1890. 
Anontmous.     Climate  of  Massachusetts.     The  Gardeners'   Chronicle.     London, 

1842. 
AssMANN.  R.     Ueber  die  Mitwirkung  von  Rauhreif  und  Glatteis  bei  der  Abtra- 

gung  von  Gesteinmassen  in  den  Gebirgen.     Naturw.  Rundschau,  1887.  Nr.  47, 

S.  421-423.     Wollny,  X.  p.  .388. 
Atwater,  W.  O.     Experiment  Station  Record,  Department  of  Agriculture.     Vol. 

I,  1889,  and  Vol.  II,  1891. 
Augustin,  F.     Ueber  die  jiihrliche  Periode  der  Richtung  des  Windes.     Separat- 

abdruck    a.    d.    Sitzungsber.    d.    k.    Biihm.    Ges.    d.    Wissensch.,    Prag,    1886. 

Zweiter  Theil,  1887.     Wollny,  X,  p.  460. 
Aymonnet.     Actinometry.     Deherain.    Annales    agronomiques.    1878.    Tome    IV, 

r*.  ""'>,  and  second  note,  p.  451.     Translated  by  C.  Abbe,  Annual  Report  Chief 

i>>-^i   il  Officer,  1881,  p.  1200. 
Bakk.   K.  F.  von.  und  IIelmersen.  G.  von.     Beitriige  zur  Kenntniss  des  Russi- 

s.  ii.  ,    Reiches.     Bd.  L-VIII. 
.  !i'      Reiches.     Bd.  I-VIII. 

(365) 


366 

Baby,    De.     Du   dcveloppeinent   des   champignons   parasites.     Ann.   d.   sc.    nat., 

1863.  4<'  serie,  Tome  XX,  pp.  39-40. 
Bastian.     Ideen  zu  einer  psychologischen  Weltanschauung. 
Becker,    J.     Untersuchungen    iiber    die   Zeit    der    Bliithe-Entwickelung    in    der 

Gegend  von  Tiibingen.     Tiibingen,  1831. 
Becquerel,  E.  and  H.     Temperatures  du  sol  et  de  I'air  observees  au  Museum 
d'Histoire  naturelle  pendant  I'aunee  1881-82.     Annales  du  Bur.  cent.  Met.  de 
France,  aunee  1882,  Tome  I,  Paris,  1884. 
Belhomme.     De  la  germination.     Brochure  sans  date,  offerte  le  10  novembre 

1854  a  la  Societe  botanique. 
Berendt,    G.     Der    Fohn.     Ein   Beitrag   zur   orographischen    Meteorologie    und 

comparativen  Klimatologie.     Gottingen,  1886.     Wollny,  X,  p.  2.59. 
Bernard,  Claude.     Legons  sur  les  phenomenes  de  la  vie  communs  aux  animaux 

et  aux  vegetaux.     1878,  passim. 
Bert,  Paul.     La  pression  barometrique.     pp.  486,  848.     Paris,  1878. 

Legons  sur  la  physiologle  comparee  de  la  respiration,     p.  .507. 

Berthelot.     Essai  de  mecanique  chimique,  fondee  sur  la  thermo-chimie.     Tome 

II,  p.  20. 
Berthelot,  M.  P.  E.     Ueber  die  directe  Fixirung  des  gasformigen  Stickstoffs 
der  Atmosphare  durch  den  Ackerboden.     Comptes  rendus.  Tome  CIV,   1887, 
Nr.  4,  pp.  205-209  (und  Biedermann's  Centralblatt  f.  Agriculturchemie,  1887, 
Heft  V,  S.  301).     Wollny,  X,  p.  205. 
Bertholon,  Uabbe.     Les  effets  de  I'electricite  artificielle  et  naturelle  appliquee 

aux  vegetaux.     Journal  de  physique  de  Rozier,  docembre  1789,  pp.  402,  403. 
Birner,  II.     Wochenschrift  der  Pommerschen  okonomischen  Gesellschaft,  1881, 

Nr.  3,  8,  18.     Wollny,  X,  p.  160. 
BoiTARD.     Journal  de  la  Societe  d'agronomie  pratique,  p.  316.     1829.     Bull.  sc. 

agron..  Tome  XIII,  p.  310. 
Bonnier,  G.,  et  Flahaut,  Ch.     Sur  les  variations  qui  se  produisent  avec  la 
latitude  dans  une  meme  espece  vegetale.     Bull,  de  la  Soc.  hot.,  seance  du  13 
decembre  1878.  pp.  300-306,  et  An.  sc.  nat.,  G^  serie,  1879,  Tome  VII. 
Borodin.     Melanges  biologiques,  tires  du  Bull,  de  I'Acad.  sci.  de  St.-Petersbourg, 

1867.     1867,  Tome  VI,  and  1869,  Tome  XIII. 
BoRZL     Nota  alia  morfologia  e  biologia  delle  Alghi  ficocromacea.     Nuovo  Gior- 

nale  botanico  italiano,  A'ol.  X,  No.  3,  pp.  236-289. 
Boussingault.     C.  R.  Ac.  Sc,  24  Avril,  Paris,  1876. 

Boussingault,  J.  J.  B.  D.     Economie  rurale  consideree  dans  ses  rapports  avec 
la  chimie,  la  physique  et  la  meteorologie.     1st  ed.,  8°,  Paris,  1837;  2d  ed., 
8°,  Paris,  1844. 
Brandis.     Regen  und  Wald  in  Indien.     Meteor.   Zeitschrift,   Bd.   IV,   1887,   S. 

369-376.     Wollny,  X,  p.  447. 
Brefeld,  O.     Botanische  Zeitung,  Nos.  24  and  25,  1877.     (A  la  societe  des  amis 

des  sciences  naturelles  de  Berlin.) 
Brewer,  W.  II.     Report  on  the  cereal  production  of  the  United  States.     Tenth 

Census,  Washington,  1883. 
Briem,  H.     Der  Einfluss  des  Regens  auf  die  Riibenernte.     Die  deutsche  Zucker 

Industrie,  1883,  Nr.  43,  S.  1074.     Wollny,  X,  p.  246. 
Brongniart,  Ad.     Note  faisant  suite  au  travail  de  Ch.   Morren.     Ann. 

nat.  Tome  XXVII,  1st  series,  1832. 
Bunsen.   R.,   and  Roscoe,   H.   E.      Photochemical    researches.     Part    I,     '  li.K 
Trans.,  London,   1857,  p.  355 ;   Part   II,   Phil.  Trans.,   London,   1857,  p       ■  ■ 
Part  III,  Phil.  Trans.,  London,  1857.  p.  601:  Part  IV,  Phil.  Trans.,  If- 
879 ;  Part  V,  Phil.  Trans.,  London,  1863,  p.  139. 


367 

Bi-KCKii.vRDT.     Friedr.     Ubev    (lie     Bestiinuiung    ties     Vogotationsnullpunktes. 

1 1858. 1     Verbandl.  il.  naturf.  Gesellscb..  Basel,  1860,  Vol.  II,  pp.  47-G2. 
BiRMEisTER.     Reise  (lurch  die  La  Plata-Staateu. 
Candolle.  a.  p.  de.     Du  mode  d'actiou  de  la  chaleiir  sur  les  plantee,  et  eu  i>ar- 

ticulier  de  I'effet  des  rayons  solaires.     Bibl.  uuiv.,  Archives  sci.,  Geneve,  1850. 
De  la  germination  sous  les  degres  divers  de  temperature  constaute.     Bi- 

blioth.  univ.  et  Revue  Suisse,  Tome  XIV,  pp.  243,  282.     1805. 

Geograpbi(iue  botanique. 

Pliysiologie  vcgi'tale.     Paris,  1832. 

Sur  la  duree  relative  de  la  faculte  de  germer  dans  les  graines  appartenant 

a  diverses  families.     Ann.  d.  sc.  naturelles,  serie  (3B),  Vol.  VI,  Paris,  1850, 

p.  373. 
— Tableaux  de  la  duree  de  la  germination  de  863  especes  observees  dans  le 

Jardin  botanique  de  Geneve.     (In  A.  P.  de  Candolle,   Physiologic  vegetale, 

Paris,  1832,  Vol.  II,  pp.  640,  (Vlt!. 
Carpmael,  C.     Report  of  the  Meteorological  Service  of  the  Dominion  of  Canada 

for  the  year  ending  December  81 ,  1887.     Ottawa,  1890. 
CoHN.     Symbola  ad  seminis  physiologiam.     Inaug.  diss.,  8°,  Berlin,  1847. 
Committee,  Senate.     Report  of  the  Special   (Select)   Committee  of  the  United 

States  Senate  on  the  Irrigation  and  Reclamation  of  Arid  Lands.     Report  928, 

Fifty-first  Congress,  first  session,  Washington,  1890.     Part  1,  reports — major- 
ity and  minority ;  part  2,  testimony,  "  The  Northwest ;  "  part  3,  testimony, 

"  The  gold  region  of  California ;  "  part  4,  testimony,  "  Rocky  Mountains  and 

Great  Phiins ;  "  part  5,  Miscellaneous ;  Part  6,  R.  J.  Iliuton,  special  agent  on 

artesian  wells. 
("oTTE,  P.  Traite  de  meteorologie,  pp.  222,  237,  389,  457.     Paris,  1774. 
Darwin,  Ch.    Des  effets  de  la  fecondation  croisee  et  directe,  etc.     Trad.  Heckel, 

1877,  Chap.  I,  p.  13. 
DEHfiRAiN,  P.  P.     Annales  agronomiques.  Vols.  I-XVII,  Paris,  1875  to  1891. 
Deh^rain   et  MoissAN.     De   la   vegetation  dans   I'obscurite.     An.   d.   sc.   nat, 

1871,  5  series.  Tome  XIX,  p.  329  et  suivantes. 
Loiseleuk-Deslongchamp.     Les  cereales,  pp.  208-219,  359.     Paris,  1842. 
Detmer,  W.     Ueber  die  Einwirkung  niederer  Temperaturen  auf  die  Pflanzen, 

Botan.  Centralblatt  von  O.  Uhlworm,  Bd.  XXIX,  1887,  S.  379.     Wollny,  X,  p.  235. 
Detmer,    W.     Vergleichende    Physiologie   des    Keimungsprocesses    der    Samen. 

.Tena,  1880. 
Dove,   H.    W.     Ueber  den   Zusammenhang  der   Temperaturveriinderungen   der 

Atmosphare  und  der  oberen  Erdschichten  mit  der  Entwickelung  der  Pflanzen. 

PoggendorfC's  Annalen,  1846,  Vol.  LXVIII,  p.  224. 
Duchartre,  Professeur.     Elements  de  Botanique.     p.  809.     2"  ed.,  1877. 
DuHAMEL  DU  MoNCEAU,  Henri  Louis.     Elements  d'Agriculture.     2  vols.,   12°. 

1754. 
Dumas.    M.      Recherches  sur   la    fermentation   alcoolique.      Ann.    de   Chim.    et 

de  Phys..  Vf  series.  Tome  III.  p.  10.5. 
Dutrociiet.     Nouv.  Arch,  du  Museum,  Tome  III,  p.  59. 
Ebermayer,  Prof.  Dr.  Ernst.     Die  physikallschen  Einwirkungen  des  Wakles  auf 

Luft  und  Boden.  etc.     Aschaffenburg.  1873. 
Ebermayer,  Theodor.     Die  Lehren  der  Forstwissenschaft.     3''  ed.     Berlin,  1882. 
EinvARDS  and  Colin.     Influence  de  la  Temperature  sur  la  (iermination.     Ann. 

sc.  nat.,  2«  serie,  1834,  Tome  I,  p.  257. 
Edwards.  W.     Traite  de  rinfluence  des  agents  i)hysi(iues  sur  la  vie.     1824. 
Erman,    G.    Adolph.     P>eitrage    zur    Kliniatologie    des    Russischen    Reiches. 

Ermans  Archiv,  Vols.  I,  IV,  VI,  IX,  XII,  XV.     1841-1856. 


368 

Ebman,  G.  Adolph.     Reise  in  Siberien.     Berlin,  1828. 

Ueber     einige     periodischen     Ersclieinungeu     der     organischen     Natur. 

Erman's  Archiv,  Vol.  IV,  p.  G17,  and  VIII,  1849,  pp.  105-115. 

Faivbe.  Le  latex  dui'ant  revolution  germinative  du  Tragopogon  porrifolius, 
eflfectuee  dans  des  conditions  diverses  de  milieu  exterieur. 

Famintzin.  Ann.  sc.  nat.,  5*  serie,  Tome  VII,  p.  203,  et  Bull  de  I'Acad.  des  sc. 
de  St.-Petersbourg,  1866,  Tome  VI,  pp.  162-171. 

Ferbel,  W.  Temperature  of  the  atmosphere  and  the  earth's  surface.  Profes- 
sional Paper  of  the  Signal  Service,  No.  XIII.     Washington,  1884. 

