Chapter L: Appendix: C

SHORT APPROXIMATE METHODS OF SOIL EXAMINATION USED AT THE CALIFORNIA EXPERIMENT STATION.

BY R. H. LOUGHRIDGE.

The California Experiment Station has for many years given the farmers of the State the privilege of having their soils examined to ascertain any physical defects, deficiency in plant-food, or the presence of alkali salts. They have quite generally taken advantage of this, and the number of samples of soil sent in each year has been very large.

A complete analysis of a soil-sample requires fully 15 days; hence the necessity of adopting some quick methods for the determination of the main elements of fertility, viz., humus, lime, potash, and phosphoric acid, that would at the same time give results sufficiently accurate for practical purposes. Similarly for alkali salts in the soil; the leaching-out and analysis of which often occupies more than a week.

The following methods have been adopted, which shorten the time of examination for the plant-food of a soil to about one hour, except for potash, which requires a much longer time. For alkali salts the time is reduced to two days, and less if a pressure filter be used.

_Humus._—The Grandeau method of ammonia extraction requires the removal of the lime and magnesia with weak hydrochloric acid, washing out of the acid and then digestion with weak ammonia; all of which, with a soil rich in humus, may require many days, though a number of samples may be put through at the same time.

The method adopted to determine adequacy or inadequacy of the humus (for this is all that is intended in this examination) is completed in less than half an hour. It is based on the color of the humus-extract and avoids the necessity of removal of the lime from the soil.

The soil is pulverized in a mortar with a rubber pestle, and passed through a half-millimeter sieve. Seven grams of the fine earth is placed in a test tube with 15 or 20 cc. of a ten per cent solution of caustic potash and boiled for ten or fifteen seconds, then allowed to settle. The humus is dissolved and the density of the color of the solution is an indication of adequacy or inadequacy. A dense black, non-translucent solution shows the presence of at least one per cent of humus in the soil; a deep brown translucent color indicates about one-half of one per cent; while a light brown color clearly shows a deficiency in the soil, and a need of a good green-manure crop.

_Lime._—Two grams of fine earth is treated with a little hydrochloric acid, boiled for a few seconds, and ammonia is added to precipitate the iron and alumina; the whole, with the soil-residue, is quickly thrown on a filter to separate the mass from the lime solution, and washed. After adding ammonium chlorid the lime is precipitated with oxalate of ammonia, and its adequacy for soil-fertility judged of by the turbidity of the solution, or the bulk of the precipitate. Or the latter may be filtered off, dried and weighed. We thus obtain a measure of the carbonate and humate of lime present, by comparing it with the precipitate obtained from a soil whose percentage of lime has been correctly ascertained.

_Potash._—The determination of potash in the soils requires more time than either of the other ingredients, and is more rarely made by us. Our knowledge of the soils of the State of California obtained through many analyses, gives us a clue to those localities where potash would probably be deficient, as well as to those whose soils are generally extremely rich in potash; the percentages reaching usually from .5 to as much as 1.5 per cent and more.

For the determination, two grams of the fine earth is digested in hydrochloric acid over a steam bath for two days, the insoluble residue filtered off, the filtrate evaporated to dryness to render the silica insoluble, again filtered and the iron; alumina and lime removed by precipitation with ammonia and oxalate of ammonia and filtration. The filtrate is then evaporated to dryness, the ammonia salts destroyed with _aqua regia_ or driven off by heat, and the alkalies changed to chlorids. Any residue is then filtered off and platin-chlorid added to precipitate the potash, which is separated and determined in the usual way, either by reduction of the platinum by ignition, or by measurement in a Plattner’s potash tube.

_Phosphoric Acid._—The determination of phosphoric acid is based on the volume of the phospho-molybdate precipitate in a tube made like a Plattner’s potash tube, but having a wider interior diameter for the smaller portion (not greater than 3 millimeters), and a length of 50 mm. With this diameter, one mm. in height of the precipitate obtained by our short method indicates one one-hundredth of one per cent of phosphoric acid in the soil. The unit of measure must be obtained for each tube, unless of uniform diameter, and is ascertained by taking a soil whose phosphoric-acid percentage has been determined gravimetrically and giving it the following quick treatment; which must, of course, be closely followed in each soil to be examined.

Two grams of the fine earth is ignited in a platinum dish to destroy the organic matter, transferred to a test-tube containing 5 cc. of nitric acid and made to boil for only a couple of seconds, thus preventing the solution of silicates to any material extent. It is not allowed to stand, but a little water is immediately added and it is quickly thrown on a small filter and washed with a little water. The phosphoric acid is then precipitated with molybdic acid at the proper temperature; allowing it to settle, the liquid is drawn off and the precipitate transferred to the measuring-tube. It settles into the small part in a short time if the latter is not too narrow, and is then measured with a millimeter scale. This represents the percentage as found in the soil by the gravimetric method, and serves as a guide for other examinations, whose agreement with gravimetric determinations is generally quite close, and quite sufficient for practical purposes. The rapidity with which the solution is made and separated from the soil is a matter of special importance for comparative results, or determination of percentages; for if the acid solution be allowed to stand for some time before filtration from the soil, silica passes into solution also, and the volume of the molybdate precipitate is increased by it; thus vitiating the results and adding to the time required for the method. By this short method the practically important phosphoric acid in the soil may be approximately determined within half an hour.

SHORT METHOD FOR ALKALI SALTS.

The old method of obtaining solutions of the salts by leaching the soil on a filter until all of the alkali had been washed out has been replaced by the following short one. 50 or 100 grams of the well-mixed soil is placed in a bottle containing 200 cc. of water, shaken up occasionally during 12 hours and allowed to settle. The solution may then be passed through a common filter (or preferably a pressure filter) and an aliquot part (usually 50 cc.) of the filtrate evaporated to dryness in a platinum basin and ignited at a temperature just below redness to destroy any organic matter that may be present. The basin and contents are weighed and the soluble salts are dissolved in a very little water and separated by filtration through a small filter into a 50 cc. cylinder and the alkali carbonates and chlorids determined by titration, being calculated as sodium compounds.

The material remaining on the filter and in the basin, consisting of insoluble earth, carbonates and calcium sulfate, is gently ignited in the basin and weighed; the difference between this and the first weight gives approximately the _total soluble salts_, which should substantially correspond to the titrations made.

The sulfates are determined by differences between these and the total alkalies. The solution may contain some sulfate of magnesia, or calcium and magnesium chlorids, and these are determined gravimetrically.

Nitrates, which may have been destroyed in the first ignition, are determined in the original solution by the picric method. Any magnesia rendered insoluble by the ignition may usually be accounted for as chlorid, unless much nitrate is present which is rarely the case in carbonated alkali. If much nitric acid was found, it should be first assigned to magnesia.

INDEX.

