yk ONS \ WAM HN DARA K SNS AS me MA ‘ WS AA RE . Ss N WO WAS SA QQ RAG TAN SOY \ SS . ~S SS SN S SON SO SRV y SOY WN AQ AQ MQM NX QA AAG IX MAG SSSA ay NX \ \ SS SS ~ Lys 3 NN ae ty A iffy Lig YSZ Ni x Seas SOS 23) =f bq CG" aa) FQ OG Pel ped EH TABLE OF CONTENTS. PNTETS ES (CVU Ui MUNCIE teresa eveistalelefe (eiale\s¥oinss/stelcis.shaiorole ficialeta cieletess se eee e ees pela alsvels/ein) 0 eee DIVISION I.—CHEMICAL COMPOSITION OF THE PLANT. CHAP Dany VOLATGE, PART OR IPLANTS s\c))\ecis oles ole cine cece cic sie cele 12 $i. Distinetions and Definitions. -<. 2.0... ete ee se pee ce we 12 § 2. Elements of the Volatile Part of Plants............... 14 Wish, Olive mii CP TDA {onde kop ooo od: Qo0C SocnaOe cl GE ean eeoere 29 §4. Vegetable Organic Compounds or Proximate Elements 36 VUE Tr alco ehcters oie stelelare cle cise levels eae cfarelelciel@ mia aie.e\sieisls sielnie si atars 37 A Orne inate ieiet) GassanpocosocconsocgIOUe Sooaseoue goo sce 39 SHEMC CELA CACIOS a eres ciske Cece scleieicves o seisiGearepep esis 75 ABUT AUS atiey rete rcreketer siete onic ieimte lo aiernioreferelsfors cial o/aeisleisdeiat hits eels 83 SEA OUMIMOLEAS; ama! STIMU MTS creer reine = «)¢ eee ccseteleleie'sis\« 87 (35 AMPOULES aad modsusons codo.ccbacnboaclanine aeieteleteterctatelatetate 114 fy ZAI HIONG Eo nmbopbedcococopegn pogo orn bosoduAUonoonbabtc 120 sh Ledovorsyelaron aleve l Siell osreH CLOSE pac onoo.onpeno abou INOsOUs 122 Sites PES ASE OF. PLANTS 62)0c00.csGsemace seca ees ocsinvescnmee se - 126 SJle Macnee hverehish Ore wel HANSA So Goccosponb coon cdbooDcecabnoDonEe 126 Non-metalive MLementS «se 22) 6 ieee sees cine cic + © sins widn'e sicicis oie ese 127 Carbon andits Com POuMdSh aiiere o awiele sess elec weiss sects ee 128 Sul phi andits; COM POUMaS 2 ecsitescwis so siclecisistele seas 129 Ehospiorns amd ats COmpPOwuwMds s.seaeenecisets ole ier ave 1-500 132 Chilorimevand ats iC ommp Oui dsixere «ciclele sels oie cleleislete!-triciel eye'a- 132 SUTCOM And Ts COnLpPOUMIS . aoc ca Ss cb aremiesins ao varine «civ 134 MCAT ETEMENES Jaci necine os (nas Mama alesis Uewles bdtereie veh arele dine wereaiow)s 138 IPOLASSHUMM aM Gis, COMMPOUMEAS ns «cre tele ='e olellele) <1n (0, ste 5 epae 138 SOCAN ANG 1S CGmMpOUMAS 4a 1-10 -1eles onde Ae ae sie cial stercie 139 Calciuiy and its Compounds... hii ei cnccugs ees’ coi stele cs 139 Maoniesitimy amavits (Comp OUI rts site) <'e1ele eicisie’arcteletsie e 140 LrOny AMCs ies COMMPOUIMES) ee a. ce cislelevetelelerefe silo sis eisieis sar 2 141 Manganese aid its Comp@unds. .... 0.02 ...0.0c. ese cens 142 Py LER Pete oteDeee eT) os cic Gye pats talo: cictarone ahotere ol tiahalsrai cual cbaraiotanatoneterciate ete aioe nvore. cigeereta nes 143 CAN WOMAGES i asic aicisorsvaiwrencicioise eieteidiaiat cle cles aistal ain slate sisies siauane ais 144 SS UDI NRCS oy ereralers erolalererars eevee Sela semiain wid Ssieialeieta e, steno oa icine cays 146 AMOS POMA UES wiererew nels se)2e Baia) wlessvaveievehal atalfarsystousiseanysisioe rab araivaterts 147 AU TPLGETOUES Ait. Gur ares ciaiste alalnd wa winless wean dale Wojcie ciehstssotetore 149 PMU ABER 5p Saou sigs Ad ay Ded wes oe ce eis Hauadtas, ome aipthe 5 oa eee 149 § 2. Quantity, Distribution, and Variations of the Ash....151 Table of Proportions of Ash in Vegetable Matter....152 § 3. Special Composition of the Ash of Agricultural Plants 161 ieeConsianty Inenedients eas: nr aC Beene Ree eee ae cee eee 222 Composition and Growth of the Oat Plant............ 223 v VI TABLE OF CONTENTS. DIVISION II.—THE STRUCTURE OF THE PLANT AND OFFICES OF ITS ORGANS. CHAP. I.—GENERALITIES..... / alah dG efatlefa efolewe chaise ttdlens aisle Sie aoe ale eerste eens 241 Organism, OTganS.........6esec cess cete een cece ec ceeensnee oie tare oes CuAP. II. 7 Rees ELEMENTS OF ORGaNte: STRUCTURE cass eeeee 243 $1. The Vegetable Cell........-... cee seee cece se ceeceeceenes 243 Ne 2: Vegetable PASSUES sic,4 siesel seh. cyssesiersieie itm oles sloiei Semele eee 254 CHAP. LIL VEGETATIVE ORGANS". /.i. 0 ce-c0 es anes ise: conte 256 § 1. The Root. .... 02.0 ce cece ec ee cece ere e ee teense ce cece cece eres 256 Offices Of ROO 255 jeiasiee sis emiee Heise isleyeeunistelerorsterasts sicleite aca Apparent Searels LOGO OG ye ctvtteelel eal iteleete ere eee 263 CONntACtIOL ROObS WHEE S OM rece relalctela rare tela sole tetera raters 266 IN OS ONE] OL OOV LOM UNO AGrwodcoouqbosd coer enobooehSSoo secs 269 Soil Roots, Water Roots, Air Roots. <5. «.- sleet 273 § 2. The Stem... .... 2... eee e eee cee cece cece cece teen eens eee 282 ISG Ie boo. ca Soe DO ROON TUONO DOQ KISS OOO FOCOT OGD AAD a sOUS O7c- 283 | Wenyends\y | bole ab ners obeoodds Cooadodo scod: o6KeC o ave abn etre Oe ROOG=SEO CUS sere tarerelcieccleielorerictetersls\oialeleretaiarttelslateteretatet Sooeocazevt AUDI OYENoe peecEee saber CadgoecoCoCebe SUC Sacden AETOONO Good ae isis SiLuUcture Of They Seem cre cites sondo> eyeteteerets «289 HIMGO PS MOWS) PUA MUS! wets ole leleerels)aselwial ela’ s/erelelel=l=latacatatet el) tienen te HYXOCENOUS lal AUS ielereielela\sleleleieleinloleietoielatalelereletelete Be Gonnocn 2s SIEViE-CElIS hi oc seetelacialcis ciao eemesers Sond dogaoNoos Soon o2I 5 83. SUCAVES «octets cinieini tle o's nia'ers eleinin(aieis nwo eisiniele® subjoined table for the elements already mentioned or described. Symbols.—For convenience in representing chemical changes, the first letter (or letters) of the Latm name of the element is employed instead of the name itself, and is termed its symbol. TABLE OF ATOMIC WEIGHTS AND SYMBOLS OF ELEMENTS.t Element. Atomic Weight. Symbol. Hydrogen 1 H Carbon 12 Cc Oxygen 16 O Nitrogen 14 N Sulphur 32 Ss Phosphorus 31 P Chlorine 35.5 Cl Mercury 200 Hg (Hydrargyrum) Potassium 3! K (EKalium) Sodium 23 Na (Natrium) Calcium 40 Ca Tron 56 Fe (Ferrum) * Unless otherwise stated, parts or proportions by weight are always to be understood. + Now, chemists receive as the true atomic weights double ths num- bers that were formerly employed, those of hydrogen, chlorine and a few others excepted. The atomic weights here given are mostly whole numbers. The actual atomic weights, as experimentally determined, differ from the above by small fractions, which may be neglected. THE VOLATILE PART OF PLANTS. 33 Multiple Proportions.—When two or more bodies unite in, several proportions, their quantities, when not expressed by the atomic weights, are twice, thrice, four, or more times, these weights; they are multiples of the atomic weights by some simple number. Thus, carbon and oxygen form two commonly occurring compounds, viz., carbon monoatde, consisting of one atom of each in- gredient, and carbon dioxide, which contains to one atom, or 12 parts by weight, of carbon, two atoms, or 32 parts by weight, of oxygen. Molecules* contain and consist of chemically-united atoms, and are the smallest particles of matter that can have an individual or physical existence. While the atoms compose and give character to the molecules, the molecules alone are sensibly known to us, and they give character to matter as we find it in masses, either solid, liquid or gaseous. In solids the molecules more or less firmly cohere together; in liquids they have but little cohesion, and in gases they are fur apart and tend to sepa- rate from each other. The so-called ‘‘ elements” are, in fact, mostly compounds whose molecules consist of two or more like atoms, while all other chemical substances are compounds whose molecules are made up of two or more unlike atoms. Molecular Weights of Compounds.—The mole- cular weight of a compound is the sum of the weights of the atoms that compose it. For example, water being composed of 1 atom, or 16 parts by weight, of oxygen, and 2 atoms, or 2 parts by weight, of hydrogen, has the molecular weight of 18. t+ The following scheme illustrates the molecular compo- sition of a somewhat complex compound, one of the car- * Latin diminutive, signifying a little mass. + We must refer to recent treatises on chemistry for fuller informa- tion as to atoms and molecules and the methods of finding the atomic and molecular weights. 3 34 HOW CROPS GROW. bonates of ammonium, which consists of four elements, ten atoms, and has a molecular weight of seventy-nine. Ammonia gas results from the union of an atom of nitrogen with three atoms of hydrogen. One molecule of ammonia gas unites with a molecule of carbon dioxide gas and a molecule of water to produce a molecule of ammonium carbonate. Atoms. Atomic Molecular weights. weights. Ammonia sl areeea” 3) =a 17 : 1mol. — {| Nitrogen 1. ¢ c= dS eee See aa ee 21) Carbonvaij=-eiss Carbon, ; 1 == weal, Syren. ae oa mol. ) Oxide 1 mol.~ { Oxygen, 2 =) 30 ieee a z Water, SAMA VanOGeny hen) a= Fe } Bee 1 mol. (| Oxygen, 1) = LO ia Notation and Formulas of Compounds.—For the purpose of expressing easily and concisely the composi- tion of compounds, and the chemical changes they undergo, chemists have agreed to make the symbol of an element signify one atom of that element. Thus H implies not only the light, combustible gas hydrogen, but also one part of it by weight as compared with other elements, and 8 suggests, in addition to the idea of the body sulphur, the idea of 32 parts of it by weight. Through this association of the atomic weight with the symbol, the composition of compounds is expressed in the simplest manner by writing the symbols of their elements one after the other. Thus, carbon monoxide is represented by CO, mercuric oxide by HgO, and iron monosulphide by FeS. The symbol CO con- veys to the chemist not only the fact of the existence of carbon monoxide, but also instructs him that its mole- cule contains an atom each of carbon and of oxygen, and from his knowledge of the atomic weights he gathers the proportions by weight of the carbon and oxygen in it. When a compound contains more than one atom of an element, this is shown by appending a small figure to the symbol of the latter. For example: water consists of two atoms of hydrogen united to one of oxygen, and its THE VOLATILE PART OF PLANTS. 3D symbol is H,O. In like manner the symbol of carbon dioxide is CQ,. When it is wished to indicate that mere than one mole- cule of a compound exists in combination or is concerned in a chemical change, this is done by prefixing a large figure to the symbol of the compound. For instance, two molecules of water are expressed by 2 H,0. The symbol of a compound is usually termed a formula and if correct is a molecular formula and shows the com- position of one molecule of the substance. Subjoined is a table of the molecular formulas of some of the com- pounds that have been already described or employed. FORMULAS OF COMPOUNDS. Name. Formula. Molecular Weight. Water H,O 18 Hydrogen Sulphide HS 34 Tron Monosulphide Fes 88 Mercurie Oxide Heo 216 Carbon Dioxide CO 44 Calcium Chloride Cacl, 111 Sulphur Dioxide SO; 64 Sulphur Trioxide SO, 80 Phosphorus Pentoxide P.O; 142 Empirical and Rational Formulas.—It is obvious that many different formulas can be made for a body of complex character. Thus, the carbonate of ammonium, whose composition has already been stated (p. 33), and ‘which contains latom of Nitrogen, 1 atom of Carbon, 3 atoms of Oxygen, and 5 atoms of Hydrogen, may be most compactly expressed by the symbol NCO H,. Such a formula merely informs us what elements and how many atoms of each element enter into the compo- sition of the substance. It is an empirical formula, being the simplest expression of the facts obtained by analysis of the substance. Rational formulas, on the other hand, are intended to convey some notion as to the constitution, formation, or 36 HOW CROPS GROW. modes of decomposition of the body. For example, the real arrangement of the atoms in ammonium carbonate is believed to be expressed by the rational (or structural) formula /O—N Hy, \O—H. 0=C in which the carbon is directly united to oxygen, to which latter one hydrogen and the uitrogen are also linked, the remaining hydrogens being combined to the nitrogen. Valence.—The connecting lines or dashes in the fore- going formula show the valence of the several atoms, i. e., their ‘‘ atom-fixing power.” The single dash from H indicates that hydrogen is wnivelent or has a valence of one. The two dashes connected with O express the bivalence of oxygen or that the atom of this element can combine with two hydrogens or other univalent atoms. The nitrogen is united on one hand with 4 hydrogen atoms, and also, on the other hand, satisfies half the val- ence of oxygen ; it is accordingly quinquivalent, 1. e., has five units of valence. Carbon is guadrivalent, being joined to oxygen by four units of valence. Equations of Formulas serve to explain the results of chemical reactions and changes. Thus, the breaking up by heat of potassium chlorate into potassium chloride and oxygen is expressed by the following statement: Potassium Chlorate. Potassium Chloride. Oxygen. 2 KC10, = 2 KCl + 3 Os, The sign of equality, =, shows that what is written before it supplies and is resolved into what follows it. The sign + indicates and distinguishes separate com- pounds. The employment of this kind of short-hand for exhib- iting chemical changes will find frequent illustration as we proceed with our subject. Modes of Stating Composition of Chemical THE VOLATILE PART OF PLANTS. 37 Compounds.—These are two: 1, atomic or molecular statements, and 2, centesimal statements, or proportions in one hundred parts (per cent, p. c., or %). These modes of expressing composition are very useful for com- paring together different compounds of the same ele- ments, and, while usually the atomic statement answers for substances which are comparatively simple in their composition, the statement per cent is more useful for complex bodies. The composition of the two compounds of carbon with oxygen is given below according to both methods. Atomic. Per cent. Atomic. Per cent. Carbon (C), 12 42.86 (C) 12 21.27 Oxygen (0), 160°) 5744 (O.) 32 72.73 Carbon Monoxide (CO), 28 100.00 Carbon Dioxide (CQ,), 44 100.00 The conversion of one mode of statement into the other is a case of simple rule of three, which is illustrated in the following calculation of the centesimal composition of water from its molecular formula. Water, H,O, has the molecular weight 18, i. e., it consists of two atoms of hydrogen, or two parts, and one atom of oxygen, or sixteen parts by weight. The arithmetical proportions subjoined serve for the calculation, viz.: H,O Water H Hydrogen 18 2 100 i A”, per cent sought (=11.11) H,O Water O Oxygen 18 2p 20) Soa) Mgt LON fae per cent sought (=88.89) By multiplying together the second and third terms of these propor- tions, and dividing by the first, we obtain the required per cent, viz., of hydrogen, 11.11; and of oxygen, 88.89. The reader must bear well in mind that chemical affin- ity manifests itself with very different degrees of inten- sity between different bodies, and is variously modified, excited, or annulled, by other natural agencies and forces, especially by heat, light and electricity. § 4, VEGETABLE ORGANIC COMPOUNDS, OR PROXIMATE PRINCIPLES. We are now prepared to enter upon the study of the organic compounds, which constitute the vegetable struc- 38 TIOW CROPS GROW. ture, and which are produced from the elements carbon, oxygen, hydrogen, nitrogen, sulphur, and phosphorus, by chemical agency. The number of distinct substances found in plants is practically unlimited. There are already well known to chemists hundreds of oils, acids, bitter principles, resins, coloring matters, etc. Almost every plant contains some organic body peculiar to itself, and usually the same plant in its different parts reveals to the senses of taste and smell the presence of several individual substances. In tea and coffee occurs an intensely bitter ‘‘ active principle,” caffeme. From tobacco an oily liquid of eminently narcotic and poison- ous properties, nicotine, can be extracted. In the orange are found no less than three ot/s ; one in the leaves, one in the flowers, and a third in the rind of the fruit. Notwithstanding the great number of bodies thus occurring in the vegetable kingdom, it is a few which form the bulk of all plants, and especially of those which have an agricultural importance as sources of food to man and animals. These substances, into which any plant may be resolved by simple, partly mechanical means, are conveniently termed proximate princivles, and we shall notice them in some detail under eight principal classes, Viz. ! 1. WATER. 2. The CARBOHYDRATES. 3. The VEGETABLE ACIDS. 4, The Fats and OILs. 5. ihe ALBUMINOIDS or PROTEIN Bopties and FER- MENTS. MW. 14,46. The Amrpzs. Lb / 7 7. The ALKALOIDS. 8. PHOSPHORIZED SUBSTANCES. 1. Water, H,0, as already stated, is the most abund- ant ingredient of plants. It is itself a compound of oxygen and hydrogen, having the following centesimal composition : THE VOLATILE PART OF PLANTS. 39 RO OTE FAY 5B igid od vutarcete ead 88.89 pCO Reis wie cu'n's o's vine cee Omicini 11.11 100.00 It exists in all parts of plants, is the immediate cause of the succulence of their tender portions, and is essen- tial to the life of the vegetable organs. In the following table are given the percentages of water in some of the more common agricultural products in the fresh state, but the pro- portions are not quite constant, even in the same part of different specimens of any given plant. WATER IN FRESH PLANTS. (PER CENT.) Average. Range. Me AL ONY OS TASS ate ct cisiersais qaisit sls wale siete ce orgies 71 60 to 78 NANCE GO Vi CIR act th ors clksre cscis Seleeieeas ch We Se eee stares 80 68 “ 86 Maize assused for OMG cicci cece sails 82 Te COUR: Cabbage BRT ep eats A evo eine ae Wisc eS araretsveupre ad oake 85 SO & Ud Potato y tubers Me Aa dias re Gade obOSS erat Sieness A eA eictc 75 THOS RY "= USTs DEVE SSS S Reade se pie Oaaodur oa soco 81 (iy CO WAT ROUGH So oo he he ecg otent Sires ares ahs shea wadsecieyae 86 TET OR POURED Sharaf aist toy ala a acts inte’ tia oie sic-eie's oinienne a ove syedn tele 91 86 ** 93 In living plants, water is usually perceptible to the eye or feel, as sap. But it is not only fresh plants that contain water. When grass is made into hay, the water is by no means all dried out, but a considerable propor- tion remains in the pores, which is not recognizable by the senses. So, too, seasoned wood, flour, and starch, when seemingly dry, contain a quantity of invisible water, which can be removed by heat. ExP. 21.—Into a wide glass tube, like that shown in Fig. 2, place a spoonful of saw dust, or starch, or a little hay. Warm over a lamp, but very slowly and cautiously, so as not to burn or blacken the sub- stance. Water will be expelled from the organic matter, and will col- lect on the cold part of the tube. It is thus obvious that vegetable substances may con- tain water in at least two different conditions. Red clover, for example, when growing or freshly cut, contains about 80 per cent of water. When the clover is dried, as for making hay, the greater share of this wa- ter escapes, so that the air-dry plant con- tains but about 15 percent. On subject- ing the air-dry clover to a temperature of 212° for some hours, the water is completely expelled, and the substance becomes really dry, i. c., water-free. 40 HOW CROPS GROW. To drive off all water from vegetable matters, the chemist usually employs a water-oven, Fig. 9, consisting of a vessel of tin or copper plate, with double walls, between which is a space that may be half filled with water. The substance to be dried is placed in the interior chamber, the door is closed, and the water is brought to boil by the heat of a lamp or stove. The precise quantity of water belonging to, or contained in, a substance, is ascertained by first weighing the sub- stance, then drying it until its weight is constant. The loss is water. In the subjoined table are given the average quantities, per cent, of water existing in various vegetable products when air-dry. WATER IN AIR-DRY PLANTS. PER CENT. Meadow? 2rass (WAY) .j.is'ssio0.ci selene be slau ae ee ea eee 15 LEAT CLOVER MAY 2..1.:0's ai tele ac \aie'y 2 etiae sare == 38 pra Lee VENISON WET sich sie cttile) 58 lacs 8.0 OVAL SE TANS crete eo croicte) ere 0» 08 612.01 40 Oat Ca Saree oe mea gees LS 1) SVE Coes Loaes.> 2 2h steak 48 Buckwheat kernel............ iy. tae ewer Pa 22a warts ace oiefe's Siminpain rene ort 48 HOW CROPS GROW. Starch (C,H,,0;)n is of very general occurrence in plants. The cells of the seeds of wheat, corn, and all other grains, and the tubers of the potato, contain this familiar body in great abundance. It occurs also in the wood of ali forest trees, especially in autumn and winter. It accumulates in extraordinary quantity in the pith of some plants. as in the Sago-palm (Sagus Rumphit), of the Maiay Islands, a single tree of which may yield 800 pounds. ‘T’he onion, and various plants of the lily tribe, are said to be entirely destitute of starch. The preparation of starch from the potato is very sim- ple. ‘The potato tuber contains about 70 per cent. water, 24 per cent starch, and 1 per cent of cellulose, while the remaining 5 per cent consist mostly of matters which are easily soluble in water. By grating, the potatoes are reduced to a pulp; the cells are thus broken and the starch-grains set at hberty. The pulp is agitated on a fine sieve, in a stream of water. The washings run off milky from suspended starch, while the cell-tissue is re- tained by the sieve. The milky liquid is allowed to rest in vats until the starch is deposited. ‘The water is then poured off, and the starch is collected and dried. Wheat-starch may be obtained by allowing wheaten flour mixed with water to ferment for several weeks. In this process the gluten, etc., are converted into soluble matters, which are removed by washing, from the unal- tered starch. Starch is now most largely manufactured from maize. A dilute solution of caustic soda is used to dissolve the albuminoids (see p. 87). ‘The starch and bran remaining are separated by diffusing both in water, when the bran rapidly settles, and the water, being run off at the proper time, deposits nearly pure starch, the corn-starch of com- merce. Starch is prepared by similar methods from rice, horse- chestnuts, and various other plants. THE VOLATILE PART OF PLANTS. 49 Arrow-root is starch obtained by grating and washing the root-sprouts of Maranta Indica, and M. arundinacea, plants native to the Hast and West Indies. EXP. 25.—Reduce a clean potato to pulp by means of a tin grater. Tie up the pulp in a piece of not too fine muslin, and squeeze it repeatedly in a quart or more of water. The starch grains thus pass the meshes of the cloth, while the cellulose is retained. Let the liquid stand until the starch settles, pour off the water, and dry the residue. Starch, as usually seen, is either a white powder which consists of minute, rounded grains, and hence has a slightly harsh feel, or occurs in 5 or 6-sided columnar masses which readily crush to a powder. Columnar starch acquires that shape by rapid drying of the wet substance. When observed under a powerful magnifier, the starch-grains often present characteristic forms and dimensions. In potato-starch they are egg or kidney-shaped, and are distinctly marked with curved lines or ridges, which surround a point or eye; a, Fig. 12. Wheat-starch con- sists of grains shaped like a thick burning-glass, or spec- tacle-lens, having a cavity in the centre, b. Oat-starch is made up of compound grains, which are easily crushed into smaller granules, c. In maize and rice the grains are usually so densely packed in the cells as to present an angular (six-sided) outline, as in d. The starch of the bean and pea has the appearance of e. The minute 4 50 HOW CROPS GROW. starch-grains of the parsnip are represented at f, and those of the beet at g. The grains of potato-starch are among the largest, be- ing often s3}9 of an inch in diameter; wheat-starch grains are about yo55 Of an inch; those of rice, so of an inch, while those of the beet-root are still smaller. The starch-grains have an organized structure, plainly seen in those from the potato, which are marked with curved lines or ridges surrounding a point or eye; @, Fig. 12. When a starch-grain is heated cautiously, it swells and exfoliates into a series of more or less distinct layers. Starch, when air-dry, contiins a considerable amount of water, which may range from 12 to 23 per cent. Most of this water escapes readily when starch is dried at 212°, but a temperature of 230° F. is needful to expel 1t com- pletely. Starch, thus dried, has the same composition in 100 parts as cellulose, viz. : CAT DOM acs oe coe eek eames 44.44 lg bigs b toreds1 Nea gathat Gaia cd ACGOUGAL 6.17 GEV ROT Hick sade cee nee 49.39 100.00 Starch-grains are unacted upon by cold water, unless broken (see Exp. 26), and quickly settle from suspension in it, having a specific gravity of 1.5. Lodine-Test for Starch.—The chemist 1s usually able to recognize starch with the greatest ease and certainty by its peculiar deportment towards iodine, which, when dis- solved in water or alcohol and brought in contact with starch-grains, most commonly gives them a beautiful blue or violet color. This test may be used even in microscopic observations with the utmost facility. Some kinds of starch-grains are, however, colored red, some yellow, and a few brown, probably because of the pres- ence of other substances. ExP. 26.—Shake together in a test-tube 30¢c. ce. of water and starch of the bulk of a kernel of maize. Add solution of iodine drop by drop, agitating until a faint purplish color appears. Pour off half the liquid THE VOLATILE PART OF PLANTS. 51 into another test-tube, and add at once to it one-fourth its bulk of iodine solution. The latter portion becomes intensely blue by trans- mitted, or almost black by reflected, light. On standing, observe that in the first case, where starch preponderates, it settles to the bottom, leaving a colorless liquid, which shows the insolubility of starch in cold water ; the starch itself has a purple or red tint. In the ‘case iodine was used in excess, the deposited starch is blue-black. By the prolonged action of dry heat, hot watei, acids, or alkalies, starch is converted first into amidulin, then iuto dextrin, and finally into the sugars maltose and dox- trose, as will be presently noticed. Similar transformations are accomplished by the action of living yeast, and of the so-called diastase of germinat- ing secds. The saliva of man and plant-eating animals likewise disintegrates the starch-grains and mostly dissolves the starch by converting it into maltose (sugar). Tt is much more promptly converted into sugar by the liquids of the large intestine. It is thus digested when eaten by ani- mals. Starch is, in fact, one of the most important ingredients of the food of man and domestic animals. The starch-grains are not homogeneous. After pro- longed action of saliva, hot water, or of dilute acids on starch-grains, an undissolved residue remains which De- Saussure (1819) regarded as nearly related to cellnlose. This residue is not changed by boiling water, but, under prolonged action of ditute acids, it finally dissolves. With iodine, after treatment with strong sulphuric acid, it gives the blue color characteristic of cellulose. There- fore it is commonly termed starch-cellulose. Starch-celiulose amounts to 0.5 to 6 per cent of the starch-grains, varying with the kind of starch and the ature and durat:on of the solvent action. Whether it be originally present or a result of the treatment by acids, etc., is undecided. The chemical composition of starch-cellulose is identi- eal with that of the entire starch-grain, viz.: (C¢tlo0;5)n. The starch-grains also contain a small proportion of amidulin, or soluble starch, presently to be noticed. 52 HOW CROPS GROW. Gelatinous Starch. When starch is heated to near boiling with 12 to 15 times its weight of water, the grains swell and burst, or exfoliate, the water is absorbed, and the whole forms a jelly. This is the starch- paste used by the laundress for stiffening muslin. The starch is but very slightly dissolved by this treatment. On freezing gelatinous starch, the water belonging to it is separated as ice and on melting remains for the most part distinct. EXP. 27.—Place a bit of starch as large as a grain of wheat in 30 ¢. ¢. of cold water and heat to boiling. The starch is converted into thin, translucent paste. Thata portion is dissolved is shown by filtering through paper and adding to one-half of the filtrate a few drops of jodine solution, when a perfectly clear blue liquid is obtained. The delicacy of the reaction is shown by adding to 30 ¢. ce. of water a little solution of iodine, and noting that a few drops of the solution of starch suffice to make the large mass of liquid perceptibly blue. When starch-paste is dried, it forms a hard, horn-like mass. Tapioca and Sago are starch, which, from being heated while still moist, is partially converted into starch-paste, and, on drying, acquires a more or less translucent aspect. Tapioca is obtained from the roots of various kinds of Manihot, cultivated in the West Indies and South America. Cassava is a preparation of the same starch, roasted. Sago is made in the islands of the East Indian Archipelago, from the pith of pals (Sagus). It is granulated by forcing the paste through metallic sieves. Both tapioca and sago are now imitated from maize starch. Next to water and cellulose, starch is the most abund- ant ingredient of agricultural plants. In the subjoined table are given the proportions of starch in certain vegetable products, as determined by Dr. Dragendorff. The quantities are, however, somewhat variable. Since the figures below mostly refer to air-dry substances, the proportions of hygroscopic water found in the plants by Dragendorff are also given, the quantity of which, being changeable, must be taken into account in making any strict comparisons. AMOUNT OF STARCH IN PLANTS. Water. Starch. Per cent. Per cent. Wheati....... a Taseteveraralesiennee ee 13.2 59.5 DWAIN ae OUT erejetejehats «cree cera eaee 15.8 68.7 TERN cht Sie oc teteotanne outa stcrete ie ; 11.0 59.7 Datars eidm celeters ohieielo aires lecciele ee 11.9 46.6 isle N os enoneotar sooeodoatodce 11.5 57.5 PIMMO TM V=SCEMs c)cfoyseieie as ereelsek 12.6 45.0 RIGO COUNN EC Ne eonpdisaoooencec 13.3 61.7 ILGAS SA Mee ene rie iretelciers isles - 5.0 37.3 RGR (On AME eg oueeeenobe bode 16.7 33.0 GIOVET-SCEG IS ois ce wiercuis edicla rere 10.8 10.8 TD Giasvereve Uh mtian Oat aae eae inn fmerae 7.6 23.4 IMimStard-Seed)...cs sc scce eee. 8.5 9°29 WOU ZA=SCC Ce ceceretc,s.crteesemiie ae tne 5.8 8.6 MelGOw, tUCIPS*. ci. <2. iets: dry substance 9.8 IPOLATORS! . sce see ieee sie .... dry substance 62.5 * A sweet and mealy turnip, grown on light soils, for table use. THE VOLATILE PART OF PLANTS. 53 Starch is quantitatively estimated by various methods. 1. In case of potatoes or cereal grains, it may be determined roughly by direct mechanical separation. For this purpose 5 to 20 grams of the substance are reduced to fine division by grating (potatoes) or by sof- tening in warm water, and crushing in a mortar (grains). The pulp thus obtained is washed either upon a fine hair-sieve or in a bag of muslin, until the water runs oif clear. The starch is allowed to settle, is dried, and weighed. The value of this method depends upon the care employed in the operations. The amount of starch falls out too low, because it is impossible to break open all the minute cells of the sub- stance analyzed. 2. In many eases starch may be estimated with great precision by conversion into sugar. For this purpose Sachsse heats 3 grams of air- dry substance, contained in a flask with reflux condenser, in a boiling water bath for 3 hours, with 200 ec. c. of water and 20 ¢. c. of a 25 per cent hydrochloric acid. After cooling, the acid is nearly neutralized with sodium hydroxide, and the dextrose into which the starch bas been con- verted is determined by Allihn’s method, described on p. 65. Winton, Report Ct. Ag. Exp. St., 1887, p. 182. 3. For Dragendorfl’s method, see Henneberg’s Journal, fir Land- wirthschaft, 1862, p. 206. Amidulin, or Soluble Starch.—A substance soluble in cold water appears to exist in small quantity in the in- terior of ordinary starch-grains. It is not extracted by cold water from the unbroken starch, as shown by Exp. 26. On pulverizing starch-grains under cold water by rubbing in a mortar with sharp sand, the water, made clear by standing or filtration, gives with iodine the char- acteristic blue coloration. Exp. 27 shows that when starch is gelatin*sed by hot water, as in making starch paste, a small quantity of starch goes into actual solu- tion. Ordinary insoluble starch may be largely converted into soluble starch by moderate heating, either for a long time to the temperature of boiling water or for a short space to 375° F. Maschke obtained a perfectly clear solu- tion of potato-starch by heating it with 30 times its bulk of water in a sealed glass tube kept immersed for 8 days in boiling water. Zulkowski reached the same result by heating potato-starch (1 part) with commercial glycerine (16 parts). In this case the starch at first swells and the mixture acquires a pasty consistence, but, when the a How CROPS GROW. temperature rises to 375° F., the starch dissolves to a nearly clear thin liquid. Amidulin ‘also appears to be the first product of the action of diastase (the ferment of sprouting seeds) on starch and doubtless exists in malt. Soluble starch is colored blue by iodine and is thrown down from its solution in water, or glycerine, by addition of strong alcohol. It redissolves in water or weak alco- hol. Its concentrated aqueous solutions gelatinize on keeping and the jelly is no lerger soluble in water. Dilute solutions when evaporated leave a transparent residuc that is insoluble in water. On boiling together diluted sulphuric acid and starch the latter shortly dissolves, and if as soon as solution has taken place, the acid be neutralized with carbonate of lime and removed by filtration, soluble starch. remains dissolved. (Schulze’s Amidulin. ) Amylodextrin. Nageli has described as Amylodextrin I and Amylo- dextrin II, two substances that result from the action of moderately strong acids on potato-starch at common temperatures. The starch when soaked for many weeks in 12% hydrochlorie acid remains nearly unchanged in appearance, but the interior parts of the grains grad- ually dissolve out, being changed into amylodextrin Il, which closely resembles and is probably identical with amidulin. The starech-grains that remain unchanged in outward appearance, if tested with iodine solution from time to time, are at first colored blue, but after some days they take on a violet tinge and after prolonged action of the acid are made red and finally yellow by iodine. The grains, which are now but empty shells, may be freed from acid by washing with cold water, and then, if heated to boiling with pure water, they readily dissolve toa clear solution (amylodextrin D, from which Naceli, by freezing and by evaporation, obtained erystalline disks. These bodies, when dry, have the same composition as cellulose, starch, and amidulin. Dextrin (C,4,,0;) was formerly thonght to occur dissolved in the sap of all plants. Accorling to Von Bibra’s investigations, the substance existing in bread- grains, which earlier experimenters believed to be dex- trin, is for the most part gum. Busse, who examined various young cereal plants and seeds, and potato tubers, for dextrin, found it only in old potatoes and young THE VOLATILE PART OF PLANTS. wy. OH wheat plants, and there in very small quantity. Accerd- ing to Meissl, the soy bean contains 10 per cent of dex- trin. ; ' Dextrin is easily prepared artificially by the trans- formation of starch, or, rather, of amidulin derived from starch, and its interest to us is chiefly due to this fact. When starch is exposed some hours to the heat of an oven, or for 80 minutes to the temperature of 415° F., the grains swell, burst open, and are gradually converted into a light-brown substance, which dissolves readily in water, forming a clear, gummy solution. This is dex- trin, and thus prepared it is largely used in the arts, especially in calico-printing, as a cheap substitute for gum arabic. In the baking of bread it is formed from the starch of the flour, and often constitutes ten per cent of the loaf. The glazing on the crust of bread, or upon biscuits that have been steamed, is chiefly due to a coat- ing of dextrin. Dextrin is thus an important ingredient of those kinds of food which are prepared from the starchy grains by ccoking. Commercial dextrin appears either in translucent brown masses or as a yellowish-white powder. On ad- dition ef cold water, the dextrin readily dissolves, leaving behind a portion of unaltered starch. When the solu- tion is mixed with strong alcohol, the dextrin separates in white flocks. With iodine, solution of commercial dextrin gives a fine purplish-red color. Thereare doubsless several distinct dextrins scarcely dis- tinguishable except by the different degrees to which they affect polarized light or by various chemical deportment (reducing effect on alkaline copper solutions). They are characterized as erythrodextrins, which give with iodine a red color, and achroodextrins, which give no color with iodine. Investigators do not agree as to the precise num- ber of dextrins that result from the transformaticn of starch. 56 HOW CROPS GROW. EXP. 28.