Recent  advances  in  meteorology.     Report  of  the  Chief  Signal  Officer  for 

1885.     Part  II,  pp.  375-380.     Washington,  1885. 

On  certain  measures  of  the  intensity  of  solar  radiation.     Am.  Jour,  of 


Science,  series  III,  No.  CXLI,  Vol.  XLI,  May,  1891,  p.  378. 
Fittbggen,   J.     Landw.   Jahrbiicher,   II.   Jahrgang,    1873,    S.   353.     Wolluy,   X, 

p.  158. 
Flahaut,  Ch.     Nouvelles    observations    sur    les    modifications    des    vegetaux 

suivant  les  conditions  physiques  du  milieu.     Ann.   Sc.  Nat.,  5   Series,  1868, 

Tome  IX,  Nos.  2  et  3,  p.  159. 

Sur   la   presence  de   la   matiere   verte  dans   les   organes   actuellement 

soustraits  k  I'influence  de  la  lumiere.     Bull.  Soc.  Bot,  1879,  p.  229. 

Fleischeb.     Beitrage  zur  Eehre  vom  Keimen  der  Samen.     S.  31.     1851. 
Fbank.     Bot.  Zeitg.,  cited  by  J.  Sachs  (Physiol,  veget). 

Fbitsch,  K.  (of  Prague  and  Vienna).     Kaleuder  der  Flora  des  Horizontes  von 
Prag  nach  lOjiihrigen  Beobachtungen.     Beilage,  Sitz.-Ber.,  Wien,  1852  (Jan.). 

Instruction  fiir  phiinologische  Beobachtungen  aus  dem  Pflanzen-  und 

Thierreiche.     Wien.  Sitzuugsbericht,  Bd.  XXXVII,  part  2   (1859). 

Phaenologische  Untersuchungen.     Wien.  Sitz.-Ber.,  1866,  Vol.  LIII,  part 


2,  p.  264. 
Reisebilder    von    den    Canarischen    luseln.     Petermann,    Geog.    Mitth., 


Ergjlnzungs-Band  V,  Heft  22.     Gotha,  1867. 
Resultate  mehrjiihriger  Beobachtungen  iiber  die  Belaubung  und   Ent- 


laubung   der   Baume   und    Striiuche   im    Wiener   botanischen    Garten.     Sitz.- 
Ber.,  Wien,  1861,  Vol.  XLIII,  part  2.  p.  81. 
Thermische  Constanten  fiir  die  Bliithe  und  Fruchtreife  von  889  Pflan- 


zenarten,  abgeleitet  aus  zehnjahrigen  Beobachtungen  im  Iv.  k.  Botanischen  Gar- 
ten zu  Wien.  Wien.  Denkschriften,  1861.  Abstract  in  Wien  Sitzuugsbericht, 
Vol.  XXV,  part  2,  pp.  711-718. 

Untersuchungen  iiber  das  Gesetz  des  Einflusses  der  Lufttemperatur  auf 

die  Zeiten  bestimmter  Entwickelungsphasen  der  Pflanzen.  mit  Beriicksichti- 
gung  der  Insolation  und  Feuchtigkeit.  Wien.  Denkschriften,  1857.  Abstract 
in  Wien  Sitzuugsbericht,  Vol.  XV,  part  2,  pp.  240-250. 

Vergleichung  der  Bliithezeit  der  Planzeu  in  Nord-Auierika  niit  Europa. 

Wien.  Sitz.-Ber.,  1871,  Vol.  LXIII,  part  1. 

Feitz,  H.     Die  wichtigsten  periodischen  Erscheinungen  der  Meteorologie  und 

Kosmologie.      Internationale    wissenschaftliche    Bibliothek.    Baud    LXVIII. 

Leipzig,  1889. 
Dir  Perioden  der  Weinertrage.     pp.  671-686.     Vol.  X,   1881,  H.  Thiel's 

Zeitschrift  fur  Wissenschaftlicher-Landwirthschaft. 
Gabbeau.  Ann.  d.  Sci.  Nat.,  serie  3,  Tome  XV,  1851. 
Gasparin,  Comte  de.     Cours  d' Agriculture,  Tome  I,  II. 

Elements  de  Botanique.     2"  M.,  p.  799. 

Gbandeau.     La  nutrition  de  la  plante.    p.  403. 

Gbassmann,    P.     Einfluss   des    Regens   auf   die   Riibe.     Zeitschrift   f.    Zucker- 

industrie,  1887,  37,  S.  247.     Wollny,  X,  p.  247. 


369 

Gray,  Asa.     Manual  of  the  Botany  of  the  Xortliorii  United  States.     r)tli  ed.,  2t) 

pi.     New  York  and  Chicago.  1880. 
Gray.  Asa.  Watson.  Sekeno,  and  C'ori/rKK.  John  M.     Manual  of  the  Rotany  of 

the  Northern    United   States.     0th  ed..   700   pp..   S°.   LM   pi.     New    York   and 

Chicago.  1890. 
Greenwich  Observatory.     Reduction     of     Photographic     Records,     1847-1873. 

London.  1878. 
Grisebach.  a.     Berlcht  iiber  die   Leistungen   in  der   I'ttanzen-Geographie  und 

systematischer  Botanik  wiihrend  das  Jahr  1847.     Berlin,  1850. 
GuNTZ.  H.  E.  M.     Untersuchungen  iiber  die  anatomische  Struktur  der  Granii- 

neenblatter  in  ihreni  Verhaltniss  zu  Standort  und  Klima.     Inaugural-Disser- 
tation.    Leipzig,  1886.     Wollny.  X.  p.  2.34. 
Kaberlandt,   F.     Centralblatt  fiir  die  gesammte   Landescultur,    1800,   Nos.    11 

and  12. 
Der    landwirthschaftliehe    Pflanzenbau.    5.    number,    p.    397.     Cited    by 

Grandeau. 

Oesterr.  landw.  Wochenblatt.  1875.  No.  30,  S.  352.     Wollny.  X,  p.  159. 

Zentralblatt  fiir  die  gesammte  Landeskultur,  1860.  S.  345.     Wollny,  X,  p. 

155. 
Halder.  F.  a.     Beobachtungen  iiber  die  Temperatur  der  Vegetabilien.     Tiibin- 

gen,  1820. 
Kammoxd.  H.     Report  on  the  Cotton  Production  of  the  State  of  South  Carolina. 

Tenth  Census,  U.  S.     Washington.  1884. 
Haughton.  Samuel.     New  Researches  on  Sunheat.  Terrestrial  Radiation,  etc. 

Parts  I-III,  Dublin,  1881. 
Heckel.  Edouard.     De  Taction  des  temperatures  elevees  et  humides  sur  la  ger- 
mination de  quelques  graines.     Comptes  rendus  Acad,  sciences,  juillet  1880. 
Heiden.     Abhandlung  iiber  das  Keimen  der  Gerste.     S.  45.     1859. 
Heinrich,  R.     Anualen  des  Mecklenb.  patriotischen  Vereins.  u.  F.,  1870,  Nr.  7. 

E.  Wollny,  X,  p.  101. 
Hellmann.     G.     Beitriige    zur     Statistik     der     Blitzschlage     in     Deutsehland. 

Zeitschrift  d.  k.  preuss.  statist.  Bureaus,  1886,  S.  177-190.     Wollny,  X,  p.  254. 
Hellriegel,  H.     Beitrage  zu  den  uaturwissenchaftlichen  Grundlagen  des  Acker- 

baues.     Braunschweig,  1883.     Wollny.  X,  p.  157. 

Landw.  Zentralblatt  fiir  Deutsehland,  1871,  II,  S.  194.     Wollny,  X.  p.  157. 

Hempel,  W.     Ueber  den   Sauerstoffgehalt  der  atmosphiirischen  Luft.     Ber.  d. 

Deutsch.  chem.  Ges..  1887,  Bd.  XX.  s.  1804.     Wollny,  X.  p.  450. 
Heraeus.  W.     Ueber  reduzirende  und  oxydirende  Eigenschaften  der  Bakterien. 

Zeitschrift  fiir  Hygiene,  Bd.  I.  1880,  S.  211-232.     Wollny,  X,  p.  207. 
HiLGARD,  E.  W.     Report  on  the  Cotton  Production  in  the  United  States.     Tenth 

Census  (1880),  U.  S.,  Vols.  V,  VI.     Washington,  1884. 
Hoffmann,   Professor.     Comparative   Phenological   Chart   for   Central    Europe. 

Petermann's  Geog.  Mitth.,  1881. 

Phaenologische  und  thermische  Constanten.     Zeit.  Ost.  Ges.  Met.,  1868. 

Ill,  p.  93;  1809,  IV,  pp.  208,  392,  553;  1875,  X,  p.  250;  1881,  XVI,  p.  159,  330; 
1882.  XVII,  pp.  121,  457.  Met.  Zeit..  1884.  I,  p.  407;  1885.  II,  p.  455;  1886, 
III,  pp.  113,  540 ;  1887,  IV,  p.  129. 

Phanologische    Beobachtungen    aus    den    Jahren    1879-1882.     in    Ihne    & 

Hoffmann  Beitrage  zur  Phiinologie,  Giessen,  1884. 

Phanologische  Untersuchungen.     Gies.sen,  1887.     Wollny,  X,  p.  402. 

Witterung  und  Wachsthum.     1857,  p.  525,  etc. 

Humboldt,  A.  von.     Aphorismen.     Deutsch  von  Fischer,  S.  90.     1794. 

Cosmos,  Vol.  I,  pp.  347-349.     1845. 

Hunt.     Bot.  Zeitg.,  1851,  p.  304.     Also,  pp.  203,  270,  303,  450. 
2667—05  M 24 


370 

Ihne.  Egon.    Geschichte  der  Pflauzen ;  pbiiuologiscbe  Beobachtungen  iu  Europa, 

iiebst  Verzeicbuiss  der  Scbriften,  in  welcben  dieselben  niedergelegt  sind.     In 

Ibne  and  Hoffmann,  Beitrage  zur  Pbiinologie.     Giesseu,  1884. 
Ilienkoff.     Annalen  der  Cbemie  uud  Pbarmacie,  Bd.  136,  p.  160.     Wolluy,  X, 

p.  154. 
Ingenhousz.     Experience  de  la  vegetation.     Traduit  de  I'auglais  par  I'auteur. 

2  vols.,  1787-1780.     1st  Englisb  ed.,  1787. 
International   Meteorological   Committee.     Tables   meteorologiques    Interna- 
tionales.    Paris,  1890. 
Jager.  O.     Der  Nordpol,  ein  tbier-geograpbiscber  Centrum.     Petermann's  Geog. 

Mittb.,  Ergjinzungs-Band  IV,  Heft  16. 
Johnston,  Jas.  F.  W.    Tbe  cbemistry  of  common  life.    New  ed.,  by  A.  H.  Cburcb. 

New  York,  1880. 
JouLiE.     Etude   sur    la    culture   du    ble.    Revue   des    industries   cbim.    et   agric. 

Paris,  1882. 
JussiEU,  A.  DE,  et  Brongniart,  Ad.     Comptes  Rendus  Acad.  Sci.,  Tome  XXXI, 

p.  876. 
Kabsch,  W.     Ueber  die  Vegetationswiirme  der  Pflanzen  und  die  Metbode  sie 

zu  berecbnen.    Flora,  1863,  XLVI,  pp.  520,  545,  566. 
Katzerowsky.      Periodizitat     der     Ueberscbwemmungen.      Mittb.    d.    Ver.    f. 

Gescbicbte    d.    Deutscben    in    Bobmen,    XXV.    Jabrg.,    Heft    2.     Prag,    1886. 

Wollny,  X,  p.  259. 
Keith.     A  system  of  pbysiological  botany.  Vol.  II,  p.  5.     London,  1816. 
KiNCH,  E.     Der  Cbloi'gebalt  des  auf  der  meteorologiscbeu  Station  in  Cirencester 

aufgefangenen   Regenwassers.     Journ.    Cbem.    Soc,    Jan.,    1887,    Vols.    L,   LI. 

Wollny,  X,  p.  455. 
KosTLivY,    S.     Ueber   den   Temperaturunterscbied   zwiscben    Stadt   und   Land. 

Aus :  Ueber  die  Temperatur  von  Prag.     Abb.  d.  k.  bobm.  Ges.  d.  Wissenscb., 

(7)  Folge,  II.  Bd.  Prag.  1887.     Wollny,  X,  p.  459. 
Kraus,  C.     Versucbe  iiber  den  Hopfenscbnitt,   angestellt  in  Mittelfranken   im 

Jabre     1886.     Allgemeine     Brauer-     und     Hopfenzeitung.     Niirnberg,     1887. 