A.
PAGE
Absorption and movements of water in soils, 221
of solids from solutions, 267
of gases by soils, 272, 275
Acacias, tolerance of alkali, 480
Accessory minerals, 50
Acid, strength used in soil analysis, 341
Acidic and basic eruptive and metamorphic rocks, 49
Acidity, neutrality, alkalinity of soils, 322
Acids of different strengths, analysis with; table, 326, 341
Action of plants in soil formation, mechanical and chemical, 19
Aeration and reduction as influencing nitrification, 147
effects of insufficient, in soils, 280
excessive, injury in arid regions, 280
Aerobic and anerobic bacteria, 144
Air, functions in soils, 279
“ of soils, composition of, 280
Air-space in soils; figure, 108
Alabama, vegetation and soil-characters, 511
Alaska current, effects on California climate, 296
Alinit, 149
Alkali carbonates and sulfates, inverse ratio, 451, 452
carbonates, effects on clay, 62
effects on culture plants; figure, 426, 427
Alkali-heath, range, tolerance of alkali, figure, 544, 545
Alkali lands, crops for strong, 468
effects of irrigation on, 428
efficacy of shading, 457
exceptionally productive when reclaimed, 483
fertilization not needed in, 483
formation from leachings of slopes, 453
geographical distribution of, 423
high and lasting production when reclaimed, 482
inducements toward reclamation of, 481
in the San Joaquin valley, Cal., figure, 425
possible injury to, from excessive leaching, 462
Alkali lands, summary of conclusions, 453
surface and substrata of, 429
utilization and reclamation of, 455
of world-wide importance, 424
vegetation of, 534
Alkali-resistant crops, 455
Alkali salts, black and white, 441
composition of, 439
composition of; general table, 442, 443
distribution in heavy lands, 436, 437
effects on beet crop, 465
horizontal distribution of, 439
in hill lands, 439
in sandy lands, 433, 435
in Salton Basin, distribution of, 4, 36, 438
leaching-down of, 459
nature of, 423
plant food in, 441, 444
reactions between, 449, 450
reduction by cropping, 463
relative injuriousness of, 464
removal from the soil, 458
removal by deep-furrow irrigation; figure, 460, 461
tolerance of various crop plants; table, 466, 467
total in lands; estimation of, 444
underdrainage the universal remedy for, 460
upward translocation from irrigation, 433
vertical distribution in soils, 429, 431, 432, 434
Alkali soils and seashore lands, 422
calcareous character of, 28
composition of, as a whole, 445, 446, 447
how native plants live in, 430
origin of, 422
repellent aspect, cause of, 424
retention of silica in, 392
Alkali spots, white, 286
Alkali, rise of, 428
turning under of surface, 456
weeds as cattle food, 468
study of, by Loughridge and Davy, 535
Aluminic hydrate, in soils of California and Mississippi;
table 101, 390
Alluvial soils, 12
Ammonia-forming bacteria, 149
Ammonia gas, absorption of, by soils; figure, 274, 275
Ammonic carbonate, effects on glass, 18
Ancient civilizations, preference for arid countries, 417
rare in humid countries, 418
Apatite, 63
Arid and humid climates, rock-weathering in, 47
Arid and humid regions, criteria of soils of, 371
contrast between soils of, 28
soils of, 111, 371
Arid and humid soils, general comparison; table, 375, 377
Arid belts, subtropic, 298, 299
utilization of, 299
Arid conditions, local, in tropical countries, 401
Aridity, influence upon civilization, 417
Arid region, bunch grasses on soils of, 111
standing hay in, 300
upland soils of; table, 373, 374
Arid soils, productiveness induces permanent civil organization, 412
Arroyo Grande and Yazoo buckshot soils, 345
Asparagus, resistant to salts, 475
Atmosphere, composition of; table, 16
Azotobacter, 156
Lipman on, 156

B.
Bacteria, active in soil-formation, 20
aerobic and anaerobic, 144
denitrifying, 148
food and functions of, 145
in soils, numbers of, 142
micro-organisms of soils, 142
multiplication of, 144
nitrifying, 146
Bacterial life, effect on soil, condition, 149
relation of carbonic dioxid to, 281
Bacteroids, 151
Mork figures, 152, 153
Basaltic rocks, 49
Basalts, red soils from, 52
Basic slag, 64
Basin irrigation, advantages of, 243
Bauxite in soils, 101, 390
Beet, sugar, effects of salts on, 474
tolerant of common salt, 474
Bhil soils, 414
Bicarbonate of soda, 78
Black-alkali lands, difficulty in draining, 462
neutralizing of, 457
waters, use of, 250
why so called, 78
Black earth of Russia, humus in; table, 130
Black sand, 45
Black prairie soils, 53
Black soils and lands, 283
Blizzards in continental America, 298
Blown-out lands, 9
Blue tint in clays and subsoils, 45
Bodengare, 149, 150, 281
Bog ore, formation of, in subsoils, 46, 66
Bones, composition of, 64
Bone meal, efficacy of, 65
Borax, borate of soda, 79
Bottom water, 227
rise of, from irrigation, 227, 230
Bottoms, first and second, contrast between, 506, 507, 509
Bottoms, first, tree growth of, 507, 509
Brahmaputra alluvium, Assam, 413
Brown iron ore, 44
“Buckshot” soils of Yazoo bottom, 116
“Bunch grasses” as alkali-resistants, 471
Burning-out of humus, effects of, 118
Burrowing animals, work in soil-formation, 160