—Cautiously heat a spoonful of powdered starch in a porce: lain dish, with constant stirring so that it may not burn, for the space of five minutes; it acquires a yellow, and later, a brown color. Now add thrice its bulk of water, and heat nearly to boiling. Observe that a slimy solution is formed. Pour it upon a filter; the liquid that runs through contains dextrin. Toa portion add twice its bulk of alcohol; dextrin is precipitated. To another portion, add solution of iodine; this shows the presence of dissolved but unaltered starch. To a third portion of the filtrate add one drop of strong sulphurie acid and boilafew minutes. Test with iodine, which, as soon as all starch is transformed, will give a red instead of a blue color. Not only heat but likewise acids and ferments produce dextrins from starch and, according to some authors, from cellulcse. In the sprouting of seeds, dextrin is abundantly formed from starch and hence is an ingre- dient of malt liquors. The agencies that convert starch into the dextrins easily transform the dextrins into sugars (maltose or dextrose), as will be presently noticed. The chemical composition of dry dextrin is identical with that of dry cellulose, starch, and amidulin. Inulin, C3,H,.:03., closely resembles starch in many points, and appears to replace that body in the roots of the American artichoke,* elecampane, dahha, dandelion, chicory, and other plants of the same natural family (composite). It may be obtained in the form of minute white grains, which dissolve easily in hot water, and sep- arate again as the water cools. According to Bouchardat, the juice of the dahlia tuber, expressed in winter, becomes a semi-solid white mass after reposing some hours, from the separation of 8 per cent of inulin. Inulin, when pure, gives no coluration with iodine. It may be recognized in plants, where it occurs as a solu- tion, usually of the consistence of a thin oil, by souking a slice of the plant in strong alcohol. Inulin is insolu- ble in this liquid, and under its influence shortly separ- * Helianthus tuberosus, commonly known as Jerusalem artichoke, and cultivated in Europe under the name topinambour, is a native of the Northern Mississippi States. THE VOLATILE PART OF PLANTS. 57 ates as a solid in the form of spherical granules, which may be identified with the aid of the microscope, and have an evident crystalline structure. ‘When long heated with water it is slowly but complete- lv converted into a kind of sugar (levulose); hot dilute acids accomplish the same transformation in a short time. It is digested by animals, and doubtless has the same value for food as starch. In chemical composition, nulin, dried at 212°, differs from cellulose and starch by containing for six times C,H, 0;, the elements of an additional molecule of water ; Cs6Ho20sg = 6 Cp.H,.0; + HO Atlant. Levulin (C,H,)O;)n coexists with inulin in the mature or frozen tubers of the artichoke, dahlia, etc., and, accord- ing to Muentz, isfound inunriperye-grain. Itisahighly soluble, tasteless, gum-like substance resembling dextrin, but without effect on polarized hight. It appears to be formed from inulin when the latter is long heated with water at the boiling point, or when the tubers contain- ing inulin sprout. Dilute acids readily transform it into levulose, as they convert dextrin into dextrose. ' ¥LYCOGEN (C,H,,0;)n exists in the blood and mus- cles of animals in small quantity, and abundantly in the liver, especially soon after hearty eating. It is obtained by boiling minced fresh livers with water, or weak potash solution, and adding alcohol to the filtered liquid. It is a white powder which, with water, makes an opalescent solution. It is colored wine-red by iodine. Boiling di- lute sulphuric acid converts it into dextrose. With saliva, it is said to yield dextrin, maltose and dextrose. Accord- ing to late observations, glycogen occurs in the vegetable kingdom, having been identified in various fungi and in plants of the flax and the potato families. The Gums and Pectin Bodies.—A number of bodies exist in the vegetable kingdom, which, from the similarity of their properties, have received the commoy D8 HOW CROPS GROW. designation of gums. The best known are Gum Arabic, the gums of the Peach, Cherry and Pium, Gum Traga- canth and Bassora Gum, Agar-Agar and the Mucilages of various roots, viz., of mallow anid comfrey; and of certain seeds, as those of flax and quince. Gum Arabie exudes from the stems of various species of acacia that grow in the tropical countries of the Kast, especialiy in Arabia and Egypt. It occurs in tear-like, transparent, and, in its purest form, colorless masses. These dissolve easily in their own weight of water, form- ing a viscid liquid, or mucilage, which is employed for causing adhesion between surfaces of paper, and for thickening colors in calico-printing. Gum Arabic is, however, commonly a mixture of at least two very similar gums, which are distinguished by their opposite effect on polarized hght and by the differ- ent products which they yield when boiled with dilute acids. Cherry Gum.—The gum which frequently forms glassy masses on the bark of cherry, plum, apricot, peach and almond trees, is a mixture in variable proportions of two gums, one of which is apparently the same as occurs in gum arabic, and is fully dissolved in cold water, while the other remains undissolved, buf 5 2. 2 swollen to a pasty mass or jelly. | Gum Tragacanth, which comes to us from Persia and Siberia, has much similarity in its properties to the insoluble part of cherry gum, as it dissolves but slightly in water and swells up to a paste or jelly. The so-called Vegetable mucilages much resemble the insoludle part of cherry gum and are found in the sceds of flax, quince, lemon, and in various parts of many plants. THE VOLATILE PART OF PLANTS. 59 ~ Flax-seed mucilage is procured by soaking unbroken flaxseed in cold water, with frequent agitation, heating the liquid to boiling, strain- ing, and evaporating, until addition of alcohol separates tenacious threads from it. Itis then precipitated by alcohol containing a little hydrochloric acid, and washed by the same mixture. On drying, it forms a horny, colorless, and friable mass. Fig. 13 represents a highly magnified section of the ripe flaxseed. The external cells, a, contain the dry mucilage. When soaked in water, the mucilage swells, bursts the cells, and exudes. The Pectin Bodies.—The flesh of beets, turnips, and similar roots, and of most unripe fruits, as apples, peaches, plums, and berries of various kinds, contain one or several bodies which are totally insoluble in water, but which, under the action of weak acids or alkaline solu- tions, become soluble and yield substances having gummy or gelatinous characters, that have been described under the names pectin, pectic acid, pectosic acid, metapectic acid, etc. ‘Their true composition is, for the most part, not positively established. They are, however, closely related to the gums. ‘The insoluble substance thus trans- formed into gum-like bodies, Fremy termed pectose. The gums, as they occur naturally, are mostly mix- tures. By boiling with dilute sulphuric or hydrochloric acid they are transformed into sugars. In the present state of knowledge it appears probable that the common gums, for the most part, consist of a few chemically distinct bodies, some of which have been’ distinguished more or less explicitly by such names as Arabin, Metarabin, Pararabin, Galactin, Paragalactin, ete. Arabin, or Arabic Acid, is obtained from some va- rieties of Gum Arabic* by mixing their aqueous solution with acetic acid and alcohol. It is best prepared from sugar-bect pulp, out of which the juice has been ex- pressed, by heating with milk of lime; the pulp is thereby broken down, and to a large extent dissolves. * Those sorts of commercial Gum Arabie which deviate the plane of polarization of light to the left contain arabin in largest proportion. 60 HOW CROPS GROW. The liquid, after separating excess of lime and adding acetic acid, is mixed with alcohol, whereupon arabin is precipitated. Arabin, thus prepared, is a milk-white mass which, while still moist, readily dissolves in water to a mucilage. It strongly reddens blue litmus and ex- pels carbonic acid from carbonates. When dried at 212° arabin becomes transparent and has the composition C,.H2.0;,.° Dried at 230° 1t becomes (by loss of a mole- cule of water) Cy.HoOi0, or 2 Celi100s. ; Arabin forms compounds with various metals. Those with an alkali, lime, or magnesia as base are soluble in water. Gum arabic, when burned, leaves 3 to 4 per cent of ash, chiefly carbonates of potassium, calcium and mag- nesium. Arzbic acid, obtained by Fremy from beets by the foregoing method, but not in a state of purity, was described by him as ‘‘metapectic acid.” ‘To Scheibler we owe the proof of its identity with the arabin of gura arabic. | Metarabin.—When arabin is dried and kept at 212° for some time, it becomes a transparent mass which is no longer freeiy soluble in water, but in contact therewith swells up to a gelatinous mass. This is designated metarabin by Scheibler. It 1s dissolved by alkahes, and thus converted into arabates, from which arabi may be again obtained. The body named pararabin by Reichardt, obtained from beet and carrot pulp by treatment with dilute hy- drochloric acid, is related to er the same as metarabin. Fremy’s ‘* pectin,” obtaimed by similar treatment from beets, is probably impure metarabin. Exp. 34.—Reduce several white turnips or beets to pulp by grating. Tnelose the pulp in a piece of muslin, and wash by squeezing in water until all soluble matters are removed, or until the water comes off nearly tasteless. Bring the washed pulp into a glass vessel, with enough dilute hydrochloric acid (1 part by bulk of commercial muriatic acid to 15 parts of water) to saturate the mass, and let it stand 48 hours. Squeeze the acid liquid, filter it, and add alcohol, when * pectin ” will separate. THE VOLATILE PART OF PLANTS. 61 It may be that metarabin is identical with the ‘‘pec- tose ” of the sugar beet, since both yield arabin under the influence of alkalies. It is evident that the composition found for dried arabin properly belongs to metarabin, and itis probable that arabin consists of metarabin C,,H..01, plus one or several molecules of water, and that metara- Lin is an anhydride of arabin. Arabin and metarabin, when heated with dilute sul- phuric acid, are converted into a crystallizable sugar called arabinose, C;H,.0;. The gums that exude from the stems of cherry, plum and peach trees appear to con- sist chiefly of a mixture of frecly soluble arabates with insoluble metarabin. Gum Tragacanth is perhaps mostly metarabin. All these gums yield, by the action of hot dilute acids, the sugar arabinose. Galactin, C,H,.0;, discovered by Miintz in the seeds of alfalfa and found in other legumes, has the appearance, solubility in water and general properties of arabin, and is probably the right-polarizing ingredient of gum arabic. Boiled with dilute acids it is converted into the sugar galactose, C,Hy20¢. Paragalactin, 0,H,.0;.—In the seeds of the yellow Iupin exists up to 20 per cent of a body that is insoluble in water, but dissolves by warming with alkali solutions, and when heated with dilute acids yields galactose. Ac- cording to Steiger it probably has the composition C,H,)0;. Maxwell has shown it to exist in other leguminous seeds, viz., the pea, horse-bean (Faba vulgaris) and veten. In the ‘‘ Chinese moss,” an article of food prepared in China from sea-weeds, and in the similar gum agar or ‘‘vegetable gelatine” of Japan, existsasubstance which is insoluble in cold water, but with that liquid swells up to a bulky jelly, and yields galactose when heated with dilute acids. This corresponds to metarabin. Xylin, or Wood Gum.—ihe wood of many decidu- ous trees, the vegetable ivory nut, the cob of Indian 62 HOW CROPS GROW. corn and barley husks, contain 6 to 20 per cent of a sub- stance insoluble in cold water, but readily taken up in cold solution of caustic soda. On adding to the solution an acid, and afterwards alcohol, a bulky white substance separates, which may be obtained dry as a white powder or a translucent gum-like mass. It dissolves very slightly in boiling water, yielding an opalescent solution. The composition of this substance was found by Thomsen to be CeHis0;. Xylin differs from pararabin and pectose in not béing soluble in milk of lime. It is converted by boiling with dilute sulphuric acid into a crystallizable sugar, vylose, whose properties have been but little investigated. Flax-seed Mucilage, C,H,,.0;, resembles metarabin, but by action of hot dilute acids is resolved into cellulose anda gum, which latter is further transformed into dex- trose. The yield of cellulose is about four per cent. Quince-Seed Mucilage appears to be a compound of cellulose and a body like arabin. On boiling with dilute sulphuric acid it yields nearly one-third its weight of cel- lulose, together with a soluble gum and a sugar, the last being a result of the alteration of the gum. The sugar is similar to arabinose. The Soluble Gums in Bread-grains.—In the bread- grains, freely soluble gums occur often in considerable proportion. TABLE OF THE PROPORTIONS (per cent.) OF GUM* IN VARIOUS AIR-DRY GRAINS OR MILL PRODUCTS. (According to Von Bibra, Die Getreidearten und das Brod.) Wine aiG Sere a oro) screie cls'e ees 4.50) |, Barley ALOU eae wo ca eienetertel tetas 6.33 Wheat flour, superfine........ 6.25 | Barley bran.................-+. 6.88 Spelt hour CM tticunt spelta).s 2-48 | Oa gered emai sellin 3.50 Wires th Dramicee «x!asisiacesteisieta oleae 8.85" |! RAC SOMME. acres) cae ore itaenene 2.00 SHOU OIE o Gapeno oOo bods oeaaD 12.52))). WG GR ONE. F 2.7.5 «10 = «it te eee 10.60 CAG STRIVE 55 Seqnoo caconddo osc 4.10:|| Maize” mieales...).:...- HsO,, a solid nearly insoluble in water, but also convertible into lactic acid by water, and into lactates by alkalies. * 2 (C3H¢03) = CgHy.0; + H,O t CgHy 0; = CgH,0, + H,9 18 HOW CROrS GROW. Dibasie Acids. —Vhe acids of this class requiring notice are COOH Oxalic acid, C,H,0,, or ; SOOH i 7] : y ~COOH Malonie acid, C3H4O4, or CH, < COOH CH,—COOH Succinic acid, C,H,0,4, or | CH,—COOIL CH,—COOHU biom—coox CHOH) COOH Tartarie acid (Dioxysuccinic CyH,0,, or acid), H(OH) COOH Matic acid (Oxysuccinic acid), CyH,0;, or The salts formed by union cf these acids with metallic bases are either primary or secondary, according as the metal enters into one or two of the carboxyls. Oxalic acid, C,H,O,, exists largely im the common sorrel, and is found in greater or less quantity in nearly all plants. The pure acid presents itself in the form of color- less, brilliant, transparent crystals, not unlike Epsom salts in appearance ([ig. Fig. 15. 15), but having an intensely sour taste. Primary potassium oxalate (formerly termed acid ox- alate of potash), HOOC—COOK, occasions the sour taste of the juice of sorrel, from which it may be obtained in crystals by evaporating off the water. It may also be prepared by dissolving oxalic acid in water, dividing the solution into two equal parts, neutralizing * one cf these by adding solution of potash and then mixing the two solutions and evaporating until crystals form. Secondary potassium oxalate (neutral oxalate of potash), KOOC—COOK, is the result of fully neutralizing oxalic acid with potash solution. It has no sour taste. Primary calcium oxalate exists dissolved in the cells of plants so long as they are in active growth. Second- ary calcium oxalate is extremely insoluble in water, and * As described in Exp. 38. THE VOLATILE PART OF PLANTS. v9 very frequently occurs within the plant as microscopic crystals. These are found in large quantity im the ma- ture leaves and roots of the beet, in the root of garden rhubarb, und especially in many lichens. Secondary ammonium oxalate is employed as a test for calcium. EXP. 36.—Dissolve 5 grams of oxalic acid in 50 c. ¢. of hot water, add solution of ammonia orsolid carbonate of ammonium until the odor of the latter slightly prevails, and allow the liquid to cool slowly. Long, needle-like crystals of ammonium oxalate separate on cooling, the compound being sparingly soluble in cold water. Preserve for future use. EXP. 37.—Add to any solution of lime, as lime-water (see note, p. 20), or hard well-water, a few drops of solution of ammonium oxalate. Secondary Calcium oxalate immediately appears as a Wiiite, powdery precipitate, which, from its extreme insolubility, serves to indicate the presence of the minutest quantities of lime. Add a few drops of hydro- chlorie or nitric acid to the calcium oxalate; it disappears. Hence ammonium oxalate is atest for lime only in solutions containing no free mineralacid. (Aceticand oxalic acids, however, have little effect upon the test.) Malonic acid and Succinic acid occur in plants in but small quantities. The former has been found in sugar-beets, the latter in lettuce and unripe grapes. Malic acid, C,H,0;, is the chief sour principle of ap- ples, currants, gooseberries, plums, cherries, strawberries, and most common fruits. It exists in small quantity in a multitude of plants. It is found abundantly in the gar- den rhubarb, and primary potassium malate may be ob- tained in crystals by simply evaporating the juice of the leaf-stalks of this plant. It is likewise abundant as ca!- cium salt in the nearly ripe berries of the mountain ash, and in barberries. Calcium malate also occurs in con- siderable quantity in the leaves of tobacco, and is often encountered in the manufacture of maple sugar, separat- ing as a white or gray sandy powder during the evapora- tion of the sap. Pure malic acid is only seen in the chemical laboratory, and presents white, crystalline masses of an intensely sour taste. It is extremely soluble in water. 80 HOW CROPS GROW. Tartaric acid, 0,H,0,, is abundant in the grape, from the juice of which, during fermentation, 16 is de- posited as argol. This, on purification, Rota yields the cream of tartar (bitartrate of potash) of commerce. ‘'Tartrates of po- tassium and calcium exist In small quan- tities in tamarinds, in the unripe berries Fig. 16, of the mountain ash, in the berries of the sumach, in cu- cumbers, potatoes, pineapples, and many other fruits. The acid itself may be obtained in large glassy crystals (see Fig. 16), which are very sour to the taste. Of the Tribasie Acids known to occur in plants, but one need be noticed here, viz., eifrie acid. CH,COOH Cz Hs O;, or C(O H) COOH CH,COOH Citric acid exists in the free state in the juice of the lemon, and in unripe tomatoes. It accompanies malic acid in the currant, gooseberry, cherry, strawberry, and raspberry. It is found in small quantity in tobacco leaves, in the tubers of the artichoke (Helianthus), in the bulbs of onions, in beet-roots, in coffee-berries, in seeds of lupin, vetch, the pea and bean, and in the needles of the fir tree, mostly as potassium or calcium salt. It also exists In cows’ milk. In the pure state, citric acid forms large transparent or white crystals, very sour to the taste. Relations of the Vegetable Acids to each other, and to the Amyloses.~ Oxalic, malic, tartarie and citric acids usually occur together in our ordinary fruits, and some of them undergo niutual conversion in the living plant. According to Liebig, the unripe berries of the mountain ash contain much tartaric acid, which, as the fruit ripens, is converted into malic acid. Tartaric acid can be artificially transformed into malic acid, and this into suecinie acid. When citric, malic and tartarie acids are boiled with nitrie acid, or heated with caustic potash, they all yield oxalic acid. Cellulose, starch, dextrin, the sugars, yield oxalic acid when heated THE VOLATILE PART OF PLANTS. 81 with potash or nitric acid. Commercial oxalie acid is thus made from sawdust. Gum (Arabic), sugar and starch yield tartaric acid by the action of nitric acid. Definition of Acids, Bases, and Salts.—In the popular sense, an acid is any body having a sour taste. It is, in fact, true that all sour substances are acids, but all acids are not sour, some being tasteless, others bitter, and some sweet. A better characteristic of an acid is its capability of forming salts by its interaction with dases. The strong- est acids, 1. e., those bodies whose acid characters are most highly developed, if soluble, so as to have any effect on the nerves of taste, are sour, viz., sulphuric acid, phos- phoric acid, nitric acid, ete. Bases are the opposite of acids. The strongest bases, when soluble, are bitter and biting to the taste, and cor- rode the skin. Potash, soda, lime, and ammonia are ex- amples. Magnesia, oxide of iron, and many cther com- pounds of metals with oxygen, are insoluble bases, and hence destitute of taste. Potash, soda, and ammonia are termed alkalies ; lime and magnesia, alkali-earths. Salis are compounds that result from the mutual ac- tion of acids and bases. Thus, in Exp. 20, the salt, cal- cium phosphate, was produced by bringing together phosphoric acid, and the base, lime. In Exp. 37, cal- cium oxalate was made in a similar manner. Common salt—in chemical language, sodium chloride—is formed when caustic soda is mixed with hydrochloric acid, water being, in this case, produced at the same time. NaOH Selby (2 = Wacl. “6 HO Sodium hydroxide. Hydrochloric acid. Sodium chloride. Water. In general, salts having a metallic base are formed by substituting the metal for the hydrogen of the acid ; or if an organic acid, for the hydrogen that is united to oxy- gen, 1.¢e., of carboxyl, COOH. Ammonia, NH;, and many organic bases unite directly to acids in forming salts. 6 82 HOW CROPS GROW. Ammonia. Hydrochloric acid. Ammoniune chloride.* NH, oe CH;COOH = CH,COONH, Ammonia. Acetic acid. Ammonium Acetaté. Test for acids and alkalies.—Many vegetable colors are altered by sol. uble acids or soluble bases (alkalies), in such a manner as to answer the purpose of distinguishing these two classes of bodies. 4 H,0 Ammonium acetate. Acctamide. Water. The above equation shows that acetamide is ammonia, NH;, or HNH,, one of whose hydrogens has been re- placed by the group of atoms, CH,CO, the acetic acid radical, so called. Acetamide is a white crystalline body. The simple amides, like acetamide, are as yet not known to exist in plants, They readily unite with water to produce ammonium salts. Carbamide, or Urea CO(NH,).. This substance— the amide of carbonic acid CO(OH),—naturally occurs in considerable proportion in the urine of man and mam- malian apimals. It is a white, crystalline body, with a cooling, slightly salty taste, which readily takes up the elements of water and passes into ammonium carbonate. Urea has not been found in plants, but derivatives of it in which acid radicals replace a part of its hydrogen are of common occurrence. (Guanin, allantoin.) Amidoacids are acids containing the NH, group as a part of the acid radical. Amidoacetic Acid, C,H;NO., or CH.(NH.)COOH, is derived from acetic acid, CH;COOH, by the replace- ment of H in CH; by NH,. The amidoacids have not a sour, but usually a sweetish taste, and, like the amides, act both as weak acids and weak bases. Amidoacetic 116 HOW CROPS GROW. acid, also called glycocoll, has not as yet been found in plants, but exists in the scallop and probably in other shell-fish, and a compound of it, benzoylglycocoll or hip- puric acid, is a nearly constant ingredient of the urine of the horse and other domestic herbivorous animals. Betain, or trimethylglycocoll, C;1,N Oz, a crystalliza- ble substance found in beet-juice, stands in close chem- ical relations to amidoacetic acid. Amidovaleric acid, C;H,,NO., occurs in ox-pancreas and in young lupin plants. Amidocaproic acid, or Leucin, C,H,;N Oz, first observed in animals, has lately been discovered in various plants. ‘The same is true of Tyrosin, or oxyphenyl-amidopropionic acid, C,H,,NO;, and of phenyl-amidopropionic acid, C,H1,NO,. The above amidoacids are readily obtainéd as products of decomposition of animal and vegetable albuminoids by the action of hot acids. Amidoacetic acid was thus first obtained from gelatin. Leucin and Tyrosin are com- monly prepared by boiling horn shavings with dilute sul- phuric acid ; they are also formed from vegetable albu- minoids by similar treatment and are final results of the digestion of proto- and deutero-proteoses (hemialbumose) under the action of trypsin and papain. Asparagin and Glutamin.—These bodies, which are found only in plants, are amides of amidoacids, being de- rived from dibasic acids. Asparagin, the amide of umidosuccinie acid, CH(NH,)COOH du,conn, has been found in very many plants, especially in those just sprouted, as in asparagus, peas, beans, etc. Aspara- gin forms white, rhombic crystals, and is very soluble in water. Glutamin, the amide of amidoglutaric acid, CONH, CsHANHX COOH THE VOLATILE PART OF PLANTS. 117 has been found, together with asparagin, in bect-juice and in squash seedlings. The amides, when heated with water alone, and more easily in presence of strong acids and alkalies, are con- verted into ammonia and the acids from which they are derived. Thus, asparagin yields ammonia and amido- succinic acid at the boiling heat under the influence of hydrochloric acid, or of potassium hydroxide, and gluta- min is broken up by the last-named reagent at common temperatures, and by water alone at the boiling point, with formation of atamonia and amidoglutaric acid. The amidoacids are not decomposed by hot water or acids with separation of ammonia. Amidosuccinic and amidoglutaric acids result from albuminoids by boiling with dilute sulphuric acid, and by the action of bromine. The latter acid as yet has been obtained from vegetable albuminoids only, and is prepared most abundantly from gluten, and especially from mucedin. Imides, closely related to the amides, are a series of very interesting substances, into whose chemical consti- tution we cannot enter here further than to say that they contain several NH* groups, i. e., ammonia, NHs, in which two hydrogens are replaced by hydro-carbon, or oxycarbon groups or carbon atoms. These bodies are Uric acid, C;H4,N,Os, Adenin, C;H;N;, Guanin, C;H;N;O, HeoN,O,. Of these the first, so far as now known, occurs exclusively in the ani- mal. Adenin, Guanin, Allantoin, Xanthin, and Hypo- xanthin, are common to animals and plants; the last three are exclusively vegetable. Caffein exists in coffee and tea combined with tannic acid. In the pure state it forms white, silky, fibrous erystals, and has a bitter taste. In coffee it is found to * Or its hydro-carbon derivatives. 118 HOW CROPS GROW. the extent of one-half per cent ; in tea it occurs in much larger quantity, sometimes as high as 6 per cent. Theobromin resembles caffein in its characters. It is found in the cacao-bean, from which chocolate is man- ufactured. | Vernin, discovered recently in various plants, young clover, vetches, squash-seedlings, etc., yields guanin by the action of hydrochloric acid. All these bodies stand in close chemical relations to each other, being complex imide derivatives of dioxymalonic (mesoxalic) acid. The amides and amidoacids, like ammonia, are able to combine directly with acids, are accordingly bases, but they are weak bases, because the basic quality of their ammonia is largely neutralized by the acid radicals already present in them. On the other hand, amides and ami- doacids often act as weak acids, for a portion of the hydro- gen of the NH, group is easily displaced by metals. The amides thus in fact possess in a degree the quali- ties of both the acid and of the base (ammonia) from which they are derived. They also are commonly “neu- tral” in the sense of having no sharp acid or alkaline taste or corrosive character. In vegetation amides appear as intermediate stages be- tween ammonium salts and albuminoids. - They are, on the one hand, formed in growing plants from ammo- nium salts by a constructive process, and from them or by their aid, probably, the albuminoids are built up. On the other hand, in animal nutrition they are stages through which the elements of the albuminoids pass in their reversion to purely mineral matters. In germinat- ing seeds and developing buds they probably combine both these offices, being first formed in the germ from the albumincids of the seed, entering the young plant or shoot, and in it being reconstructed into albuminoids. Their free solubility in water and ability to penetrate moist membranes adapt them for this movement. They THE VOLATILE PART OF PLANTS. 119 temporarily accumulate in seedlings and buds, but disap- pear agiin as growth takes place, being converted into albuminoids, in which transformation they require the conjunction of carbhydrates. Their ability to unite with acid as well as bases further qualifies them to take part in these physiological processes. The imides are also at once weak bases and weak acids. Uric acid and allantoin, relatively rich in oxygen, have the acid qualities best developed. Guanin and caffein, with less oxygen and more hydrogen, are commonly classed among the organic bases, as in them the basic cnaracters are most evident. Amines.— When the hydrogen of ammonia is replaced by hydrocarbon groups (radicals) such as Methyl, CHs, Kthyl, C.H;, Phenyl, C.H;, ete., compound ammonias or amines result which often resemble ammonia in physical and chemical characters, and some of them appear to be stronger bases than ammonia, being able to displace the latter from its combinations. Trimethylamine, N(CH3)3, may be regarded as ammo- nia whose hydrogens are all substituted by the methyl group, CH;, and is a very volatile liquid having a rank, fishy odor, which may be obtained from herring pickle, and exhales from some plants, as from the foliage of Chenopo- dium vulvaria, and the flowers of Crataegus oxycantha. It is produced from bedain (trimethylamidoacetic acid), by heating with potash solution, just as ammonia is formed from many amides under similar treatment. Cholin, C;H,;NO., and Newrin, C;H,,NO, are organic bases related to trimethylamine, which were first ob- tained from the animal. Cholin is an ingredient of the bile, and is found also in the brain and yolk of eggs, where it exists asacomponent of lecithin. It has latterly been discovered in the hop, lupin and pumpkin plants, and in cotton seed ; by oxidation it yields betain. Neu- rim is readily formed from cholin by the action of alka- 120 HOW CROPS GROW. lies and in the process of putrefaction. It is a violent poison, and is perhaps one of the ingredients which, in the seeds of the vetch and of cotton, prove injurious, or even fatal, when these seeds are too largely eaten by ani- mals. Cholin and Neurin are syrupy, highly alkaline liquids. 7. ALKALOIDS is the general designation that has been applied to the organic bases found in many plants, which are characterized in general by their poisonous and medicinal qualities. Caffein and Theobromin, already noticed, were formerly ranked as alkaloids. We may mention the following : Nicotin, CyoHi,Ne, is the narcotic and intensely poi- sonous principle in tobacco, where it exists in combina- tion with malic and citric acids. In the pure state it is a colorless, oily liquid, having the odor cf tobacco in an extreme degree. It is inflammable and volatile, and so deadly that a single drop will kill a large dog. French tobacco contains 7 or 8 per cent; Virginia, 6 or 7 per cent; and Maryland and Havana, about 2 per cent of nicotin. Nicotin contains 17.3 per cent of nitrogen, but no oxygen. Lupinidin, CsH,;N, Lupanin, C,;sH.;N,0, and Lu- pinin, Cx Hy)N.O., are bases existing in the seeds of the lupin. The first two are liquids; the last is a crystal- line solid. They are poisonous and are believed to occa- sion the sickness which usually follows the use of lupin- seeds in cattle food. Sinapin, C,¢H.sNO;, occurs in white mustard. When boiled with an alkali it is decomposed, yielding neurin as one product. Vicin, CssHs,Ni11021, and Convicin, CioHi,N3;0,, are crystalline bases that occur in the seeds of the vetch, with regard to whose nature and properties little is known. Avenin, Cs eHe:NO;3, according to Sanson, is a sub- stance of alkaloidal character, existing in oats. It is said id THE VOLATILE PART OF PLANTS. 121 to be more abundant in dark than in light-colored oats, and, when present to the extent of more than nine-tenths of one per cent, to act as a decided nerve-excitant on ani- mals fed mainly on oats. Aveuin is described as a gran- ular, brown, non-crystallizable substance, but neither Osborne (at the Connecticut Experiment Station) nor Wrampelmeyer (Vs. St., XXXVI, p. 299) have been able to find any evidence of the presence of such a body in oats. Morphin, C,,;Hi:>NO3, occurs, together with several other alkaloids, in opium, the dried milky juice of the seed-vessels of the poppy cultivated in India. Its use in ~allaying pain and obtaining sleep and its abuse in the ‘‘opium habit” are well known. Piperin, C,,;H,,NOs, the active principle of white and black pepper, is a white crystalline body isomeric with morphin. Quinin, CooH.4N2O2, is the most important of several bases used as anti-malarial remedies obtained from the bark of various species of cinchona growing in the forests of tropical South America, and cultivated in India. Strychnin, Co;Ho2N.O2, and Brucin, Co;H..N.OH, is the intensely poisonous alkaloid of nux vomica (dog button). Atropin, C,;H.3NOs, is the chief poisonous principle of the ‘* Nightshade” or belladonna, and of stramonium or *‘ Jamestown weed.” - Veratrin, Cs,Hy,NOv, is the chief toxic ingredient of the common White Hellebore, so much used -as an insecticide. — Solanin, CyHs;NO,; (?), is a poisonous crystalline alkaloid found in many species of Solanum, especially in the black nightshade (Solanum nigrum). It occurs in the sprouted tubers and green fruit of the potato (Solanum tuberosum) and in the stems and leaves of the tomato (Solanum lycopersicun). The alkaloids, so far as investigated, appear to be more 322 HOW CROPS GROW. or less complex derivatives of the bases Pyridin, C;H;N, and Quinolin, CysH;N, which are colorless, volatile hquids with sharp, unpleasant odor, produced from albn- minoids at high temperatures, and existing in smoke, bone-oil and tar. ‘The alkaloids bear to these bases simi- lar relations to those subsisting between the amines and ammonia. 8. PHOSPHORIZED SUBSTANCES.—This class of bodies are important because of their obvious relations to the nutrition of the brain and nerve tissues of the animal, which have long been known to contain phosphorus as an essential ingredient. All our knowledge goes to show that phosphorus invariably exists in both plants and ani- mals as phosphoric acid or some derivative of this acid, or, in other words, that their phosphorus is always united to oxygen as in the phosphates, and is not directly combined to carbon, hydrogen, or nitrogen. Nuclein.—This term is currently employed to desig- nate various imperfectly-studied bodies that resemble the albuminoids in many respects, but contain several per cent of phosphorus. They are easily decomposable, boiling water being able to remove from them phosphoric acid, and under the action of dilute acids they mostly yield phosphoric acid, albuminoids and hypoxanthin, C;H,N,0, or similar imide bases. They are very difficult of digestion by the gastric juice. The nucleins are found in the protoplasm and especially in the cell-nuclei (see p. 245), of both plants and animals, and have been ob- tained from yeast, eggs, milk, ete., by a process based on their indigestibility by pepsin. Chemists are far from agreed as to the nature or composition of the nucleins. Lecithin, C,,H ))>9NPO,.—This name applies to a num- ber of substances that have been obtained from the brain and nerve tissue of animals, eggs and milk, as well as from yeast, and the seeds of maize, peas, and wheat. The lecithins are described as white, wax-like substances, THE VOLATILE PART OF PLANTS. 123 imperfectly crystallizable, similar to protagon in their deportment toward water, and readily decomposed into cholin, glycerophosphoric acid, and one or more fatty acids. ‘l'hree lecithins appear to have been identified, yielding respectively, on decomposition, stearic, palmitic, and oleic acids. The formula C,H )NPO, is that of distearic lecithin, which is composed of glyceryl, C;H;, united to two stearic acid radicals, and also to phosphoric acid, which again is joined to cholin, as represented by the formula— . / OCisH5,0 C3H,;—OC,¢. HO SOO ( OGHN(CH,),0H Lecithin is believed to be a constant and essential in- gredient of plants and animals. Protagon, Cyg0H3osN;PO3;, discovered by Liebreich in the brain of animals, has been further studied by Gam- gee & Blankenhorn. It is a white substance that swells up with water to a gelatinous mass and finally forms an opake solution. From solution in ether or alcohol it can be easily obtained in needle-shaped crystals, whose com- position is given below. Alkalies decompose protagon inte glycero-phosphoric acid, stearic and other fatty acids, and cholin or neurin. Protagon was formerly confounded with lecithin and thought to exist in plants, but its presence in the latter has not been established. Protagon. Lecithin. CATON gs accosted sx cco lene ots 66.39 65.43 TAI OPE 0 Gel ean Oars Be gee cre 10.69 11.16 NIN RO OEE cc Paes cis elec cies) tOO 1.73 AMOS PPINOTUS ioecin\esciine on eal i wee, 2.0F 3.84 Oy MOM ae eth tan foe ic oe Meet Se 19.46 17.84 100.00 100.00 Knop was the first to show that the crude fat which is extracted from plants by ether contains an admixture of some substance of which phosphorus is an ingredient. In the oil obtained from the sugar-pea he found 1.25 per eent. of phosphorus. ‘Tdpler afterwards examined the 124 HOW CROPS GROW. oils of a large number of seeds for phosphorus with the subjoined results : Source of Per cent. of | Source of Per cent. of at. phosphorus. Sat. phosphorus. IU WUT Sadoscu codoubdosooecoac 0:29 AWE WOU UGBasearoo Hoo dsebn oe trace PPB ik ch dis Sekererretioeielereroe eee LAT. QOUVING: « ose eh teas eee none HOLTSO=D CAME os dc -rseciesecteicicteheie 0.72 W BOCA iit ie weeneeeneeee 0.25 NAWOlINS oe coscdsoac bono peud Secs 0.50 IBPWONENT po nooccese doom oo obec 0.28 Wilmer We miller errr rerertetere 0.39 RY. Cri ea iete chee oe eer 0.31 Horse-chestuiitie.. «2-2 es 0.40 Oath Ase sose tee eee 0.44 Chocolate-bean.. ...... none DES p. Geese OS Acre. OO Shs oc none INERT eee eee ware cleskererere ce “6 Col Zee. ee eee ee eae GC IRGYO Dp coagdadosed bos soDdC BS NIRS UEC bso ogc5 a4 So oncaanos e It is probable that the phosphorus in these oils existed in the seeds as lecithin, or as glycerophosphoric acid, which is produced in the decomposition of lecithin. Max- well (Constitution of the Legumes), reckoning from the phosphoric acid found in the ether-extract, estimates the pea kernel to contain 0.368 per cent, the horse-bean (Faba vulgaris) 0.600 per cent, and the vetch 0.532 per cent of lecithin. Lecithin is thus calculated to make up 19.63 per cent of the crude fat of the pea, 31.54 per cent of the crude fat of the horse-bean, and 35.24 per cent of that of the vetch. Chlorophyl, i. e., leaf-green, is the name applied to the substance which occasions the green color in vegeta- tion. Itis found inall those parts of most annual plants and of the annually renewed parts of, perennial plants which are exposed to light. The green parts of plants usually contain chlorophyl only near their surface, and in quantity not greater than one or two per cent of the fresh vegetable substance. Chlorophyl, being soluble in ether, accompanies fat or wax when these are removed from green vegetable mat- ters by this solvent. It is soluble in aleohol and hydro- chloric and sulphuric acids, imparting to these liquids an intense green color, but it suffers alteration and decom- position so readily that it is doubtful if the composition of chlorophyl, as it exists in the living leaf, is accurately known, especially since it is there mixed with other sub- THE VOLATILE PART OF PLANTS. 