PROCEEDINGS OF THE VOLUME XXI EDITED BY THE SECRETARY PUBLISHED BY THE STATE DES MOINES . Robert Hendbbson, State Printer I ,,, .. 'Vi'":',' -' ;:'''' W’" 'M PROCEEDINGS OF THE Iowa Academy of Science FOR 1914 VOLUME XXI EDITED BY THE SECRETARY '-if'' ( ■ I ■ 4 i9i-'r PUBLISHED BY THE STAmi^^„j,| DES MOINES* ROBERT HENDERSON, STATE PRINTER 1914 LETTER OF TRANSMITTAL. Des Moines, Iowa, July 1, 1914. To His Excellency, George W. Clarke, Governor of Iowa: In accordance with the provisions of title 2, chapter 5, section 136, code supplement, 1907, I have the honor to transmit herewith the pro- ceedings of the twenty-eighth annual session of the Iowa Academy of Science and request that you order the same to be printed. Respectfully submitted, James H. Lees, Secretary Iowa Academy of Science. IOWA ACADEMY OP SCIENCE iii OFFICERS OF THE ACADEMY. 1913. President — C. N, Kinney. First Vice President — H. S. Conaed. Second Vice President Albeet. Secretary — L. S. Ross. Treasurer — Geoege P. Kay. EXECUTIVE COMMITTEE. Ex-officio — C. N. Kinney, H. S. Conaed, Heney Albeet, L. S. Ross, Geoege P. Kay. Elective — E. N. Wentwoeth, E. J. Cable, A. G. Smith. 1914. President — H. S. Conaed. . ■ . . . First Vice President — H. M. Kelly.' Second Vice President — L. S. Ross. Secretary — James H. Lees. Treasurer — A. O. Thomas. executive committee. Ex-officio—Vl. S- Conaed, H. M. Kelly, L. S. Ross, James H. Lees, A. O. Thomas. Elective — E. J. Cable, A. G. Smith, C. 0. Bates. PAST PRESIDENTS. OSBOEN, Herbeet Todd, J. E. WiTTEE, F. M. Nutting, C. C. Pammel, L. H. Andeews, L. W. Noeris, H. W Hall, T. P. Pranklin, W. S Macbeide, T. H. Hendrixson, W. S Norton, W. H. Veblen, a. a. . . • • Summers, H. E Pink, Bruce Shimek, ■ B. Arey, M. P Bates, C. O. Tilton, John L. Calvin, Samuel Almy, Prank P. Houser, Gilbert L. Begeman, L. Bennett, A. A. Kin^ney, C. N; 1887- 88 1888- 89 1889- 90 1890- 92 1893 1894 1895 1896 . 1897 1897-98 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 IV IOWA ACADEMY OF SCIENCE. MEMBERS OF THE IOWA ACADEMY OF SCIENCE. LIFE. Beyer, S. W Ames Clarke, J. FtiED Fairfield CoNARD, Henry S Grinnell Erwin, A. T Ames Fitzpatrick, T. J Lamoni Greene, Wesley Des Moines Houser, G. L Iowa City Kay, G. F Iowa City Kuntz, Albert, St. Louis Univ., St. Louis, Mo. Norton, W. H Mt. Vernon Pellett, Frank C Atlantic Ricker, Maurice Des Moines Ross, L. S Des Moines Seashore, C. E Iowa City Shimek, B. Iowa City Summers, H. E Ames Sylvester, R. H Iowa City Tilton, J. L Indianola Williams, Mabel C lowa^City Wylie, R. B Iowa City FELLOWS. Albert, Henry Iowa City Almy, P. F ' Grinnell Anderson, J. P ...... Sitka, Alaska Arey, M. F Cedar Falls Bailey, Bert H .Cedar Rapids Baker, H. P., College of Forestry, Syracuse, N. Y. Baker, J. A Indianola Baker, R. P Iowa City Bakke, a. L Ames Bates, C. O Cedar Rapids Begeman, Louis Cedar Falls Bennett, A. A .Orange, Cal. Bond, P. A Iowa City Brown,. F. C Iowa City Buchanan, R. E Ames Burnett, L. C Ames Cable, E. .1 Cedar Falls CoNDiT, Ira S Cedar Falls Cratty, R. I Armstrong Dodge, H. L Iowa City Dox, A. W Ames Evvard, j. M Ames Farr, Clifford H Iowa City Fawcett, H. S Whittier, Cal. Fay, Oliver J Des Moines Finch, G. E Dillon, Mont. Ford, A. H Iowa City Getchell, R. W Cedar Falls Gow, Jas. E Cedar Rapids Guthe, Karl E Ann Arbor, Mich. Guthrie, Jos. E Ames Hadden, David E Alta Hayden, Ada Ames Hendrixson, W. S Grinnell Hersey, S. F Cedar Falls Jenner, E. a Indianola Kellogg, Harriette S Ames Kelly, H. M Mt. Vernon Keyes, Charles R Des Moines King, Charlotte M Ames Kinney, C. N Des Moines Knight, Nicholas Mt. Vernon Knupp, N. D Santa Monica, Cal. Kunerth, Wm Ames Learn, C. D Stillwater, Okla. Lees, Jas. H.. Des Moines Macbride, T. H Iowa City McClintock, j. T Iowa City Miller, A. A Davenport Morehouse, D. W Des Moines Mueller, H.. A St. Charles Norris, H. W Grinnell Nutting, C. C Iowa City Orr, Ellison W aukon Pammel, L. H Ames Pearce, J. N Iowa City Pearson, R. A Ames Peck, Morton E Salem, Ore. Pew, W. H Ames Rockwood, E. W Iowa City Sanders, W. E .Des Moines SiEG, L. P Iowa City Smith, A. G Iowa CHy Spinney, L. B Ames Stange, C. H Ames Stanton, E. W Ames Stevenson, W. H Ames Stewart, G. W Iowa City Stromsten, Frank A Iowa City Thomas, A. O Iowa City Trowbridge, A. C Iowa City Turpin, C. M Ames Van Hyning, T Gainesville, Fla. Van Tuyl, F. M., Univ. Chicago, Chicago Watson, E. B Merced, Cal. Webster, R. L Ames Wells, A. A Ames Wentworth, E. N., Agri. College Manhattan, Kas. Wickham, H. F Iowa City Williams, Ira A Corvallis, Ore. Wilson, Guy West Iowa City Woodward, S. M Iowa City IOWA ACADEMY OF SCIENCE, ASSOCIATE. Aitchison, Miss A. E Cedar Falls Allen, F. W Ames Andeeson, Miss Helvig Rock Island, 111. Anderson, W. B Ames (Armstrong, Leona Spencer Arnold, John F Dallas Center Ball, Theo. R Champaign, 111. Bardwell, Etta M Cedar Rapids Begg, a. S Cambridge, Mass. Bennett, Walter W. ...... . Sioux City Berninghausen, FkED Eldora Berninghausen, Feed W • New Hartford Beery, George H Cedar Rapids Bonney, a. F Buck Grove Boot, Davip H Iowa City Boyd, Mark F., Uni. of Nevada, Reno, Nev. Brook, A. H Boone Brown, Percy E Ames Buchanan, John H Ames Butterfield, E. J Dallas Center Carlisle, L. B. Dawson Carter, Chas Fairfield Case, Chauncey Larrabee Cavan AGH, Lucy M Iowa City Churchill, E. P Anamosa Coe, H. S Brookings, S. D. CoLGEOVE, C. P Cedar Palls Collett, S. W Payette Conklin, R. E Des Moines Coffin, Chas. L., Penn College.. Oskaloosa CoTTEN, Ruth H Iowa City Curtis, L. D Wausa, Neb. Davis, W. H Cedar Palls Dieterich, E. O Iowa- City Dill, Homer R Iowa City Dodd, L. E Iowa City Dole, J. Wilbur Fairfield Doty, H. S Ames Eggleston, H. Ray Storm Lake Ellis, S. P Des Moines Ellyson, C. W Alta Ewers, A. F St. Louis, Mo. PiNLAYSON, Jessie. Des Moines Poft, Samuel P Waukee PoEDYCE, Emma J Cedar Rapids Fraser, Chas. M Nanaimo, B. C. Frazier, Sabena S Oskaloosa Frazier, Zoe R Oskaloosa French, R. A Des Moines Pry, E. j.. Queens College Kingston, Ont. Gabrielson, Ira N Marshalltown Giddings, Levi A Cincinnati, O. Gittins, E. Mae Williamsburg Goodell, P. E Des Moines Griffith, Mary C Whittier, Cal. Hagan, Wayne Clinton Hammer, B. H Ames Hanson, Elma May Des Moines Hawkins, H. L. Arlington Hayer, Walter E Woodbine Hayward, W. J Sioux City Heuse, E. O Champaign, 111. Higbee, P. G. Iowa City Higley, Ruth Grinnell Hills, P. B Newark, Del. Jeffs, Royal E Wichita, Kan. Jewell, Susan G Tabor Johns, E. W Kingsley Johnson, F. W Chicago, 111. Kemp, Elda M Hibbing, Minn. Kenoyer, L. a Independence, Kan. King, Inez Naomi. ..... .Mt. Pleasant Kuser, Wm. L Eldora Larson, G. A. Des Moines Lawrence, P. A Morse Bluff, Neb. Lazell, Fred J Cedar Rapids Leighton, Morris M., Univ. Chi- cago Chicago. 111. Lindley, John M Winfield Lloyd-Jones, Orren Ames MacDonald, G. B Ames McCracken, H. W Columbus, O. McKenzie R. Monroe Fairfield Merrill, D. E., State Coll., New Mex. Messenger, G. H Linden Moeller, Otto P Cedar Rapids Morbeck, Geo. C Sta. A., Ames Mount, Geo. H Cedar Palls Muilenburg, G. a Golden, Colo. Mull, Lewis B Chicago, 111. Neidig, R. E ' Ames Ness, Henry Ames Newell, Walter S Cedar Rapids Nollen, Sara M Des Moines Oleson, O. M Ft. Dodge Paige, F. W Ft. Dodge Patrick, W. W Iowa City Paull, Mabel A Sigourney Pierson, Elvers St. Charles, 111. Plagge, H. j Ames Quigley, T. H Fargo, N. D. Read, O. B Cedar Falls Redenbaugh, H. E Stillwater, Okla. Reilly, John F Iowa City Riggs, L. K Toledo Roberts, T. St. Charles Robinson, C. L Norwalk ScHATz, A. H Merrill Schmitt, C. J Avoca IOWA ACADEMY OP SCIENCE. Vi Schultz, Okville Postville Shimek, Ella Iowa City Shipton, W. D Iowa City Smith, De. Geo. L. Shenandoah Somes, M. P Mountain Grove, Mo. Stanley, Foerester C Oskaloosa Stephens, T. C Sioux City Stevens, Wilbert A. Tabor Stewart, Katherine L R. P. D. 1. Davenport Stiles, Harold Ame§ Stoner, Dayton Iowa City Taylor, Miss Beryl Macon, Ga. Teeuween, Mrs. Gladys .... Iowa City Tenney, Glenn I ' . Des Moines Treganza, J. a Britt Truax, T. R Ames Tuttle, E. V Lanesboro Verink, E. D Cedar Rapids VORHIES, F'red : .Lansing Walters, G. W .Cedar Palls Watson, E. E, . Fairfield Webster, C. L Charles City Weigle, C. M Appleton, Wis. Wheat, G. G Cambridge, Mass. Whitney, Thomas H Atlantic WiFVAT, Samuel, U. P. Sta!, Des Moines Williams, Arthur J Iowa City Wolden, B. O Wallingford Wylie, Charles A . U. P. Sta., Des Moines Yothers, j. P .Toledo CORROiSPONDING MEMBERS. Andrews, L. W Davenport Arthur, J. C. Purdue University, Lafayette, Ind. Bain, H. P San Francisco, Cal. Ball, C. R Department of Agriculture, Washington, D. C.^ Ball, E. D State Agricultural College, Logan, Utah Barbour, E. H ^ State University, Lincoln, Nebr. Bartsch, Paul .Smithsonian Institution, Washington, D. C. ' Beach, Alice M University of Illinois, Urbaha, 111. Bessey, C. E ...State University, Lincoln, Nebr. Bruner, H. L Irvington, Ind. Carver, G. W Tuskegee, Ala. Conrad, A. H 18 Abbott Court, Chicago, 111. Cook, A. N University of South Dakota, Vermillion, S. Dak. Drew, Gilman C Orono, Maine Eckels, C. W : University of Missouri, Columbia, Mo. Fink, Bruce Oxford, Ohio Franklin, W. S Lehigh University, South Bethlehem, Pa. Frye, T. C State University, Seattle, Wash. Gili.ette, C. P Agricultural College, Port Collins, Colo. Goodwin, J. G East St. Louis, 111. Gossard, H. a Wooster, Ohio Halsted, B. D New Brunswick, N. J. Hansen, N. E Brookings, S. D. Haworth, Erasmus State University, Lawrence, Kans. Hitchcock, A. S Department of Agriculture, Washington, D. C. Hume, N. H Glen St. Mary, Fla. Leonard, A. G ..Grand Forks, N. Dak. Leverett, Prank Ann Arbor, Mich. Miller, ‘B. L ...South Bethlehem, Pa. Newell, Wilmon College Station, Texas Osborn, Herbert .State University, Columbus, Ohio Patrick, G. E Department of Agriculture, Washington, D. C. Price, H. C State University, Columbus, Ohio Read, C, D ..Weather Bureau, Sioux City, Iowa Savage, T. E Urbana, 111. SiRRiNE, Emma Dysart, Iowa SiRRiNE, P. A 124 South Ave., Riverhead, New York Todd, J. E. .Lawrence, Kan. Trelease, William University of Illinois, Urbana, 111. Udden, j. a Rock Island, 111. IOWA ACADEMY OP SCIENCE. vii TABLE OF CONTENTS P' Page Butterflies of Chance Occurrence in Cass County, Fkank C. Pellett. . . . • . .347 Butterflies of Woodbury County, A. W. Lindsey 341 Calcium and Protein Fed Pregnant Swine, Effect of, on Offspring, John M. Evvard, Arthur W. Dox, S. C. Guernsey 261 Carbonic Succession, Early, in Continental Interior, Serial Subdivision of, Charles Keyes 189 Clear Creek Canon, Colorado, Introduced Plants of, L. H. Pammel 119 Coleoptera of Henry County, Inez Naomi King. 317 Diphtheria Epidemic of 1912-13, Des Moines, Chas. W. Wylie 23 Dolomites, Unusual, Nicholas Knight 127 Earth Movements and Drainage Lines in Iowa, James H. Lees 17? Egg, Desiccated, Bacterial Content of, L. S. Ross 3? Electrolytes in Organic Solvents, Electrical Conductivity of Solutions of, ^ J. N. Pearce ..131 Eskers, The Formation of, Arthur C. Trowbridge... 211 Evaporation in Limited Areas, Variation in, D. H. Boot 125 Flora of Linn County, Preliminary Report on, E. D. Verink 77^ Floras, Field and Forest, in Monona County, Comparison of, D. H. Boot.... 53 Geology, Recent Progress in. Some Evidence of, George F. Kay 169 Graf, New Section in Railway Cut Near, A. O. Thomas 225 Hydra, Longitudinal Division of, L. S. Ross 349 Incubator Opening to Outside of Building, L. S. Ross 51 Iowa, Northeastern, Geological Work in, Arthur C. Trowbridge 205 Kerosenes Used in Iowa, Illuminating Power of, Wm. Kunerth ...241 Lepidoptera of Linn County, List of, Geo. H. Berry 279 Lichens, Iowa, Notes on Ecology of, Zoe R. Frazier 67 Mammae, Rudimentary, in Svune, Inheritance of, Edward N. Wentworth. . .265 Meek, Seth Eugene, Memorial Note on, Charles Keyes 11 Mercuric Iodide and Anilin, Equilibrium in the System, E. J. Fry, J. N. Pearce .' 161 Micranthes Texana, Notes on Variation in, L. A. Kenoyer 123 Mountain Making, Iowa’s Great Period of, Charles Keyes 181 Pleistocene Exposures in Cedar Rapids and Vicinity, W. D. Shipton 221 Pottery, Indian, of Oneota River Valley, Ellison Orr 231 Pre-Cambrian Rocks, Our, Charles Keyes 195 Precious Stones in Drift, Occurrence of, G. A. Muilenburg .’ 203 Selenium, Adaptation of, to Measurements of Energy, L. P. Sieg, F. C. Brown .259 Selenium Bridges, Construction of, E. O. Dieterich ....257 Soils, Sulfoflcation in. P. E. Brown, E. H. Kellogg 17 Sound Intensity, Variation of. With Distance from Source, Harold Stiles, G. W. Stewart 255 Story County, Weed Survey of, L. H. Pammel, Charlotte M. King 115 “Sunflecks”, W. H. Davis 101 Sycamore Blight and Accompanying Fungi, J. P. Anderson 109 Sylvan Beach, The Sand of, Nicholas Knight 129 Tree-Fern, Fossil, of Iowa, Notes on, Clifford H. Farr 59 Wisconsin Drift, An Area of, in Polk County, John L. Tilton 219 Vlll IOWA ACADEMY OP SCIENCE. AUTHORS’ INDEX Page Anderson, J. P 109 Berry, George H 279 Boot, D. H 53, 125 Brown, P. C 259 Brown, P. E 17 Davis, W. H 101 Dieterich, E. O 257 Dox, Arthur W 269 Evvard, John M 269 Parr, Clifeord H 59 Prazier, Zoe R 67 Pry, E. J 161 Guernsey, S. C 269 Kay, George F 169 Kellogg, E. H 17 Kenoyer, L. a 123 Keyes, Charles 11, 181, 189, 195 King, Charlotte M 115 King, Inez Naomi 317 Knight, Nicholas 127, 129 Page Kunerth, William 241 Lees, James H 173 Lindsey, A. W 341 Muilenburg, Garrett A 203 Orr, Ellison 231 Pammel, L. H 115, 119 Pearce, J. N 131, 161 Pellett, Prank C 347 Ross, L. S 33, 51, 349 Shipton, W. D 221 SiEG, L. P 259 Ste\vaet, G. W 255 Stiles, Harold.. 255 Thomas, A. 0 225 Tilton, John L 219 Trowbridge, Arthur C 205, 211 Verink, E. D 77 Wentworth, Edward N 265 Wylie, Charles A 23 PROCEEDINGS OF THE Twenty-Eighth Annual Session of the Iowa Academy of Science EEPORT OF THE SECRETARY. Fellows and Members of the Iowa Academy of Science: During the year the secretary has carried on the usual correspondence with the members, sending out three or fou):* circular letters relative to the annual meeting, and on April 18 the printed program, of titles re- ceived to that date, was mailed. Since the printing of the program five other titles have been received, making a total of fifty-five, only three below the largest number ever presented before the Academy. Last year fifty-eight titles were presented. Following out the instruction of the Academy at the 1913 meeting, ad- dressed postal cards were sent to all fellows and associate members in a circular letter, asking for the educational positions occupied, or posi- tions of honor, the information to he used in making up the lists of the members in the Proceedings. Something over ninety replies were received. This will make a beginning toward a more nearly complete directory. The volume of the Proceedings for 1913 is the largest that has yet appeared ; in fact, it is beyond the size allowed bj^ the State. The ruling at the office of the Secretary of State is to the effect that all pages including blanks, but excepting the inserts, are to be counted toward the allotted 300. Such a ruling makes the number of pages in Vol. XX, fifty-six in excess of the number paid for by the State. The expense of this excess must be borne by the Academy. The number of pages included in the manuscript submitted cannot be determined until the type is set; and it is not practicable for the secretary to attempt to eliminate articles in order that the number may be kept within the 300. It is to be hoped that the committee appointed by the president to take up with the legislature the matter of increased number of pages may be successful in their work, and may obtain a removal of restriction or may secure an increase sufficient for years to come. 1 IOWA ACADEMY OF SCIENCE. There are three groups of members in the Academy; one of these groups consists of ‘ ‘ corresponding fellows, to be elected by vote from original workers in science in other states; also, any fellow removing to another state from this may be classed as a corresponding fellow.” Those elected from original workers in other states are in reality elected to honorary fellowships, the honor, sometimes perchance, being to the Academy rather than to the one so elected. On April 29, 1911, an amendment to Sec. 4 was adopted reading as follows: ‘‘An annual fee of $1.00 shall he required from each corresponding fellow.” The requirement of such a fee may he justifiable hut the secretary is at a loss to know upon what grounds. In his opinion the amendment should he modified or should be stricken out. A portion of an amendment adopted May 1, 1909, reads: “A person may become a life member on the payment of $7.00 after his election as a fellow, the transfer to be made by the treasurer.” The secretary begs leave to suggest his belief that the life membership is too small, and that it should be increased to $15.00 at least. Would it be advisable on the part of the Academy to attempt to enlarge the scope of its work sufficiently to have sectional meetings at the annual meeting? Would it be possible to have a biological section, a chemical section, a physical section, geological, psychological, mathemati- cal ? Why not have the archeologists, mathematicians, and the psycholo- gists of the state in the ranks of the Academy? Possibly the botanist might not find papers on mathematics of absorbing interest, and most certainly the mathematician can imagine things more interesting to him than papers on zoology. But in the sectional meeting a member would find that which is of interest on topics which he might feel fitted to discuss. Isn’t the Academy established firmly enough to contemplate such an enlargement, and wouldn’t its infiuence in the state be in- creased thereby ? The work of the Academy should be known by every educated person in the state, and should appeal to every one interested in any phase of science. Respectfully submitted, L. S. Ross, Secretary. IOWA ACADEMY OP SCIENCE. 3 TREASURER’S REPORT. RECEIPTS. Cash on hand April 26th, 1913 $162.70 Dues and initiation fees from fellows and members ... 215.00 Life members fees 28.00 Sale of Proceedings 3.52 Interest on Deposits 4.00 Total $413.22 EXPENDITURES. Expense of Lecturer, 27th meeting $ 35.00 Postage, record book and stenographic work for treasurer... 