Wollny,  X.  p.  236. 
Kreusler,    U.     Beobacbtungen    iiber    die    Koblensaureaufnabme    und     Ausgabe 

(Assimilation   und  Atbmung)    der  Pflanzen.     II.    Mittbeilung:    Abbiingigkeit 

vom  Entwickelungs-Zustande ;  Eintluss  der  Temperatur.     Landw.  JabrJ).,  Bd. 

XVI  (1887),  Heft  5,  p.  711-755.     Wollny,  X,  p.  408. 
Lachmann.     Entwickelung  der  Vegetation  durcb  die  Warme ;  nacb  30jabrigen 

Beobacbtungen     an     24     Pflanzen.     XXX.     Jabres-Bericbt     d.     Scblesiscben 

Gesellscbaft. 
Landolt,  E.     Die  BJicbe,  Scbneelawinen  und  Steinscblage,  und  die  Mittel  zur 

Scbjidigung  durcb  dieselben.     Ziiricb.  1887.     Wollny,  X,  p.  462. 
Lanessan,  ue.     Manuel  d'bistoire  nat.  med.,  1"  partie,  p.  198. 
I;ANG,     C     Die     Vorausbestimmung    des     Nacbtfrostes.     Braunscbweig,     1887. 

Wollny,  X,  p.  259. 
Lavoisier.  Traite  elementaire  de  cbimie,  edit.  Dumas,  Tome  I,  p.  257. 
Leclerc.     Recbercbes  sur   la   germination.     Ann.   de  pbys.   et  de  cbim.,   1875. 

5^  serie,  Tome  IV,  p.  2. 
Lefebure.     Experiences  sur  la  germination  des  plants,  2"  partie,  Cbap.  V,  pp. 

127  et  suivantes.     Strasbourg,  1800. 
Leitgeb,  H.     L'influence  de  la  lumiere  sur  la  germination  des  spores  d'bepati- 

ques.     Sitzber.  der  Akad.  der  Wissenscb.,  XXIV,  1876,  et  Bot.  Zeitg.,  Nr.  22, 

p.  355,  1877. 
LtYEiLLt,  J.  H.     Considex-atious  mycologiques,  etc.,  p.  39. 


371 

Lfivy,   Albekt.     L'actinonif'tre   Ariij;o-I);ivy.     DC'liorain.    Annnles    iigronoiniques, 

1878,  Toiue  IV,  p.  510.     Translation  by  C.  Abbe,  Report  C.  S.  O.,  1881,  p.  1191. 
Levy,  Albert.     Analyse  chinuiiue  de  I'air,  des  eaux   nu'teoriques  et  des  eaux 

courantes.     Annuaire  de   TObservatoire  de  Montsouris,   pp.   180-277.     Paris, 

1887. 
Analyse  chimique  de  I'air  et  des  eaux.     Annuaire  de  I'Observatoire  de 

Montsouris,  pp.  209-355.     Paris,  1889. 
liAWES,  J.  B..  Gilbert,  J.  H..  and  Warington.  R.     On  the  amount  and  composi- 
tion of  the  rain  and  drainage  waters  collected  at  Rothamsted.     .Jouru.  of  the 

Roy.  Agric.  Soc.  of  England.  Vol.  XVII  and  XVII 1 :  1881  and  1882. 
LiNN.i:i.  C.     Philosophia  Botanica.     Stockholmise,  1751. 
Linsser.  Carl.     Die  periodischen  Erscheinungen  des  Pflanzen-Lebens  in  ihrem 

Verhaltniss  zu  den  Wiirme-Erscheiuungen.     Mem.   Acad.   Imp.   St.-Petersbourg. 

(7).  Tome  XI,  18(37. 
Untersuchwugen  iiber  die  periodischen  Lebens-Erscheinungen  der  Pflauzen. 

Zweite   Abhandluug.     Mem.    Acad.    Imp.    St.-Petersbourg.    (7),    Tome    XIII, 

1869. 
LippiNCOTT.  J.   S.     The  geography  of  plants.     Report  of  the  Commissioner  of 

Agriculture  for  1803.  pp.  464-525. 
LoFFELHOLz-CoLBERG.  Friedrich,  Freiherb  VON.     Beitrag  zu  einer  systematisch- 

kritischen  Nachweisung  und  Beleuchtung  der  Literatur  der  Einleitung  in  die 

Forstwissenschaft,    der    Forstgeschichte,    B^orststatistik    und    Forstliteratur. 

Heft  I  (Berlin,  1866),  II,  III,  IV,  V  (Iste  Abth.,  Berlin,  1874). 
LoBEY,  Prof.  Dr.     Handbuch  der  Forstwissenschaft.     Vol.  I.     Tiibiugen,  1888, 
LuKAS,    Fb.     Versuche   iiber   die   Keimung   und   das   Wachsthum    im    luftver- 

diinnten  Raum.  -  Lotos,  Jahrb.  f.  Naturw.,  ueue  Folge,  Bd.  VII,  1885.     Wollny, 

X,  p.  243. 
Malmgren.     Botanische  Uutersuchungen.     Petermann's  Geog.  Mitth.,  1863. 
Maxgon,  Herve.     Des  conditions  climatologiques  des  annees  1860-1879  en  Nor- 

mandie,   et    leur    influence   sur   la   maturation   des   recoltes.     Paris,   Comptes 

reudus,  1879,  Tome  LXXXIX. 
Maqlt:nne,  Mons.     L'azote  atmospherique  et   la  vegetation.     Conference  faite 

a  I'Association  frangaise  pour  I'avaucement  des  sciences,  7  mars  1891.     An- 

nales  agrouomiques,  1891.  Vol.  XVII,  p.  145. 
Mabchand,   Eugene.     Etude  sur  la  force  chimique  contenue  dans  la  lumiere 

du  soleil ;    la  mesure  de  sa  puissance  et  la  determination  des  climats  qu'elle 

caracterise.     Paris,  1875. 
Marie-Davy.     1873.   Annuaire   meteorologique  de   I'Observatoire  physique  cen- 
tral.    1874-1876.  Ann.  Met.  et  Agricole  de  I'Obs.  de  Montsouris.     1877-1887. 

Ann.  de  I'Obs.  Montsouris.     1888-1890.     Ann.  de  I'Obs.  municipal  de  Mont- 
souris. 
:\Iabtens,  Ch.     Du  Spitzberg  au  Sahara.     Paris,  1866. 
Meech,  L.  W.     On  the  relative  intensity  of  the  heat  and  light  of  the  sun  upon 

different   latitudes   of   the   earth.     Smithsonian   Contributions.     Washington, 

1855. 
.Mendenhall,  T.   C.     On  a  differential   resistance  thermometer.     Am.   J.   Sci., 

1855,  III.  series.  Vol.  XXX,  p.  114. 
Meyen.     Neues  System  der  Pflanzen-Physiologie,  Bd.  II,  p.  312.     1837. 
MiDDENDORFF,  A.  K.  V.     Sibcrisclie  Reise. 
MiESSE,  Bernard  Christophe.     Experiences  sur  I'influence  de  la  lumiere  sur 

les  plantes.     Journ.  de  physique  de  Rozier,  Tome  VI,  num^ro  de  d^cembre  1775, 

pp.  445  et  suivantes. 
Milde.     De  Sporarum  Equisitorum  germinatioue.     Dissert,  inaug.  bot.,  1850. 


372 

MoiGNo.     Optique    moleeulaire.     Effets    de    i)recii)itatiou    de    decomposition    et 

d'illumiuation  produits  par  la  lumiere.     Actualites  scientifiques,  Paris,  1873. 
MoLEScHOTT.     Licht    und    Leben.     Discours    d'inauguration     (21    juin    1856). 

Revue  des  cours  scientifiques,  1864-65,  p.  698. 
.MoKOT.     Rechercbes  sur   la   coloration  des   vegetaux.     Ann.    sc.   nat.,   3"   serie, 

1850,  Tome  XIII,  pp.  206,  et  suivantes. 
IMoKREN,  Ch.     Belgique  borticole,  pour  1859-60. 
Communication  sur  Tinfluence  des  rayons  colores  sur  la  germination  des 

plantes.     An  sc.  nat..  1st  series,  1832,  Tome  XXVII,  pp.  201  et  suivantes. 
MiJTTRiCH,    Prof.    Dr.    A.     Beobacbtungen    der    Erdbodeutemperatur    auf    den 

forstlicb-meteorologiscben   Statiouen  in  Preussen,  Braunscbweig  und  Elsass- 

Lotbringen.     Berlin,  1880. 
Neubert.  G.  a.     Die  Tempera tur  des  Erdbodens  in  Dresden.     Abb.  d.  Ges.  Isis 

in  Dresden,  1886.     Wollny,  X,  p.  367. 
Niederhofer.  E.  a.     Ueber  den  Einfluss  des  Bodens  und  des  Klimas  auf  die 

Verbreitung  der  Pflanzeu.     Arbeiten  d.   vSt.  Petersburger  Naturf.  Ges.,  XVI, 

1887.  Heft  I.  p.  415-461.     Wollny.  X.  p.  462. 
Nobbe.     Handbucb  der  Samenkunde,  S.  240. 
NOBBE,  E.,  et  HoENLEiN.     Resistance  des  graines  a   la  germination.     ^Nlemoire- 

analyse  par  Marc-Micbeli.     Bibl.  univ.  de  Geneve,  p.  135,  1878. 
NoRDLiNGER,  Dr.  Theodor.     Dcr  Einfluss  des  Waldes  auf  die  Luft  und  Boden- 

warme.     Berlin,  1885. 
Pasteur,  L.     Observations  Verbales.     Comptes  Rendus,  Acad.  Sci.,  Paris,  1876, 

T.  XXXIII.  pp.  792.  942. 

Etudes  sur  la  biere,  Paris,  1876,  p.  323. 

Pauchon,   a.     Recbercbes   sur   le   Role   de   la    Lumiere   dans    la    Germination. 

Paris,  1880. 
Peschel,  Oscar.     Neue  Probleme  der  vergleicbenden  Erdkunde. 
Petebmann,   a.     Recbercbes  sur   les  graines  originaires  des   bautes  latitudes. 

1877. 
Pfeffer.     Observations    sur    le    Marcbantia    polymorpba.     Arbeiten    d.    Botan. 

Instituts  zu  Wiirzburg,  Bd,  I,  S.  77. 
PiEPER,    Ph.    a.     Das    wecbselnde    Farben-Verbiiltniss    in    den    verschiedeneu 

Lebens-Periodeu  des  Blattes,  etc.     Berlin,  1834. 
PoucHET.  G.     De  I'influence  de  la  lumiere  sur  les  larves  de  Dipteres.     Revue  et 

Magazin  de  Zool.,  2^  serie.  1871,  Tome  XXIII,  p.  110. 
Prillieux,  E.     Sur  les  Mouvements  des  grains  de  cbloropbyll  sous  I'influence 

de  la  lumiere.     Comptes  Rendus,  Acad.  Sci.,  Paris,  1870,  Tome  XX,  p.  46. 
Prixgsheim,  N.     Ueber  Licbtwlrkung  und  Cbloropbyll  Function  in  der  Pflanze. 

Jlonatsbericbt.     Akad.  de  Wiss.,  Berlin,  1879,  pp.  532-546. 

Wollny.     Forscbungen.  1880,  Band  III,  pp.  66-72. 

Pringsbeini.  .Tabrbucb  Botanik,  1882,  Vol.  13,  pp.  177-390. 

Probst,  J.     Klima  und  Gestaltung  der  Erdoberfliicbe  in  ihren  Wec-bsehvirkun 

gen.     Stuttgart.  1887.     Wollny,  X,  p.  402. 
Prohaska,  K.     Zur  Frage  der  Senkung  der  Isotbermenflticben  vor  Gewittern. 

Das    Wetter.     Meteor.     Moutscbrift    von    Assmann,    1886.    S.    169    bis    175. 

Wollny,  X,  p.  259. 
QuETELET,  A.     Sur  le  Climat  de  la  Belgique.     Cbapitre  IV.     Phenomenes  perio- 

diques  des  Plantes.     Annales  de  I'Observatoire,  Bruxelles,  1849. 
Radau,  M.  R.     Actionometrie.     Actualites  Scientifiques,  Paris,  1877. 
La  lumiere  et  les  climats.     Actualites  Scientifiques,  Paris,  1877. 


373 

Rawson.  Sir  li.  W..  Governor  of  Ikirbadoos.  Report  upon  the  Rainfall  of 
Barbadoes  and  upon  its  Influence  on  the  Sugar  Crops,  1847-1871,  with  two 
Supplements.  1878-74.  Barbadoes.  1874.  [The  tabular  data  are  by  Dr.  R.  B. 
Walcott] 

REAUMUR.  R.  A.  F.  DE.  Observations  du  thermometre,  faites  k  Paris  pendant 
I'annee  1785,  couiparees  avec  celles  qui  ont  ete  faites  sous  la  ligne,  a  I'lsle  de 
France,  a  Alger  et  en  quelques-unes  de  nos  isles  de  I'Amerique.  Paris 
^Memoirs.  Acad,  des  Science.  Annee  1735,  p.  545. 