125 stances, separation from which is difficult or imprac- ticable. Chlorophyllan, obtained by Hoppe-Seyler from grass, separates from its solution in hot alcohol in characteristic ucicular crystals which are brown to transmitted light, and in reflected light are blackish green, with a velvety, somewhat metallic lustre. This substance has the con- sistence of beeswax, adheres firmly to glass, and at about 230° melts to a brilliant black liquid. The crystallized chlorophyllan has a composition as follows : CHLOROPHYLLAN. Garo my piracy ayers: Serato cele ose tesa era mi lereietoic 73.36 EVO DCM jars crater a crete, robes = conic yeieleroisiere ee oie 9.72 INDE MR OFTEN T itlo ot a onad on ooo sD OD OU.soDpcocomuUE 5.68 JANOS OH oO TUS haven epcoodasdougscconpade aa alesis) MIG ETCERITEIN Gos cuetcooonooe wedocdosotoect 0.34 UATE len og pone coasbocconcenoonosns onoounoE 9.52 100.00 Chlorophyllan is chemically distinct from chlorophyl, as proved by its optical properties, but in what the dit- ference consists is not understood. Boiling alkali decom- poses it with formation of chlorophyllanic acid that may be obtained in blue-black crystals, and at the same time glycerophosphoric acid and cholin, the decomposi- tion-products of lecithin, are produced. Tschirch found that chlorophyllan, by treatment with zine oxide, yields a substance whose optical properties lead to the belief that it is identical with the chlorophyl that occurs in the living plant. It was obtained as a dark-green powder, but its exact chemical composition is not known. The special interest of chlorophyl lies in the fact that it is to all appearance directly concerned in those con- structive processes by which the plant composes starch and other carbhydrates out of the mineral substances which form its food. Xanthophyl is the yellow coloring matter of leaves and of many flowers. It occurs, together with chlorophyl, in green leaves, and after disappearance of chloroplhyl remains as the principal pigment of autumn foliage. 126 HOW CROPS GROW. CHAPTER II. THE ASH OF PLANTS. ay THE INGREDIENTS OF THE ASH. As has been stated, the volatile or destructible part of plants, i. e., the part which is converted into gases or vapors under the ordinary conditions of burning, con- sists chiefly of Carbon, Hydrogen, Oxygen and Nitro- gen, together with small quantities of Sulphur and Phos- phorus. ‘These elements, and such of their compounds as are of general occurrence in agricultural plants, viz., the Organic Proximate Principles, have been already described in detail. The non-volatile part or ash of plants also contains, or may contain, Carbon, Oxygen, Sulphur, and Phos- phorus. It is, however, in general, chiefly made up of eight other elements, whose common compounds are permanent at the ordinary heat of burning. In the subjoined table, the names of the 12 elements of the ash of plants are given, and they are grouped under two heads, the non-metals and the metals, by rea- son of an important distinction in their chemical nature. ELEMENTS OF THE ASH OF PLANTS. Non-Metals. Metals. Oxygen. Potassium, Carbon. Sodium. Sulphur. Calcium. Phosphorus. Magnesium. Silicon. Iron. Chlorine. Manganese. If to the above be added Hydrogen and Nitrogen THE ASH OF PLANTS. 127 the list includes all the elementary substances that belong to agricultural vegetation. Hydrogen is never an ingredient of the perfectly burned and dry ash of any plant. | Nitrogen may remain in the ash under certain con- ditions in the form of a Cyanide (compound of Carbon and Nitrogen), as will be noticed hereafter. Besides the above, certain other elements are found, either ocecasion- ally in common plants, or in some particular kind of vegetation ; these are Iodine, Bromine, Fluorine, Titanium, Boron, Arsenic, Lithium, Rubidium, Barium, Aluminum, Zine, Copper. These elements, how- ever, so far as known, have no special importance in agricultural chemistry, and mostly require no further notice. We may now complete our study of the Composition of the Plant by attending to a description of those ele- ments that are peculiar to the ash, and of those com- pounds which may occur in it. It will be convenient also to describe in this section some substances, which, although not ingredients of the ash, may exist in the plant, or are otherwise important to be considered. The Non-metallic Elements, which we shall first notice, though differing more or less widely among them- selves, have one point of resemblance, viz., they and their compounds with each other have acid properties, i. e., they either are acids in the ordinary sense of being sour to the taste, or enact the part of acids by uniting to met- als or metallic oxides to form salts. We may, therefore, designate them as the acid elements. They are Oxygen, Sulphur, Phosphorus, Carbon, Silicon, and Chlorine. With the exception of Silicon, and the denser forms of Carbon, these elements by themselves are readily volatile. Their compounds with each other, which may occur in vegetation, are also volatile, with two exceptions, viz., Silicic and Phosphoric acids. In order that they may resist the high temperature at which ashes are formed, they must be combined with the metallic elements or their oxides as sal/s. 128 HOW CROPS GROW. Oxygen, Symbol O, atomic weight 16, is an ingredient of the ash, since it unites with nearly all the other ele- ments of vegetation, either during the life of the plant, or in the act of combustion. It unites with Carbon, Sulphur, Phosphorus, and Silicon, forming acid bodies ; while with the metals it produces oxides, which have the characters of bases. Chlorine alone of the elements of the plant does not unite with oxygen, either in the living plant, or during its combustion. CARBON AND ITS COMPOUNDS. Carbon, Sym. C, at. wt. 12, has been noticed already with sufficient fullness (p. 14). It is often contained as charcoal in the ashes of the plant, owing to its being en- veloped in a coating of fused saline matters, which shield it from the action of oxygen. Carbon Dioxide, commonly termed Carbonic acid, Sym. COs, molecular weight 44, is the colorless gas which causes the sparkling or effervescence of beer and soda water, and the frothing of yeast. It is formed by the oxidation of carbon, when vegeta- ble matter is burned (Exp. 6). It is, therefore, found in the ash of plants, combined with those bases which in the living organism existed in union with organic acids ; the latter being destroyed by burning. It also occurs in combination with calcium in the tissues of many plants. Its compounds with bases are carbon- ates, to be noticed presently. When a carbonate, as mar- ble or limestone, is drenched with a strong acid, like vinegar or muriatic acid, the carbon dioxide is set free with effervescence. Carbonic Acid, H,0O;3, or CO(OH)., mo. wt. 62. This, the carbonic acid of modern chemistry, is not known asa distinct substance, since, when set free from carbon- ates by the action of a stronger acid, it falls into carbon dioxide and water : THE ASH OF PLANTS. 129 CaCO, + 2 HCl = CaCl, + H,CO; and H,CO; = H,O + CO,. Carbon dioxide is also termed anhydrous carbonic acid, or again, carbonic anhydride. CYANOGEN, Sym. C,N,.—This important compound of Carbon and Ni- trogen is a gas which has an odor like that of peach-pits, and which burns on contact with a lighted taper with a fine purple flame. In its union with oxygen by combustion, carbon dioxide is formed, and nitro- gen set free: C.N, +40 = 2 CO, + No. Cyanogen may be prepared by heating an intimate mixture of two parts by weight of ferrocyanide of potassium (yellow prussiate of potash) and three parts of corrosive sublimate. The operation may be conducted in a test-tube or small flask, to the mouth of which is fitted a cork penetrated by a narrow glass tube. On applying heat, the gas issues, and may be set on fire to observe its beautiful flame. Cyanogen, combined with iron, forms the Prussian blue of com- merce, and its name, signifying the blue-producer, was given to it from that circumstance. Cyanogen unites with the metallic elements, giving rise to a series of bodies which are termed Cyanides. Some of these often oceur in small quantity in the ashes of plants, being produced in the act of burning by the union of nitrogen with carbon andametal. For this result, the temperature must be very high, carbon must be in excess, the metal is usually potassium or calcium, the nitrogen may be either free nitrogen of the atmosphere or that originally existing in the organic matter. With hydrogen, cyanogen forms the deadly poison hydrocyanic or prussic acid, HCy, which is produced from amygdalin, one of the ingre- dients of bitter almonds, peach, and cherry seeds, when these are erushed in contact with water. When a cyanide is brought in contact with steam at high tempera- tures, itis decomposed, allits nitrogen being converted into ammonia. Cyanogen is anormal ingredient of one common plant. The oil of mustard is allylsulphocyanate, C;H;CNS. SULPHUR AND iTS COMPOUNDS. Sulphur, Sym. 8, at. wt. 32.—The properties of this element have been already described (p. 25). Some of its compounds have also been briefly alluded to, but re- quire more detailed notice. HYDROGEN SULPHIDE, Sym. H.S, mo. wt. 34. This substance, familiarly known as sulphuretted hydrogen, occurs dissolved in the water of nu- merous so-called sulphur springs, as those of Avon and Sharon,N. Y., from which it escapes as a fetid gas. It is not unfrequently emitted from volcanoes and fumaroles. Itis likewise produced in the decay of organie bodies which contain sulphur, especially eggs, the intolerable odor of which, when rotten, is largely due to this gas. It is evolved from manure heaps, from salt marshes, and even from the soil of moist meadows. 9 130 HOW CROPS GROW. The ashes of plants sometimes yield this gas when they are moistened with water. In such cases, a sulphide of potassium or caleium has been formed in small quantity during the incineration. Hydrogen Sulphide is set free in the gaseous form by the action of an acid on various sulphides, as those of iron (Exp. 17), antimony, ete., as well as by the action of water on the sulphides of the alkali and alkali- earth metals. It may be also generated by passing hydrogen gas into melted sulphur. Sulphuretted hydrogen has a slight acid taste. It is highly poisonous and destructive, both to animals and plants. SULPHUR DIOXIDE, Commonly called SULPHUROUS ACID, Sym. SO., mo. wt. 64. When sulphur is burned in the air, or in oxygen gas, it forms copious white suffocating fumes, which consist of one atom of sulphur, united to two atoms of oxygen; SO, (Exp. 15). Sulphur dioxide is characterized by its power of discharging, for a time at least, most of the red and blue vegetable colors. It has, how- ever, no action on many yellow colors. Straw and wool are bleached by it in the arts. Sulphur dioxide is emitted from volcanoes, and from fissures in the soil of volcanic regions. It is produced when bodies containing sul- phur are burned with imperfect access of air, and is thrown into the atmosphere in large quantities from fires which are fed by mineral coal, as well as from the numerous roasting heaps of certain metallic ores (sulphides) which are wrought in mining regions. Sulphur dioxide may unite with bases, yielding salts known as swl- phites, some of which, viz., calcium sulphite and sodium sulphite, are employed to check or prevent fermentation, an effect also produced by the acid itself. Sulphur-Trioxide, Sym. SO3, mo. wt. 80, is known to the chemist as a white, silky solid, which attracts moisture with great avidity, and, when thrown into water, hisses like « hot iron, forming sulphuric acid. Sulphur trioxide was formerly termed sulphuric acid or anhydrous sulphuric acid, and now it is common in statements of analysis to fol this usage. Sulphuric Acid, Sym. H.50,, mo. wt. 98, is a sub- stance of the highest importance, its manufacture being the basis of the chemical arts. In its concentrated form it is known as otl of vitriol, and is a colorless, heavy liquid, of an oily consistency, and sharp, sour taste. It is manufactured on the large scale by mingling sul- phur dioxide gas, nitric acid gas, and steam, in large lead-lined chambers, the floors of which are covered with water. The sulphur dioxide takes up oxygen from the THE ASH OF PLANTS. 131 nitric acid, and the sulphuric acid thus formed dissolves in the water, and is afterwards boiled down to the proper strength in glass vessels. The chief agricultural application of sulphuric acid is in the preparation of ‘superphosphate of iime,” which is consumed as a fertilizer in immense quantities. This is made by mixing together sulphuric acid, somewhat diluted with water, with bone-dust, bone-ash, or some mineral phosphate. Commercial oil of vitriol is a mix- ture of sulphuric acid with more or less water. The strongest oil of vitriol commonly made, or ‘‘66° acid,” contains 93.5% of H,SO, The so-called ‘60° acid” contains 77.6% U.SO, or 83% of 66° acid. Chamber acid or **51° acid” contains 68.6% H,SO,, or 67% of 66° acid. Sulphuric acid occurs in the free state, though ex- tremely dilute, in certain natural waters, as in the Oak Orchard Acid Spring of Orleans, N. Y., where it is pro- duced by the oxidation of sulphide of iron. Sulphuric acid is very corrosive and destructive to most vegetable and animal matters. EXP. 53.—Stir a little oil of vitriol with a pine stick. The wood is im- mediately browned or blackened, and a portion of it dissolves in the acid, communicating a dark color to the latter. The commercial acid is often brown from contact with straws and chips. Strong sulphurie acid produces great heat when mixed with water, as is done for making superphosphate. EXP. 54.—Place in a thin glass vessel, as a beaker glass, 30 c. c. of water; into this pour in a fine stream 120 grams of oil of vitriol, stirring all the while with a narrow test-tube, containing a teaspoonful of water. If the acid be of full strength, so much heat is thus generated as to boil the water in the stirring tube. In mixing oil of vitriol and water, the acid should always be slowly poured into the water, with stirring, as above directed. When water is added to the acid, it floats upon the latter, or mixes with it but super- ficially, and the liquids may be thrown about by the sudden formation of steam at the points of contact, when subsequently stirred. Sulphuric acid forms with the bases an important class of salts—the sudphates, to be presently noticed—some of which exist in the ash, as well as in the sap of plants. 132 HOW CROPS GROW. When organic matters containing sulphur—as_ hair, albumin, etc.—are burned with full access of air, this element remains in the ash as sulphates, or is partially. dissipated as sulphur dioxide. FHOSPHORUS AND ITS COMPOUNDS. Phosphorus, Sym. P, at. wt. 81, has been sufficiently described (p. %7). Of its numerous compounds but two require additional notice. Phosphorus Pentoxide, Sym. P.0;, mo. wt. 142, does not occur as such in nature. When phosphorus is burned in dry air or oxygen, anhydrous phosphoric acid is the snow-like product (Exp. 18). The term ‘‘ phos- phoric acid,” as now encountered in fertilizer analyses, has reference to ‘‘anhydrous phosphoric acid,” as phos- phorus pentoxide was formerly designated. Phosphorus pentoxide has no sensible acid properties until it has united to water, which it combines with so energetically as to produce a hissing noise from the heat developed. On boiling it with water for some time, it completely dis- solves, and the solution contains— Phosphoric Acid, Sym. H;PO,, 98.—The chief in- terest which this compound has for the agriculturist lies in the fact that the combinations which are formed be- tween it and various bases—phosphates—are among the most important ingredients of plants and their ashes. When organic bodies containing phosphorus, as le- cithin (p. 122), and, perhaps, some of the albuminoids, are decomposed by heat or decay, the phosphorus appears in the ashes or residue, in the condition of phosphoric acid or phosphates. The formation of several phosphates has been shown in Exp. 20. Further account of them will be given under the metals. CHLORINE AND ITS COMPOUNDS. Chlorine, Sym. Cl., aé. wt. 35.5.—This element exists THE ASH OF PLANTS. 133 in the free state as a greenish-yellow, suffocating gas, which has a peculiar odor, and the property of bleaching vegetable colors. It is endowed with the most vigorous affinities for many other elements, and hence is never met with, naturally, in the free state. Exp. 55.—Chlorine may be prepared by heating a mixture of hydio- ehlorie acid and black oxide of manganese or red-lead. The gas being nearly five times as heavy as common air, may be collected in glass bottles by passing the tube which delivers it to the bottom of the re- ceiving vessel. Care must be taken not to inhale it, as it energetically attacks the interior of the breathing passages, producing the disagree- able symptoms of a cold. Chlorine dissolves in water, forming a yellow solution. In some form of combination chlorine is distributed over the whole earth, and is never absent from the plant. The compounds of chlorine are termed chlorides, and may be prepared, in most cases, by simply putting their elements in contact, at ordinary or slightly elevated tem- peratures. HYDROCHLORIC ACID, Sym. HCl, mo. wt. 36.5.—When Chlorine and Hydrogen gases are mingled together, they slowly combine if exposed to diffused light ; but if placed in the sunshine, they unite explosively, and hydrogen chloride or hydrochloric acid is formed. This compound isagas that dissolves with great avidity in water, forming a liquid which has a sharp, sour taste, and possesses all the characters of an acid. The muriatie acid of the apothecary is water holding in solution several hundred times its bulk of hydrochloric acid gas, and is pre- - pared from common salt, whence its ancient name, spirits of salt. Hydrochlorie acid is the usual source of chlorine gas. The latter is evolved from a heated mixture of this acid with black oxide of manga- nese. In this reaction hydrogen of the hydrochloric acid unites with oxygen of the oxide of manganese, producing water, while chloride of manganese and free chlorine are separated. 4 HCl + MnO, = MnCl, + 2H, O+4 2 Cl. When chlorine, dissolved in water, is exposed to the sunlight, there ensues a change the reverse of that just noticed. Water is decom- posed, its oxygen is set free, and hydrochloric acid is formed. H,O + 2 Cl= 2 HCl + O. The two reactions iust noticed are instructive examples of the differ- ent play of affinities between several elements under unlike circum- stances. This acid is a ready means of converting various metals or metallic oxides into chlorides, and its solution in water is a valuable solvent and reagent for the purpose of the chemist. 134 HOW CROPS GROW. IODINE, Sym. I, at. wt. 127.—This interesting body is a black solid at ordinary temperatures, having an odor resembling that of chlorine. Gently heated, it is converted into a violet vapor. It occurs in sea- weeds, and is obtained from their ashes. It gives with starch a blue or purple compound, and is hence employed as a test for that substance (p 49). It is analogous to chlorine in its chemical relations. It is not known to occur in sensible quantity in agricultural plants, although it may well exist in the grasses of salt-bogs, and in the produce of soils which are manured with sea-weed. BROMINE and FLUORINE may also exist in very small quantity in plants, but these elements require no further notice in this treatise. SILICON AND ITS COMPOUNDS. Silicon, Sym. Si, at. wt. 28.—This element, in the free state, is only known to the chemist. It may be pre- pared in three modifications: one, a brown, powdery substance ; another, resembling plambago, and a third, that occurs in crystals, having the form and nearly the hardness of the diamond. Silicon Dioxide, Sym. SiO0., mo. wt. 60.—This com- pound, known also as Silica, is widely diffused in nature, and occurs to an enormous extent in rocks and soils, both in the free state and in combination with other bodies. Free silica exists in nearly all soils, and in many rocks, especially in sandstones and granites, in the form known to mineralogists as quartz. The glassy, white, or trans- parent, often yellowish or red, fragments of common sand, which are hard enough to scratch glass, are almost inva- riably this mineral. In the purest state, it 1s rock-crys- tal. Jasper, flint, aud agate are somewhat less pure silica. Stlicates.—Silica is extremely insoluble in pure water and in most acids. It has, therefore, none of the sensi- ble qualities of acids, but is nevertheless capable of union with bases. It is slowly dissolved by strong, and espe- cially by hot, solutions of potash and soda, forming sol- uble silicates of the alkali metais. EXP. 56.—Formation of potassium silicate. Heat apiece of quartz or flint, as large as a chestnut, as hot as possible in the fire, and quench suddenly in cold water. Reduce it to fine powder in a porcelain mor- tar, and boil it in a porcelain dish with twice its weight of caustic p>*- THE ASH OF PLANTS. 135 ash, and eight or ten times as much water, for two hours, taking care to supply the water as it evaporates. Pour off the whole into a tall narrow bottle, and leave at rest until the undissolved silica has settled. The clear liquid is a basic potassium silicate, i. e., a silicate which con. tains a number of molecules of base for each molecule of silica. It has, in fact, the taste and feelof potash solution. The so-called water- glass, now employed in the arts, is a similar sodium silicate. When silica is strongly heated with potash or soda, or with lime, magnesia, or oxide of iron, it readily melts to- gether and unites with these bodies, though nearly infus- ible by itself, and silicates are the ‘result. The silicates thus formed with potash and soda are soluble in water, like the product of Exp. 56, when the alkali excceds a certain proportion—when highly basic ; but, with silica in excess (acid silicates), they dissolve with diificulty. A mixed silicate of sodium, calcium, and aluminum, with a large proportion of silica, is nearly or altogether insol- uble, not only in water, but in most acids—constitutes, in fact, ordinary glass. A multitude of silicates exist in nature as rocks and minerals. Ordinary clay, common slate, soapstone, mica, or mineral isinglass, feldspar, hornblende, garnet, and other compounds of frequent and abundant occurrence, are silicates. The natural silicates may be roughly dis- tinguished as belonging to two classes, viz., the acid sil- icates (containing a preponderance of silica) and basic stdicates (with large proportion of base). ‘The former are but slowly dissolved or decomposed by acids, while the latter are readily attacked, even by carbon dioxide acid. Many native silicates are anhydrous, or destitute of water; others are hydrous, i. e., they contain water as a large and essential ingredient. The Silicic Acids.—Various silicic acids—compounds of silica with water—are known to the chemist, or are represented by the silicates found in nature. The silicic acids themselves have little stability and are readily re- solved into water and silica. Soluble Silica, 8i(OH),?—This bedy ts Known only in 136 HOW CROPS GROW. solution. It is formed when the solution of an alkali- silicate is decomposed by means of a large excess of some strong acid, like the hydrochloric or sulphuric. Exp. 57.—Dilute half the solution of potassium silicate obtained in Exp. 56 with ten times its volume of water, and add diluted hydrochlorie acid gradually until the liquid tastes sour. In this Exp. the hydrochlo- ric acid decomposes and destroys the potassium silicate, uniting itself to the base with production of chloride of potassium, which dis- solves in the water present. The siliva thus liberated unites chemi- cally with water, and remains also in solution. By appropriate methods Doverl and Graham have obtained solutions of silica in pure water. Graham pre- pared a liquid that gave, when evaporated and heated, 14 per cent of anhydrous silica. ‘This solution was clear, colorless, and not viscid. It reddened litmus-paper like an acid. Though not sour to the taste, it produced a peculiar feeling on the tongue. Evaporated to dryness at alow temperature, it left a transparent, glassy mass, which bad the composition H.SiO;. This dry residue was insoluble in water. These solutions of silica in pure water are incapable of existing for a long time without suffering a remarkable change. Even when protected as much as possible from all external agencies, they sooner or later, usually in a few days or weeks, lose their fluidity and transparency, and coagulate to a stiff jelly, from the separation of a nearly insoluble hydrate of silica, which we shall designate as gelatinous silica. The addition of ;5}55 of an alkali or earthy carbon- ate, or of a few bubbles of carbon dioxide gas to the strong solutions, occasions their immediate gelatinization. A minute quantity of potash or soda, or excess of hydro- chloric acid, prevents their coagulation. Gelatinous Silica.—TVhis substance, which results from the coagulation of the soluble silica just described, usually appears also when the strong solution of a silicate has strong hydrochloric acid added to it, or when a sili- cate is decomposed by direct treatment with a concen- trated acid. THE ASH OF PLANTS. 137 It is a white, opaline, or transparent jelly, which, on drying in the air, becomes a fine, white powder, or forms transparent grains. ‘This powder, if dried at ordinary temperatures, has a composition nearly corresponding to the formula H,8i;0s, or to a compound of 3 SiO, with 2 H,O. - At the temperature of 212° F., it loses half its water. Ata red heat it becomes anhydrous. Gelatinous silica is distinctly, though very shghtly, soluble in water. Fuchs and Bresser have found by ex- periment that 100,000 parts of water dissolve 13 to 14 parts of gelatinous silica. The hydrates of silica which have been subjected to a heat of 212°, or more, appear to be totally insoluble in pure water. These hydrates of silica are readily soluble in solutions of the alkalies and alkali carbonates, and readily unite with moist, slaked lime, forming silicates. EXP. 58.—Gelatinous Silica.—Pour a small portion of the solution of silicate potassium of Exp. 56 into strong hydrochloric acid. Gelatinous silica separates and falls to the bottom, or the whole liquid becomes a transparent jelly. EXP. 59.—Conversion of soluble into insoluble hydrated silica.—Evapo- rate the solution of silica of Exp. 57, which contains free hydrochlorie acid, in a porcelain dish. As it becomes concentrated, it is very likely to gelatinize, as happened in Exp. 58, on account of the removal of the solvent. Evaporate to perfect dryness, finally on a water-bath (i. e., on a vessel of boiling water which is covered by the dish containing the solution). Add to the residue water, which dissolves away the chlo- ride of potassium, and leaves insoluble hydrated silica, 3 SiO, H,O, as a gritty powder. In the ash of plants, silica is usually found in com- bination with alkali-metals or calcium, owing to the high temperature to which it has been subjected. In the plant, however, it exists chiefly, if not entirely, in the free state. TITANIUM, an element which has many analogies with silicon, though rarely occurring in large quantities, is yet often present in the form of Titanic acid, TiO,, in rocks and soils, and, according to Salm-Horst- mar, may exist in the ashes of barley and oats. ARSENIC, in minute quantity, was found by Davy in turnips which had been manured with a fertilizer (superphosphate), in whose prep- aration arsenical oil of vitriol was employed. 138 HOW CROPS GROW. When arsenic, in the form of Paris green or London purple, is applied to land the arsenic soon becomes converted into highly insoluble iron compounds and is not taken up by plants in appreciable quantity. The Metallic Elements which remain to be noticed, viz.: Potassium, Sodium, Calcium, Magnesium, Iron, Manganese, Aluminium, Zinc, and Copper, are basic in their character, i. e., they unite with the acid bodies that have just been described, to produce salts. Each one is, in this sense, the base of a series of saline com- pounds. ALKALI-METALS.—The elements Potassium and Sodium are termed alxali-metals. ‘Their oxides dissolve in and chemically unite to water, forming hydroxides that are called alkalies. ‘The metals themselves do not occur in nature, and can only be prepared by tedious chemical processes. They are silvery-white bodies, and are lighter than water. Exposed to the air, they quickly tarnish from the absorption of oxygen and moisture, and are rapidly converted into the corresponding alkalies. Thrown upon water, they mostly inflame and burn with great violence, decomposing the liquid. Exp. 11. Of the alkali-metals, Potassium is invariably found in all plants. Sodium is especially abundant in marine and strand vegetation ; it is generally found in agricultural plants, but is sometimes present in them in but small quantity. POTASSIUM AND ITS COMPOUNDS. Potassium, Sym. K ;* at. wt. 39.—When heated in the air, this metal burns with a beautiful violet light, and forms potassium oxide. Potassium Oxide, or Potash, K,O, 94, is the so- ealled ‘‘actual potash” that figures in the analyses of plants and valuation of fertilizers. Itis, however, scarcely known as a substance, because it energetically unites with water and forms hydroxide. * ¥rom the Latin name Aalium. THE ASH OF PLANTS. 139 Potassium Hydroxide, KOH, 56, is the caustic potash of the apothecary and chemist. It may be pro- cured in white, opaque masses or sticks, which rapidly absorb moisture and carbonic acid from the air, and readily dissolve in water, forming potash-lye. It strongly corrodes many vegetable and most animal matters, and dissolves fats, forming potash-soaps. Both the oxice and hydroxide of potassium unite to acids forming salts. SODIUM AND ITS COMPOUNDS. Sodium, Na,* 23.—Burns with a brilliant, orange- yellow flame, yielding sodium oxide. Sodium Oxide, or Soda, Na,O, 62, is practically lit- tle known, though constantly referred to as the base of the sodium salts. It unites to water, producing the hy- droxide. Sodium Hydroxide, or Caustic Soda, NaOH, 40.— This body is like caustic potash in appearance and gen- eral characters. It forms soaps with the various fats. While the potash-soaps are usually soft, those made with soda are commonly hard. ALKALI-EARTH Msrtats.—The two metallic elements next to be noticed, viz., Calcium and Magnesium, give, with oxygen, the alkali-earths, lime and magnesia. 'The metals are only procurable by difficult chemical pro- cesses, and from their eminent oxidability are not found in nature. They are but a little heavier than water. Their oxides are but slightly soluble in water. CALCIUM AND ITS COMPOUNDS. Calcium, Ca, 40, is a brilliant ductile metal having a light yellow color. In moist air it rapidly tarnishes and acquires a coating of lime. Calcium Oxide, or Lime, CaO, 56, is the result *From the Latin name Natrium. 140 HOW CROPS GROW. of the oxidation of calcium. It is prepared for use in the arts by subjecting limestone or oyster-sheils to an intense heat, and usually retains the form and much of the hardness of the material from which it is made. It has the bitter taste and corroding properties of the alka- lies, though in a less degree. It is often called quick. lime, to distinguish it from its compound with water. it may occur in the ashes of plants when they have been maintained at a high heat after the volatile matter has been burned away. Calcium Hydroxide, Ca (OH)., 74.—Quick-lime, when exposed to the air, gradually absorbs water and falls to a fine powder. It is then said to be air-slacked. When water is poured upon quick-lime it penetrates the pores of the latter, and shortly the falling to powder of the lime and the development of much heat give evi- dence of chemical union between the lime and the water. This chemical combination is further proved by the in- crease of weight of the lime, 56 Ibs. of quick-lime becom- ing 74 lbs. by water-slacking. On heating slacked lime to redness, water is expelled, and calcium oxide remains. When lime is agitated for some time with much water, and the mixture is allowed to settle, the clear liquid is found to contain a small amount of lime in solution (one part of lime to 700 parts of water). This liquid is called lime-water, and has already been noticed as a test for carbonic acid. Lime-water has the alkaline taste In a marked degree. MAGNESIUM AND ITS COMPOUNDS. Magnesium, Mg, 24.—Metallic magnesium has a sil- ver-white color. When heated in the air it burns with extreme brilliancy (magnesium light), and is converted into magnesia. Magnesium Oxide, or Magnesia, MgO, 40, is found in the drug-stores in the shape of a bulky white powder, THE ASH OF PLANTS. 141 under the name of calcined magnesia. It is prepared by subjecting either magnesium hydroxide, carbonate, or nitrate, to a strong heat. It occurs in the ashes of plants. Magnesium Hydroxide, Mg(OH),, is produced slowly and without heat, when magnesia is mixed with water. It occurs rarely as a transparent, glassy mineral (Brucite) at Texas, Pa., Hoboken, N. J., and a few other places. It readily absorbs carbon dioxide and passes into carbonate of magnesium. Magnesium hydroxide is so slightly soluble in water as to be tasteless. It requires 55,000 times its weight of water for solution (Fresenius). Heavy Merarts.—The two metals remaining to notice are Iron and Manganese. These again considerably re- semble each other, though they differ exceedingly from the metals of the alkalies and alkali-earths. They are about eight times heavier than water. Each of these metals forms two basic oxides, which are commonly insoluble in pure water. IRON AND ITS COMPOUNDS. Iron, Fe,* 56.—The properties of metallic iron are go well known that we need not occupy any space in reca- pitulating them. Ferrous Oxide, or Protoxide of Iron, FeO, 72.— When sulphuric acid in a diluted state is put in contact with metallic iron, hydrogen gas shortly begins to escape in bubbles from the liquid, and the iron dissolves, unit- ing with the acid to form ferrous sulphate, the salt known commonly as copperas or green-vitriol. H,SO,, + Fe = FeSO, + H,. If, now, lime-water or potash-lye be added to the solu- tion of iron thus obtained, a white or greenish white pre- cipitate separates, which is ferrous hydroxide, Fe(OIL)’. *From the Latin name Ferrum. 142 HOW CROPS GROW. This precipitate rapidly absorbs oxyger from the air, be- coming black and finally brown. The anhydrous pro- toxide of iron is black. Carbonate of protoxide of iron is of frequent occurrence as a mineral (spathic iron), and exists dissolved in many mineral waters, especially in the so-called chalybeates. The ferrous salts are mostly white or green. Ferric Oxide, or Peroxide of Iron, Fe,O;, 160.— When ferrous hydroxide is exposed to the air, it acquires a brown color from union with more oxygen, and becomes ferric hydroxide Fe(OH);. The yellow or brown rust which forms on surfaces of metallic iron when exposed to moist air is the same body. Ferric oxide is found in the ashes of all agricultural plants, the other oxides of iron passing into this when exposed to air at high tem- peratures. It is found in immense beds in the earth, and is an important ore (specular iron, hematite). It dissolves in acids, forming the ferric salts, which have a yellow color. ? MAGNETIC OXIDE OF IRON, Fe,0,, or FeO.Fe,03, is a combination of the two oxides above mentioned. It is black, and is strongly at- tracted by the magnet. It constitutes, in fact, the native magnet, or loadstone, and is a valuable ore of iron. MANGANESE AND ITS COMPOUNDS. Manganese, Mn, 55.—Metallic manganese is difficult to procure in the free state, and much resembles iron. Its oxides are analogous to those of iron just noticed. Manganous Oxide, or Protoxide of Manganese, MnO, 71, has an olive-green color. It is the base of all the usually occurring salts of manganese. Its hydrox- ide, prepared by decomposing manganous sulphate by hme-water, is a white substance, which, on exposure to the air, shortly becomes brown and finally black from absorption of oxygen. ‘The manganous salts are mostly pale rose-red in color. MANGANIC OXIDE, Mn,O;, occurs native as the mineral braunite, or, THE ASH OF PLANTS. 143 combined with water, as manganite. Itis asubstance having ared or black-brown color. It dissolves in cold acids, forming salts of an in- tensely red colcr. These are, however, easily decomposed by heat, or by organic bodies, into oxygen and mapganous salts. RED OXIDE OF MANGANESE, Mn;Q,, or MnO. Mn,03.—This oxide re- mains when manganese or any of its other oxides are subjected to a high temperature with access of air. The metal and the protoxide gain oxygen by this treatment, the higher oxides lose oxygen until this compound oxide is formed, which, as its symbol shows, corres- ponds to the magnetic oxide of iron. It is found in the ashes of plants. BLACK OXIDE OF MANGANESE, MnO,.