19.30 Programs, letter heads, post cards, etc., for Secretary 19.25 300 copies of Iowa Academy of Science Vol. XIX 221.27 Reprinting pages of Volume XIX 17.85 Cutting, stitching, pasting and trimming 100 copies, Vol. XIX. 20.00 100 reprints of Vol. XIX 16.00 Wrapping and sending out Vol. XIX 10.00 Honorarium to Secretary 25.00 Postage, stamped envelopes, envelopes, etc., for Secretary 24.58 Cash on hand 4.97 Total $413.22 Respectfully submitted. George P. Kay, Treasurer. REPORT OF COMMITTEE ON SECRETARY’S REPORT. The committee on Secretary’s report, mindful of the suggestions made by the secretary and the treasurer, beg leave to submit the following resolution: Pirst; that the present annual fee for corresponding fellows be discontinued and that an amendment to this effect be submitted to the voting fellows before the next meeting in accordance with the provision of the constitution. Second; that an amendment raising the life membership fee from $7.00 to $15.00 be also submitted to the voting fellows of the Academy in accordance with the pro- vision of the constitution. Third; that it is the sense of the Academy that hereafter the program of the Academy shall consist of two divisions; a general program Priday afternoon followed by sectional programs on Saturday morn- ing or vice versa. That the president be authorized to appoint a committee, with full power to act, to determine the nature of these sections for next year. The report of the committee shall be provisional or tentative for the next meet- ing of the Academy.. We would suggest that if the sectional plan be adopted, separate leaders be appointed by the president unless otherwise provided for, who shall have charge of the various sectional programs. L. Begeman, G. W. “Stewart, ' . ' _ : ^ S. P. Hershey, Committee. 4 IOWA ACADEMY OP SCIENCE. EEPOET OF COMMITTEE ON MEMBEESHIP. The Committee .on Membership recommended the following: Transfers from list of members to list of fellows. — P. A. Bond, Cedar Palls; Clifford H. Parr, Iowa City; W. Kunerth, Ames; Ellison Orr, Waukon; G. W. Walters, Cedar Palls; R. L. Webster, Ames; Prancis M. Van Tuyl, Denmark. To he eleeted to memhersJiip. — Miss Leona Armstrong, Spencer; A.. C. Bailey, Steamboat Rock; Walter W. Bennett, Sioux City; Pred W. Berninghausen, Marble Rock; A. P. Bonney, Buck Grove; P. H. Broos, Boone; L. B. Carlisle, Eldora; Chas. L. Coffin, Iowa City; Ruth Cotton, Iowa City; L. E. Dodd, Iowa City; J. Wilbur Dole, Pairfield; H. Ray Eggleston, Storm Lake; Samuel P. Taft, Waukee; Jessie Pinlayson, Des Moines; E. J. Pry, Iowa City; Wayne Hagen, Clinton; Elma May Hanson, Des Moines; W. J. Hayward, Sioux City; E. W. Johns, Kingsley; Inez Naomi King, Mt. Pleasant; Orren Lloyd-Jones, Ames; Otto P. Moeller, Cedar Rapids; G. C. Morbeck, Ames; E. L. Palmer, Cedar Palls; Herman E. Redenbaugh, Tabor; Orville Schultz, Ames; W. D. Shipton, Cedar Rapids; Arthur Smith, Little Rock; Wright Stacy, Iowa City; T. R. Truax, Ames; E. D. Verink, Cedar Rapids; E. E. Watson, Pairfield; Samuel Wifvat, U. P. Station, Des Moines; Arthur J. Williams, Iowa City; B. O. Wolden, Wall- ingford; Chas. A. Wylie, U. P. Station, Des Moines; J. P. Yothers, Toledo. Report adopted. L. S. Ross, G. P. Kay, Committee. INCOMPLETE LIST OF THOSE IN ATTENDANCE. A. P. Aitchison, M. P. Arey, C. O. Bates, L. Begeman, P. C. Brown, E. J. Cable, H. S. Conard, Ira S. Condit, W. H. Davis, Clifford H. Parr, J. E. Guthrie, J. C. Jensen, H. M. Kelley, G. P. Kay, L. E. Kenoyer, W. Kunerth, C, N. Kinney, G. A. Larson, D. W. Morehouse, L. H. Pammel, H. J. Plagge, O. B. Read, L. S. Ross, E. W. Rockwood, Dayton Stoner, L. P. Sieg, G. W. Stewart, H. E. Summers, Mabel C. Williams, G. W. Walters, Pred Berninghausen, D. H. Boot, Nicholas Knight, J. N. Pearce, J. H. Lees, P. A. Bond, S. P. Hershey. OFFICEES OF THE ACADEMY FOE 1914-1915. President First Vice-President . . Second Vice-President Secretary Treasurer H. S. Conard, Grinnell H. M. Kelly, Mount Vernon L. S. Eoss, Des Moines .James H. Lees, Des Moines . . . .A. 0. Thomas, Iowa City ELECTIVE MEMBERS OP THE EXECUTIVE COMMITTEE. E. J. Cable, Cedar Falls; A. O. Smith, Iowa City; C. 0. Bates, Cedar Eapids. IOWA ACADEMY OP SCIENCE. 5 PROGRAM. The meetings of the Academy were held in the General Assembly Room, Science Hall, Iowa State Teachers College, Cedar Falls, begin- ning at 1 :30 p. m., Friday, April 24. A business meeting was called first, after which scientific papers were presented. The time Saturday forenoon was occupied with the remaining papers and with the final business meeting. Dr. N. H. Winchell of the Minnesota Historical Society, gave the public address at 8:00 p. m. Friday. His subject was ‘‘The Antiquity of Man in America in Comparison With Europe.” A reception was given to the members of the Academy and friends after the address. Following the business session of Saturday forenoon a luncheon was served in the Gymnasium. TITLES OP PAPERS RECEIVED. 1. Sulfofication in Soils P. E. Brown Bact. Lab., la. State Coll. 2. The Des Moines Diphtheria Epidemic of 1912-13 Chas. A. Wylie Bact. Lab., Drake Univ. 3. Bacterial Content of .Desiccated Egg L. S. Ross Bact, Lab,, Drake Univ. 4. An Incubator Opening to the Outside of the Building L. S. Ross Bact. Lab., Drake Univ. 5. U. S. Kelp Investigations in Alaska Robert B. Wylie Botan. Lab., S. U. I. Read by Title. 6. The Pollination of Vallisnaria Robert B. Wylie Botan. Lab., S. U. I. Read by Title. 7. Pield and Porest Ploras of Monona County David H. Boot Botan. Lab., S. U. I. 8. The Origin of the Cocklebur Clifford H. Parr Botan. Lab., S. U. I. Read but not offered for publication. 9. Notes on a Possil Tree-Pern of Iowa.. Clifford H. Parr Botan. Lab., S. U. I. 10. The Myxomycetes of Puget Sound Thomas H, Macbride Botan. Lab., S. U. I. Read by Title. 11. Some Notes on the Ecology of Iowa Lichens Zoe R. Prazier Newton, Iowa. 12. Preliminary Report on the Plora of Linn County : Ellis D. Verink Botan. Lab., Coe Coll. 13. The Male Gametophyte of Arisaema .....James E. Gow Botan. Lab., Coe Coll. Read by Title. 6 IOWA ACADEMY OF SCIENCE. 14. Sunflecks W. H. Davis Botan. Lab., la. State Teachers’ Coll. 15. Some Observations on Sycamore Blight and Accompanying Fungi J. P. Anderson Botan. Lab., la. State Coll. 16. Weed Survey in Story County L. H. Pammel Botan. Lab., la. State Coll. 17. Alien Plants of Clear Creek Valley, Colorado L. H. Pammel '' Botan. Lab., la. State Coll. 18. Notes on Variation in Micranthes Texana.... L. A. Kenoyer Biol. Lab., Leander Clark Coll. 19. Barium in Tobacco and Other Plants Nicholas Knight Chem. Lab., Cornell Coll. Read by Title. 20. Colloidal Common Salt Nicholas Knight Chem. Lab., Cornell Coll. Read by Title. 21. Electromotive Forces and Electrode Potentials in Mixed Solvents J. N. Pearce Chem. Lab., S. U. I. 22. Equilibrium in the System — Mercuric lodide-Anilin J. N. Pearce and E. J. Fry Chem. Lab., S. U. I. 23. Earth Movements and Drainage Lines in Iowa James H. Lees State Geol. Surv. 24. Some Evidences of Recent Progress in Geology .G. F. Kay State Geol. Surv. 25. Siouan Mountains; An Iowan Triassic Episode Charles Keyes Des Moines, Iowa. 26. Serial Unit in Stratigraphic Classification Charles Keyes 27. Stratigraphic Position of Our Oldest Rocks Charles Keyes 28. On Precious Stones in the Glacial Drift ...Garrett A. Muilenburg Geol. Lab., S. U. I. 29. A New Section of the Railway Cut Near Graf, Iowa ...A. O. Thomas Geol. Lab., S. U. I. 30. The Surface Clay of Adair County (Second Paper) James E. Gow Geol. Lab., Coe Coll. Read by Title. 31. Evidences of Sand Dune Formation in Cedar Rapids and Vicinity Washburn D. Shipton Geol. Lab., Coe Coll. Read by Title. 32. Indian Pottery of the Oneota or Upper Iowa River Valley Ellison Orr Waukon, Iowa. 33. Longitude by Wireless D. W. Morehouse Phys. Lab., Drake Univ, Read but not offered for publication. 34. Illuminating Power of Kerosenes Used in Iowa. William Kunerth Phys. Lab., la. State Coll. 35. Certain Diffraction Experiments in Sound. .Harold Stiles and G. W. Stewart Phys. Lab., S. U. I. IOWA ACADEMY OF SCIENCE. 7 ABSTRACT. This paper describes three experiments in sound diffraction, viz., the shadow of a rigid sphere, the passage of sound through narrow slits, and the sound through circular apertures. Previous theoretical investigations are verified to within a reasonable degree in all three experiments. The paper is published in full in the Physical Eeview for April, 1914. 36. The Variation of Sound Intensity with Distance from the Source; An Interesting Case of Deviation from the Inverse Square Law G. W. Stewart Phys. Lab., S. U. I. 37. Notes on the Construction of Selenium Bridges .E. O. Dieterick Phys. Lab., S. U. I. 38. The Adaptation of Selenium to Measurements of Energy Too Small to be Measured by Other Devices. ..L. P. Sieg and F. C. Brown Phys. Lab., S. U. I. 39. The Effect of Pressure on the Light-Sensibility of Metallic Selenium Crystals......... !F. C. Brown and L. P. Sieg Phys. Lab., S. U. I. Read by title. 40. Sex Linked Factors in the Inheritance of Rudimentary Mammae in Swine ..... ....Edward N. Wentworth Kansas Agri. College, Manhattan, Kansas. 41. The Effect of Calcium and Protein Fed Pregnant Swine Upon the Size, Vigor, Bone and Coat of the Resulting Offspring. John M. Evvard, Arthur W. Dox and S. C. Guernsey Animal Husbandry, la. State Coll. 42. A Study of the Crow. .Frank C. Pellett Office State Inspec. of Apiaries. Read by title. 43. Butterflies of Chance Occurrence in Cass County. ...... .Frank C. Pellett Office State Inspec. of Apiaries. 44. Nature and Birds Fred Berninghausen Eldora, Iowa. ABSTRACT. Notes the failure of the oak Quereus sessiliflora to attain a vigorous development on account of its lack of adaptation to its environment and its inability to protect itself against its enemies. The characteristics and life habits of certain Iowa birds are described and their usefulness or harmfulness is discussed. The birds taken as illustrations are the kill-deer, the whippoorwill, the robin, the kingbird, the wren, the cat- bird, the screech owl, the quail, the blue jay, the horned owl and the flicker. The horned owl comes in for especial condemnation as a destroyer of our helpful singing birds. 8 IOWA ACADEMY OF SCIENCE. 45. Color Vision in Animals Mabel C. Williams Psych. Lab., S. U. I. Read but not offered for publication. 46. Effect of Low Temperature on the Oyster-Shell Scale, Lepidosapfies ulmi Linn R. L. Webster Zool. Lab. la. State Coll. ABSTRACT. The effect of the low temperatures of January, 1912, on the eggs of the oyster-shell scale in Iowa. An account based on samples of scale sent in a year later. In most cases the eggs had been killed by the severe winter. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. A Catalogue of the Lepidoptera of Linn County George H. Berry Cedar Rapids, Iowa. The Coleoptera of Henry County, Iowa... Inez Naomi King Zool. Lab., Iowa Wesleyan Univ. An Observation on Longitudinal Division in Hydra L. S. Ross Zool. Lab., Drake Univ. A Convenient Table for Microscopic Drawing L. S. Ross Zool. Lab., Drake Univ. Read but not offered for publication. Relation of Wind Velocity and Relative Humidity to Evaporation D. H. Boot Bot. Lab., S. U. I. The Origin of Eskers A. C. Trowbridge Geol. Lab., S. U. I. Preliminary Report on Physiographic Studies in Northeastern Iowa A. C. Trowbridge Geol. Lab., S. U. I. An Area of Wisconsin Drift further South in Polk County, Iowa, than Hitherto Recognized John L. Tilton Geol. Lab., Simpson College. The Question of Electron Atmospheres L. E. Dodd Phys. Lab., S. U. I. Read by title. The Butterflies of Woodbury County A. W. Lindsey Zool. Lab., Morningside College. Unusual Dolomites Nicholas Knight Chem. Lab., Cornell College. The Sand of Sylvan Beach Nicholas Knight Chem. Lab., Cornell College. Pleistocene Exposures in Cedar Rapids and Vicinity W. D. Shipton Geol. Lab., Coe College. PAPERS PRESENTED AT THE Twenty-Eighth Meeting of the .a Academy i'r .'f Plate I. SETH EUGENE MEEK. MEMORIAL TO DOCTOR MEEK 11 MEMORIAL NOTE ON SETH EUGENE MEEK. BY CHARLES KEYES. By the death of Dr. Seth Eugene Meek in Chicago on July 6, 1914, the Academy loses one of its charter members, and, in the first years of its existence, one of its most active and devoted workers. Seth E. Meek was born at Hicksville, Ohio, April 1, 1859 ; and at the time of his demise, was therefore in the fifty-fifth year of his age. After attending the public schools of his native town, young Meek entered the State University of Indiana, from which he was graduated with honors in 1884. He then attended Cornell University, at Ithaca, New York, where he took up graduate work in zoology. Towards the end of the first year at Cornell being offered the chair of Natural Science in Eureka College (Illinois), he entered upon full professorial duties in that institution, and performed them with great credit for a year, when he was called to Iowa. Professor Meek, in the autumn of 1887, came to Coe College, at Cedar Rapids, having been elected to the post of Head of the Department of Natural History. During the five years which he spent in this institu- tion he built up the natural science work into one of the leading depart- ments in the college and one of the best in the whole state. Besides working in the field of zoology, in which branch of science he was always most interested, he took a great liking to geology, and in the last mentioned science he continued to carry on important investiga- tions long years after he left the state. His activities were by no means confined wholly to Coe College, but his helpful influence was felt on the educational circles of the entire state. He took a prominent part in the doings of the various educational gatherings which were held during his residence in Iowa. It was during his sojourn in this state that in recognition of his elaborate original investigations in zoological fields the State University of Indiana conferred upon him the degree of doctor of philosophy. In 1892 Doctor Meek went to Arkansas as professor of zoology and geology in the State University at Payettesville. Here he remained four years, extending his knowledge on the fishes of the Ozark region. These investigations were conducted in the intervals of a busy school life. He resigned his chair in this institution in order that he might give more of his time and energies to original investigation; and he 12 IOWA ACADEMY OF SCIENCE. became connected with the United States Fish Commission, After a year in Washington, Doctor Meek was appointed assistant curator of the Field Museum of Natural History in Chicago, a post which he held with singular distinction until the day of his death. Other important posts held by Doctor Meek at divers times are that of Assistant Fish Comissioner of New York, lecturer in the State Uni- versity of Illinois, and Ichthyologist of the Biological Survey of Panama. Among the more extensive explorations which Professor Meek con- ducted are those in Mexico, Central America and the western parts of the United States, Doctor Meek was a member of many of the learned societies, among them the American Association for the Advancement of Science, the Washington Academy of Sciences, the Washington Biological Society, and the Chicago Academy of Sciences. He was vice-president of our Academy for the years of 1890 and 1891. Among the more pretentious publications of Doctor Meek, mention should be made of his great work on American Salt- and Fresh-water Fishes, North American Kep tiles, and Fresh-Water Fishes of Tropical America. Many shorter memoirs were published by the Federal govern- ment ; and numerous articles appeared in the periodical literature of the day. During the time that he resided in Iowa he traveled widely over the state. An important outcome of these investigations was a volume on the Food-Fishes of Iowa. Other papers to attract wide attention and to direct investigations on the zoological features of our state were published from time to time. Part of this Iowa work of research was undertaken in collaboration with Dr. David Starr Jordan. While in Iowa Doctor Meek was always in prompt attendance at the sessions of our Academy. Before its members he read many papers; and they were always of the greatest interest, since they were presented in simple, untechnical form that those in other branches of science could readily comprehend. This feature also added a singular charm to his lectures. The following were among the papers read before the Academy : Food-fishes of Iowa, 1889. Fishes of the Cedar Eiver Basin, 1890. Occurrence of Lepus Campestris in Muscatine County, 1890. Two Cases of Albinoism, 1890. Fish-fauna of Arkansas and Iowa Compared, 1891. For many years Doctor Meek was particularly interested in topics relating to the geographic distribution of animals; and from the in- MEMORIAL TO DOCTOR MEEK 13 formation that he had derived from the study of the fishes of Mexico and Central America he was impressed with the idea that an investiga- tion in the Canal Zone would throw much light upon this subject. For this reason he spent the greater part of two winters on the Isthmus of Panama, where he was assisted by Mr. S. P. Hildebrand, who repre- sented the Smithsonian Institution, the ichthyological part of the bio- logical work in the Canal Zone having been taken up jointly by that institution and the Field Museum of hTatural History, A preliminary article on the results of this work was published in 1913; but a more complete account was being prepared at the time of his death. Personally Doctor Meek was a man of singular charm of character, of pure motives and of stainless life. He was unassuming and modest to a high degree, always affable, kind, and ever willing to advise and help whomsoever called upon him for aid. As one of his daily associ- ates said of him, ‘^He was true gold.’.’ At a recent meeting of the members of the scientific staff of the Field Museum in Chicago, it was resolved: ^‘That the members of the Scientific Staff of the Museum for many years associated with the late Dr. Seth Eugene Meek, Assist- ant Curator of the Department of Zoology, appreciating his widely recognized scientific ability and worth, as well as his sterling per- sonal character, do hereby express their sincere sympathy to the members of his family in their bereavement, and their deep regret for the loss to the scientific world of one of its leading workers in his field of research. ’ ’ Doctor Meek was a rather voluminous writer. His more pretentious memoirs number upwards of sixty-five. Since the results of many of his studies on Iowa fishes especially were published elsewhere than in our state reports the complete list is appended. 1. Review of Species of Gerres found in American Waters. (Proc. AcaC Nat. Sci. Philadelphia, 1883, pp. 116-124, Philadelphia, 1884.) 2. Note on Genus Anguilla. (Bull. U. S. -Pish Commission for 1883, p. 430, Washington, 1884.) 3. Review of American Species of Scomberomorus. (Proc. Acad. Nat. Sci, Philadelphia, 1883, pp. 219-232, Philadelphia, 1884.) ^ With R. G. Newland, 4. Review of Genus Sphyrsena. (Proc. Acad. Nat. Sci. Philadelphia, 1884, pp. 67-75, Philadelphia, 1885.) With R. G. Newland. 5. Review of American Species of Hemirhamphus. (Proc. Acad. Nat. ScL Philadelphia, 1884, pp. 221-235, Philadelphia, 1885.) With D. K. Goss, 6. Notes on Collection of Anchovies from Havana and Key West; with Account of New Species Stolephorus Eurystole. (Proc. Acad. Nat. Sci. Philadelphia, 1884, pp. 34-46, Philadelphia, 1885.) With J. Swain. 7. Review of American Species of Genus Trachynotus. (Proc. Acad. Nat, Sci, Philadelphia, 1884, pp. 121-129, Philadelphia, 1885.) With D. K. Goss. 14 IOWA ACADEMY OP SCIENCE. 8. Review of American Species of Genus Synodus, (Proc. Acad. Nat. Sci. Philadelphia, 1884, pp. 130-136, Philadelphia, 1885.) 