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AMERICAN ~~ .-- JOURNAL OF BOTANY OFFICIAL PUBLICATION OF THE BOTANICAL SOCIETY OF AMERICA EDITORIAL COMMITTEE C. E. ALLEN, Editor-in-Chief University of Wisconsin WILLIAM CROCKER, L. R. JONES, University of Chicago University of Wisconsin C. Stuart GaAGER, Business Manager ARTHUR H. GRAVES, Brooklyn Botanic Garden Brooklyn Botanic Garder R. A. HARPER, JacoB R. SCHRAMM, Columbia University Cornell University C. L. SHEAR, Bureau of Plant Industry (Representing American Phytopathological Society) VOLUME VIII—1921 WITH TWENTY-SIX PLATES AND NINETY-FIVE TEXT FIGURES PUBLISHED IN COOPERATION WITH THE BOTANICAL SOCIETY OF AMERICA BY THE BROOKLYN BOTANIC GARDEN Ar 41 Norta Queen Street, LANCASTER, Pa. qo PRESS OF THE NEW ERA PRINTING COMPANY LANCASTER, FA. TABLE OF CONTENTS, VOLUME VIII, 1921 No. 1, JANUARY The fixation of free nitrogen by green plants (with one text figure and Plate I)... 0... eee cee nee ees lean FRANK B. WANN Variations in the osmotic concentrations of the guard cells during the opening and closing of stomata (with seven text figures) . a R.. G. WIGGANS The Linnaean concept of pearl millet................ AGNES CHASE The effect of cloudiness on the oxygen content of water and its sig- nificance in cranberry culture (with three text figures) : H. F. BERGMAN No. 2, FEBRUARY Influence of temperature un the relations between nutrient salt pro- portions and the early growth of wheat......... W. F. GERICKE The vascular anatomy of dimerous and trimerous seedlings of Phaseolus vulgaris (with twenty-three text figures) J. ARTHUR HARRIS, EDMUND W. SINNOTT, JOHN Y. PENNYPACKER, and G. B. DURHAM Aspergillus flavus, A. oryzae, and associated species (with one text figure)............ CHARLES THOM and MARGARET B. CHURCH No. 3, MARCH A study of Rhus diversiloba with special reference to its toxicity (with two text figures and Plate II).............. JaMEs B. MCNAIR The effect of salt proportions and concentration on the growth of Aspergillus niger (with six text figures)....... C. M. HAENSELER Suggestions with respect to the measurement of osmotic pressure (with one text figure)........... L. KNUDSON and S. GINSBURG Thick-walled root hairs of Gleditsia and related genera (with three text figures)... 0... ee een W. B. McDouGALL A simple method for growing plants (with one text figure) J. M. BRaNnNon No. 4, APRIL The morphology and anatomy of Rhus diversiloba (with Plates ITI ANd IV)... ete eee JamEes B. McNAIR PAGE 30 4I 50 59 63 103 127 147 164 171 176 179 1V TABLE OF CONTENTS Distribution of the Malvaceae in southern and western Texas (with one text figure).... 0... 0.0.0... cee eee eee HERBERT C. HANSON Note on the histology of grain roots (with four text figures) GracE A. DUNN North American Pipers of the section Ottonia (with Plates V-VIII) WILLIAM TRELEASE Monocarpy and pseudomonocarpy in the cycadeoids (with one text figure and Plates IX-XII).................... G. R. WIELAND No. 5, May Isoachlya, a new genus of the Saprolegniaceae (with Plates XIII and XIV)... ce eee eee C. H. KAUFFMAN The transmission of Rhus poison from plant to person JamMEs B. MCNAIR The type concept in systematic botany............ A. S. HitTcHcock The relation of certain nutritive elements to the composition of the oat plant (with two text figures)........ JAMES GEERE DICKSON No. 6, JUNE Specialization and fundamentals in botany. . JOSEPH CHARLES ARTHUR Certain aspects of the problem of physiological correlation C. M. CHILD Water deficit and the action of vitamines, amino-compounds, and 192 207 212 218 231 238 251 256 275 286 salts on hydration..................000005 D. T. MacDouGAaL 296 The eusporangiate ferns and the stelar theory (with seven text figures) . D. H. CAMPBELL The relation of plant pathology to human welfare..... F. L. STEVENS No. 7, JULY The relation of crop-plant botany to human welfare 303 315 CARLETON R. BALL 323 Correlations between anatomical characters in the seedling of Phaseolus vulgaris (with eight text figures) J. ARTHUR Harris, EDMUND W. SINNOTT, JOHN Y. PENNYPACKER, and G. B. DURHAM A quantitative study of the effect of anions on the permeability of plant cells II (with one text figure) .......... ORAN L. RABER The mechanism of root pressure and its relation to sap flow JAMES BERTRAM OVERTON No. 8, OCTOBER The vascular anatomy of hemitrimerous seedlings of Phaseolus vulgaris J. ARTHUR HarRIs, EDMUND W. SINNOTT, JOHN Y. PENNYPACKER, and G. B. DurHAM 339 366 369 375 TABLE OF CONTENTS Vv The effect upon permeability of polyvalent cations in combination with polyvalent anions (with one text figure)........ ORAN L. RABER 382 The floral anatomy of the Urticales (with Plates XV—X X11). ALBERT REIFF BECHTEL 386 Genetic evidence of aberrant chromosome behavior in maize endo- sperm (with one text figure).................. R. A. EMERSON 4II No. 9, NOVEMBER The interrelationship of the number of the two types of vascular bundles in the transition zone of the axis of Phaseolus vulgaris (with two text figures) J. ARTHUR HARRIS, EDMUND W. SINNOTT, JOHN Y. PENNYPACKER, and G. B. DURHAM 425 Area of vein-islets in leaves of certain plants as an age determinant (with Plate XXIII).............. 0.2... ee eee M. R. ENSIGN 433 Unusual rusts on Nyssa and Urticastrum (with six text figures) E. B. MAINS 442 Miscellaneous studies on the crown rust of oats (with Plate X XIV) G. R. HOERNER 452 Comparative studies on respiration XVIII. Respiration and antagonism in Elodea (with two text figures).................. C. J. Lyon 458 The effect upon permeability of (I) the same substance as cation and anion, and (II) changing the valency of the same ion (with two text figures)... 0... cee eee eens ORAN L. RABER 464 No. 10, DECEMBER Pollen and pollen enzymes................... JuL1a BAYLEsS PATON 471 The embryogeny of Cyrtanthus parviflorus Baker (with Plates XXV ‘ and XXVI)... 0... . cee eee eee Wn. RANDOLPH TAYLOR 502 Studies on plant cancers III. The nature of the soil as a determining factor in the health of the beet, Beta vulgaris, and its relation to the size and weight of the crown gall produced by inoculation with Bacterium tumefaciens (with nine text figures) MICHAEL LEVINE 507 Index to Volume VIII... 0... ccc ce ee ene eens 526 (Dates of publication: No. 1, Mar. 9; No. 2, Mar. 19; No. 3, Apr. 3; No. 4, Apr. 30; No. 5, May 24: No. 6, June 30; No. 7, Aug. 31; No. 8, Nov. 14; No. 9, Dec. 19; No. 10, Feb. 15, (1922.) vi ERRATA, VOLUME VIII ERRATA, VOLUME VIII Page 31, table I: Eryngium campestra should be Eryngium campestre. Page 145, 7th line should read: 26. Hooker, W. J. Flora boreali-americana 1: 126, 127. London, 1833. 8th and gth lines should read: 27. Hooker, W. J.,and Armott,G.A.W. The botany of Captain Beechey’s voyage, part 3, p. 137. London, 1841. 28th line should read: . Lyon, W.S. The flora of our southwestern archipelago II. Bot. Gaz. 11 330-336. 1886. Page 146, 9th line should read: London, 1838. In line 14: New Yor should be New York. Page 195, line 26: Malva parvifolia should be Malva parviflora. Page 231, Ist line of text After Kauffman, add and Coker Page 274, 3d line should read: Wolff, E. 1871. Aschen Analysen 1: 1-149; 2: I-170. Page 451, 18th line: Urticastrt should be Dicentrae motic. concentrations of the ne guard dels ce the prin ees pate Hig e aT ea fe RG, ee he oxygen content ot water and ay. gsicane fi rth : rb iets ude ‘AMERICAN. baie _ JOURNAL. OF BOTANY Devore TO Au Brancues OF [aE Scrence Esranuisnsn tH EDITED BY A COMMITTEE OF THE BOTANICAL’ SOCIETY OF ‘AMERICA EDITORIAL COMMITTEE C..E. Auven, Editor-in-Chief, University of Wisconsin” oa » ’ ye Wrbitam Crocker, ea er Wek ty >), ReJongs; lo ) Oniversity of Chicago OEP OS? Oniversity of Wisconste | C. Stuarr Gacér, Business Manager : ORLAND E, Waits, _ Brooklyn Botanic Garden” te “Brooklyn Botanic Garden Ry: AHA RB RR, 8 tee Jacon R, ScHRAMM, Columbia University be Cornell alesis eta he P c, Le guna Bukean of Plant Industry The, Journal is, ‘published thonthly except during August and September. _ Subscription price, $6.00 a year. Single copies 75.cents. Back numbers, 75 cents | each; $6,002. volume, 1 postane extra.'