—This body is found extensively in nature. Itis employed in the preparation of oxygen and chicrine (bleaching powder), and is an article of commerce. Some other metals occur as oxides or salts in ashes, though not in such quantity or in such plants as to possess any agricultural signifi- eance in this respect. ALUMINA, AI1,O;, the oxide of the metal Aluminium, is found in eonsiderable quantity (20 to 50 per cent) in the ashes of the ground pine (Lycopodium). Itis united with an organie acid (tartaric, according to 3erzelius ; malic, according to Ritthausen) in the plant itself. It is often found in small quantity in the ashes of agricultural plants, but whether an ingredient of the plant or due to particles of adhering clay is not in all cases clear. ZING has been found in a variety of yellow violet that grows about the zine mines of Aix-la-Chapelle. COPPER is frequently present in minute quantity in the ash of plants, especially of such as grow in the vicinity of manufacturing establish- ments, where dilute solutions containing copper are thrown to waste. The Salts or Compounds of Metals with Non- metals found in the ashes of plants or in the unburned plant remain to be considered. Of the elements, acids and oxides, that have been noticed as constituting the ash of plants, it must be re- marked that with the exception of silica, magnesia, oxide of iron, and oxide of manganese, they all exist in the ash in the form of salts (compounds of acids and bases). In the living agricultural plant it is probable that, of them all, only silica occurs in the uncombined state. We shall notice in the first place the salts which may occur in the ash of plants, and shall consider them under the following heads, viz. : Carbonates, Sulphates, Phos- phates, and Chlorides. As to the Silicates, it is unnec- essary to add anything here to what has been already mentioned. 144 HOW CROPS GROW. THE CARBONATES which occur in the ashes of plants are those of Potassium, Sodium, and Calcium. The Carbonates of Magnesium, [ron, and Manganese are de- composed by the heat at which ashes are prepared. Potassium Carbonate, or Carbonate of Potash, K,COs;, 114.—The pearl-ash of commerce is a tolerably pure form of this salt. When wood is burned, the potash which it contains is found in the ash, chiefly as carbon- ate. If wood-ashes are repeatedly washed or leached with water, all the salts soluble in this liquid are removed ; by boiling this solution down to dryness, which is done in large iron pots, crude potash is obtained, as a dark or brown mass. This, when somewhat purified, yields pearl-ash. Potassium carbonate, when pure, is white, and has a bitter, biting taste—the so-called alkaline taste. It has such attraction for water, that, when exposed to the air, it absorbs moisture and becomes a hquid. If hydrochloric acid be poured upon this carbonate a brisk effervescence immediately takes place, owing to the escape of carbon dioxide gas, and potassium chloride and water are formed, which remain behind. K,CO; + 2 HCl=2 KCl +H,0 + €O,, Potassium Bicarbonate, KHCO;.—A solution of potassium carbonate, when exposed to carbon dioxide, ab- sorbs the latter, and the potassium bicarbonate is pro- duced, so called because to a given amount of potassium it contains twice as much carbonic acid as the carbonate. Potash-saleratus consists essentially of this salt. It probably exists in the juices of various plants. Sodium Carbonate,. or Carbonate of Soda, Na,CO;, 106.—This substance, so important im the arts, was formerly made from the ashes of certain marine plants (Salsola and Salicornia), in a manner similar to that now employed in wooded countries for the prepara- tion of potash. It is at present almost wholly obtained THE ASH OF PLANTS. 145 from common salt by somewhat complicated processes. It occurs in commerce in an impure state under the name of Soda-ash. United to water, it forms sal-soda, which usually exists in transparent crystals or crystallized masses. These contain 63 per cent of water, which partly escapes when the salt is exposed to the air, leay- ing a white, opaque powder. Sodium carbonate has a nauseous alkaline taste, not nearly so decided, however, as that of the carbonate of potassium. It is often present in the ashes of plants. Sodium Bicarbonate, NaHCO;.—The supercarbon- ate of soda of the apothecary is this salt in a nearly pure state. The cooking-soda of commerce is a mixture of this with some simple carbonate. It is prepared in the same way as potassium bicarbonate. The bicarbonates, both of potassium and sodiun, give off half their carbonic acid at a moderate heat, and lose all of this ingredient by contact with excess of any acid. Their use in baking depends upon these facts. They neutralize any acid (lactic or acetic) that is formed during the “rising” of the dough, and assist to make the bread “ light” by in- flating it with carbon dioxide. Calcium Carbonate, or Carbonate of Lime, CaCO;, 112.—This compound is the white powder formed by the contact of carbon dioxide with lime-water. When slacked lime is exposed to the air, the water it contains is gradually displaced by carbon dioxide, and carbonate of lime is the result. Air-slacked lime always contains much carbonate. This salt is distinguished from lime by its being destitute of any alkaline taste. In nature carbonate of lime exists to an immense ex- tent as coral, chalk, marble, and limestone. These rocks, when strongly heated, especially in a current of air, part with carbon dioxide, and quick-lime remains behind. Calcium carbonate occurs largely in the ashes of most 10 146 TOW CROPS GROW. plants, particularly of trees. In the manufacture of potash it remains undissolved, and constitutes a chief part of the residual leached ashes. The calcium carbonate found in the ashes of plants is supposed to come mainly from the decomposition by heat of organic calcium salts (oxalate, tartrate, malate, etc.), which exist in the juices of the vegetable, or are abun- dantly deposited in its tissues in the solid form. Car- bonate of lime itself 1s, however, not an unusual compo- nent of vegetation, being found in the form of minute, rhombic crystals, in the cells of a multitude of plants. THE SULPHATES which we shall notice at length are those of Potassium, Sodium, and Calcium. Sulphate of Magnesium is well known as Epsom salts, and Sulphate of Iron is copperas or green vitriol. Potassium Sulphate, or Sulphate of Potash, K,SO,, 174.—This salt may be procured by dissolving potash or carbonate of petash in diluted sulphuric acid. On evaporating its solution, it is obtained in the form of hard, brilliant crystals, or as a white powder. It has a bitter taste. Ordinary potash, or pearl-ash, contains several per cent of this salt. Sodium Sulphate, or Sulphate of Soda, Na.SQ,, 142.— Glauber’s salt is the common name of this famil- jar substance. It has a bitter taste, and is much em- ployed as a purgative for cattle and horses. It exists, either crystallized and transparent, containing 10 mole- cules, or nearly 56 per cent of water, or anhydrous. The crystals rapidly lose their water when exposed to the air, and yield the anhydrous salt as a white powder. Calcium Sulphate, or Sulphate of Lime, CaSQ,, 136.—The burned Plaster of Paris of commerce is this salt in a more or less pure state. It is readily formed by pouring diluted sulphuric acid on lime or marble. It is found in the ash of most plants, especially in that of clover, the bean, and other legumes. THE ASH OF PLANTS. 14% In nature, sulphate of lime is usually combined with two molecules of water, and thus constitutes Gypsum, CaSO,.2 H.0, which is a rock of frequent and exten- sive occurrence. In the cells of many plants, as for instance the bean, gypsum may be discovered by the microscope in the shape of minute crystals. It requires 400 times its weight of water to dissolve it, and being almost universally distributed in the soil, is rarely absent from the water of wells and springs. Land plaster is ground gypsum, that from Nova Scotia being white, that from Onondaga and other local- ities in New York State gray in color. THE PHospHaTes which require special description are those of Potassium, Sodium, and Calcium. Numerous phosphates of each of these bases exist, or may be prepared artificially. But three classes of phos- phates have any immediate interest to the agriculturist. As has been stated (p 132), phosphoric acid, prepared by boiling phosphorus pentoxide with water, is represented by the symbol H,PO,. The phosphates may be regarded as phosphoric acid in which one, two, or all the atoms of hydrogen are substituted by one or several metals. Potassium Phosphates or Phosphates of Potash. —There are three of these phosphates formed by replac- ing one, two, or three hydrogen atoms of phosphoric acid by potassium, viz.: KH,PO,, primary or mono- potassic phosphate; K,HPO,, secondary or dipotassic phosphate, and K;PQ,, tertiary or tripotassic phos- phate.* Of these salts, the secondary and tertiary phos- phates exist largely (to the extent of 40 to 50 per cent) ip the ash of the kernels of wheat, rye, maize, and other bread grains. The potassium phosphates do not occur in commerce ; they closely resemble the corresponding sodium-salts in their external characters. *The primary phosphates are often designated acid or super-phos- phates, the secondary neutral phosphates, and the tertiary basic phos- phates. 148 TLOW CROPS GROW. Sodium Phosphates, or Phosphates of Soda.— Of these the disodic phosphate, Na.UPO,, alone needs notice. It is found in the drug-stores in the form of glassy crystals, which contain 12 molecules (56 per cent) of water. The crystals become opaque if exposed to the air, from the loss of water. This salt has a cooling, sa-. line taste, and is very soluble in water. Calcium Phosphates, or Phosphates of Lime. —Since one atom of calcium replaces two of hydrogen, the formule of the calcium phosphates are written as follows : monocalcic or primary phosphate Call,P.0s 5 dicalcic or secondary phosphate, CallPO, ; tricalcie or tertiary phosphate, CagzP,0,.* Both the secondary and tertiary phosphates probably occur in plants. The sec- ondary is a white crystalline powder, nearly insoluble in water, but easily soluble in acids. In nature it is found as a urinary conerction in the sturgeon of the Cas- pian Sea. It is also an ingredient of guanos, and proba- bly of animal excrements in general. The tricalcic phosphate, or, as it is sometimes termed, bone-phosphate, is achief ingredient of the bones of ani- ~ mals, and constitutes 90 to 95 per cent of the ash or earth of bones. It may be formed by adding a solution of lime to one of sodium phosphate, and appears as a white precipitate. It is insoluble in pure water, but dis- solves in acids and in solutions of many salts. In the mineral kingdom tricalcic phosphate is the chief ingre- dient of apatite and phosphorite. These minerals are employed in the preparation of the commercial swper- phosphates now consumed to an enormous extent as a fertilizer. Plain superphosphate is essentially a mixture of sulphate of lime with the three phosphates above no- ticed a1.d with free phosphoric acid. The Phosphates of Magnesium, Iron, Alumin- ium and Manganese, are bodies insoluble in water, *These formule correspond to 2 molecules of phosphoric acid, =H,P,0,, with 2 and 4 H-atoms replaced by Ca. THE ASH: OF PLANTS. 149 that occur in very small proportion in the ashes of plants and in soils, but are important ingredients of some fertilizers. THE CHLORIDES are all characterized by their ready solubility in water. The Chlorides of Calcium and Mag- nesium are deliquescent, 1. e., they liquefy by absorbing moisture from the air. The Chlorides of Potassium and Sodium alone need to be described. Potassium Chloride, or Muriate of Potash, KCl, 74.5.—This body may be produced either by expos- ing metallic potassium to chlorine gas, in which case the two elements unite together directly ; or by dissolving caustic potash in hydrochloric acid. In the latter case water is also formed, as is expressed by the equation KIO + HC] = KCl + Io. Potassium chloride closely resembles common salt in appearance, solubility in water, taste, etc. Itis now an important article of commerce and largely consumed as a fertilizer. It is also often present in the ash and in the juices of plants, especially of sea-weeds, and is like- wise found in most fertile soils. Chloride of Sodium, NaCl, 58.5.—This substance is common or culinary salt. It was formerly termed muri- ate of soda. It is scarcely necessary to speak of its oc- currence in immense quantities in the water of the ocean, in saline springs, and in the solid form as rock-salt, in the eartn. Its properties are so familiar as to require no description. It is rarely absent from the ash of plants. Besides the salts and compounds just described, there occur in the living plant other substances, most of which have been indeed already alluded to, but may be noticed again connectedly in this place. These compounds, being destructible by heat, do not appear in the analysis of the ash of a plant. Nitrates.—Mitric acid (the compound by which ni- trogen is chiefly furnished to plants for the elaboration 150 TOW CROPS GROW. of the albumiaoid principles) is not unfrequently pres- ent as a nitrate in the tissues of the plant. It usually occurs there as potassium nitrate (uniter, saltpeter), KNOs;. The properties of this salt scarcely need description. It is a white, crystalline body, readily soluble in water, und has a cooling, saline taste. When heated with car- bonaceous matters, it yields oxygen to them, and a defla- gration, or rapid and explosive combustion, results. Touch-paper is paper soaked in solution of niter and dried. ‘The leaves of the sugar-beet, sunflower, tobacco, and some other plants, frequently contain this salt, and, when burned, the nitric acid is decomposed, often with slight deflagration, or glowing like touch-paper, and the alkali remains in the ash as carbonate. The characters of nitric acid and the nitrates are noticed at length in “‘Tow Crops Feed.” Seealsop . OXALATES, CITRATES, MALATES, TARTRATES, and salts of other less common organic acids, are gencrally to be found in the tissues of living plants. On burning, the metals with which they were in combination—potassium and calcium, in most cases—remain as carbonates. Ammonium Salts exist in minute amount in some plants. What particular salts thus occur is uncertain, and special notice of them is unnecessary in this chapter. Since it is possible for each of the acids above described to unite with each of the bases in one or several propor- tions, and since we have as many oxides and chlorides as there are metals, and.even more, the question at once arises—which of the 60 or more compounds that may thus be formed outside the plant do actually exist within it ? In answer, we must remark that while most or all of them may exist in the plant but few have been proved to exist as such in the vegetable organism. As to the state in which iron and manganese occur, we know little or noth- ing, and we cannot always assert positively that ina given THE ASH OF PLANTS. 151 plant potassium exists as phosphate, or sulphate, or car- bonate. We judge, indeed, from the predominauce of potassium and phosphoric acid in the ash of wheat, that potassium phosphate is a large constituent of this grain, but of this we are scarcely certain, though in the absence of evidence to the contrary we are warranted in assuming these two ingredients to be united. On the other hand, caleium carbonate and calcium sulphate have been discov- ered by the microscooe in the cells of various plants, in crystals whose characters are unmistakable. For most purposes it is unnecessary to know more than that certain elements are present, without paying atten- tion to their mode ot combination. And yet there is choice in the manner of representing the composition of a plant as regards its ash-ingredients. We do not indeed so commonly speak of the calcium or the silicon in the plantas of lime and silica, because these rarely-seen elements are much less familiar than their oxides. Again, we do not speak of the sulphates or chlorides, when we desire to make statements which may be com- pared together, because, as has just been remarked, we cannot always, nor often, say what sulphates or what chlorides are present. In the paragraphs that follow, which are devoted to a more particular statement of the mode of occurrence, rel- alive abundance, special functions, and tndispensability of the fixed ingredients of plants, will be indicated the customary methods of detining them. § 2. QUANTITY, DISTRIBUTION, AND VARIATIONS OF THE ASH- INGREDIENTS. The Ash of plants consists of the various acids, oxides, and salts, that have been noticed in § 1, which are fixed or non-volatile at a heat near redness. 152 HOW CROPS GROW. Ash-ingredients are always present in each cell of every plant. | The ash-ingredients exist partly in the cell-wall, in- crusted or imbedded in the cellulose, and partly in the plasma or contents of the cell (see p 249). One portion of the ash-ingredients is soluble in water, and occurs in the juice or sap. ‘This is true, in general, of the saits of the alkali-metals, and of the sulphates and chlorides of magnesium and calcium. Another portion is insoluble, and exists in the tissues of the plant in the solid form. Silica, the calcium phosphates and the mav- hesium compounds, are mostly insoluble. The ash-ingredients may be separated from the volatile matter by burning or by any process of oxidation. In burning, portions of sulphur, chlorine, alkalies, and phos- phorus may be lost, under certain circumstances, by vola- tilization. ‘The ash remains as a skeleton of the plant, and often actually retains and exhibits the microscopic form of the tissues. The Proportion of Ash is not Invariable, even ir the same kind of plant, and in the same part of the plant. Different kinds of plants often manifest very marked dif- ferences in the quantity of ash they contain. ‘The fol- lowing table exhibits the amount of ash in 100 parts (of dry matter) of a number of plants and trees, and in their several parts. In most cases is given an average proportion as deduced froma large number of the most trustworthy cxaminations. In some instances are cited the extreme proportions hitherto put on record. PROPORTIONS OF ASH IN VARIOUS VEGETABLE MATTERS.* ENTIRE PLANTS, ROOTS EXCEPTED. Average. Average. RCL AGO IGT 3 /. ale el sists a ciavele si storemeverte 6.7 | Lurnips,’ 10:7—19. 7.2. ave cise ses WPAN Us 9 VON | AREA rs ee ee TOS aa G2, | Carroty: 15:0—21.3) 55.900 ten eel geal: PLUHINDOMAON Gare keys inie te asc ajo eieieeimteee ta Rel | FLOODS eitierwie > sie a «i ayepeloteeee ese tee eee a POURCOCRI werk! okie c)s sew cine teenie cee Eee) ERG TINIE ee ieies Sicies © cele bere eee 4.6 SuUgaARIDeSb;, 16.3—18.6 wisi Si esc | aN ey ote sis csv) « «le susie pire el she epee 4.3 Field beet, 14.0—21.8.......2....-% 18.2) VELOC aGTIIEES oo ek is. ide oleh pee eee 4.5 *These figures are copied unchanged from the old edition, and may differ from later averages, but are approximately correct. THE ASH OF PLANTS. 153 ROOTS AND TUBERS. FOGAGOES, 2.6—8.0. 5... s0d secs veh Ae Ue 5 G20—209Ee pe pace rce e's. POLO SUgA DESL, 2-9—C0eeas er oc ee Sf « 4 | Carrots dL se ee ciate act eia ere 8.2 HIeldsOeeh, 2-81 seats rote. i= viduals may differ enormously in their relative propor- tions of foliage, stem, chaff, and seed; but the seeds themselves nearly agree. Thus, in the analysis of 67 specimens of the wheat kernel, collated by the author, the extreme percentages of ash were 1.35 and 3.13. In 60 specimens out of the 67, the range of variation fell between 1.4 and 2.3 per cent. In 42 the range was from 1.7 to 2.1 per cent, while the average of the whole was aL. per ¢eent. In the stems or straw of the grains, the variation 1s THE ASH OF PLANTS. 159 much more considerable. Wheat-straw ranges from 3.8 to 6.9 ; pea-straw, from 6.5 to 9.4 per cent. In fleshy roots, the variations are great ; thus turnips range from 6 to 21 per cent. The extremest variations in ash-con- tent are, however, found, in general, in the succulent foliage. Turnip tops range from 10.7 to 19.75; potato tops vary from 11 to near 20, and tobacco from 19 to 27 per cent. Wolff (Die Naturgesetzlichen Grundlagen des Acker- baus, 3 Autl., p. 117) has deduced from a large number of analyses the following averages for three important classes of agricultural plants, viz. : Grain. Straw. SPLCOILEEODS : sos) skiestwaedo cas oie ie8 2 per cent. 5.25 per cent. MESUIMINOUS CLOPS. 2. .cees 220. ce0 ay wee J: 5 es cs OMS VAMEG se cciaa cis eos veces ela tieices Ame Se 6 ABN es oe More general averages are as follows (Wolff, loc. cit.) : Annual and biennial plants. Perennial plants. SGGCK ca goaeoousscea see ane Sipe |[SEOCS spoocognocconascnoe 3 per cent. SISTING 55 Boca eno ueaponade De eS tS IWiQOGI ei iere ra tacravetiateleieis ic) 278 i Nee A oe ah TRAY Sven Sens peaeto Gam gOreDe As Soa a ice eel Eason onouotesesoosc (ie eee EVES to atelvejccre sis 8.6 © ovals 1h 8 Le DCE MME bac se os ootOndusdas 108 Ses We may conclude this section by stating three propo- sitions which are proved in part by the facts that have been already presented, and which are a summing up of the most important points in our knowledge of this sub- ject. 1. Ash-ingredients are indispensable to the life and growth of all plants. In mold, yeast, and other plants of the simplest kind, as well as in those of the higher or- ders, analysis never fails to recognize a proportion of fixed matters. We must hence conclude that these are necessary to the primary acts of vegetation, that atmos- pheric food cannot be assimilated, that vegetable matter cannot be organized, except with the codperation of those substances which are invariably found in the ashes of the plant. This proposition is demonstrated in the most conclusive manner by numerous synthetic experiments. 160 HOW CROPS GROW. It is, of course, impossible to attempt producing a plant at all without some ash-ingredients, for the latter are present in all seeds, and during germination are trans- ferred to the seedling. By causing seeds to sprout in a totally insoluble medinm, we can observe what happens when the limited supply of fixed matters in the seeds them- selves is exhausted. Wiegmann & Polstorf (Preisschrift diber dieunorganischen Bestandthetle der Pflanzen) plant- ed 30 seeds of cress in fine platinum wire contained in a platinum vessel. The contents of the vessel were moist- ened with distilled water, and the whole was placed under a glass shade, which served to shield from dust. Through an aperture in the shade, connection was made with a gas- ometer, by which the atmosphere in the interior could be renewed with an artificial mixture, consisting, in 100, of 21 parts oxygen, 78 parts nitrogen, and 1 part carbonic acid. In two days 28 of the seeds germinated ; afterwards they developed leaves, and grew slowly with a healthy ap- pearance during 26 days, reaching a height of two or three inches. From this time on, they refused to grow, began to turn yellow, and died down. The plants were collected and burned ; the ash from them weighed pre- cisely as much as that obtained by burning 28 seeds like those originally sown. ‘This experiment demonstrates ‘most conclusively that a plant cannot grow in the absence of those substances found in its ash. The development of the cresses ceased so soon as the fixed matters of the seed had served their utmost in assisting the organization of new cells. We know from other experiments that, had the ashes of cress been applied to the plants in the above experiment, just as they exhibited signs of unhealthiness, they would have recovered, and developed to a much great- er extent. II. The proportion of ash-ingredients in the plant 3s variable within a narrow range, but cannot fall below or exceed certain limits. The evidence of this proposition THE ASH OF PLANTS. 161 is to be gathered both from the table of ash-percentages and from experiments like that of Wiegmann & Polstorf, above described. III. We have reason to believe that each part or organ (each cell) of the plant contains a certain, nearly invaria- ble, amount of fixed matters, which is indispensable to the vegetative functions. Hach part or organ may contain, besides, a variable and unessential or accidental quantity of thesame. What portion of the ash of any plant is es- sential and what accidental is a question not yet brought to asatisfactory decision. By assuming the truth of this proposition, we account for those variations in the amount of ash which cannot be attributed to the causes already noticed. The evidences of this statement must be reserved for the subsequent section. § 3. SPECIAL COMPOSITION OF THE ASH OF AGRICULTURAL PLANTS. The result of the extended inquiries which have been made into the subject of this section may be convenient- ly presented and discussed under a series of propositions, V1Z.: 1. Among the substances which have been described (§ 1) as the ingredients of the ash, the following are in- variably present in all agricultural plants, and in nearly all parts of them, viz.: ( Potash, K,O. Chlorine, Cl. Soda, Na,O. Sulphuric¢ acid, SO.. Bases < Lime, Cao. Acids < Phosphoric acid, P,O;. | Magnesia, MgO. Silicic acid, SiO,. ~ Oxide of iron, Fe,O.. Carbonic acid, CO,. 2. Different normal specimens of the same kind of plant have a nearly constant composition. The use of the word nearly in the above statement implies what has been already intimated, viz., that some variation is noticed in the relative proportions as well as in the total quantity dk 162 HOW CROPS GROW. of ash-ingredients occurring in plants. This point will shortly be discussed in full. By taking the average of many trustworthy ash-analyses we arrive ata result which does not differ very widely from the majority of the in- dividual analyses. ‘This is especially true of the seeds of plants, which attain nearly the same development under all ordinary circumstances. It is less true of foliage and roots, whose dimensions and character vary to a great extent. In the following tables (p. 164-170) is stated the composition of the ashes of a number of agricultural products which have been repeatedly subjected to analy- sis. In most cases, instead of quoting all the individual analyses, a series of averages is given. Of these, the first is the mean of all the analyses on record or obtainable by the writer,* while the subsequent ones represent either the results obtained in the examination of a number of samples by one analyst, or are the means of several single analyses. In this way, it is believed, the real variations of composition are pretty truly exhibited, independently of the errors of analysis. The lowest and highest percentages are likewise given. These are doubtless in many cases exaggerated by errors of analysis, or by impurity of the material analyzed. Chlo- rine and sulphuric acid are for the most part too low, be- cause they are liable to be dissipated in combustion, while silica is often too high, from the fact cf sand and soil ad- hering to the plant. In two cases, single and doubtless incorrect analyses by Bichon, which give exceptionally large quantities of soda, are cited separately. A number of analyses that came to notice after making out the averages are given as additional. * At the time of preparing the first edition of this book, in 1868. More recent analyses are comparatively few in number, excepting those of wheat (grain and straw) by Lawes & Gilbert, and do not differ essen- tially from those given. The numerous very incorrect ash-analyses, ‘published by Dr. E. Emmons and Dr. J. H. Salisbury, in the Natural History of New York, and in the Trans. of the New York State Agricul- tural Society, are not included. THE ASH OF PLANTS. 163 The following table includes both the kernel and straw of Wheat, Rye, Barley, Oats, Maize, Rice, Buckwheat, Beans, and Peas ; the tubers of Potatoes; the roots and tops of Sugar-Beets, Field-Beets, Carrots, Turnips, and various parts of the Cotton Plant. For the average compositicn of other plants and yego- table products, the reader is referred to a table in the ap- pendix, p. 409, compiled by Prof. Wolff, of the Royal Agricultural Academy of Wirtemberg. That table in- cludes also the averages obtained by Prof. Wolff for most of the substances, cotton excepted, whose composition is represented in the pages immediately following. In both tables the carbonic acid, CO*, which occurs in most ashes, is excluded, from the fact that its quantity aries according to the temperature at which the ash is prepared. The following is a statement of the various Names and Symbols that are or have been currently applied to the Ash-Ingredients in Chemical Literature. The changes that have been made from time to time, both in symbols and in names, are the results of progress in knowledge or of attempts to improve nomenclature : Oller Nemer Sy nbols. Symbols. Synonyms. KO K,O Potash, Potassa, Potassium Oxide, Potassie Oxide. Nao Na,O Soda, Sodium Oxide, Sodie Oxide. MeO MgO Magnesia, Magnesium Oxide, Magnesie Oxide. CaO CaO Lime, Calcium Oxide, Caleie Oxide. Fe,0. Fe,0; Iron Oxide, Peroxide of Iron, Sesquioxide of Iron, Ferric Oxide. PO; P.O; Phosphoric Acid, Anhydrous Phosphorie Acid, Phosphoric Anhydide, Phosphorus Pentox- ide, Phosphoric Oxide. SOs SO, Sulphurie Acid, Anhydrous Sulphurie Acid, Sul- phurie Anhydride, Sulphur Trioxide, Sul- phuric Oxide. SiO. SiO, Silicie Acid, Anhydrous Silicie Acid, Silicie An- hydride, Silicon Dioxide, Silicie Oxide, Silica Silex. CO, CO, Carbonie Acid, Anhydrous Carbonic Acid, Car- ’ bonie Anhydride, Carbon Dioxide, Carbcuie Dicxide. 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OLE SdOL LOUUVO ” 2 ” JSOULSTH || 3'L 9°¢ €°8 o'6 e's Q8G: | SCL | Sle | Cae) ee ‘sosATRUy f UL oSRIWIDIOd YSOMOT!! 3'Z Gar OF #9 HAG SL | OTL | Cor | orsh ¢°9OT ~ Aq SosATBUY F JO oSRIBAV| LF G's G9 9'L eT VOU Se | SSE | Sa 4- ee SadOL LAAd-Uuvons phy | ploy | | Paar > | SV OULL | WOaAT RESO soe |S eee con; y| VOHTS jolmid | orroyd] , “cy |OMUTT | Soy | VPOS| - jo ||-Orto | -ing | “Sora, | °PF*0 | Sv | tod | ee [panwu0)|—)LA ‘SLOAGOYd AGNV SINWTd IWHOLTAOTYDV AWOS AO HSV AHL fO NOILISOdNOO THE ASH OF PLANTS. 171 The composition of the dsh of a number of ordinary crops is concisely cxhibited in the subjoined general state- ment. Maq- 5 *OSDROT= casas S’ Lr= . Atatios ‘noma. Lime. yp Ge! Silica. io dota, Chlorine. CEREALS— Gram*s... 30 12 3 46 2 2.5 1 Straw... 13—27 3 v6 5 50—70 2.) 2, LEGUMES— Kernel... 44 i( 5 30 1 4 2 Straw... 27—41 7( 25—39 8 5 2—6 6—T RooTr CROPS— RGOUs...-: - 60 3—9 6—12 8—-18 1—+4 5—12 3—9I TOPS si 37 38—16 10—85 3—8 3 6—13 5—17 GRASSES— In flower.. 33 + 8 8 35 4 5 3. Different parts of any plant usually exhibit decided differences in the composition of their ash. This fact is made evident by a comparison of the figures of the table above, and is more fully illustrated by the following anal- yses of the parts of the mature oat-plant, by Arendt, 1 to 6 (Die Haferrflanze, p. 107), and Nerton, 7 to9 (Am. Jour. Ser., 2 Ser. 3, 318). 1 2 3 + 5 6 i 8 9 Lower Middle Uprer Lower Upper Ears. Chaff. Ilusk. Kernel Stem. Stem. Stem. L aves. Leaves. husked. Rds orsieveraye) dreis.aves 81.2 68.3 55.9 86.9 24.8 13.0 Soa 2 ee Pst o's Ce a FT te OA Od 10.06 12.4 31-7 Maonesia :.....-+ 2.1 3.6 3.9 3.8 3.9 8.9 | 2.3 8.6 WONG eY ote. cacy Sion 26. ..'53 S65. Test. 17-2 73 44. 43 5.3 Oxide of Iron.... 1.0 0.0 0.2 Zot 0.5 eae ig 0.3 0.8 Phosphorie¢ acid. 2.7 1c: Dall Merl IDS) 30-0 O:Ge 4 95T eb ourLe acid.. 0.0 1.3 Mei 3.2 Uc 4.9). Ds3 4.3 0.0 POUL ch eiakeiev eres s)nias 4.1 9.3 20.4 34.0 41.8 26.0 68.0 74.1 1.8 CHTOPRING sa: - a. rie 8.6 Divs 7.4 1.6 2.4 3.8 3.1 1.4 0.2 The results of Arendt and Norton are not in all respects strictly com- parable, having been obtained by different methods, but serve well to establish the fact in question. We sce from the above figures that the ash of the lower stem consists chiefly of potash (81%). This alkali is pre- dominant throughout the stem, bit in the upper parts, where the stem is not covered by the leaf sheaths, silica and lime oceur in large quantity. In the ash oi the leaves, silica, potash, and lime are the principal ingredients. In the chaff and husk, silica constitutes three-fourths of the ash, while in the grain, phosphoric acid appears as the char- *Exclusive of husk. 172 HOW CROPS GROW. acteristic ingredient, existing there in connection with a large amount of potash (52%) and considerable magne- sia. Chlorine acquires its maximum (11.7%) in the mid- dle stem, but in the kernel is present in small quantity, while sulphuric acid is totally wanting in the lower stem, and most abundant in the upper leaves. Again, the unequal distribution of the ingredients of the ash is exhibited in the leaves of the sugar-beet, which have been investigated by Bretschneider ( Hoff. Jahresbe- richt, 4, 89). This experimenter divided the leaves of 6 sugar-beets into 5 series or circles, proceeding from the outer and older leaves inward. He examined each series separately with the following results: Lt, he te IV. Vv. IPOLASING weil TORII OTE 18.7 25.9 32.8 37.4 50.3 Sodave ees ese ates 15.2 14.4 15.8 T5y(0; 4 lila! Chloride of Sodium.... 5.8 6.4 5.8 6.0 6.5 MATING SE s.Srevs he wie aisle. Bava wteness 24.2 19.2 18.2 15.8 4.7 Maem Sider et stanislpericee 24.5 22.3 13.0 8.9 6.7 Oxide Of Irons. see 2 oe = 1.4 0.5 0.6 0.6 0.5 Phosphoric acid........ sea 4.8 5.8 $4 Jag Sullplniwre acu! ey.) 5.4 5.6 5.6 5.2 5.9 SUG A i aswelts side ak jas ne 1.5 0.8 2.7 2.1 1.5 From these data we perceive that in the ash of the leaves of the sugar-beet, potash and phosphoric acid regularly and rapidly increase in relation to the other ingredients from without inward, while lime and magnesia as rapidly diminish in the same direction. The per cent of the other ingredients, viz., soda, chlorine, oxide of iron, sulphuric acid, and silica, remains nearly invariable throughout. Another illustration is furnished by the following anal- yes of the ashes of the various parts of the horse-chestnut tree made by Wolff (Ackerbau, 2. Auf., 134): Bak. Wood. Leaf-stems. Leaves. Fiower-stems. Calyx. IEC UEIS Wore apis ad eacor 12e 2b, 46.2 27.9 63.6 61.7 AM SH sir sic) rae cok tse ee NOLO! THAD 21.7 29.3 9.3 12.3 INTAIO MI CSAS: dss jc hiths,« cterercteces Mer 5.0 3.0 2.6 a Us) 5.9 sulphuric acid....... trace trace 3.8 oF 3.5 trace Phosphoric acid.....:. 6.0 19:2 14.8 22.4 ffolt 16.6 SUMING Aiscisie sss estate Aceon Vel 2.6 1.0 4.9 0.7 lat GVOTATIC Hirata. se eee 6.1 12.2 5.1 4.7 2.4 THE ASH OF PLANTS. ie Ripe Fruit. (a Stamens. Petals. Green Fruit. Kernel. Green Brown Shell. Shell. MQUASING oo. s cis serstee 60.7 61.2 58.7 61.7 75.9 54.6 WANG. «2555's shasietsiovass 3 13.8 13.6 9.8 11.5 8.6 16.4 WACIMES Lassen la es Ss 3.1 3.8 2.4 0.6 1a 2.4 Sulphuric acid....trace trace 3.7 leg 1.0 3.6 Phosphoric acid...19.5 17.0 20.8 22.8 5.3 18.6 SHITE? homoge ec Se aeaaee 0.7 1.5 0.9 0.2 0.6 0.8 WNT OTN secre :cis « << « 2.8 3°8 4.8 2.0 7.6 5.2 4, Similar kinds of plants, and especially the same parts of similar plants, exhibit a close general agreement in the composition of their ashes; while plants which are un- like in their botanical characters are also unlike in the proportions of their fixed ingredients. The three plants, wheat, rye, and maize, belong, botan- ically speaking, to the same natural order, graminee, and the ripe kernels yield ashes almost identical in composi- tion. Barley and the oat are also graminaceous plants, and their seeds should give ashes of similar composition. That such is not the case is chiefly due to the fact, that, unlike the wheat, rye, and maize-kernel, the grains of barley and oats are closely invested with a husk, which forms a part of the kernel as ordinarily seen. This husk yields an ash which is rich in silica, and we can only prop- erly compare barley and oats with wheat and rye, when the former are hulled, or the ash of the hulls is taken out of the account. There are varieties of both oats and bar- ley, whose husks separate from the kernel—the so-called naked or skinless oats and naked or skinless barley—and the ashes of these grains agree quite nearly in composi- tion with those of wheat, rye, and maize, as may be seen from the table on page 174. By reference to the table (p. 166), it will be observed that the pea and bean kernel, together with the allied vetch and lentil (p. 171), also nearly agree in ash-com- position. So, too, the ashes of the root-crops, turnips, carrots, 174 HOW CROPS GROW. and beets, exhibit a general similarity of composition, as may be seen in the table (p. 168-9). Wheat. hye. Maize. Skinless Shinles Averase Average Average oats. barleys. of of mi Analysis Analysis seventy-nine twenty-one seven by Fr. by Fr. Analyses. Analyses. Analyses. Sc ulze. Schulze. IP OCASH els Be ae ce ee eeiarets 31.3 28.8 27.7 33.4 35.9 SOC: Boteelaeine ee he aes 34 4.3 4.0 — 1.0 Nib Wena horot 6dé ooo oa5c 12.3 11.6 15.0 11.8 13.7 ANIC hecoasicke Ae eche'srore ees 3.2 3.9 1.9 3.6 2.9 OxTdewOmiromcs: 23.2 ssc 0.7 0.8 1.0 0.8 0.7 Phosphorie acid....... 46.1 45.6 47.1 46.9 45.0 Sul pie ea Cues. ce «1. We ie il sf — sens SUbKCC Baas 8 (Seeman Wes) 2.6 2.1 2.4 0.7 Chlorine seers ses. 0.2 0.7 0.1 a oe The seeds of the oil-bearing plants likewise constitute a group whose members agree in this respect (p. 170). 5. The ash of the same species of plant is more or less variable in composition, according to circumstances. The conditions that have already been noticed as in- fluencing the proportion of ash are in general the same je affect its quality. Of these we may specially notice : : . The stage of growth of the plant. i The vigor of its development. The variety of the plant or the relative development of its parts, and d. The soil er the supplies of food. a. The stage of growth. 'The facts that the different parts of a plant yield ashes of different composition, and that the different stages of growth are marked by the development of new organs or the unequal expansion of those already formed, are sufficient to sustain the point now in question, and render it needless to cite analytical evidence. Ina subsequent chapter, wherein we shall at- tempt to trace some of the various steps in the progress- ive development of the plant, numerous illustrations will be adduced (p. 241). b. Vigor of development. Arendt (die Haferpflanze, p- 18) selected from an oat-field a number of plants in blossom, and divided them into three parcels: 1, com- THE ASH OF PLANTS. ive posed of very vigorous plants ; 2, of medium ; and, 3, of very weak plants. ie analyzed the ashes of cach parcel, with results as below : 1 2 3 PUT Citererctetarsetausrttl «ays, 3 osrereik ecialeats 27.0 39.9 42.0 SUL PHUGUCRACTOR Rae sit. ine ee 4.8 4.1 5.6 PHOSPHORIC TACIA re ai. se 3-0 One 8.5 8.8 WINOPIVE ce eierticcraas clei acess 6.7 5.8 4.7 Oscieles OFS lrOninecrtee:-) 7s aes 0.4 0.5 1.0 PUAN Petes ees eich statys Mieratese/0, aero 6.1 5.4 5.1 Magnesia, Potash and Soda.45.3 34.3 30.4 Here we notice that the ash of the weak plants con- tains 15 per cent less of alkalies, and 15 per cent more of silica, than that of the vigorous ones, while the propor- tion of the other ingredients is not greatly different. ‘ Zoeller (Liebig’s Hrnihrung der Vegetabilien, p. 340) examined the ash of two specimens of clover which grew on the same soil and under similar circumstances, save that one, from being shaded by a tree, was less fully de- veloped than the other. — Six weeks after the sowing of the sced, the clover was cut, and gave the following results on partial analysis : Shadcd clover. Unshaded clover. AIO ATES: siasiek.s ccPocoyan es O4tO 36.2 | GAL ORE See ee eRe Rt ok eae 14.2 22.8 Sil aascne see cee see 5.5 12.4 ce. The variety of the plant or the relative development of tts parts must obviously influence the composition of the ash taken as a whole, since the parts themselves ar unlike in composition. Herapath (Qu. Jour. Chem. Soe., Il, p. 20) analyzed the ashes of the tubers of five varieties of potatoes, raised on the same soil and under preciscly similar cireum- stances. Ilis results are as follows: White Prince’s Arbrirge Apple. Beauty. Kidney. Magpie. Forty-fold. NOGA Ns wore, Sole © siecereveiere aig 69.7 65.2 70.6 70.0 2.1 Chloride of Sodium ..