C.
Calcareous clay, crumbling on drying, 116
formations, predominance in Europe, 525
soils, definition of, 367, 496, 524
solubility of alumina and silica in, 389
subsoils, and hardpans, 162
Calciphile, calcifuge and silicophile plants, 521
Calcite, calcareous spar, 39
recognition of, 39
Caliche, in Chile, Nevada, and California, 66, 67
Capillarity, 189
Capillary water, reserve of, 229
rise of, 202 to 207
Carbonated water, action on feldspar, 32
action on silicates, 18
universal solvent, 17
Carbonate of soda, 77
injury to soils and plants, 78
Carbonates, chlorids and sulfates of earths and alkalies,
reactions between, 449, 450
Carbonic acid, 17
secreted by roots, 20
Carbonic dioxid, absorption of, by soils, 274
heavily absorbed by ferric and aluminic hydrates, 278
occurrence, formation, 17
relation to fungous activity, 281
Cascade range, climatic divide in N. W. America, 297
Caves in limestone regions, 41
Celery, moderate tolerance of alkali, 475
Centrifugal elutriator, Yoder’s, 92
Cereals, alkali-resistance, barley, gluten wheats, 471
Channels, cutting-out by gravel, 6
Charcoal, absorption of gases by, 276, 277
Chemical absorption by soils, 270
action of roots, 20
analysis of soils (in general), 323
character of soil, recognition of, 322
decomposition, causes intensifying, 21
processes of soil formation, 16
Chile saltpeter, 66
Chernozem, 130
analyses of, table, 364
Chestnut, American, a calcifuge tree, 491, 519
Chlorin, largest ingredient of sea water, 27
Chlorite, 36
Chlorosis of vines in marly lands, 526
Churn elutriator, Hilgard’s; figure, 91
Circling of hill lands, 220
Citrus fruits, injury to, from alkali, 478
lemons most sensitive, 478
sensitiveness to common salt, 477
Classification of rocks, 47
of soils, 10
Clay as a soil ingredient, 83
colloidal, 59
functions of, in soils, 59
maintains crumb structure, 110
Clays, claystones, clay shales, 48
colors of, 58
formation, flocculation and deposition of, 33
maturing of, 60
plasticity and adhesiveness, influence of fine powders on, 85
influence of ferric hydrate on, 85
Clay-sandstones, soils from, 57
Clays, separation of, by subsidence, by centrifuge, 89
varieties, enumeration of, and characters, 57, 58
fusibility of, 58
Claystones, soils from, 59
Cleavage of rocks, 3
Cleopatra’s needle, 2
Climate, 287
Climatic and seasonal conditions, 21
Climates, continental, coast and insular, 297
Coffee soils, calcareous, 417
Colloidal clay, amount in soils. Table, 84
analysis of, by Loughridge, 385
effects of alkali carbonates upon, 62
investigation by Schloesing, 59
properties of, 61
separation of, by boiling and kneading, 61
Colloid humates, 133
Colluvial soils, 12
Colors of soils, advantages of, 283
Common salt, injuriousness in soils, 76
recognition of, 76
removal from soils, 76
Conglomerates, 48
Conifers, tall growth of, in arid regions, 517
Contraction of soils in wetting and drying, 114
Co-operation, favored by need of irrigation, 419
Corsican and maritime pine, ash analyses, 520
Cotton, compact growth and heavy boiling on calcareous soils, 503
Cracking of clay soils in drying, 113
Cressa; range, tolerance of alkali, figure, 545, 546
Creep, 12
Crops, alkali-resistant, 455
Crumbling of calcareous clays on drying, 116
Crumb-structure of soils; figure, 110
Crusting of soils, effects of, 111, 117, 221
Cultivated soils, analysis of, 325
investigation of, 316
Cultural experience the final test, 324
Cutting-out of channels by water-borne gravel, 6
Cypress, different forms of; figures, 507, 508

D.
Date palm, resistance to alkali, 478
Decomposition, chemical, of rocks, 16
Decolorizing action, of soils, charcoal, 267
Deep-rooting of native plants in arid region, 174
Deforestation, effects of, 219
Deltas, formation of, 7
Denitrifying bacteria, 148
Deserts, effects of winds in, 8
Desert sands, only lack water to become productive, 420
Dew, formation of, 307
rarely adds moisture to soils, 308
within the soil, 308
Differentiation of soil and subsoil, causes of, 121
Distance between furrows and ditches, 241
Dolomite, 42
Drainage, rights-of-way for, 461
Drainage waters, use for irrigation, 250
Drain waters, analyses of, table, 22
leaching effects of, 271
Drouth, resistance to, in arid soils, 167
Dust soils, nature of, 104
slow penetration of water in, 105
Dust storms, 9
Dynamite, used for shattering dense substrata, 181

E.
Earth’s crust, known thickness, xxiv
Earthworms, action of in soil-formation, 158
Ecological studies, 314
Egypt, obelisks of, 2
Elements constituting earth’s crust, table of, xxiv
important to agriculture, list of, xxiv
Elutriator, Hilgard’s, figure, 91
Epsomite, epsom salt, in soil, 78
Eremacausis, 129
Erosion in arid regions, 219
in Mississippi table lands; figures, 218
lowering of land by, 15
of rocks by sand; figure, 10
Eruptive rocks, basic and acidic, 49
rocks, soils from, 52
Eucalyptus, tolerance of alkali, 480
European observations on plant distribution, 519
standards of plant-food adequacy—Maercker’s table, 369
Europe, predominance of calcareous formations in, 525
Evaporation and crop yields, calculated, 193
and crop yields, observed (Fortier), 194
and plant growth, 193
counteracting, in alkali lands, 455
dependence on air temperature; Fortier’s experiments, table, 255
from reservoirs and ditches, 257
from water surfaces, 254
wet and moist soils, 254
in different climates, 192, 256
in different localities, California, 255
restrained by loose surface layer, 255
through roots and leaves, amount of, 262, 263
Expansion by oxidation, 18

F.
Farmyard or stable manure, 72
Feldspars, weathering of, 31
products of, 32
Ferghana, alkali lands in, 441
Ferric hydrate, effects of, 100
functions of, in soils, 285
high absorptive power of, 277
in Hawaiian soils; table, 356
more diffused in humid than in arid soils, 392
Ferric phosphate, unavailability of, 356
Ferroso-ferric hydrate and oxid, 18, 45
Ferrous oxid, 18
Ferruginous lands, injury from swamping of, 233
Fertilizers, mineral, 63
waste of, by leaching, 269
Flocculation and floccules, 91
Flocculated structure; cements maintaining, 110, 111
Flood-plains of rivers, 14, 15
Fool’s gold, 75
Force exerted by roots, 19
Forecasts, general, of soil quality in forest lands, 507
of soil values, popular, 313
Forest trees, forms of, 499 to 502
of Atlantic states on alkali lands, 481
Form and development of trees, differences in, 498
Forms of leaves, variation in, 502
black-jack oak, 499, 501
post oak, 499, 500
trees, deciduous, in arid region, 516
willow, scarlet, black and Spanish oaks, 502
Freezing water, effects of, 3
Frost, effect of soils, 118
Fruiting, favored by lime in soils, 503
Fungi and molds, action of, 123
functions in humus-formation, 157

G.
Gases, absorption of, by soils, 272, 275
partial pressure of, 276
Germination of seeds, 309
Glacier flour, fineness and fertility of, 5
physical analysis of, 5
Glaciers, grinding and abrasion by; figure, 3
Glauber’s salt, 77
Glauconite, in calcareous sandstones, 56
Gneiss soils, 51
Gobi desert, migration of lakes, 9
Going-back of orchards, 182
Grain-sizes, effect on percolation; table, 224
influence on soil texture, 100
Grandeau method of humus estimation, 132
Granite soils, potash and phosphoric acid in, 50
Granitic rocks, weathering of, 47
sand, formation in arid climates, 2
Grano-diorite soils, of Sierra Nevada, 51
Granular sediments, influence upon tilling qualities, 102
Grape-vine, alkali, tolerance of, 475
Grasses, cultivated, sensitive to alkali, 471
Greasewood, range, tolerance of alkali; figure, 542, 543
Greenstones, soils from, 51
Ground water, depth most favorable to crops, 228
variation of surface of, 228
Gulf-stream, 295
Gypsum or selenite, formation from sea-water evaporation, 42
how recognized, 42