.Postage will be charged to all foreign countries, ’ except Mexico, Cuba, Porto Rico, Panama Canal Zone, Republic of Panama, Hawaii, Philippine Islands, (Guam, Samoan Islands, and Shanghai. © Postage to Canada, _.20 cents a volume on annual subscriptions; to all other countries in the Postal Union, 40 cents a volume on annual subscriptions. The pages of the Journal are open to members of ‘the Botanical Society of America, or to candidates approved for membership. 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WANN (Received for publication July 3, 1920) The ability of chlorophyll-bearing plants to utilize the uncombined nitrogen of the atmosphere has been repeatedly investigated during the last three or four decades, and the results of numerous observations and experiments, covering a wide range of species, have been quite conflicting. In some of the earlier experiments with higher plants in pot cultures the beneficial effect of a surface layer of algae was often observed, and the ability to increase the nitrogen content of the soil by free nitrogen fixation was ascribed to members of both the blue-green (Cyanophyceae) and grass- green (Chlorophyceae) algae. Similar increases in soil-nitrogen content were observed when higher plants were excluded from the cultures, and, though bacteria were known to be present, the fixation was generally ascribed to the chlorophyll-containing forms. More recently, pure cultures of members of the Chlorophyceae have been used but the results in these cases have been almost uniformly negative. . This fact, together with the discovery of widely distributed soil bacteria of the Azotobacter and Clostridium types, the ability of which to fix free nitrogen can not be ques- tioned, has led to the belief that in impure cultures fixation is due not to the activities of the green plants but to the bacteria present in the soil. Thus it has come to be very generally accepted that members of the Chloro- phyceae, as well as the higher plants, are not able to use free nitrogen. However, the number of species which have been investigated in pure culture is small, and the culture methods employed have not always been those which are most favorable for the best growth of these organisms. Accordingly the experiments reported here were undertaken for the purpose of extending the observations over a larger number of species, grown on a variety of mineral nutrient solutions under culture conditions which would insure a rapid and vigorous growth. LITERATURE A complete, and in some cases detailed, review of the literature bearing on the relation of the grass-green algae (Chlorophyceae) to free nitrogen is available in a paper by Schramm (1914 a), so that a repetition of the account is unnecessary here. Nothing of importance relating to this subject has [The Journal for December (7: 409-468) was issued January 12, 1921.] I 2 AMERICAN JOURNAL OF BOTANY [Vol. 8 appeared, so far as the author is aware, since the above-cited paper. As has already been indicated, the results of experiments with pure cultures have been pretty generally negative as regards the ability of these forms to increase the nitrogen content of the culture. In the light of results pre- sented here, some of the previous experimental work will be considered in the general discussion to follow. METHODS Seven species of Chlorophyceae were isolated and used in pure culture. In making the isolations the plate culture method, as described by Schramm (1914 6), wasemployed. With the exception of one species, Protococcus sp., all isolations were made from growths occurring on soil; the material for the Protococcus culture was secured from the bark of an elm tree. The absolute identity of all the species has not as yet been determined. Cultures have been submitted to several authorities on the group, but for some of the forms the determinations received have been somewhat at variance. For that reason no attempt has been made to apply specific names to all the organisms. Moreover, as will be apparent later, the abso- lute identity of the forms, though highly desirable, does not become of paramount importance because of the very similar way in which all the species seem to react. Unless otherwise indicated, therefore, the different species will be