9. Note on Cuban Eel. (Bull. U. S. Pish Commission for 1884, p. Ill, Wash- ington, 1885.) 10. List of Pishes Collected in St. John’s River at Jacksonville, Pla. (Bull. U. S. Pish Commission for 1884, pp. 233-237, Washington, 1885.) With D. S. Jordan. 11. Description of Pour New Species of Cyprinidse. (Proc. U. S. Nat. Museum for 1884, pp. 474-477, Washington, 1885.) With D. S. Jordan. 12. Description of Zygonectes Zonifer, New Species of Zygonectes from Nash- ville, Ga. (Proc. U. S. Nat. Museum for 1884, pp. 526-527, Washington, 1885.) With D. S. Jordan. 13. Description of New Species of Hybopsis (Hybopsis Montanus). (Proc. U. S. Nat. Museum for 1884, p. 527, Washington, 1885.) 14. Notes on Pipe-fishes of Key West, Pla., with Descriptions of Two New Species. (Proc. U. S. Nat. Museum for 1884, pp. 237-239, Washington, 1885.) With J. Swain. 15. List of Pishes Collected in Iowa and Missouri in August, 1884, with De- scriptions of Three New Species, (Proc. U. S. Nat. Museum for 1885, pp. 11-17, Washington, 1886.) With D. S. Jordan. 16. Review of American Species of Plying-fishes. (Proc. U. S. Nat. Museum for 1885, pp. 46-67, Washington, 1886.) With D. S. Jordan. 17. Review of American Genera and Species of Batrachidae. (Proc. Acad. Nat. Sci. Philadelphia, 1885, pp. 52-62, Philadelphia, 1886.) With E. A. Hall. 18. Review of American Species of Genus Scorpsena. (Proc. Acad. Nat. Sci. Philadelphia, 1885, pp. 394-403, Philadelphia, 1886.) With R. G. New- land. 19. Review of Genus Esox. (Proc. Acad. Nat. Sci. Philadelphia, 1885, pp. 367- 375, Philadelphia, 1886.) With R. G. Newland. 20. Revision of American Species of Genus Gerres. (Proc. Acad. Nat. Sci. Philadelphia, 1886, pp. 256-272, Philadelphia, 1887.) With B. W. Evermann. 21. Note on Lamprey of Cayuga Lake. (Annals New York Acad. Sci., 1886, pp. 285-289, New York, 1887.) 22. Note on Elagatis Bipinnulatus. (Proc. Acad. Nat. Sci. Philadelphia, 1889, pp. 42-44, Philadelphia, 1890.) With C. H. Bollman. 23. Report on Explorations made in Missouri and Arkansas during 1889, with Account of Fishes Observed in each of River-basins Examined. (Bull U. S. Fish Commission for 1889, pp. 113-141, Washington, 1890.) 24. Note on Ammocoetes Branchialis, Linneus. (American Naturalist, Vol. XXIII, pp. 640-642, Philadelphia, 1890.) 25. Native Food-fishes of Iowa. (Proc. Iowa Acad. Sci., Vol. I, Pt. i, pp. 68-76, Des Moines, 1890.) 26. Report on Fishes of Iowa Based on Observations and Collections made during 1889, 1890 and 1891. (Bull. U. S. Fish Commission for 1890, pp. 217-248, Washington, 1891.) 27. Fishes of Cedar River Basin. (Proc. Iowa Acad. Sci., Vol. I, Pt. iii, pp. 105-112, Des Moines, 1893.) 28. Catalogue of Fishes of Arkansas. (Ann. Rept. Arkansas Geol. Surv. for 1891, Vol. II, pp. 215-276, Little Rock, 1894.) PUBLICATIONS BY DOCTOR MEEK 15 29. Description of Etheostoma Pagei. (American Naturalist, Vol. XXVIII, p. 957, Philadelphia, 1894.) 30. New Cambarus (Cambarus Paxonii) from Arkansas. (American Natural- ist, Vol. XXVIII, pp. 1042-1043, Philadelphia, 1894.) 31. Report of Investigations Respecting Pishes of Arkansas Conducted during 1891, 1892 and 1893, with Synopsis of Previous Explorations in Same State. (Bull. U. S. Pish Commission, for 1894, pp. 67-94, Washington, 1895. ) 32. Notes on Pishes of Western Iowa and Eastern Nebraska. (Bull. U. S. Pish Commission for 1894, pp. 133-138, Washington, 1895.) 33. Description of New Species of Gobiesox (Gobiesox Muscarum). (Proc. California Acad. Sci., Second Series, Vol. V, pp. 571-572, San Prancisco, 1896. ) With C. J. Pierson. 34. List of Pishes and Mollusks Collected in Arkansas and Indian Territory in ‘ 1894. (Bull. U. S. Pish Commission for 1895, pp. 341-349, Washington, 1896.) 35. List of Pishes and Reptiles Obtained by Pield Columbian Museum East African Expedition to Somali-land in 1896. (Pield Columbian Mus. Pub., Zool. Series, Vol. I, pp. 163-184, Chicago, 1897.) 36. Salmon Investigations iji Columbia River Basin and Elsewhere on Pacific Coast in 1896. (Bull. U. S. Pish Commission for 1897, pp. 15-84, Wash- ington, 1898.) With B. W. Evermann. 37. Notes on Collection of Cold-blooded Vertebrates from Olympic Mountains. (Pield Columbian Mus. Pub., Zool. Series, Vol. I, pp. 225-236, Chicago, 1899. ) 38. Notes on Collection of Pishes and Amphibians from Muskoka and Gull Lakes. (Pield Columbian Mus. Pub., Zool. Series, Vol. I, pp. 307-311, Chicago, 1899.) 39. Growth and Variation of Pishes. (Birds and Nature, Vol. VIII, pp. 84-89, 1900. ) 40. Geological Succession of Pishes. (Birds and Nature, Vol. VIII, pp. 133- 139, 1900.) 41. Genus Eupomotis. (Pield Columbian Mus. Pub., Zool. Series, Vol. Ill, No. 2, 8 pages, Chicago, 1900.) 42. Geographical Distribution of Pishes. (Birds and Nature, Vol. VIII, pp. 161-164, 1900.) 43. Contribution to Ichthyology of Mexico. (Pield Columbian Mus. Pub., Zool. Series, Vol. Ill, pp. 63-128, Chicago, 1902.) 44. Notes on Collection of Cold-blooded Vertebrates from Ontario. (Pield Columbian Mus. Pub., Zool. Series, Vol. Ill, pp. 131-140, Chicago, 1892.) With H. W. Clark. 45. Contribution to Museum Technique. (American Naturalist, Vol. XXXVI, pp. 53-62, 1902.) 46. Review of D. S. Jordan and B. W. Evermann’s “American Game and Pood Pishes.” (American Naturalist, Vol. XXXVI, pp. 557-558, 1903.) 47. Distribution of Presh-water Pishes of Mexico. (American Naturalist, Vol. XXXVII, pp. 771-784, 1903.) 48. Presh-water Pishes of Mexico north of Isthmus of Tehuantepec. (Pield Columbian Mus. Pub., Zool. Series, Vol. V, 316 pp., Chicago, 1904.) 16 IOWA ACADEMY OP SCIENCE. 49. Annotated List of Collection of Reptiles from Southern California and Northern Lower California. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. VII, No. 1, 20 pp., Chicago, 1905.) 50. Two New Species of Pishes from Brazil. (Proc. Biological Soc. Washing- ton, Vol. XVIII, pp. 241-242, Washington, 1905.) 51. Collection of Pishes from Isthmus of Tehuantepec. (Proc. Biological Soc. Washington, Vol. XVIII, pp. 243-246, Washington, 1905.) 52. Description of Three New Species of Fishes from Middle America. (Pub. Field Mus. Nat. Hist,, Zool. Series, Vol. VII, No. 3, 6 pages, Chicago, 1906.) 53. Synopsis of Fishes of Great Lakes of Nicaragua. (Pub. Field Mus. Nat. Hist,, Zool, Series, Vol. VIII, No. 4, 38 pages, Chicago, 1907.) 54. Notes on Fresh-water Pishes from Mexico and Central America. (Pub. Field Mus. Nat. Hist., Zool. Series, yol. VII, No. 5, 28 pages, Chicago.) 55. Zoology of Lakes Amatitlan and Atitlan, Guatemala, with Special Refer- ence to Ichthyology. (Pub. Field Mus. Nat. Hist., Zool. Series,. Vol. VII, No. 6, 50 pages, Chicago, 1908.) 56. New Species of Fishes from Tropical America. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. VII, No. 7, 7 pages, Chicago, 1909.) 57. Synoptic List of Fishes known to Occur within Fifty Miles of Chicago. (Pub. Field Mus. Nat. Hist., Zool. Series, Vpl. VII, No. 9, 118 pages, Chicago, 1910.) With S. P. Hildebrand. 58. Batrachians and Reptiles from British East Africa. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. VII, No. 11, 14 pages, Chicago, 1910.) 59. Notes on Batrachians and Reptiles from Islands north of Venezuela. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. VII, No. 12, 6 pages, Chicago, 1910.) 60. Descriptions of New Pishes from Panama. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. X, No. 6, 4 pages, Chicago, 1912.) With S. F. Hilde- brand. 61. Mussels of Big Buffalo Fork of White River, Arkansas. (U. S. Dept. Commerce and Labor, Bureau Fisheries, for 1912, pp. 1-20, Washington, 1913.) With H. W. Clark. 62. New Species of Fishes from Costa Rica. (Pub. Field Mus. Nat. Hist, Zool. Series, Vol. X, No. 7, 7 pages, Chicago, 1912.) 63. New Species of Pishes from Panama. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. X, No. 8, Chicago, 1913.) With S. F. Hildebrand. 64. Annotated List of Fishes Known to Occur in Fresh-waters of Costa Rica. (Pub. Field Mus. Nat. Hist., Zool. Series, Vol. X, No. 10, Chicago, 1914.) 65. Report on Pishes of Panama, (In preparation.) SULPOPICATION IN SOILS. 17 SULFOFICATION IN SOILS. P. E. BROWN AND E. H. KELLOGG. Sulfur has long been known to be one of the essential plant food con- stituents. It has always been believed, however, that there was sufficient present in all soils for optimum crop production. This assumption has been very largely based on Wolff’s analyses of the ash of various crops which showed the presence of very small amounts of sulfur. Several investigators have found a considerable loss of sulfur upon ignition of plants for ash determinations, and recently Hart and Peterson, of Wisconsin, pointed out definitely the inaccuracy of determining the total sulfur of plant tissues by examinations of the ash. They analyzed numerous feeding stuffs for total sulfur, using the Osborn method, and compared th^ir results with the earlier analyses of Wolff. This com- parison showed quite conclusively that a large proportion of the sulfur in crops is lost upon ignition. It is evident, therefore, that considerably larger amounts of sulfur are removed from soils by common farm crops than has been supposed. Analyses of various soils have shown the presence of only a limited amount of sulfur, the subsoil containing no more than the surface soil. The renewal of the sulfur supply in the surface soil from the lower soil layers is possible, therefore, for only a limited period. The suggestion of Hart and Peterson that soils may be deficient in sulfur and crops may suffer for a lack of this element seems worthy of considerable attention. Several other interesting suggestions are contained in the work of these men. For instance, it is pointed out that acid phosphate may produce increased yields, not entirely because of the phosphorus added to the soil, but because of the sulfur which is present in the form of calcium sulfate. Ammonium sulfate and potassium sulfate, when applied to soils, may bring about greater crop production, because of their sulfur content as well as their nitrogen or potassium content. Gypsum, which has ordinarily been considered an indirect fertilizer, because of its power to free other constituents, such as potassium, from an insoluble form, may exert a beneficial effect on some soils because of the sulfur contained in it. The fact that soils to which farm manure has been applied contain more sulfur than untreated soils is also clearly shown. The possibility immediately suggests itself that the benefits from the use 2 18 IOWA ACADEMY OF SCIENCE. of manure may be due in part to the sulfur present, even although it does occur in complex form. It is evident from this work that the problem of, the sulfur fertiliza- tion of soils is one which may be of considerable importance, and is at least worthy of careful study. Sulfur, as is well known, occurs in crops and in manures in complex organic form in the proteins and must be transformed into sulfates before it can be of use to plants. The rate of production of sulfates in soils must, therefore, be of considerable importance in keeping plants supplied with the amounts necessary for optimum growth. This trans- formation of sulfur from the protein form into sulfates, like the pro- duction of nitrates from proteins, takes place in several stages. First, there is the production of hydrogen' sulfide from the proteins. Large numbers of organisms, apparently, are able to decompose proteins with the liberation of this gas. All the decay bacteria are able to bring about this reaction, and, in fact, wherever protein destruction is occur- ring there is a production of hydrogen sulfide. Further oxidation of this material immediately occurs through the activities of the sulfofying bacteria, or sulfur-oxidizing bacteria. There are two groups of these, the red, Rhodobacteriaceae, or Pupur-bakterien, and the Thiobacteriaceae, or colorless group. These organisms, as far as we now know, bring about the oxidation of sulfur in two stages. The first is the change from hydrogen sulfide to free sulfur, which is then deposited in granules in the cells of the bacteria. The second stage in the process is the oxidation of this free sulfur to sulfates, in which form the sulfur is available to plants. Winogradsky has isolated nine different organisms which have the power of oxidizing hydrogen sulfide with the production first of sulfur and then of sulfates, and he has shown also the rather extensive distribution of these organ- isms in nature. It is evident, therefore, that bacteria play an important part in the preparation of sulfates for plant nourishment and the cycle through which sulfur passes in nature would be incomplete without bacterial action. The rate of production of sulfates in a soil, therefore, must be of con- siderable significance in the problem of the sulfur feeding of crops. If the sulfur present in organic form is 'very slowly oxidized to sulfates, crops will not be properly supplied with the element. In other words, if soils do not have a vigorous sulfofying power, there may be an abund- ance of total sulfur present and still there be an insufficient production of sulfates for optimum crop growth. SULPOPICATION IN SOILS. 19 The questions, therefore, immediately arise: Can we determine the sulfofying power of soils? How? Is there any relation between the sulfofying power of soils and the proper sulfur feeding of plants? Can methods be devised to increase the sulfofying power of soils, or, in other words, the efficiency of the sulfofying bacteria? This work was begun mainly to answer the first question: “Is it possil)le to determine the sulfofying power of soils? If so, how?” Further work is being carried on looking toward the solution of the other questions and considerable data are being accumulated which will be published in the near future. Most of this material is not in shape for presentation at this time and we will merely outline the work which has been carried on and the results, which have shown us that soils do have a sulfofying power and that this power is exceedingly variable in different soils and in soils under different treatment. Most of the difficulties which have confronted us in this work have been of a chemical nature and we will mention some of them, with the methods which we have devised for their elimination. In the first place, one of the main troubles we have had has been in the extraction of the sulfates from the soil. The methods given in text-books and in all the references available suggested the extraction with dilute hydro- chloric acid. A great many tests were run with this acid in varying strengths and comparisons were made with the results obtained by ex- traction with water. The latter method was found in every case to extract more sulfates than the hydrochloric acid. Magnesium sulfate and calcium sulfate were added to soils in known quantities, and, while practically the entire amounts were obtained according to the extraction with water, only very small proportions were secured when hydrochloric acid was used as a solvent. The calcium sulfate is more insoluble than the magnesium sulfate and its formation is probably more common in soils, hence the complete extraction of this material is regarded as of special significance in showing the value of the method. The stronger the acid employed the smaller was the proportion of the sulfates re- covered from the soil. The interference of iron and organic matter undoubtedly explains the low results obtained with the acid. Tests were then made to ascertain how long it was necessary to shake the soil with water in order to extract the sulfates and it was found that six hours in the shaking machine was ample for complete extraction. At first the sulfates were determined by precipitating with barium chloride in the usual way and weighing the barium sulfate produced. This was found to be a very slow method of procedure and the sulfur photometer was obtained and has proved invaluable in giving quicker and quite as 20 IOWA ACADEMY OP SCIENCE. accurate results. Comparisons made of the gravimetric and photometric methods show absolute agreement. Then came the question of deciding on some method of determining the power of the soil to produce sulfates, or its sulfofying power. Taking advantage of the results which have been secured in the study of the ammonifying and nitrifying power of soils, it was decided to use fresh soil as a medium. It was then necessary to employ some material con- taining sulfur to permit of an accumulation of sulfates to a measurable extent, or, in other words, to accentuate the sulfofying power of the soil just as dried blood or casein have been used in ammonification and ammonium sulfate in nitrification. Various sulfides were first employed, namely, calcium sulfide, barium sulfide, potassium sulfide, and sodium sulfide, and, with the exception of the barium sulfide, there was found to be very rapid transformation of these materials into sulfates, large amounts being produced in three or four days’ incubation. There was probably a transformation of the barium sulfide also, but it was im- possible to extract the sulfate formed from the soil. So rapid an oxida- tion occurred that our suspicion was aroused that the action was not entirely bacterial. Careful tests were made and it was found that on shaking a*ny of the sulfides with soil for seven hours without incubation there was a large percentage of oxidation to sulfates. This showed that in the shaking process there was a purely chemical oxidation of the sulfides. This oxidation was much greater for the calcium and potassium sulfides than for the sodium sulfide. The change did not occur in sand and the oxidation varied considerably in extent in different soils. It is evident, therefore, that it is necessary to ascertain how much chemical oxidation a sulfide will undergo in any particular soil by shaking it with water seven hours before that sulfide can be used as a measure of the sulfofying power of the soil. The percentage transforma- tion of the sulfur into sulfate by chemical means is then subtracted from the total sulfate production after incubation and the difference gives the bacterial oxidizing power of the soil for sulfur. In order to secure some material in the use of which this chemical oxidation would be avoided pure sulfur and iron sulfide have recently been employed.* The former shows practically no oxidation upon shak- ing with soils and the latter none whatever. Tests upon these materials are not sufficient yet, however, for any conclusions to be reached, as they have not been carried out with a sufficient number and variety of soils. The results which appear on the tables show the oxidation of sodium sulfide and of sulfur by chemical means and by bacterial action in several different types of soil. The SULPOFICATION IN SOILS. 21 examination of the last column, which shows in each case the percentage transformation of the sodium sulfide, or the sulfur into sulfates by bacterial means, will give some interesting comparisons. TABLE I.