— — — pa) USAIN Gs Seatens tose'cre = «Freud. ete sl ov 3.0 1.8 5.0 5.0 oo IMI STAG «230 se ois cle ole 6.5 5.5 5.0 2.1 3.5 Phosphorie acid....., 17.2 20.8 14.9 14.4 20.7 Sulphuric acid.......: 3.6 6.0 4.3 7.5 ED PMT CA areayc'> xine s to eerelaiatns ae ee 0.2 176 HOW CROPS GROW. d. The sowl, or the supplies of food, manures included, have the greatest influence in varying the proportions of the ash-ingredients of the plant. It is to a considerable degree the character of the soil which determines the vigor of the plant and the relative development of its parts. This condition, then, to a certain extent, in- cludes those already noticed. It is well known that oats have a great range of weight per bushel, being nearly twice as heavy, when grown on rich land, as when gathered from a sandy, inferior soil. According to the agricultural statistics of Scotland, for the, year 1857 (Trans. Highland and Ag. Soc., 1857-9, p- 213), the bushel of oats produced in some districts weighed 44 pounds per bushel, while in other districts it was as low as 35 pounds, and in one instance but 24 pounds per bushel. Light oats have a thick and bulky husk, and an ash-analysis gives a result quite unlike that of ood oats. Herapath (Jour. Roy. Ag. Society, XI, p- 107) has published analyses of light oats from sandy soil, the yield being six bushels per acre, and of heavy oats from the same soil, after ‘‘ warping,”’* where the produce was 64 bushels per acre. Some of his results, per cent, are as follows: Light oats. Heavy oats. POtash.-dee sees cece ens 9.8 13.1 SOG sty ieisteehes sep 53 ant 7.2 | Baik ciVencen a ae cae eae 6.8 4.2 Phosphoric acid...... ONG 17.6 Sili@a fees chem wees ose s 56.5 45.6 Wolff (Jour. fiir Prakt. Chem., 52, p, 103) has anal- ysed the ashes of several plants, cultivated in a poor soil, with the addition of various mineral fertilizers. The in- fluence of the added substances on the composition of the plant is very striking. The following figures comprise his results on the ash of buckwheat straw, which grew *Thickly covering with sediment from muddy tide-water. THE ASH OF PLANTS. Li on the unmanured soil, and on the same, after applica- tion of the substances specified below : 1 2 3 + 5 6 Unma- Ci.loride Nitrate Carbonate Suphate Carbonate nured. of of of 6, of sodium. nee es potash. magnesia. lime. BOUAUS care o cic tas slater’ ctatins 31.7 21.6 39.6 40.5 28.2 23.9 Chloride of potassium.... 7.4 26.9 0.8 3.1 6.9 9.7 Chloride of sodium....... 4.6 3.0 3.2 3.8 3.4 lofi MBIT Ger tear ate ierareie Ssvsiaie wid sae. aie 15.7 14.0 12.8 11.6 14.1 18.6 AVVO SA) se atetars nse a's wisiaicise a1Gf 1.9 3.3 1.4 4.7 4.2 SUM MUTIC AGLAS. .\.' 5. cs sse 4.7 2.8 2a 4.3 Wel 3.5 Phosphorier acid’... ... 5... 10.3 9.5 6.5 8.9 10.9 10.0 CanHonilCs acids. .5. 3 400.666 20.4 16.1 27.1 22.2 20.0 PBI SIUC 5 BeOS ORO FE eer res 3.6 4.2 4.2 4.2 4.8 5.2 100.0 100.0 100.0 100.0 100.0 100.0 It is seen from these figures that all the applications employed in this experiment exerted a manifest influ- ence, and, in general, the substance added, or at least one of its ingredients, is found in the plant in increased quantity. In 2, chlorine, but not sodium ; in 3 and 4, potash ; in 5, sulphuric acid and magnesia, 2 and in 6, lime, are present in larger proportion than in the ash from the unmanured soil. 6. What is the normal composition of the ash of a plant? It is evident from the foregoing facts and con- siderations that to pronounce upon the normal composi- tion of the ash of a plant, or, in other words, to ascer- tain what ash-ingredients and what proportions of them are proper to any species of plant or to any of its parts, is a matter of much difficulty and uncertainty. The best that can be done is to adopt the average of a great number of trustworthy analyses as the approximate expression of ash-composition. From such data, how- ever, we are still unable to decide what are the abso- lutely essential, and what are really accidental, ingredi- ents, or what amount of any given ingredient is essential, and to what extent it is accidental. Wolff, who appears to have first suggested that a part of the ash of plants 12 178 HOW CROPS GROW. may be accidental, endeavored to approach a solution of this question by comparing together the ashes of sam- ples of the same plant, cultivated under the same circum- stances in all respects, save that they were supplied with unequal quantities of readily-available ash-ingredients. The analyses of the ashes of buckwheat-stems, just quoted, belong to this investigation. Wolff showed that, by assuming the presence in each specimen of buckwheat- straw of a certain excess of certain ingredients, and de- ducting the same from the total ash, the residuary ingre- dients closely approximated in their proportions to those observed in the crop which grew in an unmanured soil. The analyses just quoted (p. 163) are here ‘‘ corrected ” in this manner, dy the subtraction of a certain per cent of those ingredients which in each ease were furnished to the plant by the fertilizer applied to it. The num- bers of the analyses correspond with those on the previ- ous page. 1 2 3 4 5 6 20 prc 20 pe: 25 p.c. 859. c..) LOG pars Chloride Carbonate Carbonate Sulphate Carbanates After detuction cf of of of ofcale’mand Of scene sae Nothing. potas: potas- potas- magn e- Myne- sium. Sine. sium. StL. Slum. MOtashisse ee pio vate ao nolint 27.0 o2.D 33.5 30.6 28.0 Chloride of potassium. 7.4 9.1 1.0 3.9 7.4 11.3 Chloride of sodium. . 4.6 3.8 4.0 4.7 3.7 19 | FINO erence america ae INHTs 17.3 16.0 14.5 15.3 14.6 NANO M ESTP he anh Gie.edtodoe ils 2.4 4.1 1.7 2.3 2.9 SUL pM UMC Cisne 4.7 3.5 3.4 5.4 2.1 4.1 Phosphorie acid...... 10.3 Tater 8.1 11.2 11.8 11.7 CarbonieG acid... ~~... 20.4 20.1 25.9 19.8 21.6 19.3 lial mers Se 99,967.64 100,000 On the other hand, too great dilution is fatal to growth. Nobbe (Vs. S¢., VUI, 337) found that ina solution con- taining but yodoo Of solid matters, which was continually renewed, barley made no progress beyond germination, and a buckwheat plant, which at first grew rapidly, was soon arrested in its development, and yielded but a few ripe seeds, and but 1.746 grm. of total dry matter. While water-culture does not provide all the normal conditions for the growth of land plants—the soil having important functions that cannot be enacted by any liquid medium—it is a metliod of producing highly-developed plants, under circumstances which admit of accurate con- 186 HOW CROPS GROW. trol and great variety of alteration, and is, therefore, of the utmost value in vegetable physiology. It has taught important facts which no other means of study could re- veal, and promises to enrich our knowledge in a still more eminent degree. Potassium, Calcium, and Magnesium as soluble Salts, Phosphorus as Phosphates and Sulphur as Sulphates, are absolutely necessary for the life of Agricultural Plants, as is demonstrated by all the ex- periments hitherto made for studying their influence. It is impossible to recount here in detail the evidence to this effect that is furnished by the investigations of Salm-Horstmar, Sachs, Knop, Nobbe, Birner and Luca- nus, and others (Vs. St., VIII, p. 128-161). Some ot the experimental proof of this statement is strikingly exhibited by the figures on Plate I, copied from Nobbe, showing results of the water-culture of buckwheat in normal nutritive solutions and in solutions variously deficient. Is Sodium Essential for Agricultural Plants? This question has occasioned much discussion. /C ’ 66 O; ce Barley kernel, { 2% Zoeller, 6% \ Veltmann. Kon 6 66 6 bis sc T% Zoeller. 49 itthausen ¢ 29:8% Ritthausen. ce 66 oar .t, /0 w a 270 I € aM Sugar beet, 7% Bretschneider, ‘“ 16.6% Bretschneider. ce Lurnrp root, 7.7% Anderson, “6 17.1% Anderson. Although, as just indicated, sodium in some instances }.as been found wanting in the wheat kernel and in po- tato tubers, it is not certain that it was absent from other parts of the same plants, nor has it been proved that sodium is wanting in any entire plant which has grown on a natural soil. | 188 HOW CROPS GROW. Weinhold found in the ash of the stem and leaves of the common live-for-ever (Sedwm telephium) no trace of sodium detectable by ordinary means ; while in the ash of the roots of the same plant there occurred 1.8 per cent of its oxide (Vs. St., IV, p. 190). It is possible then that, in the above instances, so- dium really existed in the plants, though not in those parts which were subjected to analysis. It should be added that in ordinary analyses, where sodium is stated to be absent, it is simply implied that it is present, if at all, in too small a quantity to admit of determining by the usual method, while in reality a minute amount may be present in all such cases.* The final result of all the analytical investigations hitherto made, with regard to cultivated agricultural plants, then, is that sodium is an extremely variable in- ' eredient of the ash of plants, and though generally pres- ent in sume proportion, and often in large proportion, has been ebserved to be absent in weighable quantity in the seeds of grains and in the tubers of potatoes. Salm-Horstmar, Stohmann, Knop, and Nobbe & Sie- gert have contributed experimental evidence bearing on this question. The investigations of Salm-Horstmar were made with great nicety, and especial attention was bestowed on the influence of very minute quantities of the various sub- stances employed. He gives as the result of numerous experiments, that, for wheat, oats, and barley, im the early vegetative stages of growth, Sodium, while advan- tageous, is not essential, but that for the perfection of fruit an appreciable though minute quantity of this ele- ment is indispensable. (Versuche und Reszltate «ber die Nahrung der Pflanzen, pp. 12, 27, 29, 36.) *The methods of spectral analysis, by which syan4na00 Of a erain of sodium oxide may be detected, demonstrate this element to be so uni- versally distributec that it is next to impossible to find or te prepare anything that is free from it. THE ASH OF PLANTS. 1839 Stohmann’s single experiment led to the similar con- clusion, that maize may dispense with sodium in the earlier stages of its growth, but requires it for a full Bearman (Henneberg’s Jour. fir Landwirthschaft, 1862, p. 25.) Knop, on the other hand, succeeded in bringing the maize plant to full perfection of parts, if not of size, in a solution which was intended and asserted to contain no sodium. (Vs. S¢., III, p. 301.) Nobbe & Siegert came to the same results in similar trials with buckwheat. Vaest:, 1V,; p.339.) Ae trials by Nobbe, Schréder and Erdmann, ei by others, confirm the conclusion that sodium may be nearly or altogether dispensed with by plants. The buckwheat represented in Plate I vegetated for 3 months in solutions as free as possible from sodium, with the exception of VI, in which sodium was substituted for potassium. The experiments of Knop, Nobbe, Siegert and others, while they prove that much sodium is not needful to maize and buckwheat, do not, however, satisfactorily demonstrate that a little sodiwm is not necessary, because the solutions in which the roots of the plants were im mersed stood for months in glass vessels, and coul ° scarcely fail to dissolve some sodium from the glass. Again, slight impurity of the substances which were em- ployed in making the solution could scarcely be avoided without extraordinary precautions, and, finally, the seeds of these plants might originally have contained enough sodium to supply this substance to the plants in appre- ciable quantity. To sum up, it appears from all the facts before us : 1. That sodium is never fofally absent from plants, and that, 2. If indispensable, but a minute amount of it is requisite. 190 HOW CROPS GROW. 3. That the foliage and succulent portions of the plant may include a considerable amount of sodium that is not necessary to the plant; that is, in other words, accidental. Can Sodium replace Potassium ?—The close simi- larity of potassium and sodium, and the variable quanti- ties in which the latter especially is met with in plants, have led to the assumption that one of these alkali-metals can take the place of the other. Salm-Horstmar and Knop & Schreber first demon- strated that sodium cannot entirely take the place of potassium—that, in other words, potassium is indispen- sable to plant life. Plate I, VI, shows the development of buckwheat during 3 months, in Nobbe, Schréder & Erdmann’s water-cultures, when, in a normal nutritive solution, potassium is substituted by sodium, as com- pletely as is practicable. Cameron concluded, from a series of experiments which it is unnecessary to describe, that, under natural condi- tions, sodium may partially replace potassium. . 24 C31) Soy 11 bean ATG A Bee ae 4210 6a, 581, ga, 421, 7 70 Tit ee ogo Oe wee ogame ig ho) aay PV Oe 93 (72) 90 ( 39) 91 (74) 99 (74) 84 (77) 100 (100) V, “100. (100) 100 (100) 100 (100) 100 (100) 100 (400) 100 (95%) The gain (or loss, indicated by the minus sign —) in these ash-ingredients during each period is given belew: * Exclusive of Fiber. eo Go aw COMPOSITION IN SUCCESSIVE STAGES. Sulphuric Phosphoric Silica. Oxide. Oxide. Lime. Magnesia. Potash. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. I. Period, 18 ( 22) 20 ( 42 ) 23 ( 23) 30 (31) 24 ( 31) 39 ( 42.) 10 Baume 23 32 | 19 28 aoa awe 31 35 2 40 52 42 47 ony. << ai aE aa ass ) ae ) i656 ™ a ) EV 46 23 (15) 38 (—5d*) 18 (10) 20 (—9*) 26 (4) OP Gaia) We ee % (C23)p 10 Gob: ) Se OPO SICA) Sali (Oo 9) 0 (—d*) 100 (100) 100 (100) 100 (100) 100 (100) 100 (100) 100 (100) These two independent investigations could hardly give all the discordant results observed on comparing the above figures, as the simple consequence of the unlike mode of conducting them. We observe, for example, that in the last period Arendt’s plants gathered less silica than in any other—only 7% per cent of the whole. On the other hand, Bretschneider’s crop gained more silica in this than in any other single period, viz.: 28 per cent. A similar statement.is true of phosphoric owide.t It is obvious that Bretschneider’s crop was tak- ing up fixed matters much more vigorously in its last stages of growth than were Arendt’s plants. As to potash, we observe that its accumulation ceased in the 4th Period in both cases. C.—Translocation of Substances in the Plant. —The transfer of certain matters from one part of the plant to another during its growth is revealed by the analyses of Arendt, and since such changes are of inter- est from a physiological point of view, we may recount them here briefly. It has been mentioned already that the growth of the stem, leaves, and ear of the oat plant in its later stages ‘probably takes place to a great degree at the expense of the roots. It is also probable that a transfer of carbhy- *In these instances Bretschneider’s later crops appear to contain less sulphuric oxide, lime and potash,than the earlier. This result may be due to the washing of the crop by rains, but is probably caused by unequal development of the several plots. + Phosphoric oxide is the “ phosphoric acid,’’ P,O;, of older and to a great degree of current usage. See p. 163. 239 ; HOW CROPS GROW. drates, and certain that one of albuminoids, goes on from the leaves through the stem into the ear. Silica appears not to be subject to any change of posi- tion after it has once been fixed by the plant. Chlorine likewise reveals no noticeable mobility. On the other hand, phosphoric oxide passes rapidly from the leaves and stem towards or into the fruit in the ear- lier as well as in the later stages of growth, as shown by the following figures : One thousand plants contained in the various periods quantities (grams) of phosphoric oxide as follows : 1st 2d 3d 4th 5th Period. Period. Period. Period. Period. 3 lower joints of stem, 0.47 0.20 0.21 0.20 0.19 ‘2middle “ ee 0.39 1.14 0.46 0.18 Upper joint St 0.66 1.73 0.31 0.39 3 lower leaves a 1.05 0.70 0.69 0.51 0.35 2 upper leaves “ 1.75 1.67 1.18 0.74 0.59 Ear, 2.36 5.36 10.67 12.52 Observe that these absolute quantities diminish in the stem and leaves after the 1st or 3d Period in all cases, and increase very rapidly in the ear. Arendt found that sulphuric owide existed to a much greater degree in the leaves than in the stem through- out the entire growth of the oat plant, and that, after blossoming, the lower stem no longer contained sulphur ,in the form of sulphates at all, though its total in the plant considerably increased. It is almost certain, then, that sulphuric oxide originates, either partially or wholly, by oxidation of sulphur or some sulphurized compound, in the upper organs of the oat. Magnesium is translated from the lower stem into the upper organs, and in the fruit, especially, it constantly increases in quantity. There is no evidence that Calcium moves upward in the plant. On the contrary, Arendt’s analyses. go to show that in the ear, during the last period of growth, it COMPOSITION IN SUCCESSIVE STAGES. 239 diminishes in quantity, being, perhaps, replaced by magnesium. As to potassium, no transfer is fairly indicated, except from the ears. These contained at blossoming (Period 111) a maximum of potassium, During their subsequent growth the amount of this element diminished, being probably displaced by magnesium. The data furnished by Arendt’s analyses, while they indicate a transfer of matters in the cases just named, and in most of them with great certainty, do not and cannot from their nature disprove the fact of other simi- lar changes, and cannot fix the reai limits of tie move- ments which they point out. * ican | “f Cf | w@ Er iaiOoN Ii. THE STRUCTURE OF THE PLANT AND OFFICES OF ITS ORGANS. CHAPTER. I. GENERALITIES. We have given a brief description of those elements and compounds which constitute the plant in a chemical sense. They are the materials—the stones and timbers, so to speak—out of which the vegetable edifice is built. It is important, in the next place, to learn how these building materials are put together, what positions they occupy, what purposes they serve, and on what plan the edifice is constructed. It is impossible for the builder to do his ae until he has mastered the plans and specifications of the archi- tect. So it is hardly possible for the farmer with cer- tainty to contribute in any great, especially in any new, degree, to the upbuilding of the plant, unless he is acquainted with the mode of its structure and the ele- ments that form it. It is the happy province of science to add to the vague and general information which the observation and experience of generations have taught, a more definite and particular knowledge,—a knowledge acquized by study purposely and carefully directed to special ends. An acquaintance with the parts and structure of the plant is indispensable for understanding the mode by which it derives its food from external sources, while the 16 241 242 TOW CROPS GROW. ingenious methods of propagation practiced in fruit- and flower-culture are only intelligible by the help of this knowledge. ORGANISM OF THE PLANntT.—We have at the outset spoken of organic matter, of organs and organization. It is in the world of life that these terms have their fit- test application. The vegetable and animal consist of numerous parts, differing greatly from each other, but each essential to the whole. The root, stem, leaf, flower and seed are each instruments or organs whose co-oper- ation is needful to the perfection of the plant. The plant (or animal) being thus an assemblage of organs, 1s called an Organism; it is an Organized or Organic Structure. The atmosphere, the waters, the rocks and soils of the earth, do not possess distinct co-operating parts ; they are Inorganic matter. In inorganic nature, chemical affinity rules over the transformations of matter. A plant or animal that is dead, under ordinary circumstances, soon loses its form and characters ; it is gradually consumed, and, at the ex- pense of atmospheric oxygen, is virtually burned up to air and ashes. In the organic world a something, which we call Vitality, resists and overcomes or modifies the affinities of oxygen, and insures the existence of a continuous and perpetual succession of living forms. An Organism or Organized Structure is characterized and distinguished from inorganic matter by two par- ticulars : 1. It builds up and increases its own mass by appro- priating external matter. It absorbs and assimilates food. It grows by the enlargement of all its parts. 2. It reproduces itself. It develops from a germ, and in turn gives origin to new germs. ULTIMATE AND ComMpLEX OrGANS.—In our account of the Structure of the Plant we shall first consider the ELEMENTS OF ORGANIZED STRUCTURE. 245 elements of that s annot be divided or wounded without extinguishing their life, and by whose expansion or multiplication all growth takes place. ‘Then will follow an account of the com- plex parts of the plant—its Organs—which are built up by the juxtaposition of numerous cells. Of these we have one class, viz., the Roots, Stems and Leaves, whose office is to sustain and nourish the Individual Plant. These may be distinguished as the Vegetative Organs. The other class, comprising the Flower and Fruit, are not essential to the existence of the individual, but their function is to maintain the Race. They are the Repro- ductive Organs. CHAPTER IL. PRIMARY ELEMENTS OF ORGANIZED STRUCTURE. a THE VEGETABLE CELL. One of the most interesting discoveries that the micro- scope has revealed, is that all organized matter originates in the form of minute vesicles or cells. If we examine by the microscope a seed or an egg, we find nothing but a cell-structure—a mass of rounded or many-sided bags lying closely together, and more or less filled with solid or liquid matters. From these cells, then, comes the frame or structure of the plant or of the animal. In the process of maturing, the original vesicles are vastly mul- tiplied and often greatly modified in shape and appear- ance, to suit various purposes ; but still it is always casy, especially in the plant, to find cells of the same essential characters as those occurring in the seed. 244 HOW CROPS GROW. Cellular Plants.—In the simpler forms or lower orders * of vegetation, we find plants which, throughout all the stages of their life, consist entirely of similar cells, and indeed many are known which are but a single cell. The phenomenon of red snow, frequently observed in Alpine and Arctic regions, is due to a microscopic one-celled plant which propagates with great rapidity, and gives its color to the surface of the snow. In the chemist’s laboratory it is often observed that in the clear- est solutions of salts, like the sulphates of sodium and magnesium, a flocculent mold, sometimes red, some- times green, most often white, is formed, which, under the microscope, is seen to be a vegetation consisting of single cells. Brewers’ yeast, Fig. 27, 1s nothing more than a mass of one or few-celled plants. In sea-weeds, mushrooms, the molds that grow on damp walls, or upon bread, cheese, etec., and in the blights which infest many of the farmer’s crops, we have examples of plants formed exclusively of cells. All the plants of higher orders we find likewise to consist chiefly of globular or angular cells. All the growing parts especially, as the tips of the roots, the leaves, flowers and fruit, are, for the most part, aggrega- tions of such minute vesicles. If we examine the pulp of fruits, as that of a ripe *Viz.: the Cryptoqams, including Molds and Mushrooms (Fungi), Mosses, Ferns, Sea-Weeds (dlgw) and Bacteria (Schizomycetes). ELEMENTS OF ORGANIZED STRUCTURE, RAS apple or tomato, we are able, by means of a low magni- fier, to distinguish the cells of which it almost entirely consists. Fig. 28 represents a bit of the flesh of a ripe pippin, magnified 50 diameters. ‘The cells mostly cohere together, but readily admit of separation. Structure of the Cell.—By the aid of the micro- scope it is possible to learn something with regard to the internal structure of the cell itself. Fig. 29 exhibits the appearance of a cell from the flesh of the Artichoke (Helianthus), magnified 230 diameters; externally the membrane, or wail of the cell, is seen in section. This eae membrane is filled and distended by a TE transparent liquid, the sap or free water of vegetation. Within the cell is ob- & served a round body, 6, which is called the nucleus, and upon this is seen a smaller nucleolus, c. Lining the inte- rior of the cell-membrane and connected with the nucleus, is a yellowish, turbid, semi-fluid substance of mucilaginous consistence, a, which is designated the protoplasm, or formative layer. This, when more highly magnified, is found to contain a vast number of excessively minute granules. | By the aid of chemistry the microscopist is able to dis- sect these cells, which are hardly perceptible to the unassisted eye, and ascertain to a good degree how they are constituted. On moistening them with solution of iodine, and afterward with sulphuric acid, the outer membrane—the cell-wall—shortly becomes of a fine blue color. It is accordingly cellulose, the only vegetable substance yet known which is made blue by iodine after, and only after, the action of sulphuric acid. At the same time we observe that the interior, half-liquid, pro- toplasm, coagulates and shrinks together,—scparates, therefore, from the cell-wall, and, inciuding with it the Fic. 29. 246 TIOW CROPS GROW. nucleus and the smaller granules, lies in the center of the cell like a collapsed bladder. It also assumes a deep yellow or brown color. If we moisten one of these cells with nitric acid, the cell-wall is not affected, but the liquid penetrates it, coagulates the inner membrane, and colors it yellow. In the same way this membrane is tinged violet-blue by hydrochloric acid. These reactions leave no room to doubt that the slimy inner lining of the cell or protoplasm contains abundance of alduminotds. The protoplasm is not miscible with water and main- tains itself distinct from the cell-sap. In young cells it is constantly in motion, the granules suspended in it cir- culating as in a liquid current. If we examine the cells of any other plant we find almost invariably the same structure as above described, provided the cells are young, 1. ¢., belong to growing parts. In some cases isolated cells consist only of proto- plasm and nucleus, being destitute of cell-walls during a portion or the whole of their existence. In studying many of the maturer parts of plants, viz., such as have ceased to enlarge, as the full-sized leaf, the perfectly formed wood, etc., we find the cells do not cor- respond to the description just given. In external shape, thickness, and appearance of the cell-wall, and especially in the character of the contcuts, there is indefinite va- ricty. But this is the result of change in the original cells, which, so far as our observations extend, are always, at first, forméd closely on the pattern that has been de- scribed. Vegetable Tissue.—It does not, however, usually happen that the individual cells of the higher orders of plants admit of being obtained separately. They are attached together more or less firmly by their outer sur- faces, so as to form a coherent mass of cells—a fisswe, as it is termed. In theaecompanying cut, Fig. 30, is shown a highly-magnified view of a portion of a very thin slice ELEMENTS OF ORGANIZED STRUCTURE. RAG across a young cabbage-stalk. It exhibits the outline of the irregular empty cells, the walls of which are, for the most part, exterually united and appear as one, a. At the points indicated by 4, air-filled cavities between the cells are seen, called intercellular spaces. \ regularly and uniformly, or interrupt- Gs edly. The flax-fiber, 6, Fig. 31, is an ex- ie ample of nearly uniform thickening. as The irregular deposition of cellulose is 24 shown in Fig. 32, which exhibits a see- tion from the seeds (cotyledons) of the : eommon nasturtium (Tropwolum Fig. 32. . majus). The original membrane is coated interiorly with several dis- tinct and suecessively-formed linings, which are not continuous, but are irregularly developed. Seen in section, the thickening has a waved outline, and, at points, the original cell-membrane is bare. Were these cells viewed entire, we should see at these points, on the exterior of the cell, dots or circles appearing like orifices, but being simply the ELEMENTS OF ORGANIZED STRUCTURE. 249 unthickened portions of the cell-wall. The cells in fig. 32 exhibit each a central nucleus surrounded by grains of aleurone. Cell Contents.—Besides the protoplasm and nucleus, the cell usually contains a variety of bodies, which have been, indeed, noticed already as ingredients of the plant, but which may be here recapitulated. Many cells are altogether empty, and consist of nothing but the cell- wall. Such are found in the bark or epidermis of most plants, and often in the pith, and although they remain connected with the actually living parts, they have no longer any proper life in themselves. All living or active cells are distended with liquid. This consists of water, which holds in solution gum, dex- trin, inulin, the sugars, albuminoids, organic acids, and other vegetable principles, together with various salts, both of organic and mineral acids, and constitutes the sap of the plant. In oil-plants, droplets of oil occupy certain cells, Fig. 17, p. 83; while in numerous kinds of vegetation colored and milky juices are found in certain spaces or channels between the cells. The water of the cell comes from the soil, or in some cases from the air. The matters, which are dissolved in the sap of the plant, together with the semi-solid proto- plasm, undergo transformations resulting in the produc- tion of various solid substances. By observing the sev- eral parts of a plant at the successive stages of its devel- opment, under the microscope, we are able to trace within the cells the formation and growth of starch- grains, of granular or crystalline bodies consisting chiefly of albuminoids, and of the various matters which give color to leaves and flowers. ‘ The circumstances under which a cell develops deter- mine the character of its contents. The outer cells of the potato-tuber are incrusted with corky matter, the inner ones are for the most part filled with starch. In oats, wheat, and other cereals, we find, just within wo0 HOW CROPS GROW. the skin or epidermis of the grain, a few layers of cells that contain scarcely anything but albuminoids, with a little fat ; while the interior cells are chiefly filled with starch. Big. 18) pschh0. Transformations in Cell Contents.—The same cell may exhibit a great variety of aspect and contents at different periods of growth. ‘This is especially to be observed in the seed while developing on the mother plant. Hartig has traced these changes in numerous plants under the microscope. According to this ob- server, the cell-contents of the seed (cotyledons) of the common nasturtium (Zropeolum majus) run through the following metamorphoses. Up to a certain stage in its development the interior of the cells are nearly devoid of recognizable solid matters, other than the nucleus and the adhering protoplasm. Shortly, as the growth of the seed advances, green grains of chlorophyll make their appearance upon the nucleus, completely covering it from view. Ata later stage, these grains, which have enlarged and multiplied, are seen to have mostly become detached from the nucleus, and lie near to and in contact with the cell-wall. Again, in a short time the grains lose their green color and assume, both as regards appear- ance and deportment with iodine, all the characters of starch. Subsequently, as the seed hardens and becomes firmer in its tissues, the microscope shows that the starch-grains, which were situated near the cell-wall, have vanished, while the cell-wall itself has thickened inwardly—the starch having been converted into cellu- lose or bodies of similar properties. Again, later, the nu- cleus, about which, in the meantime, more starch-grains have been formed, undergoes a change and disappears ; then the starch-grains, some of which have enlarged while others have vanished, are found to be imbedded in a pasty matter, which has the reactions of an albuminoid. From this time on, the starch-grains are gradually converted ELEMENTS OF ORGANIZED STRUCTURE. 2501 from their surfaces inwardly into smaller grains of aleu- rone, which, finally, when the seed is mature, completely occupy the cells. In the sprouting of the seed similar changes occur, but in reversed order. The nucleus reappears, the aleurone dissolves, and even the cellulose * stratified upon the inte- rior of the cell (Fig. 32) wastes away and is converted into soluble food (sugar ?) for the seedling plant. The Dimensions of Vegetable Cells are very vari- ous. A creeping marine plant is known—the Caulerpa prohfera (Fig. 33)—which consists of a single cell, though it is often a foot in length, and is branched with what have the appearance of leaves and roots. The pulp of * Or more probably metarabin, paragalactin, xylin, or the like insol- uble substances, which as yet have been but imperfectly distinguished from cellulose in the thickened cell-walls. 2D2 HOW CROPS GROW. the orange consists of cells which are one-quarter of an inch or more in diameter. ‘The fiber of cotton is a single cell, commonly from one to two inches long. In most cases, however, the cells of plants are so small as to re- quire a powerful microscope to distinguish them,—are, in fact, no more than ;355 to 54,5 of an inch in diame- ter. The spores of Fungi are still smaller. The germs of many bacteria are so minute as to be undiscoverable by the highest powers of the microscope. Growth.—The growth of a plant is nothing more than the aggregate result of the enlargement and multi- plication of the cclls which compose it. In most cases the cells attain their full size in a sbort time. ‘The con- tinuous growth of plants depends, then, chiefly on the constant and ranid formatioa of new cells. } Cell-multiplication.—The young and active cell Fig 34, Fig. 35. always contains a nucleus (Fig. 34, 6). Such a cell may produce a new cell by division. In this process the nu. cleus, from which all cell-growth appears to originate, is observed to resolve itself into two parts, then the proto- plasm, a, begins to contract or infold across the cell in a line corresponding with the division of the nucleus, until the opposite infolded edges meet,—like the skin of a sau- sage where a string is tightly tied around it,—thus sepa- rating the two nuclei and inclosing each within its new cell, which is completed by a further external growth of cellulose. ELEMENTS OF ORGANIZED STRUCTURE. 253 In one-celled plants, like yeast (Fig. 35), the new cells thus formed, bud out from the side of the parent;cell, and before they obtain full size become entirely detached from it, or, as in higher plants, the new cells remain ad- hering to the old, forming a tissue. In free cell-formation nuclei are observed to develop in the protoplasm of a parent cell, which enlarge, surround themselves with their own protoplasm and cell-membrane, and by the resorption or death of the parent cell become independent. The rapidity with which the vegetable cells may mul- tiply and grow is illustrated by many familiar facts. The most striking cases of quick growth are met with in the mushroom family. Many will recollect haying seen, on the morning of a June day, huge puff-balls, some as large as a peck measure, on the surface of a moist meadow, where the day before nothing of the kind was noticed. In such sudden growth it has been estimated that the cells are produced at the rate of three or four hundred millions per hour. Shoat Permeability of Cells to Liquids.—Although the highest magnifying power that can be brought to bear upon the membranes of the vegetable cell fails to reveal any apertures in them,—they being, so far as the best- assisted vision is concerned, completely continuous and imperforate,—they are nevertheless readily permeable to liquids. This fact may be shown by placing a delicate slice from a potato tuber, immersed in water, under the microscope, and then bringing a drop of solution of iodine in contact with it. Instantly this reagent pene- trates the walls of the unbroken cells without perceptibly affecting their appearance, and, being absorbed by the starch-grains, at once colors them intensely purplish- blue. The particles of which the cell-walls and their contents are composed must be separated from each other by distances greater than the diameter of the par- 204 _ HOW CROPS GROW. ticles of water or of other liquid matters which thus per- meate the cells. § 2. THE VEGETABLE TISSUES. As already stated, the cells of the higher kinds of plants are united together more or less firmly, and thus constitute what are known as VEGETABLE TIssugs. Of these, a large number have been distinguished by vege- table anatomists, the distinctions being based either on peculiarities of form or of function. For our piney it will be necessary to define but a few varieties, viz. Cellular Tissue, Wood-Tissue, Bast-Tissue and Sige cular Tissue. Cellular Tissue, or Pareuateae is the simplest of all, being a mere aggregation of globular or polyhedral cells whose walls are in close alieaae and whose juices commingle more or less in virtue of this connection. Cellular tissue is the groundwork of all vegetable struc- ture, being the only form of tissue in the simpler kinds of plants, and that out of which all the other tissues are developed. Prosenchyma is a name applied to all tissues composed of elongated cells, like those of wood and bast. Paren- chyma and prosenchyma insensibly shade into each other. Wood-Tissue, in its simplest form, consists of cells that are several or many times as long as they are broad, and that taper at each end to a point. These spindle-shaped cells cohere firmly together by their sides, and ‘‘break joints” by overlapping each other, in this way forming the tough fibers of wood. Wood-cells are often more or less thickened in their walls by depositions of cellulose and other matters, according to their age VEGETATIVE ORGANS OF PLANTS. 