referred to by number and genus, or by number only, and as soon as more satisfactory determinations can be made a list will be pub- lished, if possible, in this journal. The forms used in the experiments include the following: Species number 1. Chlorella vulgaris Beyr. There seems to be no doubt about the identity of this species. Species number 2. Sttchococcus sp. Species number 3. Protostphon botryoides (Kg.) Klebs. Species number 5. Chlorella sp. A small form with cup-chaped chro- matophore. Species number 6. Scenedesmus sp. Species number 7. Protococcus sp. Species number 11. Chlorella sp. A large form with clathrate chro- matophore. All these species have been carried along on mineral nutrient agar for two or three years; they have been repeatedly transferred to media con- taining glucose or sucrose, and have frequently been examined micro- scopically. They are known to be free from bacteria and are pure cultures in the strict sense. Culture Media.—In the experiments Kjeldahl flasks of Pyrex glass and of 500 cc. capacity were used as culture flasks, because of the obvious advantage of analyzing checks and cultures without transferring the material to a digestion flask. Approximately 150 grams of mineral nutrient agar were supplied as a medium for each culture. In spite of the difficulties Jan., 1921] WANN — FIXATION OF FREE NITROGEN 3 involved in its analysis, a solid medium was chosen because of the very long-continued, vigorous growth produced on it. So far as has been observed, solution cultures, at least when unaerated, do not give a very extended or abundant development of these organisms. Since many pre- vious experiments have also shown that these forms do not grow in pure culture in the complete absence of combined nitrogen, no attempt was made to include such cultures in the experiments. Two experiments were performed, the first in the winter of 1917-18 and the second in the summer of 1919. In both cases the following mineral nutrient solution was employed as a standard for the preparation of the media: NHgNO g. 2.000 ce cece eee e eee e nee neeeeteennaag 0.5 gram MgSQ,. 2... en eee ene n tne n eee e en ees 0.2 gram K;3HPQ,........... Lc ene e nee e eee e nee e tee een eens 0.2 gram CaCle. 0 eect cence nen en nee eee ee nes 0.1 gram ) SS) O 7 trace Distilled water... 0... kee eee tee ee ten nees 1000 cc. With the nitrogen content of this solution as a basis, the NH,NO3 was replaced in the various series of 1917-18 by glycocoll, asparagine, (NH,)2SO,, and Ca(NOs3)2, and by urea, (NH,)2SQ,, and Ca(NOs)e in 1919, the nitrogen content as such being approximately the same in all media. Each of these sources of nitrogen was used in duplicate series, to one of which glucose was added. (In 1919 NHiNOs, (NH,)2SQu,, and Ca(NOs)e were also used in series to which mannite was added.) No change was made in the other constituents of the full nutrient solution, so that in all series these salts were present in the proportions indicated above. The 1917-18 experiment included the following series, arranged according to nitrogen sources and presence or absence of glucose: Series 1. Glycocoll (1.07 gr. per liter)—no glucose. Series 14. Same solution, with 1 percent glucose. Series 2. Asparagine (0.942 gr. per liter)—no glucose. Series 2A. Same solution, with 1 percent glucose. Series 3. Ammonium sulphate (0.942 gr. per liter)—no glucose. Series 3A. Same solution, with 1 percent glucose. Series 4. Ammonium nitrate (0.5 gr. per liter)—no glucose. Series 44. Same solution, with 1 percent glucose. Series 5. Calcium nitrate [Ca(NOs)2.4H,O, 1.475 gr. per liter]|—no glucose. Series 5.4. Same solution, with 1 percent glucose. In making up the media for the above series, sufficient nutrient solution with any one nitrogen source was prepared to supply both the series without glucose and the series with glucose. For these solutions the required amounts of the several constituents, with the exception of ferrous sulphate, were weighed out individually and dissolved in the proper volume of distilled water. (A stock solution of ferrous sulphate was prepared by dissolving 4 AMERICAN JOURNAL OF BOTANY [Vol.