RoscoE.  H.  E.  Bakerian  lecture.  On  a  method  of  meteorological  registration 
of  the  chemical  action  of  total  daylight.     Phil.  Trans.,  London,  1865,  p.  605. 

On  the  chemical  intensity  of  total  daylight  at  Kew  and  Para,  1865,  1866, 

and  18G7.     Phil.  Trans.,  1807,  p.  555. 

and  Thorpe,  T.  E.     On  the  relation  between  the  sun's  altitude  and  the 

chemical  intensity  of  total  daylight  in  a  cloudless  sky.  Phil.  Trans.,  London, 
1870.  p.  309. 

— —  On  the  measurement  of  the  chemical  intensity  of  the  total  day- 
light, made  at  Catania  during  the  total  eclipse  of  December  22,  1870.  Phil. 
Trans.,  London,  1871,  p.  467. 

RozE.  E.  Sur  les  mouvements  des  grains  de  chlorophyll  dans  le  cellules  vege- 
tales.  sous  I'influence  de  la  lumiere.  Comptes  Rendus,  Acad.  Sci.,  Paris,  1870, 
Tome  LXX,  p.  133. 

RoziER,  F.     Diet,  d'agriculture,  art.  Espece. 

Sachs.  J.     Cucurbita  et  Vicia  faba.     Bot.  Zeitg.,  1862,  p.  366. 

Physiologic  vcgctale,  translated  by  Micheli.     Paris,  1880. 

Lectures   on   the   Physiology   of   Plants.     Translated   by   H.    Marshall 

Ward.     Oxford,  1887. 

Ueber  die  Wirkung  der  ultravioletten  Strahlen  auf  die  Bliithenbildung. 

Arbeiten  des  Botan.  Instit.  in  Wiirzburg,  Bd.  Ill,  Heft  3,  S.  372-388.  Wollny, 
X,  p.  229. 

Salkowsky,  E.     Beitriige  zur  Kenntniss  der  Nitrifikations-Vorgiinge.     Chemi- 

sches  Zentralblatt.  1887,  S.  167-168.     Wollny,  X,  p.  211. 
Sakgent,   Chas.    S.     Report  on  the  Forests  of  North   America    (exclusive  of 

Mexico),  with  folio  Atlas.     Tenth  Census  (1880),  U.  S.,  Vol.  IX.     Washington, 

1884. 
Saussuee,     Theodore    de.     Recherches     chimiques     sur     la     vegetation.     1804. 

Chaps.  I  et  IV,  pp.  21-24. 
Saweliew,  R.     Uel)er  die  Aufstellung  der  Thermometer  zur  Bestimmung  der 

Lufttemperatur  und  Feuchtigkeit.     Sapiski  der  Russ.  geogr.  Ges.  St.  Petei's- 

burg,  1887.     Wollny,  X,  p.  259. 
ScHLEiDEN.     Nutrition  de  la  plante  (sur  la  pomme  de  terre),  p.  268. 
ScHMiD,  E.  E.     Lehrbuch  der  Meteorologie.     Leipzig,  1860. 
ScHNETZLER.     Bibl.  uuiv.  de  Geneve,  1874,  Tome  LI,  p.  250. 
SCHOTT,    Chas.    A.     Tables,    distribution,    and    variations    of    the    atmospheric 

temperature    in   the   United   States   and   some   adjacent   parts   of   America. 

Smithsonian  Contributions.     Washington,  1876. 
ScHUEBELER,  F.  C.     Die  Cultur-I'flanzen  Norwegens.     Christiania,  18<)2.  pp.  2(;-.33. 
ScHUTZENBERGER,  P.     Les  fermcutations.     1876,  p.  134. 

Scott,  R.  II.     Elementary  Meteorology.     International   Scientific  Series.     Lon- 
don, 1883. 
Senebieb,  Jean.     Memoires  physico-chimiques,  1782,  Tome  III,  p.  321. 

Physiologic  vegetale,  1800,  Tome  III,  p.  396. 

Seynes,  de.     De  la  Germination,  8°,  Paris,  1863,  p.  22. 


374 

Singer,  Carl.     Die  Bodentemperatureu  an  der  k.  Sternwarte  bei  Miincbeu.  iind 

der   Zusammeuhang   ihrer    Schwankungen   mit   den   Witterungsverluiltuisseu. 

Beob.  Bayern,  XI,  1889. 
Smithsonian.     Tables,   Meteorological   and  Physical.     By   A.   Guyot  and  Wm. 

Libbey,  jr.     Washington,  1884. 
SoRAUER,  P.     Botan.  Zeitung,  1873,  Nr.  10.     Wollny,  X,  p.  171. 
Spencer,  Herbert.     Principes  de  Biologie.     Trad.  Gazelles,  Tome  I,  p.  257. 
Sporer,  J.     Novaja-Zembla  in  geographischer  und  volkswirthschaftlicher  Bezie- 

hung.     Peterinann's  Geog.  Mitth.,  Erganzungs-Band  V,  Heft  21.     1867. 
Stoklasa,   J.     Gehalt  der  atmosphariscben   Niederscblage  an  Ammoniak  und 

Salpetersjiure  im  Jabre  188.3  und  1884.     Biedermann's  Zeutralblatt  fiir  Agri- 

kulturchemie,  1887,  S.  361.     Wollny,  X,  p.  454. 
Sturtevant,  E.  L.     Influence  of  isolation  upon  vegetation.     Proc.  Am.  Assoc. 

Adv.  Science,  Vol.  XXXIII.     Philadelphia,  1884. 
Van  Tieghem,  M.     Cours  au  Museum,  1879. 

Observations  sur  la  legerete  specifique  de  quelques  legumineuses..     Ann. 

sc.  nat.,  1874,  6«  serie,  I,  p.  383. 

et  Bonnier,  G.     Recberches  sur  la  vie  ralentie  et  sur  la  vie  latente. 

Bull.  Soc.  bot.  de  France,  Tome  XXVII,  p.  117  et  suivantes. 

Traite  de  Botanique. 


Thomson,  C.  Wyville.     Les  Abimes  de  la  Mer.     Avant-propos  par  Lortet,  p.  1. 
Les  Abimes  de  la  Mer,  p.  38,  et  Voyage  of  the  Challenger,  1877,  Volume 

III,  p.  338. 
Thuret.     Recberches  sur  la  fecondation  des  Fucacees.     Ann.   des  sc.  nat,  4" 

serie,  1854,  Tome  11,  p.  197. 
Timiriazeff,  K.  a.     Sur  la  decomposition  de  Tacide  carbonique  dans  le  spectre 

solaire  par  les  parties  vertes  des  vegeteaux.     Comptes  Rendus,  Acad.   Sci.. 

Paris,  1877,  Tome  LXXXIV,  pp.  1236-12.39. 
TissERAND,  E.     Memoire  sur  la  vegetation  dans  les  hautes  latitudes,   1875.  p. 

271.     Memoires  de  la  Societe  Centrale  d'Agriculture.     Cited  by  Grandeau. 
Troska,    a.     Die    Vorherbestimmung   des    Wetters    mittelst    des    Hygrometers. 

Koln,  1886.     Wollny,  X,  p.  462. 
TscHAPKowiTZ,  Dr.  F.     Untepsuchungen  iiber  die  Einwirkung  der  Warme  und 

der    anderen    Formen    der    Naturkriifte    auf    die    Vegetations-Erscheinungeu. 

Leipsic,  1882. 
TULASNE,  MM.  C.  et  L.  R.     Historie  et  monographie  des  champignons  hypoges, 

1862,  p.  3. 
Tyndall,  J.     Calorescence.     Trad.  Moigno,  1867,  p.  17. 
Vines,  S.  H.     Lectures  on  the  Physiology  of  Plants.     Cambridge,  1886. 
ViOLLE,  M.  J.     Sur  la  Radiation  Solaire.     Rapport,  etc.,  extrait  des  Annaies  de 

Chimie  et  de  Physique,  Paris,  1879. 
VocHTiNG,  H.     Ueber  die  Bildung  der  Knollen.     .55  S.,  5  Tafeln.     Heft  4  tier 

Bibliotheea  botanica.     Kassel.  1887.     Wollny,  X,  p.  226. 
Walker,  F.  A.,  and  Seaton,  Ch.  W.     Report  on  the  Productions  of  Agricul- 
ture.    Tenth  Census,  .Tune  1.  1880.     Washington,  1883. 
Wallace,  Alfred  A.     Acclimatization.     Encyclop.  Brit.,  9th  ed..  Vol.  I,  1878. 
Wallace,    R.     La    coloration    des    animaux    et    des    plantes.     Rev.    intern,    des 

sciences.  15  juillet  1879. 
Wallich,  Dr.  G.  C.     North  Atlantic.     Sea-bed,  p.  131. 
Warington,  R.     a  contribution  to  the  study  of  well  waters.     Jour.  Chem.  Soc, 

June,  1887,  Vol.  LI,  pp.  500-552.     Wollny,  X,  p.  370. 
Ueber  die  Vertheilung  des  nitrifizirenden  Organismus  im  Boden.     Jour. 

Chem.  Soc,  February,  1887.  Vol.  LI,  pp.  118-129.     Wollny,  X,  p.  211. 


375 

Weber.  L.     Zunahme  der  Blitzscbliige  in  don  letztou  Jahrzehnten.     Scbles.  Ges. 

f.  vaterl.  Kultiir,  ()8.  Jahrg.,  Breslau,  1880,  S.  125.    Wollny,  X,  p.  259. 
Wesseloffski.     Das  Kliuia  Kusslands. 
Wilson,  John,  and  Thorxton,  W.  T.     Agriculture.     Euclycop.   Brit.,  9th  ed., 

Vol.  I,  1878. 
Wilson.     Gardener's  Chronicle,  pp.  107-358.     1867. 
Wollny,  E.     Die  Kultur  der  Getreideartcn,  Heidelberg,  1887,  S.  75.     Wollny,  X, 

p.  176. 
Der  Einfluss  der  Pflanzendecke  und  Besehattuug  auf  die  phy.sikalischen 

Eigenschaften  und  die  Fruebtbarkeit  des  Bodens,   Berlin,   1877,   S.   123-12.5. 

Wollny,  X,  p.  280. 
Untersucbungeu   iiber  die  Temperaturverbilltnisse  des   Bodens  bei   ver- 


schiedener  Neigung  des  Terrains  gegen  die  Himmelsrichtung  und  gegen  den 

Hoi'izont.     (Nacbtnige.)     Wollny,  X,  p.  245. 

Forstlicb-meleorologiscbe  Beobacbtungeu.     Aliinchen.     Wollny,  X,  p.  415. 

Journ.  fiir  Landw..  XXIX,  .Tahrg.  1881,  pp.  25-62.    Wollny,  X.  p.  175. 

Untersucbungeu  iiber  den  Einfluss  der  Pflanzendecke  und  der  Beschat- 


tung  auf  die  physikalischeu  Eigenschaften  des  Bodens.     (Zweite  Mittheilung.) 

Miiucben.     Wollny.  X,  p.  261. 
Forscbungen  auf  dem  Gebiete  der  Agricultur-Physik.     Vols.   I  to  XIV, 

Heidelberg,  1878-1891. 
WuRSTER,  C.     Die  Aktivirung  des  Sauerstoffs  der  Atmosphiire  und  deren  Zusam- 

menhang  mit  den  elektriscben  Erscbeinungen  der  Luft  und  mit  der  Entstehung 

der  Gewitter.     Ber.   der   Deutsch.   chem.   Ges.,   Jahrg.   XIX,    1886,    Ileft   18. 

Wollny,  X,  p.  249. 
Yung,  E.     Arch,  de  Zool.  experiment,  et  gen.,  1878,  Tome  VII,  No.  2,  p.  251. 
Zantedeschi.     De  I'intiueiice  qu'excercent  sur  la  vegetation  des  plantes  et  la 

germination  des  graines   los   rayons  solaires  trausmis  a  travers  des  verres 

colores.     Paris,  1843,  C.  R.,  XVI,  p.  747. 


INDEX. 


In  this  index  special  attention  has  been  paid  to  the  spelUng  of  proper  names,  ami 
in  case  of  any  discrepancy  being  detected  between  the  index  and  the  text,  the  reader 
will  kindly  consider  the  former  as  the  proper  authority. 


Abbott,  assimilation,  68. 
Absorption,  atmospheric,  90. 

of  oxygen,  by  plants,  18,  47-52. 
Acclimatization,  7,  41,  215-221,  231,  233,  244,  362. 

barley,  217. 

gardens,  221. 

heredity  and,  295-308. 

Linsser's  law,  215,  242. 
Actinometer,  82. 

Arago-Davy,  83,  273. 