H.
Halite, 76
Hardpans, causes, formation and cements of, 185
Hardpan, physical, analysis of, 103
plowsole, 241
Hawaiian Islands, humid and arid sides of, 297
soils, analyses of, 356
Hay bacillus; figure, 149, 150
Heat and cold, effects on rocks, 1
of high and low intensity, 304
reflection and dispersion from soil surface, 304
relations to soils and plant growth, 301
trapping of suns, 288
Heaviest clay soils, physical analysis of, 115
Heaving-out of grain, 119
Hematite, 44
Herbaceous plants as soil indicators, 517
Hog-wallows, 114
Hornblende and pyroxene, 33
weathering of, 33
Horsetail rushes, secretion of silica by, 31
Humates and ulmates, 133
cementing effects of, 111
Humid and arid climates, rock-weathering in, 47
Humid region, upland soils of; table, 372, 374
Humification in soils, 20
normal conditions of, 129
tests; Snyder, tables, 140
Humin substances, formation of, 123
Humus, amidic constitution of, 125
and coal, amounts of, from vegetable substance, 128
amount in soils, 133
ash of, from Minnesota soils, analysis, 134
decrease of nitrogen-content with depth, 135
determination in soils, 132
distribution in the surface soil, 157
functions in soils, 21
in arid and humid regions, 138
in black earth of Russia, 130
in Minnesota soils, 131
in North Dakota soils, 133
in the surface soil, 120
losses from cultivation and fallow, 131
nitrogen of, 124, 135
percentage in soils, and nitrogen-content of,
tables, 135, 136, 137
porosity of, 124
progressive changes in soils, 126
relation to bacterial content, 144
scanty in arid soils, but rich in nitrogen, 397
substances, physical and chemical nature of, 124
variation of, with original materials, 139
volume weight of, table, 125
versus adipocere, 140
Hydraulic elutriation, 90
Hydromica, 35
Hydrous silicates in soils of arid region, 388

I.
Ice-flowers on soils, 119
Immediate plant-food requirements, ascertainment of, 333
productiveness, chemical tests of, 337
productiveness vs. permanent value of soils, 318, 327
India, climatic contrasts, 401
Indian soils, table of analyses, 410 412
types of soils, 411
Indo-Gangetic plain; calcareous hardpan, kankar, 411
Injury from excessive runoff, prevention of, 220
to plants from the various salts, 531
to soils and plants from carbonate of soda, 78
Insects, work in soil-formation, 160
Insoluble residue of soils; less in arid than humid, 384
Insufficient rainfall, leaves sea salts in soils, 28
Insular climate, of Britain, western Europe, 298
Introduction, xxiii
Injury from swamping, permanent, 232
Iron carbonate solution, how formed, 44
coloring clays, 58
minerals, 44
pyrite, how recognized, 75
Irrigation, basin, advantages and disadvantages, 244
by check flooding, 237
flooding, 237
furrows, 238
lateral seepage, 242, 241
shallow, deep and wide furrows; diagram, 239
surface sprinkling, 237
underground pipes, 245
ditches, leaky, effects on alkali lands, 429
excessive surface rooting caused by, 245
methods of, 236
necessitates co-operation, 419
Irrigation water, abundant use of saline, 249
duty of, 251
economy in use of, 243
effects of saline, figures, 247
heavy losses in using, 252
limits of salinity, 246, 248
loss by evaporation, 252
loss by percolation; diagram, 253
quality of, 246
saline, how to use, 249
testing penetration of, 242
temperature of, 244
Irrigation, winter, advantages of, 236
Isinglass, 43

J.
Janesville loam, chemical analysis of, 331
Japan current, 296
Jasper and hornstone pebbles, weathering of, 30

K.
Kainit, composition of, 71
Kaolinite and clay; kaolin, 32
assumes plasticity on trituration with water, 60
crystalline form of, 22, 59
lacks plasticity, 60
Kaolinization, results in zeolite-formation, 395
slow in arid regions, 87, 386

L.
Landholding, units of, smaller in arid than in humid region, 420
Landlocked lakes, water of, 27
Land plaster as a fertilizer; effects on soils, 43
Landslides, 12
Laterite soils, Wohltmann’s definition, 416
Terra roxa of Brazil, 416
Leaching of the land, 22
Legumes, bacteria of, 150
mostly sensitive to alkali, 472
Leguminous plants, mostly calciphile; exceptions, 518
Leucite, potash content, 32
Lichens, action on rock-surfaces, 19, 20
Lignites and coal, how formed, 127
Lime a dominant factor in productiveness, 353
Lime carbonate in sea water, 26, 27
removed from earth’s surface, 41
summary of effects in soils, 379
Lime-content, effects of high, in soils, 365
effects on availability of phosophates, table, 366
“Lime-country is a rich country”, 365
Lime, excess of, in arid soils, 378
Lime feldspars, leave lime carbonate in soils, 32
in alkali lands protects plants from salts, 532
lands, failure of tea on, 414
Lime-loving trees, 490 to 492, 497
Lime, most abundantly leached out, 24
percentages, what are adequate, 367
in coast-belt soils, 496, 497
in heavy clay soils; table, 368
Lime renders lower amounts of plant-food adequate, 354
Limestone countries, 53
Rotten, 54
soils, excluded from comparison of arid and humid soils, 376
residual, 53
Limestones, impure, as soil-formers, 40, 53
residual soils of, how formed, 40
soft, or marls, 40
slow disintegration of pure, 63
Limit of acid action on soils, investigation of, by Loughridge, 340
Limonite, 44
Loamy and sandy soils, show little shrinkage, 117
Loose surface layer, illustration of effect, figure, 258, 260
prevention of evaporation by, 257
Loss of humus in summer mulch, 132
Louisiana, vegetation and soil-characters, 512
Lowland tree-growth, 506
Lysimeter, 227

