^^^

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LIBRARV

OF THE

University of California.

GIFT OF-

Class

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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

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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.

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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.

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