— THE SULPOFICATION OP SODIUM SULFIDE. Soil No. Soil Source Percentwater in soils Mgs. S. as sul- fate 1 Av. mgs. S. as sulfate Mgs. S. as sul- fate in soils Mgs. S. as sul- fate oxidized by shaking Mgs. S. as sul- fate oxidized in soils Per cent sul- fur added ox- idized in soils 1 Sandy loam, graveyard 16 9.21 1 Same _ _ _ _ 16 10.95 10.08 trace 2.61 7.47 56,03 2 Sandy loam, low, poorly drained area 21 16.91 2 Same _ __ _ 21 17.29 17.10 5.56 3.61 7.93 59.48 3 Heavy, black woodland soil— 26 18.17 3 26 18.98 18.57 13.13* 5.44 40.81 4 Typical sand, river bank _ _ 11 4.41 4 Same 11 4.02 4.21 trace trace 4.21 31.58 5 Wisconsin drift soil, un- treated 18 15.55 5 Same 18 15.37 15.46 3.19 2.33 9.94 74.56 6 Wisconsin drift soil, manured at rate of 25 tons per acre— 15 12.15 6 Same 15 13.92 13.03 1.52 1.18 10.33 77.49 TABLE II.— THE SULPOFICATION OP FREE SULFUR. 1 Sandy loam, graveyard 16 6.15 1 Same 16 6.01 6.08 trace 1.48 4.60 4.60 2 Sandy loam, low, poorly drained area 21 12.43 2 Same 21 11.98 12.20 5.56 1.76 4.88 4.88 3 Heavy, black woodland soil— 26 11.57 3 Samp 26 lost 11.57 9.87* 1.70 1.70 4 Typical sand, river bank 11 3.61 4 Same 11 3.51 3.56 trace trace 3.56 3.56 5 Wisconsin drift soil, un- treated _ 18 10.05 5 Same — 18 10.34 10.19 3.19 1.37 6.63 6.63 6 Wisconsin drift soil, manured at rate of 25 tons per acre— 15 12.48 6 Same 15 13.11 12.79 1.52 0.48 10.79 10.79 *Includes sulfate from soil and that due to oxidation by shaking. The method, as we are employing it, may be given as follows: Fresh soil is obtained, with the usual precautions that it shall be representative and that it shall not be contaminated in the sampling. 100 gm. quanti- ties are weighed out in tumblers and thoroughly mixed. The sulfide is then added, 0.1 gm. of the sodium sulfide or the sulfur. The moisture conditions are then brought up to the optimum by additions of sterile 22 / IOWA ACADEMY OF SCIENCE. water. The soils are then incubated for five to ten days at room tempera- ture, at the end of which time the sulfates are leached out with water by shaking for seven hours in the shaking machine. The sulfates present are estimated by the use of the sulfur photometer. The sulfates present in untreated soils are also determined and the purely chemical oxidation of the sulfide in the particular soil is ascer- tained. The difference between the sum of these two determinations and the total sulfur as sulfates at the end of the incubation period gives the sulfur oxidation or sulfofication by bacteria. The results so far secured by the use of this method show that soils may vary considerably in their sulfur oxidizing power and that this variation in sulfofying power may be of considerable importance from the fertility standpoint. The possibilities of the future development of this subject are so clearly evident that it is unnecessary to mention them here. Suffice it to say that the question of sulfur fertilization is one which is commanding more and more attention, and if deficiencies in sulfur are to be avoided means must be employed which will return to the soil some of the element removed by crops, just as is the case with other elements. Farm manure and green manure are the logical farm materials which can be employed for this purpose and when the sulfur is applied in this form it must be transformed into sulfate and the rate at which this change occurs will determine the efficiency of the means of applying sulfur. The efficiency of the bacteria which oxidize sulfur to sulfates in the soil, or the sulfofying power of soils, will determine, therefore, the material which should be employed to prevent the depletion of the soil in the element sulfur. Soil Chemistry and Bacteriology Laboratory, Iowa State College, Ames. DES MOINES DIPHTHERIA EPIDEMIC, 23 THE DES MOINES DIPHTHERIA EPIDEMIC OF 1912-13. BY CHAS. A. WYLIE. The diphtheria epidemic which this investigation covers began Septem- ber, 1912, and closed April 19, 1913. Its beginning was coincident with the closing of the annual State Fair and the opening of the public schools. Its appearance was almost simultaneous all over the city, new cases appearing in remote sections and then cropping out again in the infected districts. Its center was very plainly in the so- called down town district, inhabited by the poorer classes of people. Yet it was no respecter of persons; rich and poor, learned and ignorant alike, suffered its dread ravages. Nor was it confined to youth alone; it seized upon whomever it could make prey. This epidemic presented many different angles for investigations. We were constantly tempted to follow divers paths, many of them remote from the purpose of this investigation. We shall confine ourselves principally to a plain statement of facts, as nearly as we could discover them. We shall not make any claim to accuracy in any of our data or conclusions, for reasons obvious to all vFo have endeavored to make similar reports. Absolutely accurate data and accurate conclusions therefrom were impossible. The data from which we constructed our charts are not correct, which fact we repeatedly discovered, much to our dismay. These data we secured at the city physician’s office, where they had not been properly reported as the law provides. We do not vouch for our report of the total number of cases, total number of deaths, or for the accuracy of our statement of conditions or conclusions drawn. We are convinced that the total count of diphtheria cases is too low, for we learned of cases which were not reported. At many places where two or paore cases occurred in the same house only the first case was reported ; and in other places, it is our opinion, there were cases which were not reported at all. This would lead to the conclusion that the death ratio is too large. Of this we are uncertain, for, especially at the beginning of the epidemic, some deaths occurred which were reported as caused by other diseases, and subsequent to the burial of the deceased clearly defined cases of diphtheria appeared among other members of the family. In one case which we found which occurred at the beginning of the epidemic, the child died only a 24 IOWA ACADEMY OP SCIENCE. few hours after the doctor was called. He treated the child for another disease, and doubtless reported the death as caused by that disease. Very soon after, another child in the family showed similar symptoms, although more marked. The same doctor was called again. He at once diagnosed the case as diphtheria, administered antitoxin, and the child quickly recovered. From these facts we can draw no conclusion at all as to the degree of correctness of the death ratio. For, while on the one hand, not all the eases were reported; on the other hand, we are convinced some deaths occurred which were credited to other diseases. We shall assume, therefore, that the death ratio is approximately correct and shall present our figures on that assumption. The investigation of the diphtheria cases among school children was most interesting. Chart 'No. I shows the total number of cases per month in each one of the schools of the city where children were re- moved because of diphtheria. In this it is seen that Irving school leads by an alarmingly large margin. This is in the center of the so-called down town section and is the poorer section of the city. Many of the houses and flats are dingy and dilapidated. Many of the back yards are littered with rubbish, the doors of some of the houses were poorly screened, and the interior of many of the homes visited bore striking evidence of a conservation of domestic labor. This section is the CHART I.— DIPHTHERIA CASES PER MONTH IN THE DES MOINES SCHOOLS. School Total Benton Bird Bremer Brooks Bryant — Cary C. C. C. College Casady Cattell - Clarkson Crocker _ Curtis __ Des Moines College High School, East Des Moines— High School, North Des Moines. High School, West Des Moines— 4 1* 2 6 4 5 1 1 2 4 2 7 6 F 6 2 1 3 DES MOINES DIPHTHERIA EPIDEMIC. 25 CHART I.~DIPHTHERIA CASES PER MONTH IN THE DES MOINES SCHOOLS. — Continued. School G CD CO ■4^ o O Nov, 6 , I 1 ! i i i ! 1 ! 1 1 1 1 ; i ! ! >, 1 1 1 ! i ; i ; ! 1 ; ; ! ! I ! 1 1 1 ! 1 1 1 < 1 ; 1 ! 1 1 1 1 1 1 1 ; 1 1 1 1 1 1 I ! 1 ! 1 ! ! 1 ! 1 1 1 1 1 1 1 j be 1 j 1 j 1 I 1 1 1 1 1 I j 1 1 1 be be 1 , 1 1 1 J 1 1 I [ 1 1 i ! i ! i 1 iw ! j ! 1 1 1 ! 1 ! 1 1 ! ! 1 1 j IWW 1 { ! 1 1 i 1 j 1 I ! oJ 1 Q3 j oJ j oJ j « qJ j j 1 o 1 o 1 o 1 1 '^T-^'-lNe^oooo<35(3le)IHOt^l^-^(K)e'C000Cji05OO(MC0c0THrH)L£5i^':0<0i>-t>05OOOrHi-ICMCM(MC0C0^^<2>«:DJt>JC*-C0ej005 CqGrH»HClAlftCpCC>(X)00 00<3^0:>0iOOrHi-IrHrH(N(>lC0CQCOl^lrt«:0^^ T-li-HrHrHrHrHrHrHrHTHrHTHrHTHrHrHT-lrHT-lr-lCN(MC oiPQ -Q > c : 0000>-lrHCNC3MM^^iOiOJt-JC-oO®030iOC>i-li-l rHO oo :8: COMCtI C-lrHo50>tMT«(Mt-Si-lMC<100MiHi-1i>' Mr3 SUO tU) ^ 6j0 9 ^ CD .1^ rM -"t^ ""o O ^ '.*^i ' ^ "o fg o ig o 'o ig ; 44 .13 4« .13 44 : i i-H ‘rH 'e-» r— I ; ^ "5.2 iPilz; ^<;Q':or-t-»oooo050iOc>THTH qq q q qq q q q 5.355^2^^.25^ ppppppppppBppppppppp -iCl TABLE II — BACTERIAL TESTS DESICCATED EGG FROM APRIL 5 TO JULY 6, 1911. BACTERIAL CONTENT OP DESICCATED EGG 41 I fCj 0.3 a o (i> hi) a “ 03 <13 1-4 . Occo 01 iH . « ..0. ^ ii5 2 lO < :S8 “"Si 'C^3<:CC;50iOrHrH|>rJi< §ass o o o <13 o p tl o-g oH-S'3 i— I cs o (K o 03 O p O p P p o mopqomo i o « P I p p p lOWOlli a s a a a a 3 03 ^ 3, Pi P< 03 cj aaaaaaaaaaaaaaa pp(^o3pp,c3p|<^0ic3i:3ppip( rHCi5-C<5- w '•V '•V ’•'O <.>J W <.« '•V V.VJ W VO <.W VO WJ Wv CQ VO WO WO CO WO WO wo WO WO WO wo wo “ 3-1 Oo p p SSS- ” p PU OOOOsOiOiiSOTPoOJOCO ft IS •g^Q O5£o nil in o 'It iM Jiii SSS38SSS§i®S5SSS?3gSSgggSgSS“>g88gS8SgSS:S^ rH r-l i-l r-l i-l CO l-l C«5 05 r-( <50 (M O r-l i-H <35 W lO p,o,ftp,p,p,p,p,(^p,p,0pip,ftp,p,af;i,p,p,p,p,p,p,p,p,p,p,p,pip,p,p,p,p,p,p,«« TABLE II— Continued— BACTERIAL TESTS DESICCATED EGG FROM APRIL 5 TO JULY 6, 1911. 42 IOWA ACADEMY OP SCIENCE, Per Cent Gas 24 hrs. .01 gram Lac- tose Broth oooooocggooooggbusoooogoo® No. Colonies per gram 48 hrs. at 37° C. 215.000 800.000 215.000 255.000 425.000 145.000 185.000 70,000 265.000' 900.000 300.000 230.000 130.000 250.000 75.000 510,000' 20.000 285.000 60,000 75.000 50.000 85.000 255.000 390.000 bD bjo > > > > > > > > > > > > > > > > > > > > > > > g OOOOOOOQOOOOPPOPOOPPPOOO P^(l|P^P^^lfl^F^P^P^P^P^(l|P^P^P^P-IP^(^P-lP^P^P^PMPd Lot No. 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 i 1 t 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 1 t 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 »$OtrOOO:«OrH^-00050rH-/:-ooaDoOC30c 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t i 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 i O ^ ^ W o8 Date June 19 June 19 June 19 June 19 June 23 June 23 June 23 June 23 .Tune 23 __ June 23 June 28 June 28 June 28 June 28 June 28 June 28 July 6 July 6 July 6 duly 0 July .6 July 6 July 6 July 6 Per Cent Gas 24 hrs .01 gram Dex- trose Broth ^ OJ No. Colonies per gram 48 hrs. at . 37° C. (ic.c.) 3,000 (Ic.c.) ? (le.c.) 205,000 (le.c.) 275,000- 300,000 300.000 130.000 500.000 445.000 425.000 890.000 800.000 400.000 445.000 800.000 60,000 150.000 37.000 65.000 93.000 350.000 260.000 275,000 bjo bD W .2^ .2.2.2 oooooooooooooooooop 1-4 1-4 Ph Ph Ph Ph pii P8 Ph Ph Pm Ph Pm ft Ph Ph PM Ah P4 Ah Lot No. 48 Pan 48 Beater 48 Cooler 48 2d Tank- — 46 47 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 ( 1 t 1 1 1 1 1 1 1 1 1 1 1 1 t I 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 :)05Oi-i(MC0r!HlACC>l>00 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 t 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 S S ?D ^ S S Date Majf 24 May 24 May 24 May 24 May 24 May 24 jy±a,y — - May 26 May 26 May 31 May 31 May 31 June 3 June 3 June 3 June 12 _ June 12 June 12 June 12 June 12__ June 12 June 12 _ June 19 TABLE III — BACTERIAL TESTS DESICCATED EGG FROM MAY 6 TO JULY 3, 1912. BACTERIAL CONTENT OF DESICCATED EGG 43 mojq asojD'Bi •uiS io“Sjq 8?- BBS ?aao o £ iiiiiiliiiiiiiliissiiiiiiiliiiiii 2222 22222 'O'a'O'O'd'aH.'S.^S'p'O'a'O'O'a'C'O'O'CTS^'a'd'p'a'a'aSSSS.'H lllllllllllllllllllllllllllllllll 2 a, eh |S2 ^^jg|gjgj5j5|0|5jC5H5.5Hr;jgHg-^^g.^eowcococccococoeocococo« I i § I i I i I S § § i 1 1 i 1 i i i mojq8So:jOB[ •m3 iQ-'Sjqs^ BBS !jaao I8J 5 cS ^ . bjo^ |r~ Geo m 4^ .2i n * O ^ 6 Izi ii§i§isisiiii§iii§iii§iisiiisiisis 'a'OTS'OxJ'a'O'd'O'a'd'a'S'O'O'a'a'O'P'^'O'O'S'P'^'p'a'a'O'a'C'ots'O ooooooooopoQooppooooppoooooopooooo P^Cl^P^P^P^P^P^P^P^A^pL|P^P^P^P^P^P^P^P^Pl|P^P^P^P^P^P^P^P^|l|P^P^P^pL|fL| 2285^ g3g5 s3g3S? 03(Si03(S03 03 0je3(s5o3eSc3c3c3e383o3c303Kic3cS9HBBgS«B99SS TABLE IV — BACTERIAL TESTS DESICCATED EGG FROM MAY 7 TO JULY 2, 1913. 44 IOWA ACADEMY OP SCIENCE. Ill ISoS (u M --I PQ ^ o Sis 'S X I; 6 S g iiiiiiiiiiisisiliiliiililililiilisiliil rc)'a'ax3n3TdT3'a'T3'T3'0'a'^t3T3'0'^'a'^'Q'a'an3'T3?*'a'a'a'a'eT3'^'a'r!33'a'rS'OT3 > > > > > > > > h > > > > > > > > > > > ^ > > > > > > > > > ^ > > > > opoooooooooopooooooooooo^oopoooopopoooo P^|i^P^P^ll|P^P^P^P^P^P^P^P^P^P^P^P^pl^P^P^P^f^P^P^pHp^f^P^CI|f^p^p^P^pl^P^p^p^fL|fL| i i i ililitilililililili §gH§S^ggg||8gggS88gS|||g|2||g§||||g|gg >S >5 >> 03 03 es ®aJcua>Ciaiaia3a3ai4)a>aja3ai g§§§ggg§g§aapapp«apaappa|« 1-3 l-J *-3 *-3 * is:i sis ssi“|i C!3 ■ Pl-w 8888®‘^g8S^iSS8®888Sg8S^8SSS^g8®?3®^^gg^gS ^OO'O 000000^0^0 Ogq^©OOW5^;JHOg^O^Og©te;^^Og^« Sis r- ii o 9 g ii§is§iiiisisisiissiiiiiiissisiis§iiiii 'O'p'P'P'p'P'OTj'ps'p'P'p'p'p'p'^'p'p'p'tJ'PSTS'P'a'p'pJ'p'a'P'P'P'a'P'PJ'P'p'a'pi'p OPPPPPPpPPPPPPpPPPPPPPPPPPOPPPQPPOPPPpP P^P^P^P^p^P^P^pL|P^P^P^P^P^P^P^(l^P^P^P^p^P^P^P^P^P^P^P^P^P^P^P^P^P^f^P^P^(l|P^P^ ! iMisSliiiiJiiiiliiiiiidisiliillillli §S§Sga§gSSSSSSSI§sSSSsSIS333§iSS2232S3S »-*-*-‘-ssssss3 33 3Ssssasaasssssasa5!sass5assa 030303e303o3C3c303'^c3^03®3c3c3(SoSKSe3(^c3c303«3e3o3o3c3C30303c3 5«®«W» BACTERIAL CONTENT OP DESICCATED EGG 45 O O Os o o © c> iiiiliiili xi'axt'axixs'rsxS'T^’o »»»»>> ooooooooqo A^P^P^A^pL^P^P^P^P^P^ III: SSgggsgsgs igiiSttt'SS l^t-5t-3t-3l-sl-3l-Sl-5l-Sl-;) ss!='®s°ssa'=’“ ceiAOOjgoo&o* iiliiSiiSi iiai'iiiisi >>>>>>>>>> o p p p o o p o p p P^(1iPhPL|PhPl,(1|PL(^Ph ! i ! i I iiii; §§ssssssss liinmii TABLE V — BACTERIAL TESTS DESICCATED EGG AT INTERVALS; 1912 PRODUCT. 46 IOWA ACADEMY OP SCIENCE. liol Sl'-I gs8sssissggssssssssgs&ss§iss8^ssss§§§si Id Ip s=>»s»£ oooooooooocooooeoooeooooooooooooooooooo “»d lis 6 Sits m SaS<»SSi5Sa*-”'" q2 W. J, ss rfJSrSaaasasssasaaasaaasasaasassasa^asss 2asSSSS3'-'3*-'3'^‘i*-‘3*'“3''i'-'3'''3'-‘"3'-'3Saa3S3S3?3i lllllilllllllllllllllslllllllllllilll -I Id®; «qacQ ooeooooooooooooooo'^oeooooooooooooooeooo S»Q irs I -I i I s 1 1 1 1 1 1 i_ * 1 1 1 1 1 1 s 1 1 It It i 1 1 1 1 1 1 1 1 1 1 1 1 O 1- lA ^ (N JH ^ ^ rH -s as ac-f I ! I ! ! I ! I I ; 11111 '‘’IIIN gggddsisigggggg ■IMiiMNIMMN J I CO ^:.o^C^V" jgV-'i^ oo\djgV"^V^|gV co « d d' =0 w 00 co BACTERIAL CONTENT OP DESICCATED EGG 47 OOOOOOOOO^OOMOOOO' iiiiiiiiiiiiiii§iii CO;^C0 3rH isisisis§§i§isiig§i g S S « 8 53 B 53 33 53 53 53“ B 53 B 53“ B « . gsg§gg§ggsgigggagg§ S 3353813 So Si8Si888§8g8SS888l28&888 OOOOOOOOOOOOOOOOOoOO §iiliiiiiiiiiiiiiiii 1 SSSSS33S33SS33 33^33 33 33SS^33 S i ;2; ^ i gf ;£ ^ ^ ^“ ;5“ 33 s B 53“ 8 53“ lllilllllillllilllll Ij TABLE VI — BACTERIAL TESTS DESICCATED EGG AT INTERVALS; 1913 PRODUCT. 48 IOWA ACADEMY OF SCIENCE. ooooooi>c>ooooooooo Per Cent Decrease No. Col. 8S8S8gg888S^SfeS88 III8888888S88888S 1 Days Storage •0 oCS •0 o6I oo ooooooooooooooo •draox •qBT; Lot No. Date 1913 IllSslilsIlllllSI Per Ct. Gas 48 hrs. .01 gram Lact’se Broth ooooooooooooooooo© Per Cent Decrease No. Col. fe8S3§^?S888fe§B8888^S;8 8 §8835 8888888888888 No. Col. per gram 48 hrs. at 37° C. iOigigooo|g|og3|o| 1 o •0 oSS ®8®S^888SS888§S8Sg CQ 03 ‘0 o6T 3000^0©0000000©000 Q •doaoj, Lot No. m last— 167 last— . 144' last 144 last— 146 first— 140 first- 147 last— 1481 last— 153 last— 165 first- 150 first__ 160 last— 157 first— 157 last— 158 last— 101 first— 162 first— 163 last— 1- IIIIIIIIIISsllllls BACTERIAL CONTENT OP DESICCATED EGG 49 TABLE VII. liquid white 1910 PRODUCT. LIQUID YOLK 1910 PRODUCT. No. Colonies Per c. c. Number of Samples Per Cent of Total No. Colonies Per c. c. .'lumber of Samples Per Cent of Total To 10,000 12 15.78 To 10,000 6 9.09 10^000 to 10 13.15 10,000 to ?;o,ooo 7 10.60 50,000 to 100, COO 12 15.78 50,000 to 100,000- 7 10.60 lOO^Onn t.n KOO^OOO SI 40.78 100,000 to 500,000— 44 66.66 500,0'00 to 1,000,000 9 11.84 500,000 to 1,000,000 0 0 1,000,000 to 7,000,000 2 2.63 1,000,000 to 7,000,000 2 3.03 76 1 99.96 66 99.98 DESICCATED EGG PRODUCT OP No. Colonies per gram 1911 1912 1913 Number of Samples Per Cent of Total Number of Samples Per Cent of Total Number of Samples Per Cent of Total To 10,000 0 0 1 1.78 5 5.10 10,000 to 50,000 7 7.44 6 10.71 5 5.10 5O,0C0 to 100,000 15 15.91 8 14.28 10 10.20 100,000 to 500,000 63 67.02 40 71.42 70 71.42 500,000 to 1,000,000 9 9.57 1 1.78 S 8.16 94 99.94 56 99.97 98 99.98 SUMMARY OP DESICCATED PRODUCT, No. Colonies per gram Number of Samples Per Cent of Total To 10,000 6 2.41 10,000 to 50,000 18 7.25 50,000 to 100,000— 83 13.30 10O,COo to 500,000 173 69.75 500,000 to 1,000,000 18 7.25 248 99.96 Bacteriological Laboratory, Drake University, Des Moines. 4 INCUBATOR OPENING TO OUTSIDE. 51 AN INCUBATOR OPENING TO THE OUTSIDE OF THE BUILDING. BY L. S. ROSS. Having had the experience more than once of being routed out of bed after ten o’clock on winter nights to make journeys to the laboratory with diphtheria tubes to put into the incubator for early morning micro- scopical examination, and also of many an after-supper trip to see if any belated tubes had been dropped into the box prepared for them, it occurred to me that an incubator might be arranged so a tube in its containing case could be dropped into it from the outside of the build- ing. I had a box so arranged, why not an incubator? Upon searching, an old incubator was found, one that is opened by lifting off the entire top as a lid. The top was replaced with a wooden top, made in two parts and covered with heavy felt. A hole was cut in one part of the W. — ^Wall of building. C. C.— Chute. O. — Opening into chute. T. D. — Trap door. D. — Door of chute. I. — Incubator. S. — Galvanized iron slide. F. — ^Floor. G.' — Basement floor. I 52 IOWA ACADEMY OP SCIENCE. lid to admit a four inch galvanized iron pipe entering at an oblique angle. The pipe leads directly from the incubator, which is in the base- ment, up to the floor, where it connects with a wooden chute that in turn opens by a two inch square aperture to the outside of the building. ^ The aperture is closed by two galvanized iron flaps, one on the inside of the wall and the other at the outside ; the latter is kept closed by a spring in order to prevent the wind from opening it and sending gusts down into the incubator. At the lower oblique end of the pipe, the end in the incubator, is a hinged door that is opened by the force of the diphtheria tube case as it strikes after sliding down the chute. Then the door closes of its own weight after the tube has fallen into the incubator. A glass door, and a galvanized iron slide arranged to be opened or closed, are in the wooden chute above the floor. If desired, the slide may be closed so that tubes dropped into the chute during the day time may not go down into the incubator in the basement, but may be taken out and put into the incubator in the laboratory. The temperature of the incubator varies but little. It may be made more nearly constant by wrapping the iron pipe with asbestos paper, or with felt. The device has proved eminently successful and has saved many an after-supper trip to the laboratory. See figure 2. Bacteriological Laboratory, Drake University, Des Moines. ^ FIELD AND FOREST FLORAS. 