M.
Madagascar, character and soils of, 405, 406
climate and rocks of, 406
methods used by Müntz and Rousseaux, 406
potash and lime leached into valleys, 407
red soils, 407, 409
table of soil analyses, 408
Madras, red soils of, 415
Magnesia, effects of excess over lime, 382
exceeds lime in tropical soils, 405
high in arid soils, 381
leached out next to lime, 24
proper proportions to lime, 383
Magnesian limestones as soil-formers, 42
Magnesian soils largely poor, 36
Magnetite, 45
Maize and sorghums, alkali-resistance, 471
Maize roots in humid and arid region, 175, 176
Manganese, more in humid than arid soils, 383
stimulant effects on crops, 383
Marble and limestones, formation of, 39
Marls, gypseous and calcareous, 43
Marly substrata, 186
Marine saline lands, 527
first crops for, 533
reclamation for culture, 534
Matière noire; active nitrification of, 132, 360
Mechanical analysis of soils, 88
Melilots, white and yellow, alkali resistance, 473
Mesas of arid region, 14
Mesopotamia, rehabilitation of, 421
Metamorphic rocks, 46
Methods of irrigation, 236
soil analysis, 325
Mica as a soil ingredient, 35
weathers slowly, 35
mistaken for gold and silver, 35
Mica-schist soils, 51
Micro-organisms of soils, 142
Mineral fertilizers, 63
ingredients of soils, minor, 63
Minerals injurious to agriculture, 73
major soil-forming, and rock-forming, list of, 29
tints of, 18
unessential or injurious to soils, 75
Mirabilite, 77
Mississippi, changes in vegetation from east to west in northern, 490
investigations in, by writer, 489
northern, vegetative belts in; map, 490
vegetative belts, descriptions of, 490, 491, 492
Mississippi river, sediment carried by, 7
Mississippi, southern, central prairie, long-leaf-pine belts, 493
coast-belt; pine meadows; profile, 495
live-oak or shell hammocks, 495
Mississippi valley, climate of, 298
Mississippi water, annual variations in, 25
generalized composition of, 25
Modiola, of Chile, 469
Moisture hygroscopic, table, 196
influence of temperature and air-saturation, 197
method of determining, 197, 198
Mitscherlich’s objections, 199
utility to plant growth, 199
available to growing plants, 211
distribution in soil, as affected by vegetation, 264
evaporated from forests, 265
Eucalyptus, 265
in Russian forests and steppes, 265
requirements of crops in the arid region, 212
Loughridge’s tables of same, 214
supplied by tap roots, 229
useful to crops retained by alkali lands, 433
wasted by weeds, 264
Moraines, in North Central states, 5
Mosses, follow lichens in rock decomposition, 20
Moulds and fungi, action of, 123
Mountain chains, arid climate under lee of, 294
effects of, on rainfall, 293
Muddy waters, 251
Muir glacier, analysis of mud, 5
Mulches, loss of humus, 132
Mulching with straw, sand, 266
Mustard family, sensitive to alkali, 473
Myrobalan root, use for grafting in alkali lands, 479

N.
Native vegetation, basis of land values for farmers, 488
causes governing its distribution not an unsolvable problem, 489
result of struggle for existence, 487
Native grasses for alkali lands, 470
Native growth, cogency of conclusions based on, 314
New Mexico, soils from; analysis, 378
Nile water, Letheby’s analyses of, 25
Nitrate deposits, origin of, 67
of soda, 66
Nitrates, waste of, by leaching, 24, 68
Nitrification, active in matière noire, 360
Nitrification and denitrification, 145
in alkali lands, 68
in soil of “ten-acre tract.”, 359
intensity in arid climates, 68
list of substances favoring, 147
of organic matter in soils, experiments, 358
not active in unhumified matter, 359, 360
Nitrifying Bacteria, 146
Nitrobacterium; conditions of activity, 146
Nitrogen-absorbing bacteria, 156
Nitrogen, absorbed more abundantly than oxygen, 278
accumulation of, in humus, 124
adequacy in humus, lowest limit of, 363
in soils, 357
availability of, in soils; ascertainable, 363
content of humus, 135
deficiency, pot test, figure, 362
determination of, in soils, 357
hungry soils; table, 361
percentages in humus, what are adequate, 360
supply of plants, views on, 150
Nitrosomonas, figure, 246
Nodules of legumes, 151
North Central States, herbaceous vegetation on
calcareous soils, 514, 515
lowland growth in uplands, when, 515
vegetation and soil-character, 513
Nutritive salts in alkali, 441

O.
Ocean currents, Gulf stream and Japan stream, 295, 296
Olive, resistance to alkali, 478
Organic and organized constituents of soils, 120
Organisms influencing soil-conditions, 142
Oxalic acid, secretion by lichens, 19
Oxidation, expansion by, 18
Oxids constituting earth’s crust; table, 31
Oxygen, action in weathering rocks, 18
proportion of, in earth’s crust, 30

P.
Pamperos, 9
Peat bogs, 122
Peaty soil, shrinkage, 117
Percolation in natural soils: diagram, 223, 225, 226
rate of, as influenced by grain-sizes, 224
Permanent value of land vs. Immediate productiveness, 340
Physical and chemical causes of vegetative features, 505
conditions of plant growth, 319
Physical analyses, correlation with popular names, 96
results of, 94
table. Mississippi and California soils, 98
analysis of soils, 88
constituents of soils, 10
Physico-chemical investigation of soils, 313
Physiological soil analysis, 333
Phosphate fertilizers, importance of, 65
Phosphate fertilization, in arid region, 393
in California, 393
Phosphoric acid, limits of adequacy in soils, 355
minute amounts leached from soils, 24
no constant difference between arid and humid soils, 393
rendered inert by ferric hydrate, 355
Phosphorites, low-grade, of Nevada, Russia, 63, 64
Plane tree, oriental, resistant to alkali, 480
Plant-adaptation “varying from province to province”, 523
Plant associations, plant formations, 315
Plant distribution, Thurman’s physical theory of, 519
Plant-development under different temperatures, 309
Plant-food, accumulation in finest parts of soils, 87
high percentages mean high land value, 346
ingredients, condition of, in soils, 319
in virgin soils, lowest limit of, table, 352
limits of adequacy, 353
minute amounts may produce large crops, 410
percentages, what are high, 346
percentages, low, 346
water-soluble, reserve, unavailable, 320
Plant-growth on arid subsoils, 166
Plants, deep-rooting in arid region, 174
indicating irreclaimable alkali lands, 535, 536
Plant root action, cannot be imitated in laboratory, 324
Plasticity, absence of, in fine powders, 60
of clay, causes of, 60
lost by burning, 60
Plot tests, difficulties and uncertainties of, 334
plan of, figure, 335
Plowsole, how formed, by shallow irrigation, 186, 241
Poor chalk lands, 525
Pore-space, 108
Porosity of humus, 124
Port Hudson bluff, lignite in, figure, 128
recession of, 116
Potash, abundant in arid soils, 395
and soda in arid and humid region, 394
Potashes, production of detrimental to agriculture, 69
Potash feldspar, supplies potash to soils, 32
fertilization first in humid, last in arid region, 396
from sea water, 69
limits of adequacy in soils, 354
minerals, orthoclase feldspar, 68
preferential retention of, in soils, 272
Salts, Stassfurt, 69
slightly leached out, 24
sulfate, high-grade, 71
Pot-culture tests, 336
Powders, absorption of various gases by, table, 277
Prairie soils, black, 53
Preparation of soils for physical analysis, 89
Productive capacity and duration, forecast of, 346
Progress of humification and formation of coal, table, 126, 127
Pulverulent soils of arid regions, 87
Purifying action of soils, 269
Putrefactive processes, relation to carbonic gas and
anaerobic bacteria, 282
Putty soils, 103
Pyroxene, augite, 33, 34

Q.
Qualifications required for soil study, 524
Quality of irrigation water, 246
Quince, resistance to alkali, 479
Quartz and allied rocks, 29
sand most prominent ingredient of soils, 30
veins, formation of, 31