Bellani's  vaporization,  97,  273. 

Desains'  thermoelectric,  99. 

formulse  for,  87. 

Marchand's,  96. 

standardization  of,  85. 
Aetinometrie  constants,  168. 

degrees,  85,  86,  177. 
Adanson,  thermal  constants,  169,  170. 
Adaptation,  37,  362. 
Aerobics,  149. 

S^culus  hippocastanum ,  phenology  of,  280. 
Air,  and  respiration,  37. 
Alabama,  soil  temperatures,  61. 
Alais,  France,  phenology,  184, 185. 
Albumen  in  seed.s,  35,  48. 
Albuminoids,  and  absorption,  51. 

and  temperature,  40. 

in  cereals,  312-314. 

in  plants,  17,  18. 
Alfalfa,  fixation  of  nitrogen,  160. 
Algeria,  rye  and  wheat,  41. 
Algiers,  acclimatization  garden,  221. 
Alps,  grasses,  299. 

phonological  observations,  242. 
Alten,  Norway,  acclimatization  of  barley,  217. 

aromatic  cumin,  244. 
Altitude  and  plant  development,  242. 

as  retarding  vegetation,  186. 

See  also  Elevation. 
Amaranthus  tricolor  and  light,  27. 
Ammonia,  absorbed  by  soil,  136. 

and  plant  life,  138. 

fertilizer,  163. 

liberation  by  soil,  142. 
Anaerobies,  149. 
Angot,  insolation  and  latitude,  219. 

phenological  studies,  278-290. 

summation  of  temperatures,  278,  320. 
Apple,  time  of  blossoming,  242. 
Arago,  cyanometer,  99. 


Arago-Davy  actinometer,  82,  83,  273. 
Arata,  distribution  of  germs,  130. 
Archangel,  Russia,  187. 
Arid  region,  adaptation  of  plants,  234. 

acclimatization,  233. 
Arnstadt,  Germany,  wheat  and  temperature,  180. 
Aromatic  principle  and  latitude,  244. 
Arras,  France,  sugar  beets  and  climate,  259-263. 
Asia,  origin  of  grains,  234. 
Asparagin,  49,  51. 
Assimilation,  chemistry  of,  67. 

and  sunshine,  67-80. 
Atmosphere,  composition,  67,  133,  , 

dust  in,  130. 

electricity,  131. 

layer  traversed  by  sunlight,  84,  85. 
Atwater,  fixation  of  nitrogen,  159. 
Auburn,  Ala.,  soil  temperatures,  61. 
Austria,  phenology,  167. 
Authorities,  list  of,  365-375. 
Auvergne,  France,  soil  fertility,  144. 
Arena  orientalis,  period  of  ripening,  217. 
Aymonnet,  actinometry,  90. 

Bacteria,  nitrogen-fixing,  136-161. 
Baer,  von,  acclimatization  of  seeds,  216,  220 
Baker,  measurement  of  insolation,  82. 
Ball,  black-bulb  temperatures,  238. 
Balland,  phenological  constants,  176. 
Barbados,  sugar  crop  and  rainfall,  344-3.50. 
Barley,  acclimatization,  217. 

albuminoids  and  cellulose,  18. 

environment,  314. 

latitude,  73,  74. 

nitrogen,  136. 

phenology,  280-290. 

polar  region,  39. 

ripening  period,  243. 

thermal  constants,  319. 

water  consumption,  113,  123. 
Bastian,  acclimatization  of  plants,  220. 
Beans,  acclimatization,  306. 

albuminoids,  18. 

water  consumption,  113,  120. 
Becquerel,  soil  temperatures,  63-66. 
Beets,  sugar,  date  of  planting,  309,  310. 

rainfall,  125. 
Belgium,  progress  of  vegetation,  182. 
Belbomme,  germination,  44. 
Bellani,  radiometer,  97,  98,  273. 


(377) 


378 


Berlin,  phenology,  186. 
Bernina  hospice,  sun  temperatures,  238. 
Bert,  chlorophyl  and  light,  42. 
Berthelot,  ammonia  and  soils,  138,  139,  159. 
light  and  vegetation,  38. 
nitrifying  bacteria,  147,  161. 
Bertholon,  germination,  42. 
Bessel's  formula  in  phenology,  212. 
Bibliography,  365-375. 
Billings,  bacteriology  of  air,  130. 
Birch,  phenology  of,  281,  290. 
Birner,  potatoes  and  moisture,  119. 
Black-bulb  temperatures,  171,  238. 
Blight,  wheat,  268. 
Blooming,  see  Flowering. 
Bodo,  Norway,  sunshine  and  cloudiness,  74. 
Bogota,  Colombia,  wheat,  180. 
Bohm,  chlorophyl  and  light,  39. 
Boitard,  germination,  43. 
Bokhara,  A.sia,  plant  development,  231,  232. 
Bonnier,  climate  and  vegetation,  40. 
Boston,  Mass.,  evaporation  experiments,  105. 
Boussingault,  assimilation,  75-78. 
coefficient  of  growth,  40. 
fixation  of  nitrogen,  147,  155. 
ripening  of  grain,  73. 
soil  nitrogen,  142,  143. 
summation  of  temperatures,  169,  320-331. 
thermal  constants,  169. 
vegetation  and  light,  37. 
Braunschweig,  Germany,  phenology,  173. 
Br6al,  fixation  of  nitrogen,  137,  151-154. 
Breslau,  Germany,  plant  development,  217,  220, 

231. 
Brewer,  cereals,  300-304. 

wheat,  314-318. 
Briem,  beets  and  potatoes,  309. 

sugar  beets  and  rainfall,  125. 
Broadcast  sowing,  337,  355-358. 
Brogniart,  germination,  44. 
Brookings,  S.  Dak.,  cereals,  318-331. 

soil  temperatures,  59,  60. 
Brunswick,  Germany,  phenology,  173. 
Brussels,  Belgium,  phenology,  182-186,  213-214. 
Buckwheat,  albuminoids  and  cellulose,  18. 

water  content,  116. 
Bunsen,  photochemical  researches,  92. 
Bunt,  wheat,  341. 
Burckhardt,  germination,  28. 
Burgundy,  France,  thermal  constants,  257. 

Caldwell,  maize  experiments,  333. 
Calendar,  phenological,  292. 
Caleves,  France,  harvest  and  rainfall,  246. 
California,  plant  growth  and  cold,  129. 
Campbell-Stokes,  sunshine  recorder,  99. 
Canada,  soil  temperatures,  63. 

sunshine  recorder,  99. 

thaws  and  tree  growth,  128. 
Candolle,  de,  beans,  307,  309. 

chlorophyl,  76. 

climatic  laboratory,  7,  24. 

germination,  28-36,  43. 

summation  of  temperatures,  40. 

thermal  constants,  278. 

vegetation  and  light,  39. 


Caracas,  Venezuela,  thunderstorms  and  nitrates, 

135. 
Carbohydrates,  17. 
Carbon,  assimilation  of,  141. 
Carbonic  acid  gas,  absorption  by  plants,  18. 
decomposition  of,  38,  42. 
exhalation  of,  49,  50,  51. 
Carlsruhe,  Germany,  phenology,  186,  235. 
Catalogue  of  authorities,  365-375. 
Catania,  Italy,  chemical  intensity  of  sunshine,  94. 
Cell  structure,  16. 
Cellulose,  16-18. 

Celosia  cristata,  germination,  28-36. 
Cereals,  acclimatization,  300-304. 

albuminoids,  312-314. 

Brookings  experiments,  318-331. 

climate  and  soils,  364. 

limit  of  cultivation,  187. 

varieties,  251. 

weather,  248. 
Champagne,  France,  thermal  constants,  251. 
Charts,  isophenological,  243. 
Chemical  measurement  of  sunshine,  96. 
Chestnut,  phenology,  282-290. 
Chile,  potatoes  in,  80. 
Chinook  winds,  128. 
Chiswiek,  England,  radiation  temperatures,  235, 

238. 
Chlorophyl,  and  absorbent  media,  77. 

climate,  77. 

formation,  38,  42,  75. 

function,  22. 

light  and  air,  37. 
Christiania,  Sweden,  acclimatization,  233. 

thermal  constants,  217. 
Clausius,  sunlight,  81, 82. 
Climate  and  cereals,  364. 

changes  of,  295-298. 

control  of,  9. 

favorable  and  unfavorable,  16. 

influence  on  crops,  364. 

plant  structure,  77. 

sugar  beets,  259-263. 

wheat,  251-256,263-272. 

vegetation,  188,244,245. 
Climatic  laboratory,  7, 24-27. 
Climatic  tables,  for  phenological  study,  272-277. 
Climatic  zones,  221,224. 
Climatology,  15. 
Cloez,  chlorophyl,  75. 

Cloudiness,    and    absorption    of    carbonic    acid 
gas,  47. 

actinometry,  90. 

data  for  phenology,  273. 

soil  temperature,  21. 
Clover,  albuminoids,  18. 

fertilization  by,  158. 

fixation  of  nitrogen,  160. 

water  consumption,  113, 119. 
Codazzi,  thermal  constants,  170. 
Coefficient  of  growth,  40. 
Colin,  germination,  33, 37. 

thermal  constants,  170. 
Collomia  coccinea,  germination,  28-86. 
Colombia,  wheat,  180. 
Columbia,  S.  C,  prize  corn  crop,  165. 


379 


Comparison  of  harvests.  3(52-  363. 

Compensjition,  tlieory  of,  219. 

Composition  of  crops,  18. 

Conjugate  thermometers,  81-89,97,283. 

Constant,  solar,  91. 

Constants,  phenological,  168,189-191,223-226,239, 

uncertainty  of,  229. 
Corn.    See  Maize. 

prize  crops,  164. 
Cornell  University,  germination  experiments,  37. 
Corvallis,  Oregon,  soil  temperatures,  62. 
Cotton,  303-306. 

Coutagne,  phenological  formula,  178-179. 
Cracow,  Austria-Hungary,  fixation  of  nitrogen, 

154. 
Crops  and  fertilizers,  162-166. 

water  and,  116. 

weather  and.  247-251. 
Cultivation  and  evaporation,  108. 

crops,  331, 35.5-358. 

prize  crop,  165. 

soil  moisture  and  drainage,  114,115. 
Cuminnm  cyminum  and  latitude,  244. 
Currant,  phenology,  280. 
Cyanometer,  99. 

Darkness  and  absorption,  48,  50. 

exhalation,  51. 

germination,  42,  43,  45. 

respiration,  19. 

vegetation,  37. 
Darwin,  germination,  44. 
Daubeny,  light  and  vegetation,  26. 

sunshine  and  temperature,  71. 
Day-degrees,  73. 
Deblanchis,  leaf  temperature,  174. 

vegetation  and  temperature,  174. 
Decades,  Dove's,  274. 
Degree,  actinometric,  85,  86,  177. 
Deh4rain,  fertilization,  146,  158. 

soil  nitrogen,  142. 

transpiration,  69-71. 
Desains,  actinometer,  99. 

chlorophyl,  76. 
Descroix,  Ballani's  actinometer,  97. 

evaporation  data,  104. 

phenological  data,  273-274. 
Detmer,  germination,  44. 

plant  development  and  cold,  33.S-340. 
Diastase,  17. 
Dodge,  seeding  and  crop  yield,  357-.358. 

statistical  tables,  7. 
Dollen,  acclimatization  gardens,  221. 
Dombes,  France,  fixation  of  nitrogen.  1.50. 
Dorpat,  Rassia,  thermal  constants,  238. 
Dove,  climatic  factors,  234. 

pentads  and  decades,  102,  274. 
Drainage  and  soil  nitrogen,  364. 
Draper,  light  and  chlorophyl,  76. 

light  and  vegetation,  26. 
Drill  planting,  .^34,  337,  355-358. 
Drontheim  (Throndhjem),  Norway,  plant  devel- 
opment, .39. 
Drought,  337,  363. 

Drouin,  nitrifying  bacteria,  149,  159. 
Dryness  and  plant  growth,  19,  80. 


Duchartre,  germination,  44. 

Durasno,  Teneriffe,  acclimatization  garden,  221. 

Durin,  sugar  beets,  310. 

Dust,  atmospheric,  130. 

Ebermayer,  forest  temperatures,  7. 
Economy  in  plant-life,  232. 
Edwards,  germination,  33,37. 

thermal  constants,  170. 
Effective  temperature,  170. 
j   Eggs,  grasshopper,  36. 

hatching,  36. 
Eisenlohr,  phenology,  235. 
Elder,  phenology  of  the,  281-290. 
Electricity,  atmospheric,  131. 

and  vegetation,  27. 
Elevation,  influence  on  date  of  harvest,  278,279. 

See  a!so  Altitude. 
Emory,  soil  thermometers,  66. 
Engelmann,  chlorophyl,  77. 
England,  average  wheat  crop,  179. 