53 COMPARISON OF FIELD AND FOREST FLORAS IN MONONA COUNTY, IOWA. BY D. H. BOOT. The purpose of this paper is to present some of the results obtained in a study made of the field and forest fioras of St. Clair township, Monona county, which indicate the close relations existing between the fioras of the most extreme types of plant habitat found in Iowa. The locality selected is in the east central part of Monona county, which is at the west end of the middle tier of counties of the state of Iowa. The eastern part of this county is very heavily rolling, the clay hills consisting of wind-blown loess, with a rather thin vegetable mold for a top soil. Five areas were chosen for study. One of these was a high prairie ridge running east and west, with the south side exposed to the strong southwest Winds of summer, and carrying only a scanty xerophytic prairie vegetation. The second station was on a low prairie point between two high ridges, and with a southeast exposure. This prairie point was well protected from the southwest winds, and, like the first one, had never been disturbed by the plow. The third station was a piece of cleared ground that was reverting to forest again. This tract was on the north side of a high hill, and well protected from the hot summer winds. The fourth station was in a dense forest on the south bank of a deep gulch running east and west, so that it has a north exposure. The fifth station was on the north bank of the same gulch and differed from the fourth only in having a south exposure. The studies made included observations on the soil evaporation, on the relative humidity, the wind movement, and numerous other items that may affect plant growth; but this paper deals only with the lists of plants taken at each point and their correlation. The study was made in the fall of 1909 and the spring of 1910. Collections of all plants in bloom were made August 3, August 14, August 21, September 18, April 9, April 30, June 1, June 9, and June 16, at each of the five different stations. The plants taken, at the first station on August 3 were Cirsium discolor (Muhl.) Spreng. (Common Thistle), Petalostemum candidum Michx., (Prairie Clover), Amorpha canescens Pursh. (Lead Plant), Braiineria angustifolia (DC.) Britton (Purple Cone-flower), Potentilla arguta Pursh. (Cinquefoil), Euphorbia corrollata L. (Flowering Spurge), Verhasciim Thapsus L. (Common 54 IOWA ACADEMY OP SCIENCE. Mullein) . No plants were blooming on this date at stations two or tliree ; at station four Desmodium grandiflorum (Walt.) DC. (Tick Trefoil), Phyrma leptostacliya L. (Lopseed), Hystrix patiila Moench. (Bottle- bush Grass), Campanula americana L. (Tall Bell-flower), Geum vir- ginianum L (Avens) ; and at station five Desmodium grandiflorum (Walt.) DC. (Tick Trefoil), Campanula americana h. (Tall Bell-flower), Geum virginianum L. (Avens), Laportea canadensis (L.) Gaud. (Wood Nettle), Elymus striatus Willd. (Wild Rye), Chenopodium album L. (Lambs’ Quarters), were taken. August 14, the plants taken were Amorpha canescens Pursh. (Lead Plant), Brauneria angustifolia (DC.) Britton (Purple Cone-flower), Euphorbia corrolata L. (Flowering Spurge), Polygonum convolvulus L. (Black Bindweed), Euphorbia preslii Guss. (Spurge), Dyssodia papposa (Vent.) Hitchc. (Fetid Mari- gold), Trifolium repens L. (White Clover), Salsola kali var. tenuifolia G. F. W. Mey. (Russian Thistle), Solidago nemoralis Ait. (Goldenrod), Polygonum pennsylvanicum L, (Knotweed), Asclepias verticillata L. (Milkweed), Petalostemum purpureum (Vent.) Rydb. (Prairie Clover), Linum sulcatum Riddell (Flax), Monarda mollis L. (Horse 'Mint), Verbena stricta Vent. (Hoary Vervain), Cirsium iowense (Pammel) Fernald (Common ^Thistle), Eragrostris megastachye (Koeler) Link (A grass), Houstonia angustifolia Michx. (No common name), Sym- phoricarpos occidentalis Hook (Wolfberry), Bouteloua curtipendula (Michx.) Torr. (Mesquite Grass), Andropogon furcatus Muhl. (Beard Grass), for area No. 1. For area No. 2 there were taken Cirsium discolor (Muhl.) Spreng. (Common Thistle), Petalostemum candidum Michx. (Prairie Clover), Euphorbia corrolata L. (Flowering Spurge), Euphor- bia preslii Guss. (Spurge), Asclepias verticillata L. (Milkweed), Ver- bena stricta Vent. (Hoary Vervain), Petalostemum purpureum (Vent.) Rydb. (Prairie Clover), Linum sulcatum Riddell (Flax), 3Ionarda mollis L. (Horsemint), Andropogon furcatus Muhl. (Beard Grass), Desmodium canescens (L.) DC. (Tick Trefoil), Helianthus tuberosus L. (Jerusalem Artichoke), Lactuca ludoviciana (Nutt.) Riddell (Lettuce), Symphoricarpos occidentalis var. laevigatas Fernald (Snowberry), Astragalus canadensis L. (Milk Vetch), Desmodium grandiflorum (Walt.) DC. (Tick Trefoil). Area No. 3 was represented by Monarda mollis L. (Horse Mint), Helianthus tuberosus L. (Jerusalem Artichoke), Polygonum lapathifolium L. (Knotweed), Impatiens pallida Nutt. (Pale Touch-me-not), Amphicarpa pitcheri T. and G. (Hog Peanut), Scrophidaria leporella Bicknell (Figwort), Verbena urticaefolia L. (White vervain). From area No. 4 were taken Eupatorium urticae- folium Reichard (White Snakeroot), Phryma leptostachya L. (Lopseed), FIELD AND FOREST FLORAS. 55 Campanula americana Lf. (Tall Bell-flower), Qeum virginianum L. (Avens), Lappula virginiana (L.) Greene (Beggars’ Lice), Gircaea lutetiana L. (Enchanter’s Nightshade), Eupatorium purpureum L. (Joe-pye Weed), Laportea canadensis (L.) Gaud. (Wood Nettle). From area No. 5 Phryma leptostachya L. (Lopseed), Campanula americana L. (Tall Bellflower), Geum virginianum L. (Avens), Agrimonia mollis (T. and G.) Britton (Agrimony), Desmodium dillenii Dari. (Tick Trefoil). The plants collected on the 21st of August were: for area No. 1, Cirsium discolor -(Muhl.) Spreng. (Common Thistle), Amorpha canescens Pursh. (Lead Plant), Euphorbia corrolata L. (Flowering Spurge), Euphorbia preslii Guss. (Spurge), Dyssodia papposa (Vent.) Hitchc. (Fetid Marigold), Solidago nemoralis Ait. (Goldenrod), As- clepias verticillata L. (Milkweed), Petalostemum purpureum (Vent.) Rydb. (Prairie Clover), Monarda mollis L. (Horsemint), Verbena stricta Vent. (Hoary Vervain), Houstonia angustifolia Michx. (No common name), Bouteloua curtipendula (Michx.) Torr. (Mesquite Grass), Andropogon scoparius Michx. (Beard Grass) ; for area No. 2, Euphorbia corrolata L. (Flowering Spurge), Euphorbia preslii Guss. (Spurge), Ascelpias verticillata L. (Milkweed), Petalostemum piirpur- eum (Vent.) Rydb. (Prairie Clover), Linum sulcatum Riddell (Flax), Monarda mollis L. (Horsemint), Verbena stricta Vent. (Hoary Ver- vain), Andropogon furcatus Muhl. (Beard Grass), Andropogon scoparius Michx. (Beard Grass), Sorghastum nutans (L.) Nash. (Indian Grass), Astragalus canadensis L. (Milk Vetch), (Enothera biennis L. (Common Evening Primrose), Verbena hastata L. (Blue Vervain), Helianthus hirsutus Raf. (Sunflower), Solidago serotina Ait. (Goldenrod) ; for area No. 3, Cirsium discolor (Muhl.) Spreng. (Common Thistle), Monarda mollis L. (Horsemint), Eragrostris megastachya (Koeler) Link (A Grass), Andropogon furcatus Muhl. (Beard Grass), Bidens vulgata Greene (Beggar- ticks), (Enothera biennis' h. (Common Evening Primrose), Verbena hastata L. (Blue Vervain), Helianthus hirsutus Raf. (Sunflower), Heliopsis helianthoides (L.) Sweet. (Ox-eye), Polygonum lapathifolium L. (Knotweed), Amphicarpa pitcheri T. and G. (Hog Peanut), Verbena urticaefolia L. (White Vervain), Potentilla monspeli- ensis L. (Cinquefoil), E rig er on' canadensis L. (Horseweed), Ambrosia artemisifolia L. (Roman Wormwood), Panicum capillare L. (Old Witch Grass), Polygonum dumetorium L. (Knotweed), Scrophularia marilan- dica L. (Figwort) ; for area No. 4, Campanula americana L. (Tall Bell- flower), Am&rosm trifida var. integrifolia (Muhl.) T. and G. (Great Ragweed), Lactuca floridana (L.) Gaertn. (Lettuce), Impatiens pallida Nutt. (Pale Touch-me-not) ; for area No. 5, Euphorbia corrolata L. 56 IOWA ACADEMY OF SCIENCE. (Flowering Spurge), Salsola kali var. tenuifolia G. F. W. Mey. (Russian Thistle), Andropogon furcatus Muhl. (Beard Grass), Kuhnia eupa- toHoides var. corymhulosa T. and G. (False Boneset), Eupaiorium 'urticae folium Reichard (White Snakeroot), Phryma leptostachya L. (Lopseed), Campanula americana L. (Tall Bell-flower), Laportea cana- densis (L.) Gaud. (Woodnettle), Desmodium dillenii Dari. (Tick Tre- foil). On the 18th of September the following plants were collected: Area No. 1, Cirsium discolor (Muhl.) Spreng. (Common Thistle), Euphorbia corrolata L. (Flowering Spurge), Dyssodia papposa (Vent.) Hitchc. (Fetid Marigold), Solidago nemoralis Ait. (Goldenrod), Linum sulcatum Riddell (Flax), Kuhnia eupatorioides var. corymhidosa T. and G., Aster sericeus Vent. (Aster), Solidago rigida L. (Goldenrod), Sor- ghastum nutans (L.) Nash. (Indian Grass), Aster multifloris ysly. exiguus Fernald (Aster), Bidem vulgata Greene (Beggar Ticks) ; area No. 2, Euphorbia corrolata L. (Flowering Spurge), Kuhnia eupatorioides var. corymhulosa T. and G., Hcliopsis helianthoides (L.) Sweet. (Ox-eye), Aster cordifolius L. (Aster) ; area No. 3, Monarda mollis L. (Horsemint), Helianthus tuherosus L. (Jerusalem Artichoke), Heli'anthus hirsutus Raf. (Sunflower), Polygonum lapathifolium L. (Knotweed), Impatiens pallida Nutt. (Pale Touch-me-not), Eupatorium urticaefolium Reichard (White Snakeroot) ; area No. 4, Eupatorium urticaefolium Reichard (White Snakeroot), Campanula americana L. (Tall Bellflower) ; area No. 5, Aster cordifolius L. (Aster). In the following spring the lists of plants collected are : for April 9, area No. I, Astragalus caryocarpus Ker. (Ground Plum), Erythronium alhidum Nutt. White Dog’s-tooth Violet), Yiola sororia Willd. (Violet), Ostrya virginiana (Mill.) K. Koch. (American Hop Hornbean), Anemone patens var. wolfgangiana (Bess.) Koch. (Basque Flower), Carex pennsylvanica Lam. (Sedge), Yiola pedatifida G. Dou. (Violet), Antennaria neodioica Greene (Ever- lasting), Quercus macrocarpa var. oliviformis (Michx. f.) Gray (Bur Oak) ; area No. 2, Erythronium alhidum Nutt. (White Dog’s-tooth Violet), Taraxacum officinale Weber (Dandelion) ; area No. 3, Ery- thronium alhidum Nutt. (White Dog’s-tooth Violet), Taraxacum of- ficinale Weber (Dandelion), Bihes gracile Michx. (Missouri Gooseberry), Prunus americana Marsh. (Wild Plum), Crataegus mollis (T. and G.) Scheele. (Hawthorn), Yiola scahriuscula Schwein. (Smooth Yellow Violet) ; area No. 4, Carex pennsylvanica Lam. (Sedge), Taraxacum officinale Weber (Dandelion), Sisyrinchium campestre Bicknell (Blue- eyed Grass), Yiola scahriuscula Schwein. (Smooth Yellow Violet) ; Phlox divaricata L. (Blue Phlox), Arisaema triphyllum (L.) Schott (Indian Turnip), Ranunculus ahortivus L. (Small-flowered Crowfoot), FIELD AND FOREST FLORAS. 57 Dicentra cucullaria (L.) Bernh. (Dutchman’s Breeches), Bihes cynos- hati L. (Prickly Gooseberry), Sanguinaria canadensis L. (Bloodroot) ; area No. 5, Erythronium albidum Nutt. (White Dog’s-tooth Violet), Viola sororia Willd. (Violet), Bihes gracile Michx. (Missouri Goose- berry), Prunus americana Marsh. (Wild Plum), Phlox divaricata L. (Blue Phlox), Quercus macrocarpa Michx. (Bur Oak). The plants col- lected on the 30th of April on area No. 1 were Carex pennsylvanica Lam. (Sedge), Antennaria neodioica Greene (Everlasting), Lithosper- mum angnstifolium Michx. (Puccoon). For area No. 2 they were Sisyrinchium campestre Bicknell, (Blue-eyed Grass). For area No. 3 none were taken. For area No. 4, Viola puhescens Ait. (Downy Yellow Violet), Galium aperina L. (Cleavers), Fragaria virginiana Duchesne. (Strawberry) were collected. For area No. 5 the list included Viola sca.hriusctda Schwein. (Smooth Yellow Violet), Phlox divaricata L. (Blue Phlox), Arisaema triphyllum (L.) Schott (Indian Turnip), Banunctdus ahortivus L. (Small-flowered Crowfoot), Galium aperina L. (Cleavers), Osmorhiza longistylus var. villicaulis Fernald. (Sweet Cicely). The plants collected on the 1st of June were: Area No. 1, Poa pratensis L. (Kentucky Blue Grass), Ceanothus ovatus var. pu- hescens T. and G. (Redroot) ; area No. 2, Poa compressa L. (Canada Blue Grass), Tradescantia hracteata Small (Spiderwort) ; area No. 3, Trifolium repens, L. (White Clover), Aquilegia canadensis L. (Wild Columbine), Phlox divaricata L. (Blue Phlox), Garya glahra (Mill.) Sprach. (Pignut), Arisaema triphyllum (L.) Schott (Indian Turnip), Sanicula canadensis L. (Sanicle), Banunculus ahortivus L. (Small- flowered Crowfoot), Delphinium tricorne Michx. (Dwarf Larkspur), Fragaria vesca var. americana Porter (Strawberry) ; area No. 4, Taraxa- cum officinale Weber (Dandelion), Phlox divaricata L. (Blue Phlox), Arisaema triphyllum (L.) Schott (Indian Turnip), Banunctdus ahor- tivus L. (Small-flowered Crowfoot), Hydrophyllum virginianum L. (Waterleaf), Sanicula marilandica L. (Black Snakeroot), Galium aperina L. (Cleavers) ; for area No. 5, Taraxacum officinale Weber (Dandelion), Aquilegia canadensis L. (Wild Columbine), Phlox divari- cata Jj. (Blue Phlox) , Arisaema triphyllum (L.) Schott (Indian Turnip), Banunculus ahortivus L. (Small-flowered Crowfoot), Hydrophyllum virginianum L. (Waterleaf), Galium aperina L. (Cleavers). For June 9 on area No. 1 the plants were Ceanothus ovatus var. puhescens T. and G. (Redroot), Oxalis stricta L. (Wood Sorrel) ; on area No. 2, Oxalis stricta L. (Wood Sorrel) ; for area No. 3, Trifolium repens L. (White Clover), Poa pratensis L. (Kentucky Blue Grass), Taraxacum officinale Weber (Dandelion), Aquilegia canadensis L. (Wild Columbine), 58 IOWA ACADEMY OF SCIENCE. Arisaema triphyllum (L.) Schott (Indian Turnip), DeZptomm income Michx. (Dwarf Larkspur), Hydrophyllum virginimum L. (Waterleaf), Aquilegia canadensis L. (Wild Columbine) ; for area No. 4, none; for area No. 5, Aquilegia canadensis L. (Wild Columbine), Carya glahra (Mill.) Sprach. (Pignut), Hydrophyllum virginianum L. (Waterleaf), Sanicula marilandica L* (Black Snakeroot), Galium aperina L. (Cleavers), Carya glahra var. villosa (Sarg.) Robinson (Broom Hickory). The plants taken on June 16 are: for area No. 1, Brauneria angustifolia (DC.) Heller, (Purple Cone-flower), muUiftorus var. exogenus Fernald (Aster), Ceanothus ovatus var. puhescens T. and G. (Redroot), Rosa pratincola Greene (Rose), Capsella hursa-pastoris (L.) Medic. (Shepherd’s Purse), Physalis puhescens L. (Ground Cherry), Onosmodium occidentale Mackenzie (False Gromwell), Anemone cylin- drica Gray (Anemone) ; for area No. 2, Physalis puhescens L. (Ground Cherry), Anemone cylindrica Gray (Anemone), Triosteum perfoliatum L. (Tinker’s Weed), Trifolium hyhridum L. (Alsike Clover), Achillea millefolium L. (Common Yarrow) ; for area No. 3, Trifolium repens L. (White Clover), AquiUgia canadensis L. (Wild Columbine), Crypto- taenia canadensis (L.) DC. (JlonQ-woTi) , Evonymus afropurpureus Jaeq. (Burning Bush), Vitis velutina L. (Riverbank Grape), Sanicula mari- landica L. (Black Snakeroot), Juglans nigra L. (Black Walnut) ; for area No. 4, Trifolium repens L. (White Clover), Phlox divaricata L. (Blue Phlox), Hydrophyllum virginianum L. (Waterleaf), Cryptotaenia canadensis (L.) DC. (Honewort), Evonymus atropurpureus Jacq. (Burning Bush), Sanicula marilandica L. (Black Snakeroot), Yitis vulpina L. (Riverbank Grape) ; for area No. 5, Hydrophyllum vir- ginianum L. (Waterleaf), Cryptotaenia canadensis (L.) DC. (Hone- wort), CcJastrus scandens L. (Climbing Bittersweet). By grouping these plants under their several areas and dates there is obtained a gradual curve of transition indicated by the plant names, extending regularly from area No. 1 to area No. 5, and indicating gradual change in flora from the one locality to the next, so that we have no abrupt changes from the high dry prairie ridge to the low sheltered prairies, from the low sheltered prairie to the cleared land, from the cleared land to the dense forest with a north exposure, nor from this to the dense forest with the south exposure, but there is a gradual transition from the plant life of one area to that of the next, until finally in the dense forest we have few of the plants found out on the exposed prairies. Botanical Laboratory, State University op Iowa, Iowa City. FOSSIL TREE-FERN OF IOWA. 59 NOTES ON A FOSSIL TREE-FERN OF IOWA. BY CLIFFORD H. FARR. The members of the Psaroneae comprise a family of ferns which lived during later Paleozoic times and often developed to treelike dimensions. Some believe that they were closely related to the Cyatheaceae, to which modern tropical tree-ferns belong. Most botanists, however, consider the Psaroneae a family of the -order Marattiales. Members of this order still live, but, though tropical, are, for the most part, low forms with stumplike stems and enormous leaves. The Marratiales have been some- times thought of as ancestors of the Pteridospermae^ and it is possible that the Psaroneae may yet be associated with this latter group. Specimens of the fossil Psaronius have in rare instances been found in organic contact with the impressions of the frond of Pecopteris sterizeli. This last-named species closely resembles the leaves of Pecopteris pluceneti, which according to Grand ’Eury is one of the seed-bearing forms. The Psaroneae proper are all treelike in habit, and have been found only in the Upper Carboniferous and the Lower Permian strata. Their geographical distribution includes Saxony, Central Prance, Bohemia, Brazil, and North America. Some writers believe that at times the tree reached a height of at least sixty feet. A peculiarity of Psaronius lies in the fact that after the lower leaves had fallen off, adventitious roots grew out aitfong the leaf scars and thence downward to the ground. Though these are individually very small, they are produced in such numbers that the leaf scars were com- pletely obscured from view, and a. sort of false cortex enveloped the stem in its lower region. The genus is composed of three general types of stems distinguished by the arrangement of leaves and hence of leaf scars. Each of these ytypes is represented by a number of species. One kind has the leaves in two longitudinal rows, distichi; in another there are four longitudinal rows, tetrastichi; and the remaining species have them disposed more or less in spirals, polystichi. Several years ago some fragments of Psaronius