255 and position, and are sometimes dotted and perforated, as will be explained hereafter—Fig. 53, p. 301. Bast-Tissue is made up of long and slender cells, similar to those of wood-tissue, but commonly more del- icate and flexible. The name is derived from the occur- rence of this tissue in the bast, or inner bark. Linen, hemp, and most textile materials of vegetable origin, cotton excepted, consist of bast-fibers. Bast-cells oceupy a place in rind, corresponding to that held by wood- cells in the interior of the stem—Fig. 49, p. 293. Vascular Tissue is the term applied to those un- branched Zudes and Duets which are found in all the higner orders of plants, interpenetrating the cellular tissue. There are several varieties of ducts, viz., dutled ducts, ringed or annular ducts, and spiral ducts, of which illustrations will be given when the minute struc- ture of the stem comes under notice—Fig. 49, p. 293. The formation of vascular tissue takes place by a sim- ple alteration in cellular tissue. A longitudinal scries of adhering cells represents a tube, save that the bore is obstructed with numerous transverse partitions. By the remoyal or perforation of these partitions a tube is devel- oped. This removal or perforation actually takes place in the living plant by a process of absorption. CHAPTER III. THE VEGETATIVE ORGANS OF PLANTS. § fs THE ROOT. The roots of plants, with few exceptions, from the first moment of their development, grow dcwnward. In general, they require a moist medium. ‘They will form in water or in moist cotton, and in many cases originate from branches, or even leaves, when these parts of the plant are buried in the earth or immersed in water. It cannot be assumed that they seek to avoid the light, because they may attain a full development without being kept in darkness. The action of ight upon them, however, appears to be unfavorable to their functions. The Growth of Roots occurs mostly by lengthen- ing, and very little or very slowly by increase of thick- ness. The lengthening is chiefly manifested toward the outer extremities of the roots, as was neatly demonstrated by Wigand, who divided the young root of a sprouted pea into four equal parts by ink-marks. After three days, the first two divisions next the seed had scarcely lengthened at all, while the third was double, and the fourth eight times its previous length. Ohlerts made precisely similar observations on the roots of various kinds of plants. The growth is confined to a space of about one-sixth of an inch from the tip. (Linnea, 1837, pp. 609-631.) This peculiarity adapts the roots to extend through the soil in all directions, and to occupy 206 VEGETATIVE ORGANS OF PLANTS. 25% its smallest pores, or rifts. It is likewise the reason that a root, which has been cut off in transplanting or other- wise, never afterwards extends in length. Although the older parts of the roots of trees and of the so-called root-crops acquire a considerable diameter, the roots by which a plant feeds are usually thread-like and often exceedingly slender. Spongioles.—The tips of the rootlets have been termed spongioles, or spongelets, from the idea that their texture adapts them especially to collect food for the plant, and that the absorption of matters from the soil goes on exclusively through them. In this sense, spongioles do not-exist. The real living apex of the root is not, in fact, the outmost extremity, but is situ- ated a little within that point. Root-Cap.—The extreme end of the root usually con- sists of cells that have become loosened and in part detached from the proper cell-tis- WIR sue of the root, which, therefore, It shortly perish, and serve merely }ias an elastic cushion or cap to Y protect the true termination or living point of the root in its act of penetrating the soil. Fig. 36 represents a magnified section of part of a barley root, showing the loose cells which slough off from the tip. These cells are filled with air instead of sap. i Hl ~ Pos A striking illustration of the P2974") Mle, =, a c . . root-cap 1s furnished by the air- Fig. 36. roots of the so-called Screw Pine (Pandanus odoratissimus), exhibited in natural dimen- sions, in Fig. 3%. These air-roots issue from the stem above the ground, and, growing downwards, enter the soil, and become roots in the ordinary sense. 17 258 TOW CROPS GROW. When fresh, the diameter of the root is quite uni- form, but the parts above the root-cap shrink on dry- ing, while the root-cap itself retains ; nearly its original dimensions, and thus reveals its different structure. Distinction between Root and Stem.—Not all the subterranean parts of the plant are roots in a proper sense, although commonly spoken of as such. The tubers of the potato and artichoke, and the fleshy horizontal parts of the sweet- flaz and pepper-root, are merely underground stems, of which many varicties exist. These and ail other stems are sasily distinguished from true roots by the imbricated buds, of which indications may usually be found on their surfaces, e. g., the eyes of the gaa: potato-tuber. The side or second- i ary roots are indeed marked in their | earliest stages by a protuberance on i the primary root, but these have noth- Yai ing in common with the structure of true buds. The onion-bulb is itself a fleshy bud, as will be noticed subse- quently. The true roots of the onion are the fibers which issue from the base of the bulb. The roots of many plants exhibit no buds upon their surface, and are incapable of developing them under any conditions. Roots of other plants, such as the plum, apple, and pop- lar, may produce buds when cut off from the parent plant during the growing season. The roots of the former perish if deprived of connection with the stem and leaves. The latter may strike out new stems and VEGETATIVE ORGANS OF PLANTS. 259 leaves for themselves. Plants like the plum are, there- fore, capable of propagation by root-cuttings, 1. e., by placing pieces of their roots in warm and moist earth. Tap-roots.—All plants whose seeds divide into two seed-leaves or Ootyledons, and whose stems increase externally by addition of new rings of growth—the Dicotyledonous plants, or Exogens—have, at first, a single descending axis, the tap-root, which penetrates vertically into the ground. From this central tap-root lateral roots branch out more or less regularly, and these lateral roots subdivide again and again. In many cases, espec- ially at first, the lateral roots issue from the tap-root with great order and regularity, as much as is seen in the branches of the stem of a fir-tree or of a young grape- vine. In older plants, this order is lost, because the soil opposes mechanical hindrances to regular devclop- ment. In many cases the tap-root. grows to a great length, and forms the most striking feature of the radi- cation of the plant. In others it enters the ground but a little way, or is surpassed in extent by its side branches. The tan-root is conspicuous in the Canada thistle, dock (Rumex), and in seedling fruit trees. The upper por- tion of the tap-root of the beet, turnip, carrot, and rad- ish expands under cultivation, and becomes a fleshy, nutritive mass, in which lies the value of these plants for agriculture. The lateral roots of other plants, as of the dahlia and sweet potato, swell out at their extremi- ties to tubers. Crown Roots.—Monocotyledonous plants, or Hndo- gens, i. @., plants whose embryos have only one seed- leaf, or Ootyledon, and whose stems do not increase by external additions, such as the cereals, grasses, lilies, palms, etc., have no single descending axis or tap-root, but produce crown roots, i. e., a number of roots issue at once from the base of the stem. This is strikingly seen in the onion and hyacinth, as well as in maize. 260 HOW CROPS GROW. Rootlets.—This term we apply to the slender roots, but a few inches long, which are formed last in the order of growth, and correspond to the larger roots as twigs correspond to the branches of the stem. TH OFFICES OF THE Root are threefold : 1. To fix the plant in the earth and maintain it in an erect position. 2. ‘To absorb nutriment from the soil for the growth of ye entire plant, and, . In case of many plants, especially of ne whose terms of life extend through several or many years, to scrve as a store-house for the future use of the plant. 1. The Firmness with which a Plant is fixed in the Ground depends upon the nature of its roots. It is easy to lift an onion from the soil; a carrot requires much more force, while a dock may resist the full strength of a powerful man. A small beech or seedling apple tree, which has a tap-root, withstands the force of a wind that would prostrate a maize-plant or a poplar, which has only side roots. In the nursery it is the cus- tom to cut off the tap-root of apple, peach, and other _ trees, when very young, in order that they may be readily and safely transplanted as occasion shall require. The depth and character of the soil, however, to a certain degree influence the extent of the roots and the tenacity of their hold. The roots of maize, which in a rich and tenacious earth extend but two or three feet, have been traced to a length of ten or even fifteen feet in a light, sandy soil. The roots of clover, and especially those of alfalfa, extend very deeply into the soil, and the latter acquire in some cases a length of 30 fect. The roots of the ash have been known as much as 95 feet long. (Jour. Roy. Ag. Soc., VI, p. 342.) 2. Root-absorption.—The Office of Absorbing Plant Food from the Soil is one of the utmost impor- tance, and one for which the root is most wisely adapted by the following particulars, viz.: VEGETATIVE ORGANS OF PLANTS. 261 a. The Delicacy of its Structure, especially that of the newer portions, the cells of which are very soft and ab- sorbent, as may be readily shown by immersing a young seedling bean in solution of indigo, when the roots shortly acquire a biue color from imbibing the liquid, while the stem is for a considerable time unaltered. It is a common but erroneous idea that absorption from the soil can only take place through the ends of the roots—through the so-called spongioles. On the con- trary, the extreme tips of the rootlets cannot take up liq- uids at all. (Ohlerts, doc. cit., see p. 270.) All other parts of the roots, which are still young and delicate in surface-texture, are constantly active in the work of im- bibing nutriment from the soil. In most perennial plants, indeed, the larger branches of the roots become after a time coated with a corky or otherwise nearly 1 impervious cuticle, and the function of absorption is then transferred to the rootlets. This is. demonstrated by placing the old, brown-colored roots of a plant in water, but keeping the delicate and unindu- rated extremities above the liquid. Thus situated, the plant withers nearly as soon as if its root-surface were all exposed to the air. b. Its Rapid Extension in Length, and the vast Sur- face which it puts in contact with the soil, further adapts the root to the work of collecting food. The length of roots in a direct line from the point of their origin is not, indeed, a criterion by which to judge of the effi- - ciency wherewith the plant to which they belong is nour- ished ; for two plants may be equally flourishing—be cea fed by their Fanee< wNeN these organs, in one case, reach but one foot, and in the other extend two feet from the stem to which they are attached. In one case, the roots would be fewer and longer; in the other, shorter and more numerous. Their aggregate length, or, more correctly, the aggregate absorbing surface, would be nearly the same in both. 262 HOW CROPS GROW. The Medium in which Roots Grow has a great influ- ence on their extension. When they are situated in con- centrated solutions, or in a very fertile soil, they are short, and uumerously branched. Where their food is sparse, they are attenuated, and bear a comparatively small number of rootlets. Dlustrations of the former condition are often seen; moist bones and masses of manure are not infrequently found, completely covered and penetrated by a fleece of stout roots. On the other hand, the roots which grow in poor, dry soils are very long and slender. Nobbe has described some experiments which com- pletely establish the point under notice. (Vs. Sé., IV, p- 212.) He allowed maize to grow in a poor clay soil, contained in glass cylinders, each vessel having in it a quantity of a fertilizing mixture disposed in some pecu- liar manner for the purpose of observing its influence on the roots. When the plants had beea nearly four months in growth, the vessels were placed in water until the earth was softened, so that by gentle agitation it could be com- pletely removed from the roots. The latter, on being suspended in a glass vessel of water, assumed nearly the position they had occupied in the soil, and it was ob- served that, where the fertilizer had been thoroughly mixed with the soil, the roots uniformly occupied its entire mass. Where the fertilizer had been placed in a horizontal layer at the depth of about one inch, the roots at that depth formed a mat of the finest fibers. Where the fertilizer was situated in a horizontal layer at half the — depth of the vessel, just there the root system was sphe- roidally expanded. In the cylinders where the fertilizer formed a vertical layer on the interior walls, the external roots were developed in numberless ramifications, while the interior roots were comparatively unbranched. In pots, where the fertilizer was disposed as a central vertical core, the inner roots were far more greatly developed VEGETATIVE ORGANS OF PLANTS. 263 than the outer ones. Finally, in a vessel where the fer- tilizer was placed in a horizontal layer at the bottom, the roots extended through the soil, as attenuated and slightly branched fibers, until they came in contact with the lower stratum, where they greatly increased and ram- ified. In all cases, the principal development of the - roots occurred in the immediate vicinity of the material which could furnish them with nutriment. It has often been observed that a plant whose aerial branches are symmetrically disposed about its stem, has the larger share of its roots on one side, and again we find roots which are thick with rootlets on one side and nearly devoid of them on the other. Apparent Search for Food.—It wouid almost appear, on superficial consideration, that roots are endowed with a kind of intelligent instinct, for they seem to go in search of nutriment. The roots of a plant make their first issue mdepend- ently of the nutritive matters that may exist in their neighborhood. They are organized and put forth from the plant itself, no matter how fertile or sterile the me- dium that surrounds them. When they attain a certain development, they are ready to exercise their office of collecting food. If food be at hand, they absorb it, and, together with the entire plant, are nourished by it—they grow in consequence. The more abundant the food, the better they are nourished, and the more they multiply. The plant sends out rootlets in all directions; those which come in contact with food, live, enlarge, and ram- ify ; those which find no nourishment, remain undevel- oped or perish. The Quantity of Roots actually belonging to any Plant is usually far greater than can be estimated by roughly lifting them from the soil. To extricate the roots of wheat or clover, for example, from the earth, completely, is a matter of extreme difficulty. Schubart was the first 264 HOW CROPS GROW. to make satisfactory observations on the roots of several important crops, growing in the field. He separated them from the soil by the following expedient : An exca- vation was made in the field to the depth of 6 feet, and a stream of water was directed against the vertical wall of soil until it was washed away, so that the roots of the plants growing in it were laid bare. The roots.thus ex- posed in a field of rye, in one of beans, and in a bed of garden peas, presented the appearance of a mat or felt of white fibers, to a depth of about 4 feet from the surface of the ground. ‘The roots of winter wheat he observed as deep as 7 feet, in a light subsoil, forty-seven days after sowing. The depth of the roots of winter wheat, winter rye, and winter colza, as well as of clover, was 3 to 4 feet. The roots of clover, one year old, were 34 feet long, those of two-year-old clover but four inches longer. The quan- tity of roots in per cent of the entire plant in the dry state was found to be as follows. (Chem. Ackersmann, I, p. 193.) Winter wheat—examined last of April............. 40% ee as we OB LONE Su0 cabo coo tice 22 se rye es STIS PANE) TSUN oTataatclatsrenstetevers 34 “6 Peas examined four weeks after sowing........... 44 6 a ue atthe time Of DIOSSOMM sc. cee -ccelee 24 ¢ Vellricgel has likewise studied the radication of barley and oats (Hoff, Jahresbericht, 1864, p. 106.) He raised plants in large glass pots, and separated their roots from the soil by careful washing with water. He observed that directly from the base of the stem 20 to 30 roots branch-off sideways and downward. ‘These roots, at their point of issue, have a diameter of 3; of an inch, but a little lower the diameter diminishes to about 72,5 of an inch. Retaining this diameter, they pass downward, dividing and branching to a certain depth. From these main roots branch out innumerable side roots, which branch again, and so on, filling every crevice and pore of the soil. VEGETATIVE ORGANS OF PLANTS. 265 To ascertain the total length of root, Hellriegel weighed and ascertained the length of selected average portions. Weighing then the entire root-system, he ca:culated the entire length. He estimated the length of the roots of a vigorous barley plant at 128 feet, that of an oat plant at 150 feet.* He found that a small bulk of good fine soil sufliced for this development ; #; cubic foot (4-4-4 23 in.) answered for a barley plant, 34 cubic foot for an oat plant, in these experiments. Hellriegel observed also that the quality of the soil in- fluenced the development. In rich, porous, garden-soil, wu barley plant produced 128 feet of roots, but in a coarse-grained, com- pacter soil, a similar plant had but 80 feet of roots. | foot Hairs.—The real absorbent surface of roots is, in most cases, not to be appreciated without microscopic aid. The roots of the onion and of many other bulbs, 1. e., the fibers which issue from the base of the bulbs, are per- fectly smooth and unbranched through- out their entire length. Other agricul- tural plants have roots which are not only visibly branched, but whose finest fibers are more or less thickly covered with minute hairs, scarcely perceptible to the unassisted eye. These root-hairs consist always.of tubular elongations of the external root-cells, and through them the actual root-surface exposed to the soil beoomes something almost Fig. 38. incalculable. The accompanying fig- ures illustrate the appearance of root-hairs. Fig. 38 represents a young mustard seedling. A is *Rhenish, 34= 35 English feet. 266 HOW CROPS GROW. the plant, as carefully lifted from the sand in which it grew, and B the same plant, freed from adhering soil by agitating in water. ‘The entire root, save the tip, is thickly beset with hairs. In Fig. 39 a minute portion of a barley-root is shown highly magnified. The hairs are seen to be slender tubes that proceed from, and form part of, the outer cells of the root. The older roots lose their hairs, and suffer a thicken- ing of the outermost layer of cells. ‘These dense-walled | and nearly impervious cells cohere together and consti- tute a rind, which is not found in the young and active roots. As to the development of the root-hairs, they are more abund- ant in poor than in good soils, and appear to be most numer- ously produced from roots which have otherwise a dense and un- absorbent surface. The roots of those plants which are destitute of hairs are commonly of consid- /\ erable thickness and remain white and of delicate texture, preserving their absorbent power throughout the whole time that the plant feeds from the soil, asis the case with the onion. The Silver Fir (Adces Picea) has no root-hairs, but its rootlets are covered with a very delicate cuticle highly favorable to absorption. The want of root-hairs is fur- ther compensated by the great number of rootlets which are formed, and which, perishing mostly before they be- come superficially indurated, are continually replaced by new ones during the growing season. (Schacht, Der Baum, p. 165.) Contact of Reots with the Soil.—The root-hairs, as they extend into the soil, are naturally brought into close Fig. 39. VEGETATIVE ORGANS OF PLANTS. ef bon Te aes os She | Ss B35 (vee. p hal 268 HOW CROPS GROW. contact with its particles. This contact is much more intimate than bas been usually supposed. If we care- fully lift a young wheat-plant from dry earth, we notice that each rootlet is coated with an envelope of soil. This adheres with considerable tenacity, so that gentle shak- ing fails to displace it, and if it be mostly removed by uy Fig. 42. vigorous agitation or washing, the root-hairs are either found to be broken, or in many places inseparably at- tached to the particles of earth. Fig. 40 exhibits the appearance of a young wheat- VEGETATIVE ORGANS OF PLANTS. 269 plant as lifted from the soil and pretty strongly shaken. S, the seed; 0, the ‘blade; e, roots covered with hairs and enveloped in soil. Only the growing tips of the roots, w, which have not put forth hairs, come out clean of soil. Fig. 41 represents the rocts of a wheat-plant one month older than those of the previous figure. In this instance not only the root-tips are naked as before, but the older parts of the primary roots, e, and of the secondary roots, 2, no longer retain the particles of soil ; the hairs upon them being, in fact, dead and decom- posed. The newer parts of the root alone are clothed with active hairs, and to these the soil is firmly attached as before. The next illustration, Fig. 42, exhibits the appearance of root-hairs with ad- hering particles of earth, when mag- nified 800 diameters : A, root-hairs of wheat-seedling, like Fig. 40; B, of oat-plant, both from loamy soil. Here is plainly seen the intimate attachment of the soil and rcot- hairs. The latter, in forcing their way against considerable pressure, often expand around, and partially envelop, the particles of earth. ! (Sachs’s Hap. Phys. d. Pflanzen.) galt AY Gn) ts Imbibition of water by the root.— =@) ‘Che force with which active roots imbibe the water of the soil is — SS sufficient to force the liquid upward —==F into thestemand toexert a continu- | ==Z._ al pressure on all parts of the plant. ~ = 27> When the stem of a plant in vigor- ii beee ous growth is cut off near the root, and a pressure-gauge is attached to it, as in Fig. 438, we have the means of observing and measuring the force with which the roots absorb water. Wi i] Ae he [/| fil! | i \ field Fig. 43. 270 HOW CROPS GROW. The pressure-gauge contains a quantity of mercury iu the middle reservoir, 6, and the tube, ¢. It is attached to the stem of the plant, p, by a stout india-rubber pipe, g.* For accurate measurements, the space @ and b should be filled with water. Thus arranged, it is found that water will enter a through tbe stem, and the mer- cury will rise in the tube, e, until its pressure becomes sufficient to balarce the absorptive, power of the roots. Stephen Hales, who first experimented in this manner (1721) found in one instance that the pressure exerted on a gauge, attached in spring time to the stump of a grape-vine, supported a column of mercury 323 inches high, which is equal to a column of water of 363 feet. Hofmeister obtained on other plants, rooted in pots, the following results : Bean (Phaseolus multiflorus) 6 inches of mercury. Riethlest staan. Sa oh ey 4 “ MAT gs heh cna eens te pee 2 “ The seat of absorption Dutrochet demonstrated to be the surface of the young and active roots. At least, he found that absorption was exerted with as much force when the gauge was apphed to near the lower extremity of a root as when attached in the vicinity of the stem. In fact, when other conditions are alike, the column of liquid sustained by the roots of a plant 1s greater the less the length of stem that remains attached to them. The stem thus resists the rise of liquid in the plant. While the seat of absorptive power in the root lies near the extremities, it appears from the experiments of GChlerts that the extremities themselves are incapable of imbibing water. In trials with young pea, flax, lupine and horseradish plants with unbranched roots, he found that they withered speedily when the tips of the roots were immersed for about one-fourth of an inch in water, *For experimenting on small pan a simple tube of glass may be adjusted to the stump vertically by help of a rubber connector. VLGETATIVE ORGANS OF PLANTS. 271 the remaining parts being in moist air. Ohlerts like. wise proved that these plants flourish when only tho middle part of their roots is immersed in water. Keep- ing the root-tips, the so-called spongioles, in the air, or cutting them away altogether, was without apparent effect on the freshness and vigor of the plants. The absorbing surface would thus appear to be ccnfined to those portions of the root upon which the development of root-hairs is noticed. The absorbent force is manifested by the active root- lets, and most vigorously when these are in the state of most rapid development. For this reason we find, in case of the vine, for example, that during the autumn, when the plant is entering upon a period of repose from growth, the absorbent power is trifling. Sometimes water is absorbed at the roots so forcibly as not only to distend the plant to the utmost, but to cause the sap of the plant to exude in drops upon the foliage. This may be noticed upon newly-sprouted maize, or other cereal plants, where the water escapes from the leaves at their extreme tips, especially when the germination has pro- ceeded under the most favorable conditions for rapid development. The bleeding of the vine, when severed in the spring- time, the abundant flow of sap from the sugar-maple and the water-elm, are striking illustrations of this imbibition of water from the soil by the roots. These examples are, indeed, exceptional in degree, but not in kind. Hofmeister has shown that the bleeding of a sey- ered stump is a general fact, and occurs with all plants when the roots are active, when the soil can supply them abundantly with water, and when the tissues above the absorbent parts are full of this liquid. When it is other- wise, water may be absorbed from the gauge into the stem and large roots, until the conditions of activity are renewed. R12 HOW CROPS GROW. Of the external circumstances that affect this absorp- tive power, heat and light would appear to be influential. By observing a gauge attached to the stump of a plant during a clear summer day, it will be usually noticed that the mercury begins to rise in the morning as the sun warms the soil, and continues to ascend for a num- ber of hours, but falls again as the sun declines. Sachs found in some of his experiments that, in case of potted tobacco and squash plants, absorption was nearly or entirely suppressed by cooling the roots to 41° F., but was at once renewed by plunging the pots into warm water. The external supplies of water,—in case a plant is stationed in the soil, the degree of moisture contained in this medium,—obviously must influence any manifesta- tion of the imbibing force. But full investigation shows that this regular daily fluctuation is a habit of the plant which is independent of small changes of temperature and even of considerable variation in the amount of mois- ture of the soil. The rate of absorption is subject to changes depend- ent on causes not well understood. Sachs observed that the amount of liquid which issued from potato stalks cut off just above the ground underwent great and continual variation from hour to hour (during rainy weather) when the soil was saturated with water and when the thermometer indicated a constant temperature. Hofmeister states that the formation of new roots and buds on the stump is accompanied by a sinking of the water in the pressure-gauge. Absorption of Nutriment from the Soil.—The food of the plant, so far as it is derived from the soil, enters it in a state of solution, and is absorbed with the water which is taken up by the rootlets. ‘The absorption of the matters dissolved in water is in some degree inde- pendent of the absorption of the water itself, the plant VEGETATIVE ORGANS OF PLANTS. PAT iy having apparently, to a certain extent, a selective power. See p. 401. 3. The Root as a Magazine.—In Fleshy Tap- foots, like those of the carrot, beet, and turnip, the absorption of nutriment from the soil takes place princi- pally, if not entirely, by means of the slender rootlets which proceed abundantly from all their surface, and especially from their lower extremities, while the older fleshy part serves as a magazine in which large quantities of carbhydrates, etc., are stored up during the first year’s growth of these d¢ennial plants, to supply the wants of the flowers and seed which are developed the second year. When one of these roots, put into the ground for a sec- ond year, has produced seed, it is found to be quite exhausted of the nutritive matters which it previously contained in so large quantity. Root Tubers, like those of the dahlia and sweet; potato, are fleshy enlargements of lateral or secondary roots filled with reserve material, from which buds and new stems may develop. Small tubers (Z'ubercles) are fre- quently formed on the roots of the garden bean (Phascolus). In cultivation, the farmer not only greatly increases the size of these roots and the stores of organic nutritive materials they contain, but, by removing them from the ground in autumn, he employs to feed himself and his cattle the substances that nature primarily designed to nourish the growth of flowers and seeds during another summer. Soil-Roots; Water-Roots; Air-Roots.—We may distinguish, according to the medium in which they are formed and grow, three kinds of roots, viz.: soul- roots, water-roots, and air-roots. Most agricultural plants, and indeed by far the greater number of all plants found in temperate climates, have roots adapted especially to the soil, and which perish by 18 R14 HOW CROPS GROW. short exposure to dry air, or rot, if long immersed in water. Many aquatic plants, on the other hand, speed- ily die when their roots are removed from water, or from earth saturated with water, and exposed to the atmos- . phere or stationed in earth of the usual dryness. Air-roots are not common except among tropical plants or under tropical conditions of heat and moisture. In- dian corn, when thickly planted and of rank growth, often throws out roots from the lower joints of the stem, which extend through the air several inches before they reach the soil. The same may be observed of many com- mon plants, as the oat, grape, potato, and buckwheat, when they long remain in hot, moist air. The Banyan- tree of India sends out from its branches, vertically, pendants several yards long which penetrate the earth and there become soil-roots. On the other hand, various tropical plants, especially Orchids, emit roots which hang free in the air and never reach the earth. In the humid forest ravines of Madeira and Teneriffe, the Lawrus Canariensis, a large tree, sends out from its stem, during the autumn rains, a pro- fusion of fleshy air-roots, which cover the trunk with their interlacing branches and grow to an inch in thick- ness. The following summer they dry away and fall to the ground, to be replaced by new ones in the ensuing autumn. (Schacht, Der Baum, p. 172.) A plant, known to botanists as the Zamia spiralis, not only throws out air-roots, ¢¢, Fig. 44, from the crown of the main soil-root, but the side rootlets, 6, after extend- ing some distance horizontally in the soil, send, from the “same point, roots downward and upward, the latter of which, d, pass into and remain permanently in the air. a is the stem of the plant. (Schacht, Anatomie der Gewdchse, Bd. I, p. 151.) The formation of air-roots may be very easily observed by placing water to the depth of half an inch in a tall Px) ~3 on VEGETATIVE ORGANS OF PLANTS. vial, inserting a sprig of the common greenhouse-plant Tradescantia zebrina, so that the eut end of the stem shall stand in the water, and finally corking the vial air- tight. The plant, which is very tenacious of life, and usually grows well in spite of all neglect, is not checked in its vegetative development by the treatment just de- scribed, but immediately begins to adapt itself to its new circumstances. In a few days, if the temperature be 70° or thereabout, air-roots will be seen to issue from the joints of the stem. These are fringed with a profu- sion of delicate hairs, and rapidly extend to a length of - from one to two inches. The lower ones, if they chance Fig. 44. . to penetrate the water, become discolored and decay ; the others, however, remain for a long time fresh, and of a_ white color. Some plants have roots which are equally able to exist and perform their functions, whether in the soil or sub- 276 HOW CROPS GROW. merged in water. Many forms of vegetation found in our swamps and marshes are of this kind. Of agricul- tural plants, rice is an example in point. Rice will grow in a soil of ordinary character, in respect of moisture, as the upland cotton-soils, or even the pine-barrens of the Carolinas. It flourishes admirably in the tide-swamps of the coast, where the land is laid under water for weeks at a time during its growth, and it succeeds equally well in fields which are flowed from the time of planting to that of harvesting. (Russell, North America, its Agri- culture and Climate, p. 176.) The willow and alder, trees which grow on the margins of streams, send a part of their roots into soil that is constantly saturated with water, or into the water itself ; while others occupy the merely moist or even dry earth. Plants that customarily confine their growth to the soil occasionally throw out roots as if in search of water, and sometimes choke up drain-pipes or even wells by the profusion of water-roots which they emit. At Welbeck, England, a drain was completely stopped by roots of horse-radish plants at a depth of 7 feet. At Thornsby Park, a drain 16 feet deep was stopped entirely by the roots of gorse, growing at a distance of 6 fect from the drain. (Jour. Roy. Ag- Soc.,.1,, p. 364), In Wew Haven, Connecticut, certain wells are so obstructed by the aquatic roots of the elm trees as to require cleaning out every two or three years. This aquatic tendency has been repeatedly observed in the poplar, cypress, laurel, turnip, mangel-wurzel, and various grasses. Henrici surmised that the roots which most cultivated plants send down deep into the soil, even when the latter is by no means porous or inviting, are designed especially to bring up water from the subsoil for the use of the plant. He devised the following experiment, which ap- pears to prove the truth of this view. On the 13th of May, 1862, a young raspberry plant, having but two VEGETATIVE ORGANS OF PLANTS. QV leaves, was transplanted into a large glass funnel filled with garden soil, the throat of the funnel being closed with a paper filter. The funnel was supported in the mouth of a large glass jar, and its neck reached nearly to the bottom of the latter, where it just dipped ‘into a quantity of water. The soil in the funnel was at first kept moderately moist by occasional waterings. ‘The plant remained fresh and slowly grew, putting forth new leaves. After the lapse of several weeks, four strong roots penetrated the filter and extended down the empty funnel-neck, through which they emerged, on the 21st of June, and thenceforward spread rapidly in the water of the jar. From this time on, the soil was not watered any more, but care was taken to maintain the supply in the jar. The plant continued to develop slowly ; its leaves, however, did not acquire a vivid green color, but remained pale and yellowish ; they did not wither until the usual time, late in autumn. The roots continued to erow, and filled the water more and more. Near the end of December the plant had seven or eight leaves, and a height of eight inches. The water-roots were vigorous, very long, and beset with numerous fibrils and buds. In the funnel tube the roots made a perfect tissue of fibers. Tn the dry earth of the funnel they were less extensively developed, yet exhibited some juicy buds. The stem and the young axillary leaf-buds were also full of sap. The water-roots being cut away, the plant was put into garden soil and placed in a conservatory, where it grew vigorously, and in May bore two offshoots. (Henneberg’s Jour. fir Landwirthschaft, 1868, p. 280.) This growth towards water must be accounted for on the principles asserted in the paragraph, Apparent Search for Food (p. 263). The seeds of many ordinary land plants—of plants, indeed, that customarily grow in a dry soil, such as the bean, squash, maize, etc.