.soil  temperature,  68. 

transpiration.  69. 

wheat  and  temperature,  180,  181. 
Epernay,  France,  wine  crop  and  weather,  266, 257, 
Epochs,  phenological,  167,  172. 
Erman,  acclimatization  of  grain,  220. 

phenological  constants,  212. 
Europe,  grain  culture,  243-247. 

grape  culture,  295-298. 

phenological  charts,  243. 

phenological  epochs,  171-172. 
Evaporation  and  crop  yield,  245,  246. 

cultivation,  108. 

data  for  phenology,  273. 

from  a  plant,  19. 

.soil  temperature,  63. 

water  surface,  104. 

wind,  107. 
Evaporimeter,  Piche,  106. 
Everett,  soil  temperature,  58. 
Exhalation  of  carbonic  acid  gas,  49-52. 
Experimental  hothouses,  24-37. 

plats,  352-355. 
Factors,  climatological,  223,  232,  234. 
Faivre,  germination  and  light,  44. 
Falling  of  leaves,  epoch  of,  186. 
Fecamp,  France,  chemical  effect  of  sunshine,  96. 
Ferrel,  actinometric  theory,  83,  188. 
Fertilization,  clover,  1.5s. 
Fertilizers,  162-166. 

crop  yield,  121. 

nitrogen,  1,33,  134. 

rotation  of  crops,  162. 

soil  temperature,  54. 
Fittbogen,  water  and  crops,  118, 122, 123. 
Fitzgerald  evaporation,  105. 
Fixation  of  nitrogen,  13(i-161. 
Flahault,  chlorophyl,  39. 

sunlight,  40. 
Flax,  water  consumption,  126. 
Fleischer,  germination,  44. 
Flowering, and  altitude,  278. 
epoch  of,  182, 185, 278-290. 
phenological  constant  of,  291,  293. 
second,  218. 


380 


Flowering,  and  temperature,  172. 

thermal  constant,  191, 226. 

of  vine,  257. 

of  wheat,  262,267. 
Food  crops,  cells  of,  16. 
Forest,  and  change  of  climate,  296. 

studies,  8. 

temperature  variations  in,  7. 

thaws,  128. 
Formulae,  actinometric,  Ferrel's,  88. 
Lambert's,  84. 
Laplace's  84. 
Mari6-Davy's,  88. 

evaporation,  Fitzgerald's,  105. 
Russell's,  106. 

phenological,  Bessel's,  212. 
Kabseh's,  173. 
Foster,  maize,  324-327. 
Fractional  parts,  law  of,  223,  232. 
France,  phenology,  278-290. 

rye  and  wheat,  41. 
Frank,  fixation  of  nitrogen,  157,  159. 

fungi  and  plant  growth,  138. 
Frankfort,  Germany,  phenological  obervations, 

236,  243. 
Frear,  maize,  333. 
Freezing,  germination  at,  33. 

plants  and  seeds,  338,  340. 
Fritsch,  phenological  epochs,  167-189. 

phenological  experiments,  189-211. 

phenological  list,  191. 

phenological  predictions,  242. 
Fritz,  changes  of  climate,  295-298. 
Frondescence,  293. 
Frost,  and  plant  development,  237,  252,  256. 

and  wheat,  266,  340. 
Fructification,  293. 
Fruit,  color  and  sunlight,  77. 

ripening  of,  15. 
Fungi,  distribution,  340. 

and  plant  development,  138. 

Gardner,  light  and  vegetation,  26. 
Garreau,  assimilation,  67. 
Gasparin,  effective  temperature,  170. 

flowering  of  grape,  257. 

initial  temperature,  251,  279. 

phenological  epochs,  172. 

phenological  list,  172. 

sun  temperatures,  39. 

thermal  constants,  169,  278. 

wheat,  251,  252,  264. 

wind  and  vegetation,  129. 
Gautier,  nitrifying  bacteria,  149, 159. 
Geneva,  N.  Y.,  cultivation  and  bacteria,  108. 

fertilization  experiments,  163. 

maize  and  peas,  335-337. 

plat  experiments,  353. 

soil  temperatures,  53. 
Geneva,  Switzerland,  phenology,  186. 
Geography,  plant,  40,  233. 
Georgeson,  soil  temperatures,  54. 
Germany,  potatoes,  80. 
Germination,  absorption  of  oxygen,  18,  48,  49. 

albumen,  35. 

beginning,  35. 

light,  37,  42,  52. 


Germination,  absorption  of  moisture,  37. 

temperature,  28-36. 
Germs  and  agriculture,  130. 

forests,  130. 
Giessen,  Germany,  phenology,  236-243. 

phenological  calendar,  292. 
Gilbert,  evaporation,  245. 

fertilizers,  145. 

nitrogen,  fixation  of,  151. 
in  rain,  135. 
loss  by  soils,  142. 
sources  of,  137. 

plat  experiments,  356. 
Girard,  rainfall  and  sugar  beets,  126. 
Gluten,  in  wheat,  41. 
Goff,  percolation,  109. 

soil  temperatures,  53. 
Goodale,  physiological  studies,  15. 
Gorlitz,  plant  development,  231. 
Gossi/phan,  303-306. 
Grain,  acclimatization,  220. 

culture  in  Europe,  243-247. 

thermal  constants,  73. 
Grandeau,  nutrition  of  plants,  40. 
Grape,  and  climate,  295-298. 

crop  and  weather,  256-259. 

water  consumption,  13. 
Grasses,  acclimatization,  299. 

germination,  307. 

time  of  harvest,  310,  312. 

water  consumption,  113, 119. 
Grasshopper,  hatching,  36. 
Grassmann,  sugar  beets  and  rainfall,  126. 
Gratiolet,  chlorophyl  and  temperature,  75. 
Gray,  phenological  observations,  292. 
Green,  soil  thermometers,  65. 
Greenhouses,  79. 

Greenwich,  England,  soil  temperatures,  58,  59. 
Grignon,  France,  fertilization,  145. 
"Grobers,"  Germany,  experiment  station,  125. 
Groningen,  Netherlands,  phenology,  186. 
Growth,  coeflBcient,  40. 

factors  of,  244-245. 

influence  of  light  and  heat,  37. 

plant,  16. 
Guastalla,  Italy,  phenology,  186. 
Guettard,  transpiration,  69. 
Guillemin,  light  and  vegetation,  26. 
Guntz,  chlorophyl  and  climate,  77. 
Guyot,  phenological  observations,  292. 

Haberlandt,  crops  and  water,  116, 122, 123. 

oats  and  light,  39. 

soil  evaporation,  110. 

wheat,  germination,  339. 
Habit,  law  of,  232. 

Haddonfield,  N.  J.,  wheat  and  temperature,  180. 
Hallett,  wheat,  301. 
Halsno,  Norway,  sunshine,  74. 
Hamburg,  Germany,  plant  development,  231. 
Hammond,  cotton,  305,  306. 
Harrisburg,  Pa.,  maize  experiments,  333. 
Harvard  University,  botanical  experiments,  27. 
Harvest  and  climate,  364. 

epoch  of,  278-290. 

heat  and  moisture,  23. 

quantity  and  quality,  23. 

water  supply,  116-118. 


381 


Hatching,  grasshopper  eggs,  36. 
Heading  of  wheat,  '265. 
Heat  and  chlorophyl,  3J<,  75. 

fractional  parts,  223,  232. 

germination,  137. 

harvest,  23. 

plant  development,  221. 

respiration,  19,  48. 

ripening  of  grain,  73. 

solar,  and  latitude,  91,  219. 
Heer,  climatic  zones,  221. 
Heidelberg,  Germany,  insolation,  82. 

intensity  of  sunshine,  93. 

plant  development,  231. 
Heiden,  germination  and  light,  44. 
Heinrich,  crops  and  water,  119. 
Hellriegel,  fixation  of  nitrogen,  136,  151-155. 

shade  and  plant  development,  79. 

water  and  crops,  117. 
Helmersen,  fruit  trees,  231. 
Henry,  phenological  observations,  292. 
Heraeus,  fixation  of  nitrogen,  139. 
Heredity  and  acclimatization,  295-308. 
Herodotus,  climate  of  Assyria,  296. 
Himalayas,  grasses,  299. 

sun  temperatures,  238.  . 
Hochgebirge,  sun  temperatures,  238. 
Hoehner,  transpiration,  112. 
Hoffmann,  phenological  investigations, 

phenological  notation,  291. 

thermal  constants,  174. 
Holter,  grasses,  311. 
Hooker,  black-bulb  temperatures,  238. 
Hop  vines,  pruning,  341. 
Horse  chestnut,  phenology,  280. 
Hough,  phenology,  5. 

Houghton  Farm,  N.  Y.,  soil  temperatures,  63,  66. 
Humboldt,  germination,  45. 

phenology,  72. 

sunshine,  169. 
Hunt,  germination,  307. 

maize  experiments,  334,  335. 
Huron,  S.  Dak.,  meteorological  data,  320-330. 
Hydrocarbons,  17. 
Hygrometric  data,  273. 

Iberis  amara,  germination,  28-36. 
Iceland,  acclimatization,  217. 
Ihne,  phenological  notation,  291. 
Illonkoff,  crops  and  water,  116. 
Illinois,  maize  experiments,  334-335. 
"Inclosure"  of  the  thermometer,  238. 
Indiana,  maize  experiments,  331. 
Ineffective  temperatures,  34-36. 
Ingenhousz,  germination,  42. 
Initial  date,  238. 

point  in  phenology,  168-189,  213,  214,  218. 

temperature,  279-290. 
Inoculation  of  soils,  136-161. 
Insolation,  measurement,  82,  90,  91. 

compensation,  theory  of,  219. 
Instructions,  phenological,  291. 
International  Meteorological  Tables,  101. 
Irkutsk,  Siberia,  cereals,  187. 
Irrigation,  23,  234. 

acclimatization,  362. 

crop  yield,  116. 


Isanthesic  lines,  184.  189,  278. 
Isochimenal  lines,  72. 
Isophenological  lines,  242. 
Isotheral  lines,  72. 
Isothermal  lines,  72, 

Japan,  soil  temperatures,  54. 
Java,  climatic  zone,  225. 
Jensen,  wheat  smut,  341. 
Jordan,  sunshine  recorder,  99. 
Joulie,  fertilizer,  246. 

fixation  of  nitrogen,  150. 

Kabsch,  phenological  formula,  173. 
Kalm,  acclimatization  of  maize,  220. 
Kansas,  oats,  337. 

sorghum,  337. 
Keith,  germination,  43. 
Kentucky  blue  grass,  307. 
Kew,  atmospheric  electricity,  131. 

insolation,  82. 

photochemical  researches,  93,  94. 
Khiva,  Central  Asia,  plant  development,  231. 
Kidney  beans,  transpiration,  71. 
Kief,  Russia,  plant  development,  231. 
Kiel,  Germany,  intensity  of  sunlight,  95. 
Knight,  pruning  and  tuber  development,  80. 
Koppen,  germination,  335. 
Kraus,  pruning,  341. 

Krakow,    Austria-Hungary,    fixation    of    nitro- 
gen, 154. 
Kupffer,  limit  of  cultivation,  187. 

Laboratory,  climatic,  24-27. 
Lachmann,  thermal  constants,  173. 
Ladd,  fertilizers,  163. 

grasses,  310. 
Lambert's  formula,  84. 

Langenthal,  pruning  and  tuber  development,  80 
Laplace,  sunshine,  84. 
Lapland,  acclimatization,  '2'20. 

phenology,  186. 
Latitude,  and  plant  development,  242. 

ripening,  243. 

solar  heat,  91. 

vegetation,  183-186, 218. 
Laurent,  fixation  of  nitrogen,  150,151. 

plant  nutrition,  77. 
Lausanne,  phenology,  186. 
Lavoisier,  light  and  plants,  37. 
Lawes,  evaporation,  245. 

fertilizers,  145. 

fixation  of  nitrogen,  151. 

nitrogen  in  rain,  135. 

plat  experiments,  3.55. 

soil  nitrogen,  142. 

sources  of  nitrogen,  137. 

transpiration,  113. 
Lazenby,  plat  experiments,  355. 
Leafing,  epoch  of,  181, 185, '238, 278-290. 

of  vine,  256. 

temperature,  172. 

thermal  con.stant,  '2'26,'291,293. 
LeClerc,  germination,  43. 
Lef^bure,  germination,  35,  43. 
Legumin,  49,  51. 
Leguminosae,  fixation  of  nitrogen,  136,151-161. 

tubercles  on,  151. 


382 


Leone,  nitrification,  160. 

sources  of  nitrogen,  160. 
Lepidium  sativuyn,  germination,  28-36. 
Leyst,  earth  temperatures,  65. 
Libbey,  sunshine  tables,  101,102. 
Light,  and  absorption  of  oxygen,  47, 48, 50, 51, 

germination,  37,42-52. 