were found in the Upper Carboniferous of Hardin county, Iowa. They consisted for the most part of petrifactions of adventitious roots, while one showed a small portion of the periphery of the stem. Dr. T. H. Macbride re- 60 IOWA ACADEMY OP SCIENCE. ferred these to a new species, Psaronius horealis, and described them in the Proceedings of the Davenport Academy of Science for 1907, That description has been appended to this paper. During the summer of 1913 Mr. Ralph Gray found another specimen of Psaronius in that same region. It had been eroded from the bank of a nearby stream, so that its geological position unfortunately cannot be exactly determined. Its composition is sandstone infiltrated with a large amount of iron. Since it bears no marks of glaciation there is no evidence that it grew and was fossilized in any other locality than, that in which it was found. The country rock at that place is Upper Carboniferous, and this also lends strength to this interpretation, that it grew near the place of finding. The fossil is cylindrical, about fourteen inches in length, and three inches in diameter. Judging from the thickness of the false cortex of roots the portion fossilized is that part of the stem some distance above the ground. The vascular system at the upper end indicates that the living stem must have extended upward at least twenty inches farther, so that this tree-fern was doubtless several feet in height. The leaf scars are arranged in eight longitudinal rows, those of ad- jacent rows alternating. They thus appear to be spirally disposed, and hence this specimen should be classed with the polysticM. The distance between successive leaf scars of the same longitudinal row varies from twenty-five to thirty-two millimeters. Each leaf scar is oval in form, and its absciss surface has a vertical diameter of thirty-eight millimeters and a horizontal diameter of nineteen millimeters. On this surface there is a Y shaped elevation somewhat below the center, doubtless marking the leaf trace. A very prominent .groove extends downward from the lateral margin of each leaf scar, defining the boundary of the leaf base as it enters the stem proper. This groove varies from eight to thirteen millimeters in length. The leaf scars are not all well pre- served, about half of them being hollow cavities which were packed with friable sand when the specimen was found. These poorly pre- served leaf bases are for the most 'part on one side of the stem, which indicates that the latter lay on the surface of the ground for some time before it was petrified. In this way decomposition took place on the lower, more moist, side. Between adjacent rows there appears a ridge, one centimeter in di- ameter, and perpendicular in direction. It is bounded on either side by the leaf scars and the grooves which are associated with them. The degree of convexity of the ridge is rather variable. It may be almost FOSSIL TREE-FERN OF IOWA. 61 flat, or be iiniforinly rounded, or a sharp edge may be found on either side or along the center. Among the leaf bases are the attachments of the rootlets which grew out after the leaves had fallen off. These are very minute, being not more than one millimeter in diameter. They, are especially prominent along the grooves, but may occur in any part of the inter-abscissal area. The roots themselves were probably torn off in some way before petri- faction took place, for no evidence of abrasion is seen on the fossil remains. At the lower end of the stem an area of about twenty-eight square centimeters is covered with a mass of these rootlets about eight millimeters in thickness. These present a very fibrous appearance due to the parallel arrangement of the rootlets. It cannot be absolutely determined whether this represents the entire thickness of the false cortex at this place or not; but the general appearance favors such an interpretation. A few of the absciss surfaces of the leaf scars appear fibrous; it is probable that this indicates the overlying of rootlets, most of which had in some way been removed. By polishing the upper end of the specimen it was possible to define the general system of vascular supply. From the marked radial sym- metry of the leaf arrangement it seemed probable that the vascular system would also be symmetrically disposed. On this account the Fig". 3. — Diagram of the slightly oblique polished surface of the upper end of the specimen, showing the arrangement of vascular bundles. 62 IOWA ACADEMY OF SCIENCE. Fig-. 4. — Schematic dra-wing of vascular system in longitudinal aspect. polished surface was made slightly oblique, making possible the deter- mination of the form and general course of the strands from a single section (Fig. 3). hbgure 4 is a schematic drawing of the bundle ar- rangement in longitudinal aspect, constructed from a study of the polished section and the leaf scars. The leaf traces of only four rows of leaves are indicated in this scheme, those of the other four being omitted for the sake of simplicity. In order, to distinguish between the leaf traces of successive nodes they have been represented alternately by broken and entire lines. Beneath each ridge, which runs longitudinally between two rows of leaf scars, a horseshoe-shaped vascular strand extends from the base to the apex of the stem. This strand is convex outward and measures^ about eight millimeters from edge to edge. Small accessory bundles may sometimes be seen along these edges; they probably arise from the horseshoe-shaped strand and proceed to the rootlets. Other root bundles arise from the junction of the strand with the leaf trace itself. FOSSIL TREE-FERN OF IOWA. 63 For each leaf base there is a single leaf trace. As it enters the leaf base it is broad, and slightly convex outward. As it passes in its out- ward course between two of the horseshoe-shaped peripheral strands it connects with them along either edge. It will thus be seen that the peripheral strand in its upward course unites with a leaf trace first on one side and then on the other, but at no one level do peripheral strands and leaf traces constitute a complete ring. The four leaf traces of the leaves of the next node above may be found alternate with those just described and on their inner side. They are similarly convex outward and in addition their edges are slightly recurved. They are at least two centimeters in width and are separated laterally by a distance of not more than one centimeter. The leaf traces of the second node above the polished surface form a similar cycle within the one last mentioned. They are, however, less convex ; and their edges are in no instance recurved. Within this cycle the system is somewhat more complicated. Each leaf trace of the third node above is broken into three vascular strands arranged side by side in the form of a curve. The middle strand is fused along its edges with the two adjacent traces of the next outer, or second, cycle. Since in this way each leaf trace of the second node unites on either side with the middle strand of the leaf trace of the third node there is formed a complete vascular ring. Each of the lateral strands of the leaf trace of the third node is joined to the middle strand of the leaf trace of the fourth node; while the lateral strand of the fourth some- times remains independent or may connect with both the middle strand of the fourth and the lateral of the third node, forming a triradiate figure. This anastomosis of the leaf traces into three strands is only a local modification and does not disturb the individuality of the leaf trace as it is followed downward. It seems that these three strands unite again at a lower level to constitute the original leaf trace once more. The leaf trace of the fifth node above is seen to anastomose in a similar manner, but the strands are in this case much narrower, being only about five millimeters in width. The four leaf traces of the fifth node, when followed downward, are seen to unite together to form the central strand of the stem. It thus appears that all leaf traces originate from this central strand and after more or less anastomosis proceed individually to their respective leaf bases. It will be remembered that in their course they fuse laterally with the leaf traces of the whorl im- mediately above and that immediately below. In this way two con- 64 IOWA ACADEMY OP SCIENCE. Fig. 5. — Photograph of the specimen of Psaromus. centric vascular rings are seen to be formed enveloping the central strand. Each of these rings is, however, slightly perforate, due to the anastomosis of the individual leaf traces into three strands at different levels. It seems probable, therefore, that this stem arose from one with a single solid central vascular core, from which the leaf traces proceeded independently to the leaf bases. Such an arrangement would resemble the primitive protostele. The system, as here found, may thus have arisen by a lateral fusion of the leaf traces at different points. It is easy to see, that, should this tendency toward fusion continue a little farther, two imperforate hollow cylinders would be developed about the central strand. This might be thought of as a double siphonostele. It would furnish direct vascular connection between the roots and the leaves, irrespective of the vascular strand in the center; and, since it would be more peripheral, might, in a large stem, constitute a con- siderably shorter route, and hence transmit a larger amount of water than the central strand. According to the generally accepted theory of use and disuse the central strand would tend to abort under these circumstances. The same factor might operate to obliterate the inner of the two hollow cylinders, so that finally but one hollow cylinder or, in other words, an ordinary siphonostele would supplant the present more complex form. It is not here contended that this is the only way in which a siphonostele may have evolved from the protostele, but the specimen here described suggests the above as a possible course in this group of plants. FOSSIL TREE-FERN OF IOWA. 65 ADDENDA. The following description of Psaronnis torealis, Macbr. is taken from the Proceedings of the Davenport Academy of Science, vol. X, p. 158 : The fossil here described is represented by several fragments of a pteridophytous stem about ten centimeters in length and six in width. The whole specimen is strongly impregnated with iron, probably haematite. The iron deposits are so extensive as to have replaced almost entirely the vascular parts of the associated struc- tures. The central mass of the stem seems to have been composed of two elements, a parenchymatous, as we infer from the homologies of the case, now wholly lost and replaced by sand, and a vascular element preserved only in part, but showing the bandlike form characteristic of the stems of larger ferns, as for instance, some Cyatheas, where the section of each bundle is arcuate with the tips of the arc more or less reversed or flexed. This feature of the fossil is indicated in Plate Y, Fig. 1. The entire stem, when per- fect, must have been fifteen or eighteen centimeters in diameter. The outer part of the stem, Plate Y, Pig. 2, much better pre- served than the central axis, shows a vast multitude of vascular strands more or less parallel to each other and to the principal axis; not straight, however, but interwoven, grown through each other apparently in a most intricate mass. Between the strands a crude, rather thick-walled parenchyma is seen. Each strand has for its center a flbro-vascular bundle of the concentric type, showing scalariform ducts of unequal diameter; but the bundle is itself surrounded by a strongly developed sheath or moss of sclerenchymatous cells everywhere well preserved. Plate YI, Pigs. 1 and 2. The generic reference of this fossil would seem sufficiently clear. Specific distinctions here, as elsewhere, are purely tentative, but for convenience of reference the specimen may be called by a specific name. The distribution of the principal vascular strands may possibly here suggest specific characters, although in existing forms such arrangement is generally significant of a much larger group. Botanic AT. Laboratory, State University op Iowa, Iowa City. 5 ■7: • • ' .• , •••A.- .•-•.' ■..,' ■" ■■ ' ■ ■ ' . ■■. •■ . .{ "/t • ECOLOGY OP IOWA LICHENS. 67 NOTES ON THE ECOLOGY OF IOWA LICHHNS. ZOE R. FRAZIER. Many interesting features are presented by this group of organisms, some of which have been investigated more or less thoroughly, while others have received comparatively little attention.-^ The work with Iowa Lichens has consisted almost entirely of reporting and describing species, with only very limited reference to structural modifications of thalli, and the relation between this and the ability of lichens to with- stand adverse atmospheric conditions. In this, lichens are perhaps the most remarkable organisms in existence, and the full investigation of the secrets of this power offers an excellent field for the student of special problems. The work, of which a partial result is here presented, was undertaken at the State University with the view of adding some observation along the line suggested. Further work of this kind would probably reveal many more interesting results. All plants give off water in transpiration and it is well known that in many higher plants this process is more or less well controlled. This is especially true of xerophytic plants. Many of the lichens are ex- treme xerophytes, and the escape of moisture must be checked if they are to persist. Many forms regulate this by some modification of structure. These structural adaptations are not so marked as in the vascular xerophytes yet certain modifications of the same general nature as those presented by the latter, may be observed. In collecting material the tree forms were found to be smaller in pastures, and the more ex- posed places, than the same species on the same kind of trees at the border of timber and other more protected places. Those species growing on rocky cliffs varied greatly in size from the top of the cliff to the base, those at the crest being smaller than the same species growing at the base or in protected crevices of rock. In general, the species in the more exposed places are characterized by reduction of thallus. Loss of water is prevented, by lichens, in various ways. Some species check it by a well developed cortex which is usually on the upper sur- face, more rarely on the lower surface. This cortex may be a well developed layer of thick-walled cells several layers in thickness, or it 68 IOWA ACADEMY OP SCIENCE. may be much reduced. The thickness of the cell wall varies in different thalli as does the cortical layer. In other species there is no true cortex but a covering of closely interwoven hyphse, which serves the purpose of a cortex to a limited degree. Some facts of interest were observed in regard to the variation in cortex of some of the species. Dermatocarpon has a well developed cortex above and below, the lower cortex, however, being developed to a lesser degree. Those specimens collected from the xerophytic Sioux quartzite of Lyon county, Iowa, show a thicker cortex than those from Muscatine and Johnson counties. They are smaller, more harsh to the touch and when soaked become tougher and not so soft as the Johnson and Muscatine county material. Parmelias have an upper and more or less well developed lower cortex and are closely attached to the substratum, thus reducing transpiration. Among Placodiums a cortex is developed in all except the crustose forms. Placodiiim elegans, collected from the exposed rocky cliffs at the Palisades in Linn county, had a thicker cortex than the same species col- lected from less exposed places. The Lecanoras have no cortex but in Lecanora ruhina there is a heavy covering of closely interwoven hyphse which probably is a protection against excessive evaporation. This species is well adapted to the xerophytic conditions of exposed ledges and is represented most abundantly by specimens from the Sioux quartzite of Lyon county, where exposure is extreme. In Peltigera canina there is a well developed upper cortex only. As a rule the cortex is best de- veloped in the most xerophytic species. Excessive transpiration is also checked by reduction of the apothecia in both numbers and size. Generally those forms growing on exposed rocks as the Sioux quartzite do not show large or exposed apothecia. Rinodina and Dermatocarpon have immersed apothecia, Peltigera col- lected from the exposed crests of hills had much reduced apothecia while the same species growing in the shade and protected places had large spreading disks. Among the cliff forms the apothecia of any species varied greatly in size from the top of the cliffs to the base except in cases where the whole cliff was protected ; here there was no well marked variation. I'he specimens of Placodiiim elegans collected from the crevices of the cliffs of the Palisades in Linn county and from Turkey creek in Johnson county had larger disks than those growing on the exposed face of the rocks. These facts may account in part at least for the persistence of these organisms in areas where other forms of plant life do not thrive. ECOLOGY OF IOWA LICHENS. 69 The great resisting power of lichens has long been recognized in a general way. Some observations were made fdf the purpose of more accurately determining this power. In the following experiments the resistance of the algal cells of some lichens to heat and drying was tested. To obtain an absolute result, the lichens would have to be grown in connection with the experiment. This was not possible on account of the limited time to be devoted to the experiments, and im- practical, for it would be impossible to eliminate all other factors affect- ing the growth of the lichens. The algal cells were selected because they respond more readily to change. The most accurate results possible could be obtained only by careful observation of these cells subjected to heat and drying, and the comparison of them with fresh ones from the same thallus. Any change in the appearance of the protoplasts or cell walls would indicate a change in composition or organization of the cell. No attempt, however, was made to determine the change, if any, in the composition of the cell contents. The main point was to ascertain the decrease in water content, the change in organization of the cell, and its ability to recover from this. Each of the sets of experiments consisted in heating specimens of the selected species of lichens, which were chosen from various habitats. In the first experiment the following species were used: Dermato- c.arpon miniatum (L.) Fr., Peltigera canina (L.) Hoffm., Cladonia rangiferina (L.) Webb., Placodium elegans (Link) Aeh., Cetraria ciliaris Ach., Parmelia caperata (L.) Ach., and Physcia stellaris (L.) Nyl. The temperatures ranged from 27 7/9° C. to 101° C. during the six hours of the experiment. Comparatively fresh, healthy, vigorous repre- sentatives of the various species were chosen, and all except Placodium elegans were selected from shady places. An examination of the mate- rial at the outset showed it to contain only the usual numbers of dead algal cells in the thalli. The specimens, cut in small pieces, were placed in shallow glass dishes in the evaporating oven. Burning the specimens was prevented in all cases except Dermatocarpon and Physcia in which the hyphge were slightly browned at the end of the experiment. An hourly record of temperature was made, and a piece of each species removed, except at 11 :00 a. m. and 1 :00 p. m., and placed in distilled water for twenty-four hours to soften it for examination to deter- mine if the algal cells could be restored to their normal condition. For mounting, the specimens were crushed, as the algal cells only were to be studied. 