R.
Rain belts, temperate and tropical, 295
Rainfall, amount of, 215
distribution in California and Montana, 290
in the United States, 215
most important, 290
on the globe, figure, 294
influence on soil formation, 22
insufficient, forms alkali soils, 28
leaves lime behind, 28
natural disposition of, 216
Rains, beating, 221
cold and warm, 302
Reclaimable and irreclaimable alkali lands, 534
Red foothill soils of California, 34
Red or rust-colored soils, 34
advantages of, 284
Regur soils, Deccan, India, 414
formation of, 415
“guvarayi” hardpan, 415
present production, 414
Reh of India, 440
Reserve plant-food in soils, 320
of zeolites, carbonates, phosphates, 321
Residual soils, 11, 13, 22
Rhizobia, adaptation to symbiosis, 154
inoculation of soils with, 154
increase of crops by inoculation with, 155
of legumes, 150
mode of infection, 154
varieties of forms, 154
Rhubarb, sensitive to alkali, 475
Rhyolites, soils from, 53
River bars, formation of, 7
Rivers, amount of dissolved matters carried by, 24
flood-plains of, 13, 14
sediment carried by, 24
waters, analyses of, table, discussion, 23, 24
white and green, 4
Rock crystal, 29
Rocks as soil-formers, 47
chemical decomposition of, 16
cleavage of, 3
definition of, xxiii
disintegration of, under extremes of temperature, 2
effects of heat and cold on, 1
erosion of by sand, 10
forming minerals, 29
fragments, rounding of, by flowing water, 6
Rock powder, 85
Rock-weathering in arid and humid climates, 47
Rohhumus, 122
Rolling of soils, of influence of, on heat, 305
Root action, limitation of, 351
Root bacillus, figure, 149, 150
Root crops, effects of alkali upon, 474
Root development in the arid and humid regions, 169 to 176
Rooting, deep, from proper irrigation, 243, 245
Roots, chemical action of, 21
force exerted by, 19
secrete carbonic acid, 20
Root system in the humid region; figure, 168
Rotten Limestone, soils from, analyses, 54
Runoff of rain water, 216
Russia, black earth of; roots and humus in, 130, 363
Rye grass, giant, of Northwest; uses, 470

S.
Saline and alkali lands, vegetation of, 527
plants, analyses of ashes of, 530
selective power of, 531
Saline and xerophile vegetation, similarity of, 528
Saline contents of waters, variations of, 250
solutions, structural and functional differences caused by, 528
vegetation, general character of, 527
Saltbushes, Australian, growth and use in California, 469
of Great Basin, probable usefulness, 468
Saltgrass; range, tolerance of alkali, figure, 546, 547
Salton Basin, profile of salts in, 438
Salts, absorption of, by saline plants, 529
Saltwort: range, tolerance of alkali, figure, 540, 542
Samoa and Kamerun soils, analyses by Wohltmann; method, 402
table of, 404
Samphire, Bushy and Dwarf; range, alkali-tolerance,
figure, 538, 539, 540
Sand blasts, effects on cobbles, 10
coarse, effect of, on clays, 105
erosion of rocks by; figure, 10
hammocks, of Gulf coast, 56
Sands of arid and humid regions, differences in, 86, 386
table of analyses, 387
Sand, silt and dust, 85
Sandstones, 48
argillaceous, 57
calcareous, formation of, 56
rich soils from, 56
dolomitic, often form poor soils, 56
ferruginous, poor soils from, 56
siliceous, poor soils from, 55
varieties of, 55
zeolitic, soils from, 57
Sandstone soils, lightness of, 55
soils, poor, of humid region, 55
Sand storms, 9
Sandy lands, of arid regions, highly productive, 386
Sandy soils, 30
Schöne’s elutriator, figure, 90
Shrinkage, extent of, in drying soils; figure, 113, 114
Schübler on calcareous soils, 115
Sea water, average composition of, table, 26
chief ingredients useless to plants, 28
minor constituents of, 27
sources of salts in, 26
Sedentary soils, 11, 13, 40
Sedimentary rocks, 47, 48
Sediment deposited by Mississippi in Gulf, 7
Sediments, exhibition of, from physical analysis, 95, 96
number of, in physical analysis, 93
table of diameters and hydraulic values, 94
Seeds, germination of, 309
Semi-humid and semi-arid region, 377, 397
Serpentine, 36
Sieves, use in physical analysis of soils, 88
Silica, absorption and secretion by plants, 31
and alumina, soluble; quantitative relations, 385
solubility in water, 31
soluble, retained in alkali soils, 391
Silicate minerals, 31
Silicates of soda and potash, soluble, 31
Silicon, abundance of, in rocks, xxxi
Silicophile plants, a fiction, 522
Sinkholes, 43
Soapstone, 36
Soda in arid and humid regions, 394
Soda, nitrate of, 66
Sodium salts, leached out by drains and rivers, 24
Soil analysis, change of views regarding, 317
discrepant methods used in, 402
practical utility of, 318
Soil and subsoil, causes and processes of differentiation, 120
ill-defined, 120
Soil bacteria, numbers of, 141
Soil character, recognition from native vegetation, 487, 511
Soil-dilution experiments, 347
figures, 348, 349, 350
table of, 350
Soil-examination, short approximate methods for,
used at California station, 560
summary directions for, in field or farm, 556
Soil-formation influenced by rainfall, 22
physical processes of, 1
Soil-forming processes accelerated by high temperatures, 398
Soil-grains, number of, 99
surface of, 99
determination by air-flow, 99
by “Benetzungswärme”, 99
investigation, historical review of, 313
moisture, regulation and conservation of, 234
phosphates, solubility in water; Schloesing fils, 332
probe, mode of using, 177
profiles in arid and humid region, 165
Soil, samples, directions for taking, by Calif. Station, 553
sedentary or residual, 11, 13, 40
study, qualifications needed for, 524
surveys, early, of Kentucky, Arkansas and Mississippi, 316
temperature, annual range near surface in arctic
and tropical regions, 303
change with depth; table, 303
influence of evaporation on, 307
influence of soil material, 306
influence of surface conditions, 303
influence of vegetation and mulch, 305
tests by crop analysis, Godlewski, Vanderyst, 337, 338
by extraction with organic acids; Dyer, Maxwell, 339
water, different conditions of, 195
Soils, acid-soluble and water-soluble portions most important, 324
alluvial, 12, 13
ancient, in geological formations, xxix
calcareous, definition of, 367, 496, 524
classification of, figure, 11
colluvial, 12, 24
definition of, xxix
derived from various rocks, 49
effects of crusting on, 221
indefinite action of dilute acids on, 326
interpretation of analyses; Wohltmann, 403
physico-chemical investigation of, 313
(see Table of Contents)
Solar radiation, influence of, 302
Solubility, continuous, of soils in water, 328
King’s table, rich and poor soils, 330
Schultze’s table, rich soil, 328
Ulbricht’s table, poor soil, 329
Solvent action of water upon soils, 327
power of water, 17
Solubility, increased with nitrogen-content, 141
Sour grasses, 123
humus, antiseptic properties of, 122
soils, 122
Souring of soils, by cultivation, 123
Stable or farmyard manure, 72
composition of, table, 73
green-manuring only substitute, 74
method of using, in humid region, 74
physical effects of, 73
use of, in the arid region, 74
Stalactites and stalagmites, 41
Stassfurt Salts, discovery of, 69
importance to agriculture, 70
origin of, 70
Stassfurt Salts, nature of, 71
Stonecrops, succeed mosses, 20
Stone fruits, resistance to alkali, 478
Stratified rocks, derived from crystalline, 29
Stunted growth, caused by shallow or very heavy soils, 504
Sturdy growth on calcareous lands, 502, 503
Subsidence method, 89
Subsoils, arid region, 163
and deep plowing, 164
calcareous, 162
rawness of, in humid climates, 163
Substrata in arid region, importance of, 173
faulty, with figures, 177 to 180
impervious, injury from; figure, 181
leachy, 182
marly, 186
Subterranean rivers, 41
Sulfate of potash, high-grade, 71
of soda, dust from, 77
injuriousness to plants, 77
occurrence in arid regions, 77
Sulfates, reduction of, 232
Sulfuric acid in arid and humid regions, 394
Summer mulch, loss of humus in, 132
Sunflower family, resistance to alkali, 473
Sun’s heat, penetration into the soil, 302
Surface crusts, formation of, 111, 117
physical analyses of, 118
Surface, hydrostatic and ground waters, 215
Surface waters, chemical effects of percolation, 161
physical effects of percolation, 161
Swamping of alkali lands, consequences of, 451, 463
irrigated lands, results of, 231
Symbiosis, adaptation to, of Rhizobia, 154
Szek of Hungarian plain, 440