Pauchon's  experiments,  45. 

respiration,  19. 

vegetation,  26,40,79,80. 
Liglitning  and  fixation  of  nitrogen,  135. 
Lilac,  phenology  of,  280-290. 
Limit  of  cultivation,  187. 
Linden,  phenology,  281-290. 
Linsser,  laws  of  acclimatization,  7, 215, 242. 

phenological  studies,  6, 211-234. 

.sunlight  and  vegetation,  218,219. 

thermal  constants,  173. 

zones,  224. 
Linum  usitatissimum,  germination,  28-36. 
Lippincott,  dates  of  sowing  and  harvest, 

phenology  of  wheat,  179. 
Lisbon,  Portugal,  intensity  of  sunshine,  94. 

photochemical  researches,  94. 
Lobositz,  Austria,  rainfall  and  harvest.  111 
Locality,  influence  on  vegetation,  183. 
Lonicera  alpigena,  phenology,  237. 
Lucerne,  fixation  of  nitrogen,  137,  153. 

water  consumption,  113. 
Lucimeter,  Bellani,  99,  273. 
Lupin,  fixation  of  nitrogen,  153, 160. 
Lynden  (North  Cape)  Norway,  wheat,  39 

gluten  in  wheat,  41. 

McLeod,  soil  temperatures,  63. 
Madeira,  seasons.  221-232. 
Maize,  acclimatization,  220. 

albuminoids,  18. 

date  of  ripening,  125. 

environment,  314. 

experiments  with,  321-334. 

fertilizers,  162. 

thermal  constants,  335-337. 
Manche,  France,  climate  and  crops,  175. 
Manchester,  England,  insolation,  82. 

photochemical  action  of  daylight,  93. 
Mangon,  chlorophyl,  76. 

initial  temperatures,  279. 

thermal  constants,  174,  252,  265. 
Manitoba,  Canada,  forest  experiments,  128. 
Manures,  162-166. 

and  crops,  121. 

soil  temperatures,  54. 
Maquenne,  nitrogen  and  vegetation,  139. 
Marcano,  lightning  and  nitrogen,  135. 
Marchand,  actinometer,  96,  273. 

shade  and  plant  development,  79. 
Mari6-Davy,  acclimatization  of  plants,  41. 

actinometer,  273. 

actinometric  results,  96. 

chlorophyl,  75. 

maize,  170. 

meteorology  and  crops,  247-251. 

phenological  constant,  176,  177. 

phenological  researches,  243-277. 

prediction  of  harvest,  178. 

radiation,  measurement,  81. 

sunshine  and  transpiration,  69,  70, 113. 


Mari^-Davy,  water  and  crops,  246. 
Martins,  thermal  constant,  278. 
Martins,  von,  light  and  vegetation,  27. 
Marvin,  sunshine  recorder,  99. 
Mascagno,  light  and  assimilation,  78. 
Matotschkin-Schar,   Nova  Zembla,  acclimatiza- 
tion, 216. 

thermal  constants,  216. 
Maurer,  soil  temperatures,  21. 
Maximum  temperature  of  germination,  34. 
Mecklenburg,  Germany,  water  and  plant  develop- 
ment, 119. 
Meech,  sunshine  tables,  101. 
Meigs,  phenology,  292. 
Melon  (canteloupe),  germination,  28-36. 
Mendenhall,  soil  thermometers,  66. 
Meteorology  and  crops,  247-251. 
Mexico,  origin  of  maize,  234. 
Meyen,  germination,  44. 
Michael,  botanical  classification,  68. 
Miesse,  germination  and  light,  42. 
Mikosh,  chlorophyl,  38. 
Milk,  souring,  341. 
Millet,  silkworms,  36. 

Minimum  temperature  of  germination,  33,  34,  336. 
Miquel,  collection  of,  germs,  131. 
Modification  of  plants,  233. 
Moisson,  respiration  of  plants,  18. 
Moisture  and  germination,  37. 

plant  development,  222. 

records,  273. 

soil,  20,  104,  110-111. 
Moleschott,  light  and  vegetation,  37,  39. 
Montreal,  Canada,  soil  temperatures,  63,  64. 
Montrouge,  France,  flowering  of  wheat,  178. 
Montsouris,  France,  actinometric  percentages,  87. 

actinometric  degrees,  89,  96. 

atmospheric  electricity,  131,  132. 

bacteriology  of  air,  130,  131. 

Bellani  lucimeter,  98. 

evaporation  data,  105, 106. 

insolation  and  transpiration,  71. 

intensity  of  sunshine,  89. 

nitrogen  in  rain,  133, 134. 

researches,  243, 277. 

variations  in  atmospheric  air,  133. 
Morley,  variations  in  atmospheric  air,  133. 
Morren,  acclimatization,  220. 

germination,  43. 

phenology,  167. 
Mulder,  protein,  17. 
Munich,  phenology,  186. 

soil  temperatures,  54,  55,  57. 
Muntz,  fixation  of  nitrogen  by  lightning,  135. 

nitrifying  ferment,  142. 
Miittrich,  forestry,  7. 

Naples,  phenology,  184,  185. 

Narcissus,  phenology,  280,  282. 

Nertchinsk,  Siberia,  cereals,  187. 

New  York  State,  maize  experiments,  332,  333. 

phenological  observations,  235,  292. 
Xigella  sativa,  germination,  28-36. 
Nitrates  in  sugar  beets,  262. 
Nitrogen,  artificial  fertilizers,  162. 

fixation  by  plants,  136-161. 
by  soils,  139. 

in  rain,  133-135. 


383 


NitroRen,  loss  from  soils.  141,  142. 

nitrifying  bacteria,  148, 149. 

plant  nutrition,  133,  141,  3frl. 

sugar  beets,  262. 
Nobbe,  germination,  44. 

Nordlinger,  variations  of  temperature  in  forests,  7. 
Normandy,  thermal  constants,  175, 176. 
North  Cape,  Norway,  germination,  39. 

gluten  in  wheat,  41. 
Norway,  acclimatization,  220. 

rye,  41. 
Notation,  phenological,  291,  293. 
Nutrition,  r61e  of  water,  114. 

of  plants,  22,  140. 

Oak,  phenology,  281-290. 

water  consumption,  113. 
Oats,  cellulose,  18. 

drought,  337,  338. 

environment,  314. 

fertilizers,  162. 

light,  39. 

nitrogen,  136. 

phenological  constant,  177. 

thermal  constants,  320. 

TurkL«h,  217. 

water  consumption,  113,  123. 
Observations,  phenological,  290-294. 
Ohio,  oats  in,  338. 
Optimum  temperature,  36. 
Orange.  France,  thermal  constant  of  wheat,  39. 
Oregon,  soil  temperatures,  62. 
Orel,  Russia,  plant  development,  231. 
Orenburg,  Russia,  acclimatization,  231. 

season  of  vegetation,  221. 
Orkneys,  plant  development,  39. 
Orleansville,  Algeria,  thermal  constants,  176. 
Orotava,  Teneriffe,  acclimatization  garden,  221. 
O.xygen,  absorption  by  plants,  18,  47-52. 

absorption  by  seeds,  46, 50. 

in  asparagin,  49. 
Ozone  and  thunderstorms,  341. 

Pagnoul,  assimilation,  78, 79. 

fixation  of  nitrogen,  150, 161. 

sugar  beets,  259-263. 
Papilionaceae,  fixation  of  nitrogen,  157. 
Para,  Brazil,  insolation,  82. 

photochemical  researches,  93, 94. 
Paris,  France,  germination  of  wheat,  39. 

insolation,  82. 

.S'ec,  also,  Montsouris. 
Parma,  Itiily,  phenology,  185. 

plant  development,  231. 
Pasteur,  light  and  vegetation,  37. 

modification  of  bacteria,  157. 
Pauchon,  light  and  germination,  37, 42-52. 

northern  vegetation,  40. 
Peas,  albuminoids,  18. 

fixation  of  nitrogen,  136, 153, 155, 160. 

thermal  constant,  335-337. 

time  of  flowering,  242. 

water  consumption,  113, 124. 
Penhallow,  soil  temperatures,  53,63. 
Pendleton,  Oreg.,  soil  temperatures,  62,63. 
Pennsylvania,  maize  experiments,  333-334. 
Pentads,  in  phenology,  273-274. 
Pepper,  acclimatization,  307. 


Percolation,  109. 

Periodic  variation  of  climalo,  297. 

Periodical  phenomena,  232. 

Perret,  water  and  plant  nutrition,  114. 

Petermann,  fixation  of  nitrogen,  161. 

Pfeffer,  asparagin,  49. 

thermal  constants,  241. 
Phantupimeter,  96, 273. 
Phenological  observations,  290-294. 
Phenology,  167-294. 

climatic  tables,  272-277. 
epochs  of,  167,181. 
Linsser's  law,  214,215. 
lists  of  plants,  172, 191, 226, 242, 243. 
temperature,  172,211. 
thermal  constants,  336. 
summation  of  temperature,  279-290. 
Philadelphia,  Pa.,  bacteriological  examination  of 

air,  130. 
Photantupimeter,  96, 273. 
Photochemistry  of  sunshine,  92. 
Photographic  measurement  of  sunshine,  95. 
Physiological  constant,  224-230. 
Physiological  method,  6. 
Piche  evaporimeter,  106,  246,  273. 
Pieper,  germination,  44. 
Pine,  water  consumption,  113. 

chlorophyl  and  light,  38. 
Pinus.    See  Pine. 
Plant  growth,  15,  244,  ;245. 

respiration,  18. 
Plants,  acclimatization,  215. 
and  air,  18.    ' 
climate,  22. 

fixation  of  nitrogen,  136-161. 
phenological  lists,  172,  191,  226,  239,  240. 
soil  moisture,  114. 
sunshine,  168. 
temperature,  53,  235,  236. 
water  drainage,  115. 
water  supply,  116-127. 
Plat  experiments,  352-355. 
Plumb,  maize,  332-333. 

plat  experiments,  353. 
Poa  pratensis,  299,  307. 
Poggioli,  light  and  vegetation,  26. 
Polar  region,  vegetation,  39. 
Pollen,  dissemination,  129,  291. 
Polperro,  England,  epoch  of  awakening,  IM,  185. 
Postelberg,  Au.stria,  rainfall  and  harvest.  111. 
Potato,  cellulose,  18. 

date  of  planting,  309,  310.  • 
dryness  and  sunlight,  80. 
harvest  and  water  .supply,  127. 
water  consumption,  113-119. 
Potsdam,  Germany,  atmospheric  electricity,  131. 
Pouillet,  actinometer,  82. 
Poulkova,  Russia,  phenology,  213-215. 
PrazmofTski,  fixation  of  nitrogen,[151-155. 
Prediction  of  crop,  247-251,  363. 
tables  for,  272-277. 
time  of  harvest,  175, 189. 
Prillieux,  nitrifying  bacteria,  152. 
Prize  crops,  164. 

Progress  of  vegetation,  183,  185. 
Protection  from  frost,  340. 
Protein,  17. 
Protoplasm,  16. 


384 


Pruning  and  climate,  341,  363,  364. 
Pyrus  communis,  242. 
mains,  242. 

Quetelet,  phenological  constants,  181-189,  212. 

soil  temperatures,  286. | 

time  of  germination,  37. 
Quinchuqui,  Colombia  (?),  wheat  and  tempera- 
ture. 180. 

Radau,  measurement  of  radiation,  81,  96. 
Radiation,  conjugate  thermometers,  89. 

data  for  phenology,  273. 

influence  on  plants,  16. 

measurement  of,  81,  89. 

plant  development,  170. 

soil  temperatures,  20,  53. 

thermometer  readings,  235. 

wheat  harvest,  253,  254,  269-271. 
Radiometer,  Bellani,  97,  273. 
Rain, 'nitrogen  in,  133-135. 

soil  temperatures,  54,  110. 

sugar  crop,  344-350. 
Rainfall  and  crop  yield,  116-127,  253. 

data  for  phenology,  273. 

plant  development,  223,  234,  235,  245. 

soil  moisture,  110-111. 

sugar  beets,  125,  260. 

wheat  crop,  341-343. 
Rainy  days,  and  plant  growth,  117. 

soil  moisture.  111. 
Range  of  germination  temperatures,  35. 
Rape,  water  consumption,  120. 
Rawson,  rain  and  sugar  in  Barbados,  344-350. 
Reaumur,  thermal  constants,  168. 
Reforestation,  231. 
Respiration,  influence  of  light,  22,  37,  50. 

plants  and  seeds,  18,  47-48,  50. 

temperature,  19,  48. 
Rhone,  cold  waves,  129. 
Ribes  rubrum,  phenology,  280. 
Richardson,  grain  and  environment,  312-314. 
Richmond,  Va.,  wheat  and  temperature,  180. 
Ripening,  epoch  of,  182,  186. 

latitude,  243. 

period,  183. 

thermal  constant,  169,  173,  191,  226,  278-290. 

vine,  2.57. 

wheat,  253,  267. 
Risler,  water  consumed  by  plants,  113,  246. 
Robinet,  silk  worms,  36. 
Roscoe,  measurement  of  sunshine,  82. 

photochemical  researches,  92. 
Rotation  of  crops,  141,  144,  157. 

and  artificial  fertilizers,  162-166. 
Rothamsted,  England,  composition  of  rain,  135. 

evaporation  and  crops,  245. 
■  fertilizers,  138,  142,  145. 

plat  experiments,  355. 
Royer,  available  moisture.  111. 
Russell,  evaporation,  106. 
Russia,  acclimatization  of  wheat,  220. 
Rye,  growing  period,  243. 
phenology,  280-290. 
water  consumption,  113,  120,  124. 