—will readily germinate in 278 TOW CROPS GROW. moist cotton or sawdust, and if, when fairly sprouted, the young plants have their roots suspended in water, taking care that the seed and stem are kept above the liquid, they will continue to grow, and with due supplies of nutriment will run through all the customary stages of development, produce abundant foliage, blossoms, and perfect seeds, without a moment’s contact of their roots with soil. (See Water Culture, p. 131.) In plants thus growing with their roots in a liquid medium, after they have formed several large leaves, be carefully transplanted to the soil, they wilt and perish, unless frequently watered ; whereas similar plants, started in the soil, may be transplanted without suffering in the slightest degree, though the soil be of the usual dryness, and receive no water. The water-bred seedlings, if abundantly watered as often as the foliage wilts, recover themselves after a time, and thenceforward continue to grow without the need of watering. It might appear that the first-formed water-roots are incapable of feeding the plant from a dry soil, and hence the soil must be at first profuscly watered ; after a time, however, new roots are thrown out, which are adapted to the altered situation of the plant, and then the growth proceeds in the usual manner. The reverse experiment would seem to confirm this view. Ifa seedling that has grown for a short time only in the soil, so that its roots are but twice or thrice branched, have these immersed in water, the roots already formed mostly or entirely perish in a short time. They indeed absorb water, and the plant is sustained by © them, but immediately new roots grow from the crown with great rapidity, and take the place of the original roots, which become disorganized and useless. It is, however, only the young and active rootlets, and those covered with hairs, which thus refuse to live in water. VEGETATIVE ORGANS OF PLANTS. 279 The older parts of the roots, whieh are destitute of fibrils and which have nearly ceased to be active in the work of absorption, are not affected by the change of circum- stance. These facts, which are due to the researches of Dr. Sachs (Vs. Sé., I, p. 13), would naturally lead to the conclusion that the absorbent surface of the root un- dergoes some structural change, or produces new roots with modified characters, in order to adapt itself to the medium in which it is placed. It would appear that when this adaptation proceeds rapidly the plant is not permanently retarded in its growth by a gradual change in the character of the medium which surrounds its roots, as may happen in case of rice and marsh-plants, when the saturated soil in which they may be situated at one time is slowly dried. Sudden changes of medium about the roots of plants slow to adapt themselves would be fatal to their existence. Nobbe has, however, carefully compared the roots of buckwheat, as developed in the soil, with those emitted in water, without being able to observe any structural differences. The facts above detailed admit of partial, if not complete, explanation, without recourse to the suppo- sition that soil- and water-roots are essentially diverse in nature. When a plant which is rooted in the soil is taken up so that the fibrils are not broken or injured, and set into water, it does not suffer any hindrance in growth, as Sachs found by his later experiments. (/7- perimental Physiologie, p. 177.) Ordinarily, the suspen- sion of growth and decay of fibrils and rootlets is due, doubtless, to the mechanical injury they suffer in remoy- ing from the soil. Again, when a plant that has been reared in water is planted in carth, similar injury occurs in packing the soil about the roots, and moreover the fibrils cannot be brought into that close contact with the soil which is necessary for them to supply the foliage with water ; hence the plant wilts, and may easily perish 280 HOW CROPS GROW. unless profusely watered or shielded from evaporation. The air-roots of Orchids, which never reach the soil, have a peculiar spongy texture and take up the water which exists as vapor tn the air, as shown by the experi- ments of Unger, Chatin, and Sachs. Duchartre’s inves- tigations led him to deny their absorptive power. (£/le- ments de Botanique, p. 216.) In his experiments made on entire plants, the air-roots failed to make good the loss by evaporation from the other parts of the plant. It is evident from common observation that movstwre is the condition that chiefly determines root-develop- ment. Not only do all seeds sprout and send forth roots when provided with abundant moisture at suitable tem- peratures, but generally older roots and stems, and fleshy leaves, or cuttings frowh these, will produce new rootlets when properly circumstanced as regards moisture, whether that moisture be supplied by aid of a covering of damp soil, wet sand or paper, by stationing in humid air, or by immersion in water itself. Root-Excretions.—It was formerly supposed that the roots of plants perform a function of excretion, the reverse of absorption—that plants, like animals, reject matters which are no longer of use in their organism, and that the rejected matters are poisonous to the kind of vegetation from which they originated. De Candolle, an eminent French botanist, who first advanced this doe- trine, founded it upon the observation that certain plants exude drops of liquid from their roots when these are placed in dry sand, and that odors exhale from the roots of other plants. Numerous experiments have been in- stituted at various times for the purpose of testing this question. Noteworthy are those of Dr. Alfred Gyde (Trans. Highland and Agr. Soc., 1845-47, pp. 273-92). This experimenter planted a variety of agricultural plants, viz., wheat, barley, oats, rye, beans, peas, vetches, cab- bage, mustard, and turnips, in pots filled either with VEGETATIVE ORGANS OF PLANTS. 281 garden soul, sand, moss, or charcoal, and after they had attained considerable growth, removed the earth, etce., from their roots by washing with water, using care not to injure or wound them, and then immersed the roots in vessels of pure water. The plants were allowed to re- main in these circumstances, their roots being kept in darkness, but their foliage exposed to light, from three to seventeen days. In most cases they continued appa- rently in a good state of health. At the expiration of the time of experiment, the water which had been in contact with the roots was evaporated, and was found to leave a very minute amount of yellowish or brown mat- ter, a portion of which was of organic and the remainder of mineral origin. Dr. Gyde concluded that plants do throw off organic and» inorganic excretions similar in composition to their sap; but that the quantity is ex- ceedingly small, and is not injurious to the plants which furnish them. In the light of newer investigations touching the structure of roots and their adaptation to the medium which happens to invest them, we may well doubt whether agricultural plants in the healthy state excrete any solid or liquid matters whatever from their roots. The familar excretion of gum, resin, and sugar* from the stems of trees appears to result from wounds or dis- ease, and the matters which in the experiments of Gyde and others were observed to be communicated by the roots of plants to pure water probably came either from the continual pushing off of the tips of the rootlets by the interior growing point—a process always naturally accompanying the growth of roots—or from the disor- ganization of the absorbent root-hairs. Under certain circumstances, small quantities of sol- uble salts or free acids may indeed diffuse out of the *From the wounded bark of the sugar-pine (Pinus Lambertiand) of California. 282 HOW CROPS GROW. root-cells into the water of the soil. This is, however, no physiological action, but a purely physical process. Vitality of Roots.—It appears that in case of most plants the roots cannot long continue their vitality if their connection with the leaves be interrupted, unless, indeed, they be kept at a winter temperature. Hence weeds may be effectually destroyed by cutting down their tops; although, in many cases, the process must be several times repeated before the result is attaimed. The roots of our root-crops, properly so-called, viz., beets, turnips, carrots, and parsnips, when harvested in autumn, contain the elements of a second year’s growth of stem, etc., in the form of a bud at the crown of the root. If the crown be cut away from the root, the latter cannot vegetate, while the growth of the crown itself is not thereby prevented. As regards internal structure, the root closely resem- bles the stem, and what is stated of the latter, on subse- quent pages, applics in all essential points to the former. § 2, THE STEM. Shortly after the protrusion of the rootlet from a ger- minating seed, the STEM makes its appearance. It has, in general, an upward direction, which in many plants is permanent, while in others it shortly falls to the ground and grows thereafter horizontally. All plants of the higher orders have stems, though in many instances they do not appear above ground, but extend beneath the surface of the soil, and are usually considered to be roots. While the root, save in exceptional cases, does not develop other organs, it is the special function of the stem to bear the leaves, flowers, and seed of the plant, VEGETATIVE ORGANS OF PLANTS. 283 and even in certain tribes of vegetation, like the cacti, which have no leaves, to perform the offices of these organs. In general, the functions of the stem are sub- ordinate to those of the organs which it bears—the leaves and flowers. It is the support of these organs, and, it would appear, only extends in length or thickness with the purpose of sustaining them mechanically or provid- ing them with nutriment. Buds.—In the seed the stem exists in a rudimentary state, associated with undeveloped leaves, forming a bud. The stem always proceeds at first from a bud, during all its growth is terminated by a bud at every growing point, and only ceases to be thus tipped when it fully accom- plishes its growth by the production of seed, or dieg from injury or disease. In the /eaf-bud we find a number of embryo leaves and leaf-like scales, in close contact and within each orner, but all .at- tached at the base } to a central conical || axis, Fig. 45. The opening of the bud consists in the, lengthening of this axis, which is the stem, and the con- sequent separation from each other as Ball well a3 expansion of | Fig. 45. the leaves. If the rudimentary leaves of a bud be represented by a nest of flower-pots, the smaller placed within the larger, the stem may be signified by a rope of India-rubber passed through the holes in the bottom of the pots. The growth of the stem may now be shown by stretching the rope, whereby the pots are brought away from each 284 HOW CROPS GROW. other, and the whole combination is made to assume the character of a fully-developed stem, bearing its leaves at regular intervals; with these important differences, that the portions of stem nearest the root extend more rap- idly than those above them, and the stem has within it the material and the mechanism for the continual for- mation of new buds, which unfold in successive order. In Fig. 45, which represents the two terminal buds of a lilac twig, 1s shown not only the external appearance of the buds, which are covered with leaf-like scales, imbricated like shingles on a roof; but, m the section, are seen the edges of the undeveloped leaves attached to the conical axis. All the leaves and the whole stem of a twig of one summer’s growth thus exist in the bud, in plan and in miniature. Subsequent growth is but the development of the plan. In the flower-bud the same structure is manifest, save that the rudimentary flowers and fruit are enclosed within the leaves, and may often be seen plainly on cut- ting the bud open. Nodes; Internodes.—Nodes are those knots or parts of the stem where the leaves are attached. The portions of the stem between the nodes are termed internodes. It is from the nodes that roots most freely develop when stems (layers or cuttings) are surrounded by moist air or soil. Culms.—The grasses and the common cereal grains have single, unbranched stems, termed calms in botani- cal language. The leaves of these plants clasp the stem entirely at their base, and rest upon a well-defined, thick- ened node. Branching Stems.—Other agricultural plants besides those just mentioned, and all the trees of temperate cli- mates, have branching stems. As the principal or main stem elongates, so that the leaves arranged upon it sepa- rate from each other, we find one or more buds at the VEGETATIVE ORGANS OF PLANTS. 285 point where the base of the leaf or of the leaf-stalk unites with the stem. From these axillary buds, in case their growth is not checked, side-stems or branches issue, which again subdivide in the same manner into branchlets. In perennial plants, when young, or in their young shoots, it is easy to trace the nodes and internodes, vr the points where the leaves are attached and the inter- vening spaces, even for some time after the leaves, which only endure for one year, are fallen away. The nodes are manifest by the enlargement of the stem, or by the scar, covered with corky matter, which marks the spot where the leaf-stall was attached. As the stem grows older these indications of its early development are grad- ually obliterated. In a forest where the trees are thickly crowded, the lower branches die away from want of light; the scars resulting from their removal, or short stumps of the limbs themselves, are covered with a new growth of wood, so that the trunk finally appears as if it had always been destitute of branches, to a great height. When ail the buds develop normally and in due pro- portion, the plant, thus regularly built up, has a sym- metrical appearance, as frequently happens with many herbs, and also with some of the cone-bearing trees, especially the balsam-fir. Latent Buds.—Often, however, many of the buds remain undeveloped, either permanently. or for a time. Many of the side-buds of most of our forest and fruit trees fail entirely to grow, while others make no progress until the summer succeeding their first appearance. When the active buds are destroyed, either by frosts or by pinching off, other buds that would else remain latent are pushed into growth. In this way trees whose young leaves are destroyed by spring frosts cover themselves again, after a time, with foliage. In this way, e 286 HOW CROPS GROW. too, the gardener molds a straggling, ill-shaped shrub or plant into almost any form he chooses; for, by removing branches and buds where they have grown in undue pro- portion, he not only checks excess, but also calls forth development in the parts before suppressed. Close pruning or breaking the young twigs causes abundant development of flower-buds on fruit trees that otherwise ‘ a Sars — : i oO |e = ! rindi 2 z pa ; iis [ice S SLE SS ‘ || |S - 7 bc6 ll heal y, | | A | i > |e — a f, S| 2 ‘ | SU | | E H 7 y EZ 5 = : WAY A 22 N eA - | A oy - ie See } ~ i 00000%,9 jog 93039 500 SUN 0000 OE YYHYYYHHH g9HQ VE =e =a BS y SVEN \ : ey i aes - €& 3 { MMI! manne = 320 HOW CROPS GROW. only are self-fertile but cannot well be otherwise. Some plants which carry these closed and inconspicuous subter- ranean flowers depend upon them for reproduction by seed, their large and showy erial flowers being often bar- ren, as in violets, or totally infertile (Voandzeia.) Flax and turnips are self-fertilizing. Cross-Fertilization results from the contact of the pollen of one flower with the ovules of another. In many plants remarkable arrangements exist that hinder or totally prevent self-fertilization and favor or ensure cross- fertilization. In monecious plants, as hazel or squash, flowers of one sort yield pollen, others, different, contain the ovules ; so that two distinct and more or less distant blossoms of the same plant are necessary for seed-production. In the diewcious poplar and hops, the plant that pro- duces pollen never carries ovules and that which bears the latter is destitute of the former, so that two distinct plants must co-operate to form seeds. It often happens that the pollen of a flower cannot fer- tilize the ovules of the same flower. This may be either because the stigma is behind the pollen in development, as in case of various species of geranium, or because the stigma has passed its receptive period before the pollen is mature, as in Sweet Vernal Grass (Anthoxanthum odo- ratum). In both instances the ripened pollen may reach stigmas that are ready in other flowers and fertilize their ovules, insects being often the means of transportation. In a large number of flowers, whose pollen and stigmas are simultaneously prepared, the position of the organs is such that self-fertilization is difficult or impossible. The Iris, Crocus, Pansy, Milk-weed (A sclepias), and many Orchids, are of this class. The offices of insects in search of nectar, or attracted by odors, are here indispensable. The common red clover cannot produce seed without insect aid, and the bumblebee customarily performs this REPRODUCTIVE ORGANS OF PLANTS. ann service. The insect, in exploring a flower for nectar, leaves upon its stigma pollen taken from the flower last visited, and in emerging renews its burden of pollen to bestow it in turn upon the stigma of a third flower. Cross-fertilization is doubtless often effected by msects in case of flowers which are in all respects adapted for self-fertilization, while flowers that casual examimation would pronounce self-fertile are in fact of themselves sterile. The flowers of rye open singly, the long stamens shortly mature and discharge their pollen, which falls on the stigmas of flowers standing lower in the same head, or on neighboring heads. According to Rimepare, the individual rye-flower can fertilize neither itself nor the different flowers of an ear, nor can the different ears of one and the same plant pollinate one another with suc- cess, although no mechanical hindrance exists. (Sachs, Physiology of Plants, p. 70.) Results of Self-Fertilization and Cross-Fertili- zation.—Sprengel, one of the early students of Plant- Reproduction, wrote in 1793, ‘‘ Nature appears to be unwilling that any flower shall be fertilized by its own pollen.” Extensive observation indicates decidediy that cross-fertilization is far more general than self- fertilization, especially among the higher plants. Dar- win has shown that, 72 many cases, the pollen of a flower is incapable of fertilizing its own ovules, and that the pollen from another flower of the same plant is scarcely more potent. In these cases the pollen from a flower borne by another plant of the same kind is potent, and the more so the more unlike the two plants are. In Darwin’s trials on the reproduction of the Morning Glory, Ipomea purpurea, carried out through ten gener- ations, the average height of 73 sclf-fertilized plants was 66 inches, while that of the same number of crossed plants was 85.8 inches, or inthe ratio of 77 to 100. The relative number of seeds produced by the self-fertil- 21 322 HOW CROPS GROW. ized and cross-fertilized plants in the 1st, 3d, and 9th generations were respectively as 64 to 100; 35 to 100, and 26 to 100. In other cases, but, so far as observed, much less com- monly, self-fertilization gives the best results both as regards numbers and vigor of offspring. In Darwin’s ex- periments a variety of A/imulus luteus originated, of which the self-fertilized progeny surpassed the cross-fer- tilized, during several generations. In the seventh gen- eration the ratio of superiority of the self-fertilized, as regards numbers of fruit, was as 137 to 100, and 1n respect to size of plants as 126 to 100. Continued self-fertilization, is thus limited by its ten- dency, as statistically determined, to reduce both the vegetative and reproductive vigor of the plant. On the other hand, cross-fertilization is possible or practicable only within very narrow bounds, and the increased pro- ductiveness that follows it soon reaches a limit, as is shown by the history of vegetable hybrids. That neither mode of fertilization is exclusively or speci- ally adapted to the highest development of plants in gen- eral, orof particular kinds of plants, is shown by the fact that in the course of Darwin’s researches on the Jpomea purpurea, just referred to, in the sixth generation a self- fertilized plant (variety) appeared, which was superior to its crossed collateral, and was able to transmit its vigor and fertility to its descendants. It is evident, therefore, that the causes which lead to higher development co-operate most fully, sometimes in the one, sometimes in the other, mode of impregnation and do not necessarily belong to cither. We must be- lieve that excellence in offspring is the result of excel- lence in tle parents, no matter what lines their heredity may have followed, except as these lines have influenced their individual excellence. That crossing commonly gives better offspring than in-and-in breeding is due to REPRODUCTIVE ORGANS OF PLANTS. 32d the fact that in the latter both parents are likely to pos- sess by inheritance the same imperfections, which are thus intensified in the progeny, while in cross-breeding the parents more usually have different imperfections which often, more or less, compensate cach other in the immediate descendants. Aybridizing.—As the sexual union of quite different kinds of animals sometimes results in the birth of a hybrid, so, among plants, the ovules of one kind (spe- cies, or even genus) may be fertilized by the pollen of another different kind, and the seed thus developed, in its growth produces a hybrid plant. As in the animal, so in the vegetable kingdom, the range within which hybridization is possible appears to be very narrow. It is only between rather closely allied plants that fecunda- tion can take place, and the more close the resemblance the more ready and fruitful the result. Wheat, rye, and barley, in ordinary cultivation, show no tendency to “mix ;” the pollen of one of these similar plants rarely fertilizing * the ovules of the others. But external sim- ilarity is no certain mark of capacity for hybridization. The apple and pear have never yet been crossed, while the almond and nectarine readily form hybrids. (Sachs.) ‘Hybrids are usually less productive of seeds than the parent plants, and sometimes*are entirely sterile, but, on the other hand, they are often more vigorous in their vegetative develooment—produce larger and more numer- ous leaves, flowers, roots, and shoots, and are longer- *In the first edition was written, “being incapable of fertilizing.’’ The experiments of Mr. Carman have lately shown that wheat and rye may be made to produce fertile hybrids. A beardless wheat was fertilized by rye-pollen and produced nine seeds, eight of which were fully fertile, one nearly sterile. The last yiclded 29 heads, which bore only a few grains. The plants from the nine fertile seeds were polli- nated again with rye and produced but afew fertile seeds. A few plants, seven-cighths rye, were finally produced, which were, however, totally sterile. Of the three-fourths cross, fertile progeny has been raised for several years, and the characters of this genus-hybrid ap- pear to be nearly fixed, though occasionally a sterile head appears.— ural New Yorker, 1883, p. 644. Bef HOW CROPS GROW. lived than their progenitors. For this reason hybrids are much valued in fruit- and flower-culture. Some genera of plants have great capacity for produc- ing hybrids. The Vine and the- Willow are striking examples. ‘The cultivated Vine of Europe and Western Asia is Vitis vinifera. In the United States some twelve distinct species are found, of which three, Vitis riparia, Vitis estivalis, and Vitis labrusca, are native to New England. Nearly all these kinds of grape cross with such readiness that scores of new hybrids have been brought into cultivation. ‘*The kinds now known as Clinton, Taylor, Elvira, Franklin, are hybrids of V. riparia and V. labrusca. Yorsx-Madeira, Kumelan, Alvey, Morton’s Virginia, Cynthiana, are crosses of V. labrusca and V. estivalis. Delaware is a hybrid of V. labrusca, V. vinifera, and V. estivalis. Herbemont, tulander, and Cunningham are hybrids of V. estivalis, V. cinerea, and V. vinifera. ‘The vine known in France as ‘‘ Gaston-Bazille” is a hybrid of V. dabrusca, V. esti- valis, V. rupestris, and V. riparia.”* The foregoing are ‘‘spontaneous wild hybrids.” The ‘‘ Rogers Seed- lings,” including Salem, Wilder, Barry, Agawam, Mas- sasoit, ete., are examples of artificial hybrids of V. vin- ifera and V. labrusca. Hybridization between plants is effected, if at all, by removing from the flower of one kind the stamens before they shed their pollen, and dusting the summit of the properly-matured pistil with pollen from another kind. Commonly, when two plants hybridize, the pollen of cither will fertilize the ovules of the other. In some cases, however, two plants yield hybrids by only one order of connection. — The mixing of different Varieties, as commonly hap- pens among maize, melons, ete., is not hybridization, *Millardet in Sacis’s Lectures on the Physiology of Plants, 1887, p. 785. REPRODUCTIVE ORGANS OF PLANTS. Bye in the long-established sense of this word, but rather ““cross-breeding.” The two processes are, however, fun- damentally the same, and their results are sufficiently distinguished by the terms Species-hybrid, or Genus- hybrid, and Variety-hybrid. We are thus led to brief notice of the meaning of the terms Species and Vari- ety, and of the distinctions employed in Botanical Classification. Species.—Until recently naturalists generally held the view that in “the beginning” certain kinds of plants and animals were separately created, with the power to reproduce their own kind, but incapable of fertile hybrid- ization, so that only such original kinds could be per- petuated. Such supposed original kinds were called Speciés. At present, on the contrary, most biologists regard all existing kinds of plants and animals as prob- ably the results of a very slow and gradual development or evolution from one vastly remote ancestor of the sim- plest type. On this view a Plant-Species comprises a number of individuals, ‘‘among which we are unable to distinguish greater differences than experience shows us we should find among a number of plants raised from the seed of the same parent.” On the former view, plants yielding fertile hybrids or crosses must be Varieties of the same species. On the latter view different Species may hybridize. They are not originally different, and by Evolution or Reversion may pass into each other. On either view, the distinc- tion of plants into species is practically the same, being largely a matter of expert judgment or agreement among authorities, and not capable of exact decision by refer- ence to fixed rules or known natural laws. The charac- ters that are taken to be common to all the individuals of a species are termed specific characters. 'The differ- ences used to divide plants into species are called specific differences. 326 HOW CROPS GROW. Naturalists, acting under the older view, attempted to draw specific characters more finely than is now thought yracticable. Many plants formerly described as separate species are now united together into a single species, the various ferms at first supposed to be specifically or originally distinct having been shown to be of common origin, either by producing them from each other or by observing that they were connected through a series of intermediate forms, insensibly grading into each other. Varieties.—The individuals of any ‘‘species” differ. In fact, no two individuals are quite alike. Cirecum- stances of climate, soil, and situation increase these dif- ferences, and varieties originate when such differences are inherited and in the progeny assume a comparative permanence. But as external conditions cause variation away from any particular representative of a species, so they may cause variation back again to the original type. Varictics most commonly originate in propagation by seed, especially in case of the trees or plants commonly cultivated for their fruit. Seedling grapes, apples, or potatoes are very likely to differ from their parents. Seed which has been imperfectly ripened or long kept is said to be prone to yield new varieties. Less frequently variations arise in propagation by cuttings, buds, grafts, or tubers. Pinks and Pelargo- niums in the florist’s hands are prolific of these ‘‘ sports.” The causes that produce varieties are probably numer- ous, but in many cases their nature and their mode of action is obscure or unknown. Scarcity or abundance of nutriment, we can easily comprehend, may, on the one hand, dwarf a plant, or, on the other, lead to the pro- duction of a giant individual; but how, in some cases, the peculiarities thus impressed upon individuals become fixed, and are transmitted to subsequent generations, while in others they disappear, is difficult to explain. Varieties may often be perpetuated for a long time by REPRODUCTIVE ORGANS OF PLANTS. 327 the seed. This is true of our cereal and leguminous plants, which commonly reproduce their kind with strik- ing regularity. Varieties of some plants cannot, with certainty, be reproduced unaltered by the seed, but are continued in the possession of their peculiarities by ext- tings, layers, and grafts. The fact that the sceds of a potato, a grape, an apple, or pear cannot be depended upon to reproduce the variety, may perhaps be more commonly due to unavoidable contact of pollen from other varieties (variety-hybridization) than to inability of the mother plant to perpetuate its peculiarities. That such inability often exists is, however, well estab- lished, and is, in general, most obvious in case of varie- ties that have, to the greatest degree, departed from the original specific type and of course, in sterile hybrids. The sports which originate in the processes of propa- gating from buds (grafts, tubers, cuttings) are perpet- uated by the same processes. Species and Varicties, as established in our botanical literature, are exemplified by the Vine, whose species are vinifera, riparia, labrusea, etc., and some of whose North American Varieties, the results of hybridization, have already been enumerated. Genus (plural Genera).—Species which resemble each other in most important points of structure are grouped together by botanists into a genus. ‘Thus the various species of oaks,—white, red, black, scrub, live, etc.,—taken together, form the Oak-genus Quercus, which has a series of characters common to all oaks (generic characters), that distinguishes them from every other kind of tree or plant. Families, or Orders, in botanical language, are groups of genera that agree in certain particulars. Thus the several plants well-known as mallows, hollyhock, okra, and cotton, are representatives of as many different genera. ‘They all agree im a number of points, especially 328 HOW CROPS GROW. as regards the structure of their fruit. They are accord- ingly grouped together into a natural family or order, which differs from all others. Classes, Series, and Classification.—Classes are groups of orders, and Series are groups of classes. In botanical classification, as now universally employed— classification after the Natural System—all plants are separated into two series, as follows: 1. Flowering Plants (Phanerogams), which produce flowers and seeds with embryos, and 2. Hlowerless Plants (Cryptogams), that have no proper flowers nor seeds, and are reproduced, in part, by spores which are in most cases single cells. This series includes Ferns, Horse-tails, Mosses, Liverworts, Lichens, Sea-weeds, Mushrooms, and Molds. It was believed, until recently, that there exists a sharp and abso- lute distinetion between flowering and {flowerless plants, but our larger knowledge now recognizes that here, as among genera, species, and varieties, kinds merge or shade into each other. The use of Classification is to give precision to our notions and distinctions, and to facilitate the using and acquisition of knowledge. Series, classes, orders, genera, species, and varieties are as valuable to the naturalist as pigcon-holes are to the accountant, or shelves and draw- ers to the merchant. Botanical Nomenclature.—The Latin or Greek names which botanists employ are essential for the dis- crimination of plants, being equally received in all coun- tries, and belonging to all languages where science has a home. ‘They are made necessary, not only by the confu- sion of tongues, but by confusions in each vernacular. Botanical usage requires for each plant two names, one to specify the genus, another to indicate the species. Thus all oaks are designated by the Latin word Quercus, while the red oak is Quercus rubra, the white oak is Quercus alba, the live oak is Quercus virens, ete. REPRODUCTIVE ORGANS OF PLANTS. 329 The designation of certain important families of plants is derived from a peculiarity in the form or arrangement of the flower. ‘Thus the pulse family, comprising the bean, pea, and vetch, as well as alfalfa and clover, are called Papilionaceous plants, from the resemblance of their flowers to a butterfly (Latin, papilio). Again, the mustard family, including the radish, turnip, cabbage, water-cress, etc., are termed Cruciferous plants, because their flowers have four petals arranged like the four arms of a cross (Latin, cruz). The flowers of a large natural order of plants are arranged side by side, often in great numbers, on the expanded extremity of the flower stem. Examples are the thistle, dandelion, sunflower, artichoke, China-aster, etc., which, from bearing such compound heads, are called Composite plants. The Coniferous (cone-bearing) plants comprise the pines, spruces, larches, hemlocks, etc., whose flowers are arranged in conical receptacles. The flowers of the carrot, parsnip, and caraway are stationed at the extremities of stalks which radiate from a central stem like the arms of an umbrella ; hence they are called Umébelliferous plants (from umbel, Latin for little screen). § 2. THE FRUIT. Tue Frurr comprises the seed-vessel and the seeds, to- gether with their various appendages. Fruits are either dehiscent when the seed-vessel opens and sheds the seed or are indehiscent when it remains closed. The seed-vessel, consisting of the base of the pistil in its matured state, exhibits a great variety of forms and characters, which serve, chiefly, to define the diferent 330 HOW CROPS GROW. kinds of Fruits. Of these we shall only adduce such as are of common occurrence and belong to the farm. The Nut has a hard, leathery or bony indehiscent shell, that usually contains a single seed. Examples are the acorn, chestnut, beech-nut, and hazel-nut. The cup of the acorn and the bur or shuck of the others is a sort of fleshy calyx. The Stone-fruit, or Drupe, is a nut enveloped by a fleshy or leathery coating, like the peach, cherry, and plum, also the butternut and hickory-nut. Raspberries and bleckberries are clusters of small drupes. Pome is a term applied to fruits like the apple and pear, the core of which is the true seed-vessel, originally belonging to the pistil, while the often edible flesh is the enormously enlarged and thickened calyx, whose with- ered tips are always to be found at the end opposite the stem. The Eerry is a many-seeded fruit of which the entire seed-vessel becomes thick and soft, as the grape, currant, tomato, and huckleberry. Gourd fruits have externally a hard rind, but are fleshy in the interior. The melon, squash, and cucum- ber are of this kind. ? The Akene isa fruit containing a single seed which docs not separate from its dry envelop. The so-called seeds of the composite plants—for example, the sunflower, thistle, and dandelion—are akenes. On removing the outer husk or seed-vessel we find within the true seed. Many akenes are furnished with a pappus, a downy or hairy appendage, the remains of the calyx, as seen in the thistle, which enables the seed to float and be carried about in the wind. The fruit or grain of buckwheat is akene-like. The Grains are properly fruits. Wheat, rye, and maize consist of the seed and the seed-vessel closely united. When these grains are ground, the bran that REPRODUCTIVE ORGANS OF PLANTS. 