70 IOWA ACADEMY OP SCIENCE. Following is briefly given the temperature of the oven, the time at which the various specimens were removed, and any change noted when compared with a fresh piece of the same thallus. The specimens were placed in the oven at 8 :00 o’clock a. m., the temperature being 27 7-9° C. Cladonia rangiferina (L.) Webb., collected from the shady bluffs at Wyoming Hill, north of Muscatine. 9 :00 A. M., Temperature 77 2-3° C. The algal cells were changed from bright green to yellowish green. The protoplasts with their nuclei seemed normal. 10:00 A. M., Temperature 83 8-9° C. The cells unchanged, except that the color had become yellow. 12:00 M., Temperature 82 2-9° C. This specimen was greenish yellow like that removed at 9 a. m., and the protoplasts were somewhat shrunken, but the nuclei appeared normal. 2:30 P. M., Temperature 101° C. The algal cells had become transparent, but were still yellowish green, and the protoplasts were shrunken into irregular masses. The gelatinous sheaths were much thinner, and nuclei were seen in nearly all cells. Dcrmatocarpon miniahim (L.) Fr., collected from the shady north face of the rocky bluffs north of Iowa City. 9 :00 A. M., Temperature 77 2-3° C. All the algal cells appeared normal. 10:00 A. M., Temperature 83 8-9° C. The color was changed to yellowish green, and a slight shrinkage of the protoplasts had taken place. The nuclei appeared normal. 12 :00 M., Temperature 82 2-9° C. The color of the algal cells was yellowish green, and the protoplasts were somewhat shrunken, and no cell showed a nucleus. 2:30 P. M., Temperature 101° C. The color was changed to light brown, the cell contents were clear and shrunken into irregular masses, and the hyphse were light brown, indicating that this specimen was slightly scorched, although under conditions not different from the others. Parmelia caperata (L.) Ach., collected from a butternut tree in the woods at Mid Eiver, northwest of Iowa City. 9:00 A. M., Temperature 77 2-3° C. The color was changed from dark green to yellowish green, the nuclei were plainly visible, and the cells apparently normal. 11 :00 A. M., Temperature 83 8-9° C. ECOLOGY OF IOWA LICHENS. 71 The algal cells showed no difference from those removed from the oven at 9:00 o^clock 12 :00 M., Temperature 82 2-9° C. The color was changed to light yellow,' and the protoplasts were slightly shrunken. Most cells showed nuclei. 2:30 P. M., Temperature 101° C. The color had become yellowish brown, and the protoplasts were shrunken. Nuclei were visible in some of the cells. Peltigera canina (L.) Hoffm., collected from the exposed rocky slope north of Iowa City. 9:00 A. M., Temperature 77 2-3° C. There was no change in the bright green color, nor were the cells shrunken. The cells were smaller than those of the fresh specimen, but this may have been a variation in the plant. 10:00 A. M., Temperature 83 8-9° C. There was no perceptible change in the cells. 12:00 M., Temperature 82 2-9° C. The color had changed to yellowish green, and some cells appeared slightly shrunken. 2:30 P. M., Temperature 101° C. The algal cells had lost almost all their color ; the contents were trans- parent and shrunken into irregular masses. The hyph® were slightly brown, Cetraria ciliaris Ach., collected from an old pine board fence one and one-half miles northwest of Earlville. 9 :00 A. M., Temperature 77 2-3° C. The color had changed from bright green to yellowish green. The cells were unshrunken and nuclei visible. 10:00 A. M., Temperature 83 8-9° C. The color had changed to yellowish green, the protoplasts were con- siderably shrunken, but the granular appearance was still retained by some cells. 12:00 M., Temperature 82 2-9° C. The color was yellowish green, the sheaths were thinner, and the protoplasts shrunken into irregular masses. 2:30 P. M., Temperature 101° C. The color was still yellowish green, the protoplasts were greatly shrunken, and the walls thinner. Very few dead cells were present. 72 IOWA ACADEMY OP SCIENCE. Placodium elegans (Link) Ach., collected from the tops of the bluffs near the boat house at the Palisades in Linn county. 9:00 A. M., Temperature 77 2-3° C. The algal cells were normal with few dead cells. 10 :00 A. M., Temperature 83 8-9° C. The color had changed from bright green to greenish brown and the protoplasts were somewhat shrunken. 12:00 M., Temperature 82 2-9° C. The color was greenish brown and the protoplasts were very much shrunken. 2:30 P. M., Temperature 101° C. All the green color had disappeared, the protoplasts were much shrunken, the hyphge were light brown, and many dead cells were present. This condition may not have been due to heating, as the specimen may have been taken from an old part of the thallus. Physcia stellaris (L.) NyL, collected from a butternut tree in the woods near Bayfield. 9 :00 A. M., Temperature 77 2-3° C. The algal cells were normal. 10 :00 A. M.., Temperature 83 8-9° C. The color changed from green to yellowish green, and the protoplasts were somewhat shrunken. ^ 12:00 M., Temperature 82 2-9° C. The color was yellowish green, the protoplasts were greatly shrunken and the gelatinous sheaths were very thin. 2:30 P. M., Temperature 101° C. The color had become greenish brown and the protoplasts were greatly shrunken. Not many empty cells were present. The algal cells of the species used in this experiment, with the excep- tion of those of Peltigera, changed from bright green to yellowish green at the end of the second hour, with the maximum temperature 83 8-9° C. Cetraria, however, was greatly bleached at the end of the first hour with the temperature at 77 2-3° C. With the exception of Cetraria, Dermato- carpon and Physcia, the algal cells began to show a shrinkage at the end of the third hour, with a temperature of 83 8-9° C. Physcia, Dermato- carpon and Cetraria showed a shrinkage at the end of the second hour, with a temperature of 83 8-9° C. The purpose of the following experiment was to determine the relative resistance of those lichens from the Sioux quartzite of Iowa, collected by Professor Shimek in 1896, and kept in the Herbarium of the Uni- versity of Iowa during the intervening sixteen years, as compared with ECOLOGY OP IOWA LICHENS. 73 the resistance of those collected from the same region June 30, 1913, six days before the experiment. The temperature was recorded each hour, and pieces of various thalli removed and placed in distilled water. The specimens chosen were Parmelia conspersa, Lecanora ruMna and Dermatocarpon miniatum. The examination of the specimens before heating showed a slight difference in the shade of green of the algal cells, that of the old specimens being less brilliant than the color of the new ones, but there was no difference in the water content. The oven was started at 9:00 o’clock A. M., with a temperature of 26 2-3° C. Following is briefly given the time at which each specimen was removed, the temperature, and a comparison of the old with the new thalli. Lecanora ruhina (Lam. & DC.). 9 :00 A. M., Temperature 26 2-3° C. The algal cells of the new specimen were slightly darker green than those of the old specimen. The protoplasts were normal. 10:00 A. M., Temperature 50° C. The specimens showed no change. 11 :00 A. M., Temperature 68 1-3° C. The old specimen was bleached to very light yellow, and many empty algal cells were present, but none of the cell contents of either old or new showed any shrinkage. The old specimen was probably from a less vigorous part of the thallus, as the other parts of the same thallus were not so affected. 12:00 M., Temperature 79 4-9° C. Both old and new specimens were bright yellowish green, and a few cells in each showed a slight shrinkage. 1:00 P. M., Temperature 90 5-9° C. The old specimen had many empty algal cells. Those which were not empty were yellowish green, and all the cells of both old and new specimens were considerably shrunken. 2:00 P. M., Temperature 102 7-9° C. The protoplasts of both old and new specimens were greatly shrunken, but the algal cells of the new specimens were brighter yellow. Parmelia conspersa (Ehrh.) Ach. - r ^ 9:00 A. M., Temperature 26 2-3° C. The old specimen showed many dead algal cells and many cells were somewhat shrunken. This was a very poor part of the thallus. 10:00 A. M., Temperature 50° C. 74 IOWA ACADEMY OF SCIENCE. The algal cells of both old and new specimens were bright yellowish green, and all cells were unshrunken. 11 :00 A. M., Temperature 68 1-3° C. The algal cells were still bright yellowish green, and a few cells of each specimen were slightly shrunken. 12:00 M., Temperature 79 4-9° C. The algal cells of both specimens were slightly shrunken and yellowish green. 1 :00 P. M., Temperature 90 5-9° C. The algal cells showed no further change of color, but the protoplasts were more shrunken than at 12 o’clock. 2 :00 P. M., Temperature 102 7-9° C. All the algal cells were greenish yellow, and were considerably shrunken. Dermatocarpon miniatum (L.) Fr. 9:00 A. M., Temperature 26 2-3° C. The algal cells of both old and new specimens were dark green and unshrunken. 10:00 A. M., Temperature 50° C. The cells were not changed from those of 9 o’clock. 11 :00 A. M., Temperature 68 1-3° C. The algal cells showed no shrinkage and the color was yellowish green. 12:00 M., Temperature 79 4-9° C. There was no change in color of the algal cells. They were still yellowish green and unshrunken. 1:00 P. M., Temperature 90 5-9° C. The algal cells from the old specimen were bright green, with very few cells shrunken. The new specimen was yellowish green and slightly shrunken. The cortex of the old specimen was thicker than that of the new specimen. 2 :00 P. M., Temperature 102 7-9° C. The algal cells were yellowish green, with some bright green cells in both new and old specimens. The cells were slightly shrunken in both. The comparison in this experiment of fresh material with that which had been in the herbarium sixteen years brought out the following interesting results. The old specimens of Dermatocarpon did not seem to be affected by their life in the herbarium, and did not show the effects of drying and ECOLOGY OF IOWA LICHENS. 75 heating sooner than the fresh ones. The old specimen of Lecanora lost its color and was gTeatly shrunken sooner than the fresh one. A second experiment with other material from the same collections corresponded in all results to the one given here, and further emphasized the fact that these xerophytic forms can withstand drying to a remark- able degree. A comparison of the resisting power of those shade inhabiting species with the xerophytic forms probably would bring out some further facts of interest. The eifect of heat upon the 'color of the shaded and exposed species was equal, but the water content of the cells in the specimens from shade was reduced sooner than that in those from the Sioux quartzite. CONCLUSIONS. The following conclusions are suggested by the work recorded here : Lichens vary in adaptation to habitat; this applies to both different species and to different individuals of the same species. Variation in habitat is explained, at least in part, by structural adapta- tions. Lichens show a remarkable power of resistance to drouth. OSKALOOSA. I THE FLORA OP LINN COUNTY. 77 A PRELIMINAEY EEPOET ON THE FLOEA OF LINN COUNTY. BY E. D. VERINK. During the past twenty years, under the incumbency of a number of professors in Coe College, the college herbarium was enriched by the collection of a large number of plants indigenous to Linn county. For many years these were poorly housed, room for herbarium facilities was lacking, and the collection was consequently neglected. The build- ing of a new science hall has made it possible for the first time to revise this collection. The author has also spent three seasons collecting speci- mens in Linn county and, through the kindness of Mr. Geo. H. Berry, had access to the herbarium of the latter, which contains a number of species not found in the Coe herbarium. The accompanying list, then, should be fairly complete. While those who have worked at this collec- tion in previous years may have been guilty of some errors, every effort has been made to check their work, and it is believed that the work as here presented, while not absolutely complete, is essentially accurate. It should, therefore, be of some value to students of our eastern Iowa Flora, and in that hope it is here presented. Acknowledgments are due to Mr. Berry, not only for access to his herbarium, but for assistance given in identifying specimens, to the late Dr. J. E. Gow for the suggestion leading to the undertaking and for re, vision of the manu- script, and special thanks are due to Miss Phoebe Smith for card index- ing the entire Coe collection, as well as for valuable assistance in identi- fication of species and preparation of manuscript. AIOZACEAE. Mollugo verticAllata (L.), Carpet Weed (C) ; common. AN ACARBI ACE AE . Rhus canadensis (Marsh.), Sweet Scented Sumac (C) ; common. Elms glabra (L.), Smooth Sumac (C) ; common. Elms typhina (L.), Staghorn Sumac (C) ; common. , ARISTOLOOHIACEAE. Asarum canadensis (L.), Wild Ginger (C) ; common. (C) after the common name indicates specimens to be found in the Coe College Herbarium. (B) after the common name indicates specimens to be found in Geo. H. Berry’s. Herbarium. IOWA ACADEMY OF SCIENCE. AMARYLIilDACEAE. Hypoxds liirsuta (L.)? Yellow Star Grass (C) ; common. Narcissus poeticus (L.)? Poet’s Narcissus (C) ; common. AOERACEAE. Acer negundo (L.), Box Elder (C) ; common. Acer saccliarum (Marsh.), Sugar Maple (C) ; common. Acer saccharvm nigrum (Mx.f.), Black Maple (C) ; common. Acer saccliarinum (L.), White Maple (C) ; common. Acer rutrum (L.), Red Maple; common. Aesculus liippocastamim (L.), Horse Chestnut (C) ; common. ARACEAE. Acorus calamus (L.)> Sweet Flag (C). Arisaema dracontiiim (Schott), Green Dragon (C) ; rare. Arisaema triphyllum (Schott), Jack-in-the-Pulpit (G) ; common. Calla palustris (L.), Water Arrum (C) ; rare. Orontium aquaticum (L.)? Golden Club (C) ; rare. « ALISMACEAE. Alisma plant ago-aquatica (L.), Water Plantain (C). Lophotocarpus calycinus maximum. (J. G. Sm.) (C). Sagittaria arifolia (Nutt.), Arrow Head (C) ; common. Sagittaria engelmanniana (J. G. Sm.), Arrow Head (C). Sagittaria heterophylla (Pursh.), Arrow Head (C). ASCLEPIADACEAE. Asclepias amplexicaulus (Sm.), Milkweed (C) ; common. Asclepias incarnata (L.), Swamp Milkweed (C) ; common. Asclepias pumila (Yail), Narrow-leaved Milkweed (C) ; common. Asclepias purpurascens (L.), Purple Milkweed (C) ; common. Asclepias sullivantii (Engelm.), Milkweed (C). Asclepias syriaca (L-)? Milkweed (C). , , Asclepias tuherosa (L.), Pleurisy-root (C). Asclepias verticillata (L.)j Whorled Milkweed (C) ; common. ACANTHACEAE. Ruellia ciliosa (Pursh.), Hairy Ruellia (C). BAIiSAMINACEAE. Impatiens hiflorg (Walt.), Spotted Touch-me-not (C) ; common. / THE FLORA OF LINN COUNTY. 79 BETULACEAE. Betula nigra (L.), Ked or River Birch (C) ; common. Carpinus caroliniana (Walt.), Blue Birch (C) ; common. Corylus americama (Walt.), Hazelnut (C) ; common. Ostrya virginia^ia (K. Koch.), American Hop Horn Bean (C) ; com- Berheris vulgaris (L.)> Barberry (C) ; not uncommon, exotic. Caulophyllum thalictroides (Michx.), Pappoose Root (C). Podophyllum peltatum (L.), May Apple (C) ; common. BORAGINACEAE. Lappula virginiana (Greene), Beggars Lice. Lithospermum angustifolium (Michx.), Yellow Puccoon (C) ; common. Lithospermum canescens (Lrhm.), Orange Puccoon (C) ; common. Lithospermum gmelini (Hitchc.), Hairy Puccoon (C). Lithospermum latifolium (Michx.), Puccoon (C). Mertensia virginica (Link), Bluebells (C) ; common. Myosotis arvensis (Hill), Mouse Ear (C) ; common. Myosotis scorpioides (L.), Forget-me-not (C) ; common. Myosotis virginica (BSP), Scorpion Grass (C) ; common. Onosmodium hispidissimum (Mack), False Gromwell (C). BIGNONIACEAE. Catalpa speciosa (Warder), Catalpa Tree (C) ; common. Catalpa hignonoides (Walt.), Catalpa Tree (C) ; not uncommon; exotic. CONVOIiVULACEAE. Convolvulus arvensis (L.), Small Bindweed (C) ; common. Convolvulus sepium (L.), Hedge Bindweed (G) ; common. Cuscut a arvensis (Beyrich), Field Dodder (B.) ; common. Cuscuta compacta (Juss.), Compact Dodder (C) ; common. Cuscuta glomerata (Chois.), Dodder (C) ; common. Cuscuta gronovii (Willd.), Dodder (C). Cuscuta indecora (Chois.), Pretty Dodder (B). Cuscuta coryli (Engelm.), Dodder (C). Impomoea pandurata (G. F. W. Mey.), Man-of-the-earth (C). GHENOPODIACEAE. Chenopodium album (L.), Pigweed (C) ; common. * Chenopodium boscianum (Moa), Bose’s Goosefoot (B) ; fairly common. Chenopodium hybridum (L.), Maple-leaved Goosefoot (C) ; rare. 80 IOWA ACADEMY OF SCIENCE. Chenopodium murale (L.)V Nettle-leaved Goosefoot (C) ; rare. CJienopodium polyspermum^ Many-seeded Goosefoot (C) ; rare. Chenopodium urbicum (L.), Upright or City Goosefoot (C) ; not rare. Cycloloma atriplicifolium (Spreng.), Winged Pigweed. Kochia scoparia (L.) Schrad., Pigweed (C) ; uncommon, introduced. Salsola kali tenuifolia (G^. P. W. Mey.), Saltwort, Russian Thistle (C) ; uncommon. CARYOPHYLIiACEAE. Agrostemma githago (L.), Corn Cockle (B) ; common, introduced. Arenaria .lateriflora (L.), Sandwort (C) ; common. Cerastiumbrachypodum (Rob.), Mouse-ear Chickweed (C) ; common. C erastium nutans (Raf.), Chickweed (C) ; common. Cerastium viscosum (L.), Mouse-ear Chickweed (C) ; not uncommon. Dianthus chinesis, China Pink (C). Lychnis coronaria (Desr.), Mullein Pink (C) ; introduced. Saponaria officinalis (L.)? Bouncing Betty (C) ; common, introduced, Silene antirrhina (L.), Sleepy Catchfiy (C) ; common. ■Silene armeria (L.), Sweet William, Catchfiy (C) ; introduced. Silene dichotoma (Ehrh.), Forked Catchfiy (C) ; introduced. Silene nivea (Nutt.) Otth., Western White Campion (C). Silene noctiflora (L.)