Sachs,  climatic  laboratory,  24. 
chlorophyl,  38,  39. 
light  and  vegetation,  26,  78. 


Sachs,  limiting  temperatures,  174,  335,  339. 

physiological  studies,  6. 

tuber  growth,  79,  80. 

ultraviolet  light  and  plant  growth,  80. 
Sainfoin,  fixation  of  nitrogen,  153. 
St.  Louis,  electricity  of  air.  131,  152. 
St.  Petersburg,  phenology,  214. 

thermal  constants,  214,  216. 

.sunshine,  219. 
Salfeld,  inoculation  of  soil,  158. 
Salkowsky,  nitrifying  ba^'teria,  139. 
Sambucus  nigra,  phenology,  281. 
Sanborn,  fertilizers,  162. 
Saunders,  thaws  and  plant  life,  128. 
Sau.ssure,  de,  germination,  43. 
Schleiden,  potato  and  light,  39. 
Schloesing,  ammonia  in  soils,  136,  142,  143. 

atmospheric  ammonia,  144. 

nitric  ferment,  142. 
Schloesing,  jr.,  fixation  of  nitrogen,  150,  151. 
Schott,  sunshine  tables,  101. 
Schuebeler,  acclimatization,  217,  220. 

climate  and  plants,  40. 

culture  of  grain  in  Europe,  243-247. 
Schweitzer,  maize  experiments,  333. 
Seeds,  germination,  28,  41-52. 

relations  to  air  and  soil,  18. 
Seeding.    See  Sowing. 

and  harvest,  358-361. 
Seignette,  available  moisture.  111. 
Sendtner,  phenological  list,  189. 
S^nebier,  light  and  germination,  42. 

light  and  vegetation,  26. 
Serafina,  germs  and  forests,  130. 
Serradella,  fixation  of  nitrogen,  160. 
Sesnmum  orientate,  germination,  28-36. 
Seynes,  de,  germination,  33. 
Shade,  and  plant  development,  79. 

temperature,  238. 
Sid^ration,  158. 

Silver  chloride,  measurement  of  sunshine,  92. 
Sitmpis  alba,  germination,  28-36. 
Singer,  rain  and  soU  temperature,  54. 
Six,  soil  thermometers,  65. 
Smithsonian  Meteorological  Tables,  101. 
Smithsonian  phenological  list,  292-294. 
Smut,  wheat,  prevention,  341. 
Soaking,  influence  on  germination,  37. 
Soda,  nitrate  of,  fertilizer,  163. 
Soil,  ammonia,  136, 139. 

cereals,  364. 

evaporation,  246. 

exhaustion,  142. 

moisture,  20, 104-127. 

temperature,  20, 53-65, 235, 273. 

thermometers,  21,65,66. 

wheat,  314-318. 
Solar  constant,  91. 
Sorauer,  water  consumption,  123. 
Sorghum,  337. 

South  America,  seasons,  221. 
South  Carolina,  prize  corn  crop,  164. 
Sowing,  date  of  .and  wheatharvest,263-272, 368-361. 

and  crop  yield,  337, 339, 355-358. 
Sporer,  acclimatization  of  grasses,  299. 
Sports,  origin  of,  303,  362. 
Starch  and  light,  41. 
composition,  17. 


385 


statistical  mothod  in  botany,  7. 

Stettin,  Genniiny,  phenology,  ISti. 

Stone,  sorghum,  337. 

Stnu'ture  of  seeds,  35. 

Sturtevant,  cultivation  and  evaporation,  lOS. 

pepper,  307. 

range  of  plants,  9. 

thermal  constants,  335-337. 
Stuttgart,  Germany,  acclimatization,  220, 233. 
Sugar  beets,  and  climate,  2.59-2G3. 

rainfall,  125. 

time  of  harvest,  310. 
Sugar  crop  and  rain,  Barbados,  344-350. 

climate,  303. 
Summation  of  temperature,  279-290. 
Sunshine  and  absorption  by  seeds,  47, 48. 

assimilation,  67-80. 

chlorophyl,  75. 

diminution,  99. 

distribution,  72. 

dust  and  diffused  sunshine,  81. 

effects,  22. 

hour  degrees,  74. 

latitude,  244. 

measurement,  22, 81-103. 

Montsouris,  89, 90. 

photochemical  intensity,  92. 

photographic  measurement,  95. 

plant  development,  160,  244,  247. 

recorder,  21. 

records,  99, 100. 

ripening  of  grain,  73. 

soil  temperatures,  20. 

sugar  beets,  259. 

total  possible,  101-103,  219. 

transpiration,  69. 

wheat  crops,  255. 
Sun  temperatures,  238. 
Surface  slope  and  soil  temperature,  67. 
Sweden,  phenology,  186. 
Switzerland,  acclimatization  of  grains,  220. 
Symbiotic  life,  138. 

Tables  of  possible  sunshine,  101-103. 
Taimyr,  Siberia,  grasses,  299. 
Temperature,  black  bulb,  171. 

chlorophyl,  38. 

effective,  170. 

germination,  28-36. 

ineffective,  36. 

low,  and  vegetation,  338-340. 

phenology,  211,  273. 

plant  development,  19,  168, 211,  234,  236,  239. 

respiration,  19,  48,  50. 

soil,  20,  53-66. 

sugar  beets,  260. 

summation,  279-290. 

wheat  crop,  341-343. 
Tenerifle,  botanical  garden,  221. 
Tessier,  light  and  vegetation,  6. 
Thaws  and  plant  life,  128,  237. 
Theory  of  compensation,  219. 
Theory  of  errors  in  agriculture,  ;5.53,  354. 
Thermal  constants,  168,  189-191,  236-243,  278-290, 
320-331. 

barley,  319. 

grape,  25&-2.59. 


Thermal  constants,  ninize,  336. 

oats,  320. 

peas,  336. 

wheat,  251-256,  265,  267,  278,  319. 
Thermoelectric  aetinometer,  99. 
Thermoelectric  sun.shine  recorder,  97. 
Thermometer,  soil,  21,  65,  66. 
Thcrmometric  constants  and  plant  growth,  168. 
Thcrmometric  measurement  of  sunshine,  83-92, 

96. 
Thermophone,  65.  • 

Thorpe,  insolation  measurements,  82. 

photochemical  researches,  94. 
Thunderstorms,  and  .souring  of  milk,  341. 

and  nitrates,  135. 
Thuija,  chlorophyl  and  light,  38. 
TiUacuropcxn,  Tllin  ^ilvcittrif,  phenology,  281. 
Timiriazeff,  chlofophyl,  38,  41. 
Timothy,  cellulose,  18. 

time  of  harvest,  310. 
Tisserand,  grain  culture  in  Europe,  243-247. 

light  and  vegetation,  41. 

sun.shine  and  prain,  73. 

vegetation  in  high  latitudes,  40. 
Tokyo,  Japan,  soil  temperature,  54. 
Tomaschek,  thermal  eon.stants,  173. 
Transmission  of  solar  heat,  92. 
Transpiration,  19,  112. 

diurnal  periodicity,  70. 

plant  temperature,  53. 

and  .sunshine,  67-80. 
Treadwell,  souring  of  milk,  341. 
Trees  and  rapid  thaws,  128. 
Trifoliiun  repent,  germination,  28-36. 
Tubercles,  on  nitrogen-fixing  plants,  136,  137. 
Tubers,  dryness  and  sunlight,  80. 

Ultraviolet  light  and  plant  growth,  80. 
United  States,  average  wheat  crop,  179: 

crops  and  climates,  351-364. 

evaporation,  107. 

phenology,  186. 
Upsala,  Sweden,  germination  of  wheal,  39. 

phenological  observations,  241-242. 

Valognes,  France,  epoch  of  awakening,  185. 
Van  Tieghem,  phenological  constants,  179. 
Vegetation,  anpual  progress,  183. 

beginning  of,  238. 

climatic  factors,  188. 

development  of,  232. 

high  latitudes,  40. 

Lin.sser's  law,  214,  215. 

thermoscope,  174. 

wind,  129. 

zones,  224. 
Venice,  Italy,  phenology,  185. 

plant  development,  -M. 

sunshine,  219. 
Vienna,  Austria,  phenology,  189,  190. 

plant  development,  231. 

thermal  constants,  238. 
Ville,  atmospheric  ammonia,  144. 

fertil  ization  by  clover,  158. 

fixation  of  nitrogen,  146,  1.53,  155,  1.59. 

germination,  44. 
Vilmorin,  thermometer  expo.sure,  176. 


2667—05  M- 


-25 


386 


Vincennes,  Prance,  acclimatization  of  barley,  41. 
Vine  and  weather,  249-251,  295-298. 
Vines,  physiological  studies,  15. 
Violle,  actinometer,  82,  97,  171,  273. 

conjugate  bulbs,  97. 

sunlight,  absorption  by  air,  85. 
Vital  principle,  15-16. 
Vochting,  light  and  vegetation,  79,  80. 
Vogel,  measurement  of  sunshine,  95. 

Walcott,  rainfall  and  sugar  crop  of  Barbados, 

344-350. 
Warington,  fertilizers,  103. 

nitrifying  bacteria,  139. 

nitrogen  in  rain,  135. 
Warren,  thermophone,  Go. 
Washington,  D.  C,  soil  temperatures,  66. 
Water,  composition,  17. 

evaporation,  104. 

plant  nutrition,  114. 

supply  and  plant  growth,  116-127,  245. 
Weather,  artificial  modification,  8. 

and  prize  crops,  165. 
Weber,     photographic     measurement     of     sun- 
whine,  95. 
Welitschkowsky,  percolation,  109. 
Wheat,  average  yield,  144. 

cellulose  and  albuminoids,  18. 

climate  and  soil,  263-272,  314-318. 

date  of  flowering,  178. 

environment,  312-314. 

fertilizers,  162. 

growing  period,  243. 

heat  and  light,  39,  41,  251-256. 

latitude,  73,  74. 

low  temperatures,  339. 

nitrogen  in  rain,  142. 

phenology,  179,  278-290. 

sports,  303. 

sowing  and  harvest,  358-361. 

temperature  and  rain,  341-343. 

thermal  constants,  1G9,  170,  177,  318-319. 


Wheat,  water  consumption,  113,  123. 

weather,  250. 
Wheeler,  fixation  of  nitrogen,  159. 
Whipple,  thermophone,  65. 
Whitney,  percolation,  109. 

soil  thermometers,  65. 
Wiesner,  chlorophyl,  38. 

sun.shine  and  temperature,  71. 
Wild,  earth  temperatures,  65. 
Wilfarth,  fixation  of  nitrogen,  136,  151-16.5. 
Wind,  data  in  phenology,  273. 

evaporation,  105,  107. 

plant  growth,  19. 

vegetation,  129. 
Wind-breaks,  340-341. 
Wine  crop  and  climate,  295-298. 

weather,  250,  256-259. 
Winnipeg,  Canada,  sunshine,  100. 
Winogradski,  nitric  ferment,  142. 
Wisliczenus,  atmospheric  electricity,  131. 
Wollkoff,  actinometry,  82. 
Wollny,  crops  and  water,  116,  120,  124. 

pruning  and  tuber  growth,  80. 

soil  moisture,  110,  114,  115. 

soil  temperatures,  57. 

transpiration,  113. 
Woods,  fixation  of  nitrogen,  160. 
Woodward,  transpiration,  69,  113. 
Wright,  wheat  and  temperature,  339,  340. 
Wurttemberg,  Germany,  phenology,  235. 

Yakutsk,  Siberia,  acclimatization  of  grain,  220. 
temperature  range,  187. 

Zahner,  soil  temperatures,  62. 
Zantedeschi,  germination,  44. 
Zea  mays.     {See  also  Corn  and  maize. ) 

germination,  28-36. 
Ziegler,  phenology,  236. 
Zones  of  vegetation,  221. 

Linsser,  224. 
Zurich,  Switzerland,  soil  temperatures,  21. 

vegetation  and  light,  37. 


o 


nuriUiKuuLfiiiiiii  Biiim 

U.C.BERKELEY  LIBRARIES