331 comes off is the seed-vessel together with the outer coat- ings of the seed. Barley-grain, in addition to the seed- vessel, has the petals of the flower or inner chaff, and oats have, besides these, the calyx or outer chaff adher- ing to the seed. Pod is the name properly applied to any dry seed-ves- sel which opens and scatters its seeds when ripe. Sev- eral kinds have received special designations ; of these we need only notice one. The Legume is a pod, like that of the bean, which splits into two halves, along whose inner edges seeds are borne. The pulse family, or papilionaceous plants, are also termed leguminous, from the form of their fruit. THE SEED, or ripened ovule, is borne on a stalk which connects it with the seed-vessel. Through this stalk it is supplied with nutriment while growing. When ma- tured and detached, a scar commonly indicates the point of former connection. ; The seed has usually two distinct coats or integuments. The outer one is often hard, and is generally smooth. In the case of cotton-seed it is covered with the valuable cotton fiber. The second coat is commonly thin and delicate. The Kernel lies within the integuments. In many cases it consists exclusively of the emdryo, or rudimen- tary plant. In others it contains, besides the embryo, what has received the name of endosperm. The Endosperm forms the chief bulk of all the grains. If we cut a seed of maize in two lengthwise, we observe, extending from the point where it was attached to the cob, the soft ‘‘ chit,” 0, Fig. 68, which is the em- bryo, to be presently noticed. The remainder of the kernel, a, is endosperm; the latter, therefore, yields in ereat part the flour or meal which is so important a part of the food of man and animals. The endosperm is intended for the support of the do2 TOW CROPS GROW. young plant as it develops from the embryo, before it is capable of depending on the soil and atmosphere for sus- tenance. It is not, however, an indispensable part of the seed, and may be entirely removed from it, without thereby preventing the growth of a new plant. The Embryo, or Germ, is the essential and most important portion of the seed. It is, in fact, a ready- formed plant in miniature, and has its root, stem, leaves, and a bud, although these organs are often as undevel- oped in form as they are in size. As above mentioned, the chit of the seeds of maize and the other grains is the embryo. Its form is with dif_i- culty distinguishable in the dry seeds, but when they have been soaked for several days in water, it is readily removed from the accompanying endosperm, and plainly exhibits its three parts, viz., the Radicle, the Plumule, and the Cotyledon. In Fig. 63 is represented the embryo of maize. In A and B it is seen in section imbedded in the endosperm. C exhibits the detached embryo. The LRadicle, r, is the stem of the seed-plant, its lower extremity is the point from which downward growth proceeds, and from which the first true roots are produced. The Plumule, ec, is the central bud, out of which the stem, with new leaves, flowers, ete., is developed. The Cotyledon, 6, is in structure a ready-formed leaf, which clasps the plumule in the embryo, as the proper leaves clasp the stem in the mature | maize-plant. The coty- ledon of maize does not, however, perform the functions of a leaf; on the contrary, it remains in the soil during the act of sprouting, and its contents, like those of the endosperm, are absorbed by the seedling. The first leaves which ap- Fig. 63, REPRODUCTIVE ORGANS OF PLANTS. d0a pear above-ground, in the case of maize and the other grains (buckwheat excepted), are those which in the embryo were wrapped together in the plumule, where they can be plainly distinguished by the aid of a mag- nifier. It will be noticed that the true grains (which have sheathing leaves and hollow jointed stems) are monocot- yledonous (one-cotyledoned) in the seed. As has been mentioned, this is characteristic of plants with endoge- nous or inside-growing stems (p. 290). : The seeds of the Hxogens (outside-growers—p. 296) are dicotyledonous, 1. @, have two cotyledons. Those of buckwheat, flax, and tobacco contain an endosperm. The seeds of nearly all other exogenous agricultural plants are destitute of an endosperm, and, exclusive of the coats, consist entirely of embryo. Such are the seeds of the Leguminose, viz., the bean, pea, and clover ; of the Crucifere, viz., turnip, radish, and cabbage ; of ordi- nary fruits, the apple, pear, cherry, plum, and peach; of the Gourd family, viz., the pumpkin, melon and cucum- ber; and finally of many hard-wooded trees, viz., the oak, maple, elm, birch, and beech. We may best observe the structure of the two-cotyle- doned embryo in the ordinary garden- or kidney-bean. After a bean has been soaked in warm water for several hours, the coats may be easily removed, and the two fleshy cotyledons, ¢, c, in Fig.64, are found separated from each other save at the point where the radiele, a, is seen projecting like a blunt spur. On carefully breaking away one of the coty- ledons, we get a side view of the radicle, a, and plumule, 0, the former of which was partially and the latter entirely im- bedded between the cotyledons. The Fig. 64. plumule plainly exhibits two delicate leaves, on which the unaided eye may note the veins. Baek HOW CROPS GROW. These leaves are folded together along their mid-ribs, and may be opened and spread out with help of a needle. When the kidney-bean (Phaseolus) germinates, the cotyledons are carried up into the air, where they become green and constitute the first pair of leaves of the new plant. The second pair are the tiny leaves of the plum- ule just described, between which is the bud, whence all the subsequent aerial organs develop in succession. In the horse-bean (Vicia faba), as in the pea, the cot- yledons never assume the office of leaves, but remain in the soil and gradually yield a large share of their con- tents to the growing plant, shriveling and shrinking greatly in bulk, and finally falling away and passing into decay. § 3. VITALITY OF SEEDS AND THEIR INFLUENCE ON. THE PLANTS THEY PRODUCE. Duration of Vitality.—In the mature seed the em- bryo lies dormant. The duration of its vitality is very various. The seeds of the willow, it is asserted, will not grow after having once become dry, but must be sown when fresh; they lose their germinative power in two weeks after ripening. On the other hand, single seeds of various plants, as of sorrel (Oxvalis stricta), shepherd’s purse (7Vhlaspi aro- ense), and especially of trees like the oak, beech, and cherry, remain with moist embryos many months or sey- eral years before sprouting. (Nobbe & Haenlein, Vs. Che Xp. 79.) . Among the seeds of various plants, clover for example, which, under favorable circumstances, mostly germinate within one or two weeks, may often be found a number — which remain unchanged, sound and dry within, for months or years, though constantly wet externally. The REPRODUCTIVE ORGANS OF PLANTS. 335 outer coat of these seeds is exceptionally thick, dense, and resistant to moisture. If this coat be broken by the scratch of a needle the seed will shortly germinate. Ina collection of such seeds, kept in water, individuals sprout from time to time. In case of common sorrel (Rumex acetosella), Nobbe & Haenlein found that 10 per cent of the seeds germinated between the 400th and 500th day of keeping in the sprouting apparatus. The appearance of strange plants in earth newly thrown out of excavations may be due to the presence of such resistant seed, which, scratched by the friction of the soil in digging, are brought to germination after a long period of rest. Lyell states that seeds of the yellow Nelumbo (water lily) have sprouted after being in the eround for a century, and R. Brown is authentically said to have germinated seeds of a Nelumbo taken by him from Hans Sloane’s herbarium, where they had been kept dry for at least 150 years. The seeds of wheat usually, for the most part, lose their power of growth after having been kept from three to seven years. Count Sternberg and others are said to have succeeded in germinating wheat taken from an Egyptian mummy, but only after soaking it in ovl. Sternberg relates that this ancient wheat manifested no vitality when placed in the soil under ordinary cireum- stances, nor even when submitted to the action of acids or other substances which gardeners sometimes employ with a view to promote sprouting. Girardin claims to have sprouted beans that were over a century old. Itis said that Grimstone with great pains raised peas from a seed taken from a sealed vase found in the sarcophagus of an Egyptian mummy, presented to the British Museum by Sir G. Wilkinson, and estimated to be near 3,000 years old. Vilmorin, from his own trials, doubts altogether the authenticity of the “‘mummy wheat,” and it is probable 336 “HOW CROPS GROW. that those who have raised mummy wheat or mummy peas were deceived either by an admixture of fresh seed with the ancient, or by planting in ordinary soil, which commonly contains a variety of recent seeds that come to light under favorable conditions. Dietrich (Hoff. Jahr., 1862-3, p. 77) experimented with seeds of wheat, rye, and a species of Bromus, which were 185 years old. Nearly every means reputed to favor germination was employed, but without success. After proper exposure to moisture, the place of the germ was usually found to be occupied by a slimy, putrefying liq- uid. Commonly, among the freshest seeds, when put to the sprouting trial, some will mold or putrefy. The fact appears to be that the circumstances under which the seed is kept greatly influence the duration of its vitality. Ifseeds, when first gathered, be thoroughly dried, and then sealed up in air-tight vessels, there is no evident reason why their vitality should not endure for long periods. Moisture and the microbes that flourish where it is present, not to mention insects, are the agen- cles that usually put a speedy limit to the duration of the germinative power of seeds. In agriculture it is a general rule that the newer the seed the better the results of its use. Experiments have proved that the older the seed the more numerous the failures to germinate, and the weaker the plants it pro- duces. Londet made trials in 1856-7 with seed-wheat of the years 1856, *55, 54, and *53. The following table exhib- its the results : Number of stalks Per cent of seeds Length of leaves four days and ears per sprouted. after coming up. hundred seeds. Seedi@t U8b3e.e. 4-2-5 none ie COT Stat Sea ican 51 0.4 to 0.8 inches. 269 Ch EEC EAI RUDD Ny Sica ceaeias 73 152 ob 365 Tp Oe (a: eos mac 74 1.6 ae 404 The results of similar experiments made by Haberlandt on various grains are contained in the following table : REPRODUCTIVE ORGANS OF PLANTS. aoe Per cent of seeds that germinated in 1861 from the years: 1850 1851 1854 1855 1857 1858 1859 1860 "1G Gre Hage ae en 0 0 8 4 73 60 84 96 BIO) ots 5.20% ovaace eispoteaae 0 0 0 0 0 0 48 100 ALIS bccins seice ae 0 0 24 0 48 33 92 89 NUS S Ss Sis eee ies OO 0 56 48 72 o2 80 96 NURI Secnitosm aeons 0 nottried 76 56 not tried T77 100 97 Results of the Use of Long-kept Seeds.—The fact that old seeds yield weak plants is taken advantage of by the florist in producing new varieties. It is said that while the one-year-old seeds of Ten-weeks Stocks yield single flowers, those which have been kept four years give mostly double flowers. In case of melons, the experience of gardeners goes to show that seeds which have been kept several, even seven years, though less certain to come up, yield plants that give the greatest returns of fruit; while plantings of new seeds run excessively to vines. Unripe Seeds.—Experiments by Lucanus prove that seeds gathered while still unripe,—when the kernel is soft and milky, or, in case of cereals, even before starch has formed, and when the juice of the kernel is like water in appearance,—are nevertheless capable of germi- nation, especially if they be allowed to dry in connection with the stem (after-ripening). Such immature seeds, however, have less vigorous germinative power than those which are allowed to mature perfectly ; when sown, many of them fail to come up, and those which do, yield comparatively weak plants at first and in poor soil give a poorer harvest than well-ripened seed. In rich soil, however, the plants which dco appear from unripe seed, may, in time, become as vigorousas any. (Lucanus, Vs. Bb, UV pe 258.) According to Siegert, the sowing of unripe peas tends to produce earlier varieties. Liebig says: ‘‘ The gar- dener is aware that the flat and shining seeds in the pod of the Stock Gillyflower will give tall plants with single flowers, while the shriveled seeds will furnish low plants with double flowers throughout. 22 308 HOW CROPS GROW. Cohn found that seeds not fully ripe germinate some- what sooner than those which are more mature, and he believes that seeds in a medium stage of ripeness germi- nate most readily. Quick- and Slow-Sprouting Seeds.—When a con- siderable number of agricultural or garden seeds, fresh and of uniform appearance, are placed under favorable circumstances for germinating, it is usually observed that sprouting begins within two to ten days, and con- tinues for one or several weeks before all or nearly all the living embryos have manifestly commenced to grow. Nobbe (in 1886 and 1887) found in extensive trials with 12 varieties of stocks, Matthiola annua, that the quick- sprouting seeds, which germinated in three to four days, yielded earlier and larger plants, which blossomed with greater regularity and certainty, and produced a pre- ponderance (82 per cent) of sterile double flowers, while the slow-sprouting seeds, that were ten to twelve days in germinating, gave smaller plants that came later to bloom, and yielded 73 per cent of fertile single flowers. Should continued trials prove these results to be of constant occurrence, it is evident that by breeding exclu- sively from the quick-sprouting seeds, the double-flower- ing varieties should soon become extinct, from failure to produce seed. On the other hand, exclusive use of the slow-sprouting seeds would extinguish the tendency to variation and double-blooming, which gives this plant its value to the florist. Dwarfed or Light Seeds.—Miiller, as well as Hell- riegel, found in case of the cereals that light or small grain sprouts quicker but yields weaker plants, and is not so sure of germinating as heavy grain. Liebig asserts (Natural Laws of Husbandry, Am. Eid., 1863, p. 24) that ‘‘poor and sickly seeds will pro- duce stunted plants, which will again yield seeds bearing in a great measure the same character.” This is true ‘in the long run,” i. e., small or light seeds, the result REPRODUCTIVE ORGANS OF PLANTS. 339 of unfavorable conditions, will, under the continuance of those conditions, produce stunted plants (varieties), whose seeds will be small and light. (Compare Tuscan and pedigree wheat, p. 158.) Schubart, whose observations on the roots of agricul- tural plants are detailed in a former chapter (p. 263), says, as the result of much investigation, “the vigorous development of plants depends far less upon the size and weight of the seed than upon the depth to which it is covered with earth, and upon the stores of nourishment which it finds in its first period of life.” Reference is here had to the immediate produce under ordinary agri- cultural conditions. Value of Seed as Related to its Density.—From a series of experiments made at the Royal Agricultural College at Cirencester, in 1863-6, Church concludes that the value of seed-wheat stands in a certain connection with its specific gravity (Practice with Science, pp. 107, 342, 345, London, 1867). He found :— 1. That seed-wheat of the greatest density produces the densest seed. 2. The seed-wheat of the greatest density yields the greatest amount of dressed corn. 3. The seed-wheat of medium density generally gives the largest number of ears, but the ears are poorer than those of the densest seed. 4. The seed-wheat of medium density generally pro- duces the largest number of fruiting plants. 5. The saed- wheats which sink in water, but float in a liquid having the specific gravity 1.247, are of very low value, yielding, on an average, but 34.4 lbs. of dressed grain for every 100 yielded by the densest seed. 6. The densest wheat-seeds are the most translucent or horny, and contain about one-fourth more proteids (or 3 per cent more) than the opake or starchy grains from the same kind of wheat, or even from the same individual plant, or even from the same ear. : 340 TOW CROPS GROW. %. The weight of wheat per bushel depends upon many circumstances, and bears no constant relation to the density of the seed. a5, The densest grains are not, according to Church, always the largest. ‘The seeds he experimented with ranged from sp. gr. 1.354 to 1.401. Marek has shown that specific gravity is no universal test of the quality of seed, for while, in case of wheat, flax, and colza, the large seeds are generally the denser, the reverse is true of horse-beans (Vicia fasa) and peas (Vs. St., XIX, 40). The Absolute Weight of Seeds from different varieties of the same spacies is known to vary greatly, as is well exemplified by comparing the kernels of com- mon field maize with those of ‘pop corn.” Similar dif- ferences are also observable in different single seeds from the same plant, or even from the same pod orear. Thus, ‘ Harz obtained what were, to all appearance, normally developed ceeds that varied in weight as follows ; FROM SINGLE PLANTS. Milligrams. Wheat, Triticum vulgare, from 15 to 37 Wheat, Triticum polonicum, “ 21 to 55 Barley, Hordeum distichon, ES 31 to 41 Oats, Avena sativa, ae I9 to 30 Maize, Zea Mays cinquantino, s = 169 to 201 Pea, Pisum sativum, é sé: 148: to 502 FROM SINGLE FRUIT (PODS). BC Atencio ciclsisis Seth ere Soe eee ....from 309 to 473 ViGU Ch Skins istnia tactile sock aniee ee oe a 33 to 66 PAVDIN acy sia aaa cP ae ce tect Me eens 486 «to 639 Differences often no less marked are found among the seeds in any considerable sample, gathered from a large number of plants and representing a crop. Nobbe, with great painstaking, has ascertained the average, maxi- mum and minimum weights, of 180 kinds of seeds, such as are found in commerce or are used in Agriculture, Horticulture, and Forestry. The following table gives some of his results : REPRODUCTIVE ORGANS OF PLANTS. 341 Absolute Weight of Commercial Seeds. Number of Weight cf one Seedin Sanples Milligrams. Examined. Average. Maxunum. Minimum ATS Sates ah ale clas cues Gietein're. 84 28.8 BEAIC Vissi cicksis wiclelorerakeielen steieleieis ce 66 41.0 48.9 27.7 LRA ae Dee Ono aerng.e Hed cose 119 23.3 47.9 13.0 AVVAING idie ge iaiayois ave cai oeeiel< Oreleteimncine 95 37.6 45.8 15.2 VNC Siere chs ats viele ie oh wlesa © sveiele 22 282.7 382.9 114.5 ees oh eeks arene 39 22.0 2.4 14.2 Turnip, Brassica rapifera,.. 23 2.2 3.0 1.4 (CHIEN Oh americas Apeerios Mano cite 35 1.2 Mere 0.8 [222)-:| ce REaeeeeeneecmrdes oSccr 43 185.8 564.6 46.1 Kidney Bean, Phaseolus,.... 5 585.6 926.3 367.3 Horse Bean, Vicia,.......... 7 676.0 2061.0 256.4 OP ALO eee le =e, sieves s <2 Seid siereloisiorare 3 0.6 0.7 0.5 Bice ea tO tare) =< ws (m evsiniciel clei heisvels ae 5 2.5 2.7 2.4 OMIM OG orice jcrcig Sele cielo slelsieiersieye 4 6.9 9.0 2.4 MGS fiers class sne.a a's oe o5'6 Scie ays 5 thei 9.7 ar TANI COS jaa < oe2ic cist ac om ieieisic eters 18 api | ai 0.8 _PENES TAMAS speoce ope eGo Coon or 3 3.1 3.8 De DiC WEISS = eee BOG Ose abe caconcd 5 173.0 322.0 106.7 MMS Kes NRE TOM 5.5 sleusiccis si ccet + sieve 3 32.9 35.5 28.2 CRICUONDETS 3c ne sisliseies sedeaes 6 25.4 27.0 21.0 Timothy, Phlewn pratense,. 73 0.41 0.59 0.3 Blue Grass, /'oa pratensis, .. 28 0.15 0.21 0.10 FREOMOVONET ote, oie Oe Phosphor- Acid, Sulphurie Acid — eh HSSSS FESS SRHSON ary Clr CURD © G0 GO [s*) ARP AOOCON SD i=) el He He SD OUD BH Orw 1 Ome Rae =F= 9-9) Py PONNNWEN MT BabA SSSn o mp Silica. 1.1 0.2 1A 62 0.8 0.8 0.2 0.9 0.5 tote 0.7) 0.1 0.1! 5.5 0.8' 0.4 1.8) 0.9 pala 0.2 0.1 0.2. 0.4 0.1] 0.1 0.5' 0.3 pales 2.7 15.9 | + 1.5 24.7 2.3 18.5 1.8! 2.5 1.7| 1.8 1.9) 1.6 1.4! 3.0 4.5| 2.7 1.6] 1.6 3.6| 5.9 2.0)28.8 1.8'23.4 2.4113.1 1.2.18.2 1.1'31.0 1.6 18.8 2.7) 2.9 2.7) 2.9 3.5'50.4 0.1!66.4 74.7 0.1] 1.3 8.5] 8.1 2.2) 1.6 2.0| 1.7 0.6] 3.4 2.9 13.3 0.8[ 5.5 1.7) 6.4 cuca =] (Re Sana: a ARRON = io Ne ae ee ila Oo ee ee Rt WH RnHDAnN © HAwWhRWHwD oT RAN BP oo = rs) i Su eae NOW RS INDEX. Absorption by the root, 260, 269, 272 Acsess of air to interior of MATE be See sue ie et en enol Acstic Acid. SL tyAcdh cf heuretac nto Acetamide, . an outa, von dill Acids, Definition of te le vOl Acids, MeCSHLON UE sie wate as ome Be Aeidrelements; =... 9. . 22 « 127 INCI TYROUCTUSs |5 “5 )s" 5 ‘ys « 99 Adhesion, . 5 at s,s 9), 388 Agriculture, Art of. ae ka tsvst 1 Agricultural products, Compo- sition in 1,000 parts, 4 Agricultural Sciene er pone Olin t aAir-passages in plant, = als AGr=fOots, <... soc evupeiles INE BTiEs, Go SaniOe Ce ar CCR ero | PAM IIUUYA eee re4e ee: + fas Ze) Mw ee OO POMOMUPUMN ACCS Weis) so tet wae OD Albuminoids, Characters and composition, . 87, 104, 106 Albuminoids in animal nutrit- FOM,: ee . 108 Albuminoids, ‘Diffusion of. 403 Albuminoids in oat-plant, . 234 Albuminoids, Mutual relations QT ie a Nan ne i (07 Alb'minoids, Proportion of, in vegetable products, . . . 114 IOMMNOSC SS Se. ts ie St} LOL CAMILLE ce) Nes) wlio? . 305 Aleurone, . AR AR ee 110 Alkali- earths, : ae Ola too Alkali-earths, Metals of ay tee alloy, Alkali-me tals, Se ei ener UES reel atc: Alkalies,. . Suny Se priced ke! liste} Alkali- -proteids, cra eaet CAE Soe a 99 ACALOLAS,- . '. at) retncis a: aco Allylsulphocyanate, ol ip . 129 PAMMAMNNENT ay stes®! a> 6) ati ey @ 143 AUTEN, 5. os nt tere soe eS Aluminium phosphate, cae Cua So: Ze, AAT OS tele bs 6 6 «| SAIS TS ATT COHACOSs, sila 203 Ash-ingredients, Function of in plant, . one Ash- ingredients, State of, in WLaTiGe ye) <2) te toy el bins oe COG Ash of plants, ae ae 13, 126 Ash of plants, Analyses, Tables f iff: 16 (0) Ash of plants, Composition of, normal, . "177 Ash of plants, Composition of, variations in . 151 Ash, Proportions of, Tables, be Beer | Asparagin, ae ea 2 Ailes 16 Assimilation, . . on ea OO Atmosphere, Offices GES hs re eee Atoms,. . tr Seon ats fea cell Atomic W eight, Jib at wehy ak atone AVOUT aa ole rat De a cihee Md Daye aha eed) Barks 3) s eh tan Nelo muro estes Barium in plants, etfs Petvetis Bases, Definition of . . Bast-cells, Bast-tissue, 293, 295, 2 Bean, Leaf, Section of . . 308 BEAM, SCOC, woe, hens : 334 IDE ICEVin Meee t tote clus 9's O31 getain, . 2. 2 wee 116 siology, . Shier: iow eos a Bleeding of vine, CRs Ves es! Blood- Gi Dye bat AON As Sees (2! 30ne-blaek, . . Roy iceun 3 15 Boron, Borie UGC amine mae ie .210 Buds, Structureof |... .. . 283 Buds, Development under pres- SURG ys ih ite co. Lieb eiiie wetmeay HUGS (SUS ar ee codline Lher edition tat wener eam Butyric acid, .~. . « « « « « 412 Caesium, Action on oat, . . .209 Cattenn ste oe a Sy ee ody. Calcium, ao .139, 214 Caleium, carbonate, SP Ab ry bet cy 03) Galen) nyadroxide, )5 sm sues las Calcium, OXIGC ec pst te de nes Me aos Calcium, phosphate, . . . 28, 148 Calcium, sulphate, Seo ees de lets Caloms a 2M; We tse a sede Sake R OOS CAN EKS eBay stn dete beret © 2) Seeold Cambium, ee) ee ce eee 294, 295, 299 Cane-sugar,. . . elvis ein een Capillary attraction, by faieteere Reo, Carbanmrdles a7) tem tel > toe te Peo Welt OLD Carbhydrates, BAIN eA! nde Ge! Carbhydrates, Composition . . 72 re het Transformations AWW Coane TAL Chrhon, Properties of wa bakes Pile ke Carbonin asi.” we. 4ca uy tee. ake Warbondioxide, ) nmr ua 2 oe Carbonates; .—- i lias) que es. 144 Carbonate! or lime; oa « lee Carbonate of potash,. . . . .144 Carbonate Of 'Soda,.:. 3 3 2.21144 Carbonie acid, 19, 128 Carbonie acid as food of plant, 328 Carbonic acid in ash-analyses, 149 Carboxyl, . Me cot home AGH Thr GASES ss ie nee. cot) a eee) vod ab bie: ob WASCOSE ist oleh lies Yel vantaah (eaivide Cassava, . ej ei Causes of motion of juices, eye Well-conbemts,) o/s pied je fer ve vee Cell-multiplication, ... . . Cell astructure Of. |e" el We ce RAD CeMsSROrms: OF joo. ue) Ver sje vise seek CEellularsplamtsy. 5s Vas ote ven Legeaw CelmiarGissues ey cis. wl et a) 4-200 Cellulose, . . ARO Cellulose, Composition Ballon Ver peindet Cellulose, Estimation ... . 45 Gellulose nitrates, < 2 evs « 43 Cullulose sulphates,. ... . 43 Cellulose, Test for . . . 44 Cellulose, Quantity of, in plants, 46 Chemieal affinity, . . . 29 Chemical affinity overcome by osmose, . - . 403 Chemical combination, av cay tela, MO) Chemical dee OOS One Se are) CHEMISE, cepa ees 10 Chlorides, ‘ ‘ . 133, 149 Chloride of ammoniwun, decom- posedeby, jplamiiy a. suet ye slot: Chlorine, .. 4 5 By Chlorine essential to. crops ¢ 2. 194 Chlorine, function in plant, 218 Chlorine in strand plants, . .191 Chlorophyl, . 124, 307, 308 Chlorophyll requires iron, SRA) Chlorophyllan, c 125 Choline...) aes - 119 Cirenlation of sap, 369 CROTTCE TOTO pcnasmice ier scoirouten oC Citrates; ~.° . sae A 80, 149 Classes of plants, one P - 329 Classification botanical, oe 62D HOW CROPS GROW. Clover, washed byrain, . . . 204 Colloidisyri. ce. ie ben, ec COnelwehins fi o's wet Lent ae ee en Combustion, . So fa enue is) Composite plants, - oa Concentration of plant- food, 185 Coneretions in plant, .. . 205 Coniferous plants,. . .. . .d30 Copper in plants,... < \- sseeeO GOK We.” 5 Screg eo cs eye en es Gorm), 2. < “cles, scenes seems Corolla, “sis. s0 ve eye oh 3) te Cotyledon, . oe fb e290; aoe Coniferous plants, SEC renee 2!) Cryptogams,. . . « Olbnaed Crystalloid aleurone, a oF neha OCrystalloids,«, +... sha... Crystals in plant, ... . . =. .206 Cilmi; 3.65 va. se sees 284 MV AMICLES 5 di) sa cey, Lot Nolae ie olan oe melee Cyanogen,. . Definite proportions, Law of. . 30 Density Oseceds.y. aes Depth’ of sowing, «0.0 ae Dex, ssi SS ee eee WOXsGROSC,.< wa)'sehsssy eens . 63 Diastase, . Brat! ve "67, 103, "360 Diffusion of liquids, Meigs che! Dicecious plants; % 3). 96 = aesols Drains stopped by roots, . . .276 Drupe, . 331 Dry weather, Effect. of, on plants,. . Sab 157 IDWCUS SS oj Geter cate he oats . 255, 294 Dulcite, A : meet! Dundonald’s treatise on Agri- cultural Chemistry, .. . Elements of Matter, .... .°8 DUISY Os teli-se ho Sebunen os 300 ENOOMCUWSs) ~ thie) "959, 290, 334 IN GOSMOSC), <5, se) -s), seus somos INGOSPeLVmM, ss | se) 2) Beeler eee IDA AINE momar om oO on a 6 Wb Epidermis, . . oP ay eben aoe Epidermis of leaf, eo epee OUs EKremacausis, . Sct 740): Exeretions from roots, otis 280 Exhalation of water from foli- BONO wre eel oa ete WROPVEMS se ey | (eu bed ne 239, 293, 296, MOSMOSEy « . 394 Exudation of ash- ingredients, 203 Eyes of potato, . ... « =< «.» 20u WAMMTUNTES? 4 se, i. te, oe eee Natty acids, < co -eet ae Fats, Pec cote: Fats conver ted into starch, hes Fatin oatecrop, . oe reece!) Fat in Vegetable Products, Ap ieey fet Berments, 26%, us a eee Berrie Oxide, 5. . %., -404 Gelatinous Siliea,. .*. . - - 1386 Genus ; .. Sis Phra ictaetcte hin ice 42" Germ): . 62. Pe Eh eons Germination, é EMail iow COLO, Germination, Conditions of. . 351 Germination, Chemical Physi- Migay OF 5 vi yt es = pa aor Girdling, . ses opts Ae wey sor Glauber’ s Salt, A ERA Ee 146 Ginga eae ee re a Se 2 EGHowmolMie ie, cool e Pe eens laa DO GHICGSES.o.. fo ee ek Se UTCOSIES,, oe 15 Bs oa) of ce es 2m 69 GiloGamine se os se Cs tenis. es? at Se os SS” ote. OR Gluten-Casein, .... . GIG COTIy ee oo se Ss. a oy BB Giger es 5. es ee BO Gly cocoll, ie, scabishy ictctoNs stnetane LO Glycollie acid, ......- ~17 OME CseTIESs 2) cc es ese 331 Grains, . al Oe ORE ac aL Grape Sugar, ee oish ic) caer aembe GelOwalic woos 2 8s os Growth of roots, . . BAP Gum, Amount of, in plants, a4 CurmmeATADICs 6 os ess PE eta Gir hraracanih,,. . - 2, . - of CAMO OLLOII, es. shee ahs) mer 0, 48 Gypsum,. . +++ ++ s+ = 147 PIACMEhM,.. 2 6 ss), % 110 Hemoglobin, . . 5 109 Hallett’s pedigree wheat, 158, 344 Hybrid, Hybridizing, De Bes Vt Hydration of membranes, 396 Hydrochlori ie acid, . 23, 133 Hydroeyanic acid, . 129 Hydrogen, Fay Ad Hydrogen chloride, af Pea ae Hydrogen puaphide, i tebe co Imbibition, . . he Ne etal elec ODO: Imides, . Pa say eerie li Inorganic matter, ES tne petdle ret eves [ollie MPOMUOG ERA). 2. Mint wars Trade Pee eo oe Jewell at ed OD Invertin, F Gt Tas Nai Me on ee Todine in plants, wees | Loa akO Iodine, Solution of. ... . ... 44 Iron, eet 141, 192 Iron, Function of oF eee Pats 219 Isomerism,. . PP et pect ad Juices of the Plant, esa ACT AIGIO® Thr. Mucrita linen ste span Lactose, . at Dome clas cle lenik of Cel. ROS Latent buds, ’ ei sis) or Nar eid ea ae 285 TGREOX x). Coa | 10 | ee apm Te Layers, . Rl ian eethe. ceReee Lead in plants, — ci ois rey (siey) sp hee le Leaf pores, . Ere . 309 Leaves, Structure of sy. 2.1 306,508 Leaves, office in nutrition, . . 328 WE Cites a toe ek noes omne Legume,. . - + + + +» « Legumin,. . aie yr ne): Leguminous plants, Sig stoke cee Oee Leuc Moe ae ee ie tp oe oh ee fog Bane Beviulin, 3...’ a eee ee MEVANOSEs 9 te. 6) si ce Vediancna A Vitea yu agen Pee ae ree any a RN iil AMC en eer ee Sahl) Liquid Diffusion, Ga Ee to eo Lithia, Lithium, in plants, .209 Lupanin, Lupinin, Lae 120 Magnesia, . .. » - > .14 Magnesium, sh alee dank snake Magnesium hydroxide,. . . Magnesium ORME, ee an es Maize AiloRLy. Wy.) spicdhers) ce beeen Rene: NIDIATCS, isc ixeus "en sl emer nts WiRWROe Eel UA NA oe yo ele Matonie?r acids: ~)s.0e see sn eae Malt, Chemistry of .. .. «35 IMaLtOSGs 2s Teele) eu. spe oho saul Manganese, .. ..- « ~ 142,193 1 Ga aW iy {eee AR IEW EP N he otf: NEAMNTMOSE;.c2 . 6. oe ae ep eae MarPrasiais Sc + Maa scan ieee Medullary rays,. ... .- Z Membrane-diffusion, . . 393, 397 Membranes, Influence on mo- TLON OH JUICES) "2" 2) . 404 Metals, Metallic elements, | alee Metapectic acid, 605) 50..) s+) oo Mctarabiliye 2.) ieteetisiiss tte daa Oo ” (140, 215 141 NG GIGS rene oeen sie 304 Milk Sugar, . . 68 Molecules, Molec ular Weights, 32 Moneecious plants, .. . . 319 Motion caused by adhesion, . .389 Muecedin, . . se su eeorl Multiple Proportions, Wet rales oe Muriate’of potash, <1 Starch, Propertiesof ... . Starch, Test for . «9. + «12 . 49 Stearic acid,. « « « « « « « 86 SEGA) ohs as sane ae va /caiv)o Pe aeheatat veneer SUIGICCTS5 fe cif ta lgeht e's) relays Suecroses, . ASS Sugar, Estimation hi a a Sugar, in cereals,. . . « . « 69 Sugar TTS AO stots oh coh etemiey are Sine of milk.) Ab ee) at a: ell eh Sulphate of lime, .~ . . - .146 Sulphate of potash, . . . . . 146 Sulphate of soda, .. . . 146 Sulphates,. . ares 26, 131, 146 Sulphates, Function Ob ae aU Sulphates reduced by plant, . 208 Sulphides,. . thes Fe 26, 130 Sulphide of potassium, se) Be S30 Swiphitess (. . kh. a) od uee2o Spur cla ge. EMalile s! 0 2p kee Sulphur in oat, A eto hon at Sulphur dioxide, Auer: spas) Sulphureted hydrogen, . .26, 115 Sulphurets,. 66h i ts Se = Cee BO Sulphuric acid, . ... . 26, 130 Sulphuric acidin oat, . . . .208 Sulphurie oxide (SOx), fe « 209 Sulphur trioxide (SOx), . . .25, 130 Sulphurous acid, . . . . . 25,129 Symbols, Ghemicaly yey < acsee ol PAG LOG A ke ois cl eet ae ae Ma plOGay os elven tenes ooops panee MAp-TOOUS, cs) <0) «fu leu ’s beh ole ae Mar tare ACs soveianle: vomcel fee OU Ste Ae RRO psu urh om oko) Moll Caaich oo telly Tassels. Of MAIZE, « «i= - s old Theobromin,. .. . Sek 118 Palleriatay 5 =) valwenctos Act's (pay arene Abn one BVOC as Vogel ot be ley dinicshonuonoos oor : . 187, 209 Translocation ‘of. substances in plant,. . .- + + es > 237 MPV PEM ae abe al hat ete ergs eel oh Nea Tubers, : AP tn om iran, Hele, Tuscan hat- wheat, Baeee hlos, Olas Tyrosin, . eG Ultimate Composition of Vee- fable Mathers. «ses pelonao Umbelliferous plants,. . . . 330 Unripe seed, Plants from. . .338 | Rea Bee tae wae bar eer een ee Mees Walenees c. cia’ ve - 3D Warietiess,: <3 5 ‘<.s .158, 326, 327 Vascular bundle of maize spailc.: Suiits glia hee ve ees aoe Vascular- TISSUC ss Metis us sxe Vegetable acids, . . ... . % Vegetable albumin, « - « + Vegetable casein,. . . . . . 94 Vegetable CElem cu as ceuiicl ae Vegetable fibrin, atl View eit ae lena Vegetable globulins, Sura, sah pears hay Vegetable mucilage,. OR i) Shy Mle Tt Vegetable myosins, « «© « « 416 Vegetable parchment,. . . . 44 Vegetable tissue, .... . .246 Vegetative organs, .. . . 243 Vernin, SV Ao -118 WAGIM re as alee 120 Vitality of roots, BS onary ation (are MitalibyzOr SCCUS a. aimee Witelinny vc.) ts 5, )- a) Dowie OD Water, Composition Gf. Gieaeeen Water, Estimation of .. . .39 Water, Formation of . ./. . 24 Water in air-dry plants. Water in fresh plants,.... 38 Water in vegetation, Free. . . 39 Water in vegetation, Hygro- SCOMIC, 47a> Saline see, Meer tease HOW CROPS GROW. Wiater-OVen, se os) a oe Water-culture, 272.2.) 2) 5 eae Wiater-Glasgs, ic iletc euler yore menace Water Roots,.'< (6 6.0.00 eee Wass i Sey par veto coe SES \WAclore PER ura OO Noreo geull, Sus Woodeells, . . a ee ees Wood cells of conifers, cae: 301 Woody. ‘stems, <> evs feels WiOOdy, LISSUC, <5 ecm cnn eens >. GA bl mie Cae folds oo. 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It contains a complete de- seription of all the recognized varieties of fowls, including turkeys, ducks and geese; gives instructions to judges; glossary of technical terms and nomenclature. It contains 244 pages, handsomely bound in cloth, embellished with title in go'@ om front cover. $1.00 Stoddard’s An Egg Farm. By H. H. Stoddard. The management of poultry in large numbers, being a series of articles written for the AMERICAN AGRICULTUR- Ist. Lliustrated. Cloth, t2mio. a STAT DARD BOOKS. Stewart’s Shepherd’s Manual. A Valuable Practical Treatise on the Sheep for American farmers and sheep growers. It isso plas that a farme: or a farmer’s son who has never kept a sheep, may learn from its pages how to manage a flock successfully, and yet so complete that even the ex. perienced shepherd may gather many suggestions from it. The results of personal experience of some years with the characters of the various modern breeds of sheep, and the sheep raising capa bilities of many portions of our extensive territory and that of Canada—and the careful study of the diseases to which our shecp are chiefly subject, with those by which they may eventually be afflicted through unforseen accidents—as well as the methods of management called for under our circumstances, are carefully described. By Henry Stewart. Illustrated. Cloth, 12mo. 1.50 Wright’s Practical Poultry-Keeper. | By L. Wright. A complete and standard guide to the management of poultry, for domestic use, the markets or exhibition. It suits at once the plain poulterer, who must make the business pay, and the chicken fancier whose taste is for gay plumage and strange, bright birds. Illustrated. Cloth, 12mo. $2.00 Harris on the Pig. New Edition. Revised and enlarged by the author. The points of the various English and American breeds are thoroughly discussed, and the great advantage of using thoroughbred males clearly shown. The work is equally valuable to the farmer who keeps but few pigs, and tothe breeder on an extensive scale. By Joseph Harris. Dllustrated. Cloth, 12mo. 1.50 The Farmer’s Veterinary Adviser. A guide to the Prevention and Treatment of Disease in Domestic Animals. This is one of the best works on this subject, and is es- pecially designed to supply the need of the busy American Farm er, Who ean rarely avail himself of the advice of a Scientific Veter inarian. Itis brought up to date and treats of the Prevention of Disease as wellas of the Remetlies. By Prot. Jas. Law. Cloth. Crown, 8vo. 3.00 Dadd’s American Cattle Doctor. sy George H. Dadd, M. D., Veterinary Practitioner. To help every man to be his own ecattle-doctor; giving the necessary information for preserving the health and curing the diseases of oxen, cows, sheep and swine, with a great variety of original recipes, and val: uable information on farm and dairy management. Cloth, 12mo. 1.50 Cattle Breeding. By Wm. Warfield. This work is by common consent the most valuabie and pre-eminently practical treatise on cattle-breeding ever published in America, being the actual experience and ob-~ servance of a practical man. Cloth, 12mo. 2.00 STANDARD BOOKS, Dadd’s American Cattle Doctor. A complete work on all the Diseases of Cattle, Sheep and Swine, ins cluding every Disease pecwiar to Ainerica, and embracing all the latest information on the Cattle Plague and Trichina; containing also a guide tosymptoms,a table of Weights and Measures, and a list of Valuable Medicines. By George H. Dadd, V.58., twenty-five years ..seading Veterinary Surgeon in England and the United States, and author of the *“‘American Retormed Horse Book.’ Cloth, octavo. Llustrated. 2.50 Cattle and Their Diseases. By A.J. Murray, M.R.C. V.S. Breeding and Management of Cat- tle. This is one of the very tew works devoted exclusively to eattle diseases, and will be particularly valuable to cattlemen for that reason. Ltis written in plain, simple language, easily un- derstood by any farmer, while it is learned and technical enough tu satisfy any veterinary surgeon. Cloth, 12mo. 2.00 Silos, Ensilage, and Silage. A practical Treatise on the Ensilage of Fodder Corn, containing the most recent and authentic information on this important sub- ject, by Manly Miles, M. D. F. R. M.S. Lllustrated. Cloth, 12imno. .50 Mauures. How to Make and How to Usethem. By Frank W. Sempers. ‘The author has made a concise, practical handbook containing the lat- est researches in agriculture in al] parts of the world. The reports ef the agricultural experiment stations have furnished many val- uable suggestions. Both commercial and home-made manures are fully described, and many formulas for special Crops and souls are given. Price postpaid, paper 50 cents, cloth. 1.00 Potato Pests. No farmer ean afford to be without this little book. It gives the most complete account of the Colorado Beetle anywhere to be found, and ineludes all the latest discoveries as to the habits of the insect and the various means for its destruction. It is well illustra- ted, and exhibits in a map the spread of the insect since it left its native home. By Prot.C. V. Riley. Paper. 00 Your Plants. Plain and Practical Directions for the Treatment of Tender and Hardy Plants in the House and in the Garden. By James Sheeban. The work meets the wants of the amateur who grows a few piants in the window, or has asmall flower garden. Paper covers. AC Pedder’s Land-Measurer for Farmers. A convenient Pocket Compat.ion, showing at once the contents of any piece of land, when its length and width are unknown, up to 1500 feet either way, with various other usetul tarm tables. Cloth, 18mo. 8 STANDARD BOOKS, Hop Culture. Plain directions given by ten experienced cultivators, Revised, enlarged and edited by A. 5S. Fuller. Forty engravings. 30 Wheat Culture. How to double the yield and increase the profits. By D.S. Curtiss, Washington, D.C. Importance of the Wheat Crop. Varieties Most Grown in the United States. Examples of Successful Wheat Cul- ture. Illustrated. Paper covers. 50 Starr’s Farm Echoes. By F. Ratchford Starr, Echo Farm, Litchfield, Ct. This handsome little book tells how the author turned from a successful business career to agricultural pursuits, and has achieved health, happiness and prosperity upon his broad acres near Litchfield. Cloth, 12mo. Illustrated. 56 The American Merino. For Wool or for Mutton. A practical and most valuable work on the selection, care, breeding and diseases of the Merino sheep, in all sections of the United States. It is a full and exhaustive treatise upon this one breed of sheep. By Stephen Powers. Cloth, 12mo. 1.50 Coburn’s Swine Husbandry. New, revised and enlarged edition. The Breeding, Rearing, and Management of Swine, and the Prevention and Treatinent of their Diseases. Itisthe fullest and freshest compendium relating to Swine Breeding yet offered. By F. D. Coburn. Cloth, 12mo. 1.75 Tobacco Culture: Full Practical Details. This useful ana “aluable work contains full details of every process from the Selection and Propagation of the Seed and Soil to the Harvesting, Curing and Marketing the Crop, with illustrative en- gravings of the operations. The work was prepared by Fourteen Experienced Tobacco Growers, residing in different parts of the country. Lt also contains notes on the Tobacco Worm, with Illus- trations. 8vo. 25 Keeping Qne Cow. A collection of prize Essays and Selections from a number of other Essays, with editorial notes, suggestions, ete. This book gives thie latest information, andin a clear and condensed form, upon the Inanagement of a single Milch Cow. Illustrated with tull page en- gravings of the most famous dairy cows. Cloth, 12mo. 1.00 Guenon’s Treatise on Milch Cows. A treatise on the Bovine Species in General. An entirely new translation of the last edition of this popular and instructive book. By Thomas J. Hand, Secretary of the American Jersey Cattle Club. With over 100 illustrations, especially engraved for this work. Cioth, limo. 1.00 en x: * one a? Lar pe LEU oA mt * ts Hert TE 4 Se s\ Ky ty A . A tete A at “3 oy x fae fy ri Areacie se peires Baie WONG eR SG Ne PR OT eth, . xy fois, ile EE Ye 4 ah yt ; Hs ee SNA 4 MS Sa = ae * ST OEPES \ fa ce, an pints! A f 4 - ; i! Sire “a yi * mt NSP ES RY ‘ ~ 1 ta A ; js : $ pan } iw OG CHA Ee Dales sO Re. 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