T.
Tabashir, 31
Talc and serpentine, 36
Tap-roots, moisture supplied by, 229
Tea, failure on calcareous lands, 414

Temperature, annual mean of, 289
conditions, ascertainment and presentation of, 288
extremes, on high mountains and plateaus, 288
of stellar space, 288
seasonal, monthly and daily means, 289, 291
Temporary vs. permanent productive capacity of soils, 340
Tennessee and Kentucky, vegetation and soil-character, 513
Terraces, river and lake, 14
Testing penetration of irrigation water, 242
Textile plants, tolerance of alkali, 475
Thomas or basic slag, 64
Thurman’s physical theory of plant distribution, 519
Tillage; effects of; figure, 109, 110
how maintained in nature, 111
Titanium in soils, xxxi
Time of acid-digestion, different; table, 342
Tolerance of alkali by culture plants, 463
alkali plants; table, 548, 549
Topography, influence of, on climate, 293
Trachytes, 53
Trona, Urao, 77
Tropical soils, 398
are highly leached, 400
often highly colored with iron, 400
do not need early fertilization, 399
humus in; abundant, but low in nitrogen, 399
few determinations made, 399
possible calculation of, 399
investigations of, 401
laterites, not always rich in iron, 400
mostly have low plant-food percentages, 400
resemble the “nimble penny”, 400
Tubercles of legumes, figures, 151, 154
Tufa, calcareous, 41
Tussock grass, food value of, 470
range, alkali-tolerance, figure, 536, 537

U.
Ulmin substances, 122
Underdrainage, advantages of, 235
Underdrains, effects of, 234
Unhumified organic matter does not nitrify, 148
Unhumified vegetable matter, utility of, 135, 360
United States, good field for comparative soil study, 524
Upland and lowland growth in arid and humid regions, 515
Usar lands of India, character of, 440
not all alkali lands, 440

V.
Vegetative belts, lime a governing factor of, 492
Virgin lands, advantages of soil study in, 318
Virgin soils, analysis by extraction with strong acids, 340
Vivianite, 65
Volatile part of plants, xxxii
Volcanic ash, form soils rapidly; soils from, 20, 52
Volcanic glass, 53
Volume of soils, changes on wetting and drying, 122
Volume-weight of soils, 107

W.
Walnut, black, a lime-loving tree, 490 to 497
tolerant of white alkali, 479
Washing-away and gullying of land, 217
Water, capillary, 201
ascent in soil columns, figure, 202, 205
uniform sediments, figure, 204, 207
held at different heights in soil column, table, 208
expansion and contraction in absorbing, 208, 209
maximum and minimum of water-holding power, termination of;
figure, 202, 207
movements in moist soils, 210
carbonated, solvent power, 17
carrying power, 14
controlling factor of soil temperature, 301
density of, 190
effects of flowing, 5
Water extraction of soils, practical conclusions from, 332
Water, hard, 41
hygroscopic, 196
of lan-locked lakes, 27
loss of, by irrigation in shallow furrows, 240
physical factors of, 188
regulation of temperature by, 191
relations to heat, 189
requirements of growing plants, 192
plants in arid regions, 195
sidewise penetration of, in soils, 241
of soils, chapters on, 188, 215, 234
solvent action upon soils, 327
solvent power, 17, 191
Water-soluble plant-food, 321
specific heat of, 190, 191
table, 227
vaporization of, 191
Watery soil extracts, from European soils; tables, 327, 329
American soils, King, 329, 330
Wave action on shores, figure, 7
Weathering, by oxygen, carbonic acid, water, 16, 17
“ in humid and arid regions, 2, 86
Weight of soils, per acre-foot, 107
White soils, nature of, in humid regions, 285
in arid regions, 286
Wind deposits, 105
Winds, action of, in forming soils, 8
cyclones, and anti-cyclones, 293
effects of, in deserts, 8
heat the cause of, 291
land and sea breeze, 291
trade, and monsoons, 291, 292
Winter irrigation, 236
Wire-basket tests, of Bureau of Soils, 337

X.
Xerophile vegetation, similarity to saline, 529

Y.
Yazoo bottom, soils of, 116
Yazoo “buckshot” and Arroyo Grande soils, 345

Z.
Zeolites, decomposition by acids, 36, 38, 39
exchange of bases in analcite and leucite, 37
formation of, 37
importance in soils, 38
rocks cemented by, 38
Zeolitic sandstones, 57

AUTHORS REFERRED TO.

[NOTE.—In cases where no special credit is given
in this volume for investigations made or data given from
the Southwestern States and the Pacific Coast, these should
be understood as work done, mostly under the writers
direction, or by himself and assistants, in connections
with the geological surveys of Mississippi and Louisiana,
as well as the Tenth Census of the United States, by Drs.
Eugene A. Smith and R. H. Loughridge; the chemical work for
the Pacific Northwest, under the auspices of the Northern
Transcontinental Survey, by M. E. Jaffa and Geo. E. Colby;
that in California, at the Experiment Station, by the
latter two, Dr. R. H. Loughridge, and temporary assistants.
It would be impossible to segregate, without excessive
prolixity, the credit to be assigned to each of these
participants.]

A.
Adametz, L., 142, 281.
Agassiz, L., 4.
Aso, K., 383.

B.
Bamber, —, 401, 410, 414.
Batholomew, J. G. 294.
Beyerinck, M. W., 151, 156.
Blumtritt, E., 276.
Bonnier, G., 521.
Böttcher, O., 393.
Boussingault, J. B., 151, 276, 313.
Brick, —, 528.
Brock, see Morck, D.
Burri, R., 148.
Butler, O., 151.

C.
Cameron, F. K., 380, 466, 532, 533.
Clarke, F. W., XXIV, 23.
Colby, G. E., note above.
Colmore, C. A., 448.
Contejean, Ch., 521, 523, 531.
Coville, F. V., 536.
Crochetelle, J., 146, 147.

D.
Darton, N. H., 10.
Darwin, Ch., 158.
Davy, J. B., 535.
Deherain, P. P., 146, 147.
Detmer, W., 127.
Djemil, —, 159.
Duclaux, P. E., 144.
Duggar, J. F., 155.
Dumont, J., 146, 147.
Dyer, B., 339, 357.

E.
Ebermayer, E., 279, 305.
Eckart, C. F., 212.
Eichorn, —, 327.
Ermann, G. A., 303.

F.
Fawcett, W., 355.
Fischer, Hugo, 156.
Fliche, P., 520, 521.
Forbes, R. H., 219.
Fortier, S., 194, 254.
Fraenkel, L., 142.
Frank, A., 151.
Fuelles, P., 281.
Furry, F. E., 73.
Furuta, T., 383.

G.
Geikie, J., 14.
Gerlach, —, 156.
Gilbert, G. K., 2.
Gilbert, J. H., 151, 192.
Godlewski, E., 337, 393
Goss, A., 376, 530.
Grandeau, L., 132, 133, 139, 357, 520, 521.

H.
Haberlandt, F., 310.
Hall, A. D., 210, 227.
Hare, R. F., 378.
Harper, R. M., 494.
Hartwell, B. L., 123.
Headden, H. P., 18.
Hedin, Sven, 9.
Hellriegel, F., 130, 151, 192.
Henrici, 200.
Hillman, F. H., 536.
Hiltner, L., 154.
Hoffmann, R., 528.
Hohl, J., 143.
Hunt, T. S., 23.

J.
Jaffa, M. E., 135, 381, 450, 530.
Johnson, S. W., 60, 380.

K.
Katayama, T., 383.
Kearney, T. H., 532.
Kedzie, R. C., 343, 375.
Kellner, O., 393.
King, F. H., 99, 108, 109, 168, 192, 193, 210, 211, 212, 224,
228, 236, 305, 325, 328, 332.
Kinsley, J. S., 143.
Knop, W., 197.
Koch, R., 156, 281.
Kossovitch, P., 363.
Kosticheff, P., 130, 157.
Kröber, 156.
Krocker, F., 22.
Kuntze, O., 67, 68.

L.
Ladd, E. F., 131, 133, 134, 141.
Langley, S. P., 288.
Lawes, J., 151, 192.
Lea, E. C., 387.
Leather, J. W., 401, 410, 411, 412, 414 to 417, 440.
Lemberg, J., 272
Lesage, M., 528.
Letheby, H., 23.
Liebig, J. von, 150, 313.
Liebscher, G., 354.
Lipman, J. G., 156.
Loeb, J., 380.
Loew, O., 23, 42, 382, 383.
Loughridge, R. H., 87, 207, 213, 214, 240, 259, 340 to 342,
385, 430, 462, 466, 513, 535, 560.

M.
Maercker, M., 65, 369.
Mann, H. H., 401, 410, 413.
Manson, M., 294.
Maxwell, W., 339.
May, D. W., 42, 380.
Mayer, A., 199, 207, 209.
Mayo, N. S., 143.
Mazurenko, D. P., 87.
Means, T. H., 248, 478.
Merrill, G. P., 2, 13, 167.
Middendorff, V., 441.
Mitscherlich, E. A., 99, 199.
Miquel, P., 142, 281, 359.
Mohr, Chas., 489, 511.
Moore, G. T., 154.
Morck, D., 154.
Müller, A., 449.
Müller, P. E., 122, 184.
Müntz, A., 142, 355, 370, 401, 402, 406 to 410.
Murray, John, 23, 24.
Myers, H. C., 6, 144.

N.
Naegeli, C. v., 129.
Nagaoka, M., 65, 393.
Nobbe, F., 154.

O.
Osterhout, W. J. V., 533.
Ototzky, L., 265.
Owen, D. D., 316, 317, 343, 513.

P.
Peter, A. M., 175.
Peter, R., 316,317, 343.
Pichard, P., 147.
Porter, J. L., 23, 24.
Pumpelly, R., 110.

R.
Rafter, G. W., 217.
[204]Ramann, E.
Reade, T. M., 41.
Regnault, V., 26.
Reichert, E., 276.
Richthofen, F. von, 110.
Risler, E., 354.
Rosenberg, S., 528.
Rousseaux, E., 355, 370, 401, 402, 406 to 410.
Rudzinski, D., 87.
Russell, I. C., 24.

S.
Saussure, H. E. de, 150.
Schimper, A. F. W., 523, 528.
Schloesing, Th., 59, 111, 354.
Schloesing, Th., fils, 332, 393.
Schmidt, C., 23.
Schöne, H. E., 90.
Schübler, J. J., 116, 197, 313.
Schultze, H., 328, 329.
Seton, E. T., 159, 160.
Shaler, N. S., 12.
Shaw, G. W., 465.
Smith, E. A., 511.
Snyder, H., 131, 133, 134, 139.
Stenhouse, —, 276.
Stockbridge, H. E., 307, 308.
Stone, C. H. H., 25.
Stubenrauch, A. V., 222.
Stutzer, A., 149.

T.
Thurmann, J., 519, 520.
Tolman, L. M., 387.
Tourney, J. W., 216.
Traphagen, F. W., 23.
Tuxen, C. F. A., 184.

U.
Udden, J. A., 106.
Ulbricht, R., 328.

V.
Vanderyst, H., 338.
Ville, G., 151.
Voelcker, J. A., 22, 410.
Vogel, J. H., 156.

W.
Wagner, P., 65.
Ward, M., 144.
Warington, R., 108, 146.
Washington, H. S., xxiv.
Way, J. T., 22, 73.
Weber, A. H., 450.
Wheeler, H. J., 123.
Whitney, M., 94, 195, 207, 316, 321, 330, 332, 337.
Wilfarth, H., 151.
Williams, W. E., 60, 100.
Winogradsky, S., 146, 156.
Wohltmann, F., 355, 370, 401, 402 to 405, 406, 416.
Wolff, E., 22, 73.
Wollny, E., 110, 113, 125, 147, 159, 195, 264, 279,
281, 284, 305, 306.
Wüllner, —, 198.
Wunder, G., 327.

Y.
Yoder, P. A., 92.

Z.
Zöller, P. H., 22.

[204] This writer’s valuable “Boden Runde” (1905) unfortunately came to hand too late to be considered in this volume.

Printed in the United States of America.