? Night-fiowering Catchfiy; not uncommon. Silene stellata (L.) Ait. f.. Starry Campion (C). Stellaria media (Cyrill), Common Chickweed (C) ; common. CORNAOEAE, Cornus canadensis (L.), Bunch Berry (B) ; fairly common. Cornus paniculata (L.) L’Her., Red Osier, Cornel; fairly common. CAMPANULACE AE . Campanula americana (L.), Tall Bellflower (C), Campanula rotundifolia, Common Harebell (C). Specularia perfoliata (A. DC.), Venus’ Looking Glass (C). CUCURBIT AdEAE . Echinocystis lobata (T. & G.), Wild Balsam Apple (C). Sicyos angulatus, Bur Cucumber (C). COMMEMNACEAE. Commelina communis ' {Jj.) ^ Asiatic Day Flower ( C) ; introduced. Tradescantiabracteata (Small), Spiderwort (B). T rades cant ia Occident alis (Smyth), Pink Spiderwort (B). Tradescantia virginiana (L.), Spiderwort (C). THE FLORA OP LINN COUNTY. 81 CAPRIFOIilACEAE. Lonicera dioica (L.), Smooth-leaved Honeysuckle (C) ; common. Lonicera flava (Sims), Yellow Honeysuckle (C) ; common. Lonicera glaucescens (Rybd.), Douglas Honeysuckle (B). Lonicera sempervirens (L.), Trumpet Honeysuckle (B). Lonicera suUivantii (Gray), Sullivant’s Honeysuckle (C). Lonicera xy lost eum (L.), European Ply, or Honeysuckle (C). Samhucus canadensis (L.), Common Elder (C) ; common. Triosteum perfoliatum (L.), Wild Coffee (B). Viburnum cassinoides (L.)> White Rod, or Wild Raison (C) ; common. Viburnum prunifolium (L.), Black Haw (C). Viburnum pub escens (Pursh.), Downy Arrowhead (C). COMPOSITAE. Boltonia asteriodes (L.), L’her. (C). Achillea millefolium (L.), Yarrow (C) ; common. Ambrosia art emisiifolia (L.), Hogweed, Bitterweed (C) ; common. Ambrosia trifida (L.)? Great Ragweed (C) ; common. Anaphalis margaritacea (B. & H.), Pearly Everlasting (C) ; common. Ant ennaria canadensis (Greene), Ladies’ Tobacco (C) ; common. Ant ennaria neglect a (Greene), Indian Tobacco (C) ; common. Antennaria neodioica (Greene), Cudweed (C) ; common. Ant ennaria plant aginifolia (Greene), Pussy’s Toes (C) ; common. Anthemis cotida (L.), Mayweed (C) ; common. Anthemis tinctoria (L.), Yellow Chamomile (C) ; common. Aplopappus ciliatus (DC.), Cass (C). Artemisia caudat a (Michx.), Wormwood (C) ; common. Artemisia kansana (Britton), Wormwood (C) ; common. Artemisialongifolia (Nutt.), Long-eared Mugwort (C). Artemisialudoviciana (Nutt.), Western Mugwort (C). Artemisia serrata (Nutt.) , Wormwood (C). Aster azureus (LindL), Skyblue Aster (C) ; common. Aster commutatus (Gray), Aster (C) ; common. Aster cor difolius (L.), Bushy Aster (C) ; common. Aster dr ummondii (LindL), Aster (C) ; common. Aster ericoides (L.), Frost- weed Aster; common. Aster lowrieanus (Porter), Lowrie ’s Aster (C) ; common. Aster novae-angliae (L.), New^England Aster (C) ; common. Aster paniculat us simplex (Burgess), Aster (C). Aster ptarmicoides (T. & G.) , Upland White Aster (C). Aster tradescanti (L.), Michaelmas Daisy (C). 6 82 IOWA ACADEMY OF SCIENCE. Aster vimineiis foliolosus (Ait.) , Gray Aster (C) . Beilis, per ennis (L.), Daisy (B). Bidens discoidea (T. & G.), (C). Braiineria angiisfifoUa (DC.) Heller, Purple Cone-flower (C) ; com- mon. Braiineria pallida (Nutt.) Britton, Pale Purple Cone-flower (C). Chrysanthemum leucanthemum var. pinnatifidum (Lecoq & La Motte), White Daisy (C). Chrysanthemum segetum (L.), Corn Marigold (B) ; introduced. Cirsium altissimus (L.) Spreng., Fall Thistle (C) ; common. Cirsium undulatum (Nutt.) Spreng., Thistle (C) ; common. Cirsium discolor (Muhl.) Spreng., Field Thistle (C) ; common. Cirsium lanceolatum (L.) Hill, Bull Thistle (C) ; common. Coreopsis palmata (Nutt.), Stiff Tickseed (B). Coreopsis tinctoria (Nutt.), Garden Tickseed (B). Dyssodia papposa (Vent.) Hitchc., Fetid Marigold (B). Erigeron philadelphicus (L.), Fleabane (C) ; common. Erigeron pulchellus (Michx.), Kobin’s Plantain (C) ; common. Erigeron 7^amosus (Walt.) BSP., Daisy Fleabane (C). Eupatorium altissimum (L.), Tall Thoroughwort (C). Eupatorium capillifolium (Lam.) Small, Dog Fennel (C). Eupatorium purpureum maculatum (L.) Dark, Spotted Joe Pye Weed (C). . Eupatorium pe^ioliatum (L.), Boneset (C) ; common. Eupatorium purpureum (L.), Joe Pye Weed (C) ; common. Eupatorium semiserratum (DC.), Small-flowered Thoroughwort (C). Eupatorium urdicae folium (Keichard), White Snakeroot (B). Gutierrezia sarothrae (Pursh.) Britton & Rushby, Gutierrezia (C). Helenium autumnale (L.), Sneezeweed (C). Helianthus decapetalus (L.), Wild Sunflower (C) ; common. Helianthus giganteus (L.), Tall Sunflower (C). Helianthus maximiliani (Schrad.), Maximilian’s Sunflower (C). Helianthus mollis (Lam.), Hairy Sunflower (B). Helianthus occidentalis (Riddell), Few-leaved Sunflower (C). Helianthus petiolaris (Nutt.), Prairie Sunflower (C). Helianthus scat) errimus (Eli.)? Sunflower (C). Helianthus tut) erosus (L.), Jerusalem Artichoke (C) ; common. Hieracium aui'antiacum (L.), Devil’s Paint Brush (C) ; common, introduced. Hieracium longipilum (Torr.), Long-bearded Hawkweed (C). Hieracium venosum (L.), Rattlesnake Weed (C). THE FLORA OP LINN COUNTY. 83 Iva xanthifolia (Nutt.), Burweed Marsh Elder (C) ; common. Lactuca canadensis (L.), Wild Lettuce, Horseweed (C) ; common. Lactuca floridana (L.) Gaertn., False or Florida Lettuce (C). Lactuca spicata (Lam.) Hitchc., Tall Blue Lettuce (C). Lactuca scariola (L.), Prickly Lettuce; common. LepacJiys pinnata (Vent.) T. & G., Gray Headed Cone-flower (C). Liatris cylindracea (Michx.), Blazing Star (B). Liatris punctata (Hook.), Dotted Button Snakeroot (C) ; not common. Liatris pycnostacliya (Michx.), Blazing Star (C) ; common. Liatris scar iosa (Willd.), Large Button Snakeroot (B). Mikania scandens (L.) Willd., Climbing Wild Hemp (B). Partlienium integrifolium (L.), American Fever-few (C). Prenanthes alba (L.), White Lettuce (B). Prenanthes serpentaria (Pursh.), Gall-of-the-earth (C) ; common. Rudbeckia Jiirta (L.), Black-eyed Susan (C) ; common. Budbeckialaciniata (L.), Tall or Green-headed Cone-flower (C). Rudbeckia triloba (L.), Thin-leaved Cone-flower (C). Senecio aureus (L.), Golden Ragwort (C) ; common. Senecio balsamitae (Muhl.), Balsam Groundsel (C). Senecio canus (Hook.), Silvery Groundsel (C). Senecio int eg errimus (Nutt.), Entire-leaved Groundsel (C). Senecio palustris (L.) Hook., Marsh Groundsel (C). Senecio tomentosus (Michx.), Wooly Ragwort (C). Sericocarpus linifolius (L.) BSP., Narrow-leaved White-topped Aster ^C). Solidago canadensis (L.), Canada Goldenrod (C) ; common. Solidago canadensis gilvocanescens (Rybd.), Goldenrod (C). Solidago houghtonii (T. & G.), Houghton’s Goldenrod (B). Solidago latifolia (L.), Broad-leaved Goldenrod (C) ; common. Solidago neglect a (T. & G.), Swamp Goldenrod (C) ; common. Solidago nemoralis (Ait.), Gray or Field Goldenrod (C) ; common. Solidago rigida (L.), Stiff or Hard-leaved Goldenrod (C) ; common. Solidago serotina (Ait.), Late Goldenrod (C) ; common. Solidago strict a (Ait.), Wandlike or Willow-leaved Goldenrod (B). Solidago ulmi folia (Muhl,), Elm-leaved Goldenrod (B). Tanacetum vulgare (L.), Common Tansy (C) ; common. Taraxacum officinale (Weber), Common Dandelion (C) ; common, introduced. Vernonia fascicidata (Michx.), Western Ironweed (C). y ernonia noveboracenis (Willd.), Flat Top or New York Ironweed (C). 84 IOWA ACADEMY OF SCIENCE. Xanthmm canaderisis, (Mill), American Cocklebnr (B). Xanthium commune (Britton), Cocklebnr *(B). CEIiASTRAOEAE. Celastrus scandens (L.), Climbing Bittersweet (C). CRASSULACEAE. Penthorum sedoides (L.), Ditch Stonecrop (C). Sedumacre (L.), Mossy Stonecrop (B). Sedum purpureum (Tausch.), Garden Orpine, Live-for-ever (C) ; introduced. Sedum rose%m (L.), Rose Root (B) ; Rare. CRUCIFERAE. Alyssum alyssoides (L.), Yellow or Small Alyssum (C) ; common, introduced. Arahis deniaia (T. & G.), Toothed Rock Cress (C) ; common. Brassica arvensis (L.) Ktze., Mustard (C) ; not uncommon. Brassica juncea (L.), Indian Mustard (C) ; not uncommon. Brassica nigra (L.) Koch., Black Mustard (C) ; very common. Brassica alba (L.) Boiss., White Mustard (C) ; rare. Capsella bursa pastoris (L.) Medic., Shepherds Purse (C) ; very com- mon. Cardamine bulbosa (Sehre) BSP., Spring Cress (C) ; Abundant. Cardamine douglassii (Torr.) Britton, Purple Cress (C) ; common. Dentaria laciniata (Muhl.), Pepper Root, Toothwort (C) ; common. Draba cuneifolia (Nutt.), Wedge-leaved Whitlow Grass (C). Erysimum chiranthoides (L.), Wormseed Mustard (C) ; common. Erysimum parviflorum (Nutt.), Wild Mustard (C). Hesperis matronalis (L.), Dame’s Violet (B) ; occasional. Lepidium campestre (L.) R. Br., Cow Cress (C) ; introduced. Lepidium draba (L.)j Hoary Cress (C). Lepidium virginicum (L.), Wild Peppergrass (C) ; common. Lunar ia annua (L.), Honesty (B) ; Rare. Baphanus sativus (L.), Radish (C) ; occasional. Badicula armoracia (L.) Robinson, Horseradish (C) ; common. Radicida nasturtium-aquaticum (Britton & Rondle), True Water Cress ; common. Badicula palustris (L.) Moench, Marsh Cress (C) ; common. Badicula palustris hispida (Desv.) Robinson, Water Cress (C) ; scarce. Boripa curvisiliqua, Curved-fruited Cress (C). Sisymbrium altissimum (L.), Tumble Mustard (C). THE FLORA OF LINN COUNTY. 85 Sisymbrium incisum (Engelm.), Western Mustard Tansy (C) ; com- mon. Sisymbrium officinale (L.) Scop., Hedge Mustard (C) ; common. Sisymbrium sopJiia (L.), Flizweed (C) ; common. EQUISETACEAE. Equisetum arvense (L.), Common Horsetail (C) ; common. Equisetum Jiymale (L.), Scouring Rush (C) ; common. Equisetum pratense (Ehrh.), Thicket Horsetail (C) ; common. • ERICACEAE. Chimaphila maculata (L.) (Pursh.), Spotted Wintergreen (B). Monotropa hypopitys (L.)? Pinesap (C) ; rare. Monotropa uniflora (L.)> Corpse Plant (C) ; rare. Pyrola americana (Sweet), Wintergreen (B). Pyrola elliptica (Nutt.), Shin Leaf (B) ; scarce. Vaccinium stamineum (L.), Squaw Huckleberry (C). EUPHORBIACEAE. Euphorbia corrollata (L.), Flowering Spurge (C) ; abundant. Euphorbia cyparissias (L.), Cypress Spurge (C). Euphorbia geyeri (Engelm.), Geyer’s Spurge (C) ; not rare. Euphorbia heterophylla (L.), Painted Leaf (C) ; common. Euphorbia humistrala (Engelm.), Hairy Spreading Spurge (C). Euphorbia maculata (L.), Milk Spurge; not uncommon. Euphorbia preslii (Guss.), Upright Spotted Spurge (C) ; common. AMARANTHACEAE. Amaranthus blitoides (Wats.), Amaranth (C) ; common. Amaranthus palmeri (Wats.), Amaranth (C). Amaranthus spinosus, Amaranth (C). Amaranthus retroflexus. ARALIACEAE. Aralia nudicaulis (L.), Wild Sarsaparilla (B). Aralia racemosa (L.), Spikenard (B). Panax quinquifolium (L.), Ginseng (B). APOCYNACEAE. Apocynum androsaemifolium {Ij.) {Q) , ' CERATOPHYLLACEAE. Ceratophyllum demersum (L.), Hornwort (B). 86 IOWA ACADEMY OF SCIENCE. CYPERACEAE. Cy perns erythrorhizos (MuhL), Eed-rooted Cyperus (C). Cyperus aristatus (Rottb.), Awned Cyperus (C). DIOSCOREACEAE. Dioscorea villosa (L.), Wild Yam (B). DROSERACEAE. Drosera rotundifolia (L.), Sun-dew (B). LINACEAE. Linum floridanum (Planch.), Florida Yellow Flax (C). Linum medium (Planch.), False Yellow Flax (B). Linum usitatissimum (L.), Common Flax (B) ; common. liYTHRACEAE. Ammannia auriculata (Wild.), Loosestrife (B). Lythrum alatum (Pursh.), Purple -Loosestrife (C). Lythrum salicaria (L.), Spiked Loosestrife (L). MELASTOMACEAE. Rhexia virginica (L.), Deer Grass (B). OROBANOHACEAE. OrohancJie uniflora (L.), One-flowered Cancer Root. SPARGANIAGEAE. Sparganium eurycarpum (Engelm.), Bur-reed (C). FUMARIACEAE. Corydalis flavula (Raf.) DC., One-Spurred Yellow Dutchman’s Breeches. Corydalis sempervirens (L.) Pers., Pale Rose Pink Corydalis (C). Dicentra canadensis (Goldie) Walp., Squirrel Corn (C). FAGAOEAE. Quercus alba (L.), White Oak (C) ; common. Castanea dent at a (Marsh.) Borkh., American Chesnut (C) ; intro- duced. GRAMINEAE. Agrostis alba (L.), Red Top (C) ; common. Agropyrum repens (L.) Beauv., Quick Grass (C) ; common. Aristida basiramea (Englm.), Triple-awned Poverty Grass (C). Aristida tuberculosa (Nutt.), Triple-awned Poverty Grass (C). THE FLORA OP LINN COUNTY. 87 Arrhenatherum elatius (L.) Beauv., Tall Oat Grass (C). Bouteloua curtipendiila (Michx.) Torr., Mesquite Grass (C) ; common. Calamvilfea longifolia (Hook.) Hack., C. Cenchrus carolinianus (Walt.), Sand Bur (C) ; common. Cynodon daciylon (L.) Pers., Bermuda Grass (C). Dactylis glomerata (L.), Orchard Grass (C) ; common. Digit aria sanguinalis (L.) Scop., Crab Grass (C). Echinochloa crus-galli (L.) Beauv., Barnyard grass (C). Eleusine indica (Gaertn.), Goose Grass (C). Elymus canadensis (L.), Nodding Wild Eye (C) ; common. Elymus glaucus (Buckley), Smooth Wild Eye (C). Elymus virginicus (L.), Virginia Wild Eye (C) ; common. Eragrostis franMi (Fisch., Mey., & Lall.) Steud., Frank’s Eragrostis (C). Eragrostis megastachya (Koeler) Link, Strong-scented Eragrostis (C). Milium ejfusus (L.), Tall Millet-grass (C). Muhlenhergia sylvatica (Torn), Wood Muhlenbergia (C). Paspalum compressum (Sw.) Nees, (C). Phleum pratense (L.), Timothy (C) ; common. Poa compressa (L.), Canada Blue Grass (C) ; common. Poa pratensis (L.), June Grass (C), Kentucky Blue Grass; common. Setaria glauca (L.) Beauv., Foxtail (C) ; common. Setaria italica (L.) Beauv., Hungarian Grass (C) ; common. Setaria viridis (L.) Beauv., Bottle Grass (C) ; common. Sorgliastrum nutans (L.) Nash., Indian Grass (C) ; common. Spartina cynosuroides (L.) Eoth., Salt Eeed Grass (C). GENTIANACEAE. Gentiana andrewsii (Griseb.), Closed Gentian (C) ; rather rare. Gentiana crinita (Froel.), Fringed Gentian (B) ; rare. Gentiana quinquifolia (L.), Stiff Gentian (C). Gentiana saponeria (L.), Soapwort Gentian (C). GERANEACEAE. % Geranium maculatum (L.), Wild Cranesbill (C) ; common. HYDROPHYLLACEAE. Hydrophyllum appendiculatum (Michx.), Appendaged waterleaf (C). liydrophyllum macrophyllum (Nutt.), Large-leaved waterleaf (C). Hydrophyllum virginianum (L.), Virginia waterleaf (C). Ellisia nyctelea (L.), Nyctelea (C) ; common. 88 IOWA ACADEMY OP SCIENCE. HYPERICAGEAE. Hypericum adpressum (Bart.), This specimen was found in Mid- River park in Johnson county and shows strongly punctate leaves. This characteristic is not mentioned in the description, but is unlike our specimens of Hypericum cistifolium (Lam.). Otherwise it answers the description of Hypericum adpressum. Hypericum cistifolium (Lam.), St. John’s Wort (C). Hypericum canadense (L.), Canadian St. John’s Wort (C). Hypericum gentianoides (L.) BSP., Pineweed (C). Hypericum virginicum (L.), Marsh St. John’s Wort (C). IRIDACEAE. Iris versicolor (L.), Larger Blue Flag (C). Sisyrinchium angustifolium (Mill.), Northern Blue-eyed Grass (C). Sisyrinchium gramineum (Curtis), Common Blue-eyed Grass (C). JUGLANDACEAE. Carya alba (L.) K. Koch., White-heart Hickory (C). Carya glabra (Mill.) Spach., Pignut (C). Carya ovata (Mill.) K. Koch., Shag-bark Hickory (C) ; common. Juglans nigra (L.), Black Walnut (C). IiABIATAE. Agastache scropJiulariaefolia (Willd.) Ktze., Figwort Giant Hyssop (C). Collinsonia canadensis (L.), Richweed (C). Hedeoma hispida (Pursh.), Rough Pennyroyal (C). Hedeoma pulegioides (L.) Pers., American Pennyroyal (C). Isanthus brachiantus (L.) BSP., False Pennyroyal (C). Lamium amplexicaide (L.), Henbit (C). Ly copus americanus (Muhl.), Cutleaved Water Hoarhound (C). Lycopus europaeus (L.), Water Hoarhound (C). Lycopus lucidus americanus (Gray), Western Water Hoarhound (C). Lycopus virginicus (L.), Bugle Weed (C). Mentha arvensis (L.), American Wild Mint (C). Mentha longifolia (L.) Huds., Horsemint (C). Mentha piperita (L.), Peppermint (C). Mentha spicat a (L.), Spearmint (C). Monarda didyma (L.), Oswego Tea (B). Monarda fistulosa (L.), Wild Bergamot (C). Monarda punctata (L.), Horsemint (C). Nepeta cataria (L.), Catnip (C). THE FLORA OF LINN COUNTY. 89 N epeta hederacea (L.) Trevisan, Ground Ivy (C). Physostegia virginiana (L.) Benth., False Dragon-head (C). Prunella vulgaris (L.),Healall (C). Pycnanthemum flexuosum (Walt.) BSP., Narrow-leaved Mountain Mint (C). Pycnanthemum pilosum (Nutt.), Hairy Mountain Mint (C). Pycnanthemum virginianum (L.) Dur. & Jackson, Virginia Mountain Mint (C). Scutellaria galericulata (L.), Marsh Skullcap (C). Scutellaria lateriflora (L.), Mad-dog Skullcap (C). Scutellaria versicolor (Nutt.), Heart-leaved Skullcap (C). Stachys palustris (L.), Woundwort (C). Stachys tenuifolia (Willd.), Smooth Hedge Nettle (C). Teucrium canadense (L.), American Germander (C). Teucrium occidentale (Gray), Hairy Germander- (B). lilLIAOEAE. Allium canadense (L.), Wild Garlic (C). Allium mutahile (Michx.), Wild Onion (C). Allium schoenoprasum sihiricum (L.) Hartm., Chives (B) ; Escape. Amianthium muscaetoxicum (Walt.) Gray, Ply Poison (C). Erythronium albidum- (Nutt.), Wild Dog’s-tooth Violet (C) ; com- mon. Erythronium americanum (Ker.), Yellow Adder’s Tongue (C). Hemerocallis fulva (L.), Common Day Lily (C) ; rare, escape. Lilium canadense (L,) , 'Wild Yellow hily {G) . Lilium philadelphicum (L.), Wild Orange-red Lily (C). Lilium philadelphicum andinum (Nutt.) Ker., Western Eed Lily (C). Lilium superhum (L.), American Turk’s Cap (C). Trillium sessile (L.), Sessile-flowered Wake Robin (B). Trillium declinatum (Gray) Gleason, Birthwort (C). Trillium grandiflorum (Michx.) Salisb., Giant White Trillium (C) ; common. Trillium nivale (Riddell), Wake Robin (C) ; common. Trillium recurvatum (Beck.), Red Trillium (C) ; common. Melanthium virginicum (L.), Bunch Flower (C) ; abundant. Oakesia sessili folia (L.) Wats., Sessile-leaved Bellwort (C). Orinthogalum umhellatum (L.), Star-of -Bethlehem (C). Polygonatum commutatum (R. S.) Dietr., Smooth Solomon’s Seal. (C). ^ Smilacina racemosa (L.) Desf., False Spikenard (C). 90 IOWA ACADEMY OF SCIENCE. Smilacina stellata (L.) Desf., Star-flowered Solomon’s Seal (C). Smilax ecirrJiata (Engelm.) Wats., Upright Smilax (C). Smilax herhacea (L.), Carrion Flower (C). Uvularia grandi flora (Sm.), Large-flowered Bellwort (C). LOBELIACEAE. Lobelia cardinalis (L.), Cardinal Flower (C). Lobelia inflata (L.), Indian Tobacco (C). Lobelia spicata (Lam.), Pale Spike Lobelia (C). Lobelia sipMlitica (L.), Great Lobelia (C). liENTIBULARIACEAE. TJtricularia vulgaris (L.), Greater Bladderwort (C). ’ TJtricularia vulgaris americana (Gray), Bladderwort (B). LYOOPODIACEAE. Lycopodium clavatum (L.), Common Club Moss (C). Lycopodium complanatum flabelliforme (Female!) , Ground Pine (C) ; very rare. liEGUMINOSAE. Amorpha canescens (Pursh.), Lead Plant (C). Amorpha fruticosa (L.), False Indigo (C). Amphicarpa monoica (L.) Ell., Hog Peanut (C). Apios tuberosa (Moench.), Groundnut (C). " Astragalus canadensis (L.), Canada Milk Vetch (C). Astragalus distortus (T. & G.), Bent Milk Vetch (B). Astragalus mexicanus (A.) DC., Ground Plum (C). Astragalus plattensis (Nutt.), Platte Milk Vetch (C). Baptisia australis (L.) R. Br., Blue False Indigo (C). Baptisia bracteata (Muhl.) Ell., Large-bracted Wild Indigo (C). Baptisia lanceolata, False Indigo. Baptisia leucantha (T. & G.), Large White Wild Indigo (C) Baptisia tinctoria (L.) .R. Br., Wild Indigo (C). Cassia chamaecrista (L.), Partridge Pea (C) ; common. Cassia nictitans (L.), Wild Sensitive Plant (C) ; rare. Desmodium bract eosum longifolium (T. & G.), Robinson, Long-leaved Tick Foil (C). Desmodium canadensis (L.) DC., Showy Tick Foil (C). Desmodium illinoense (Gray), Illinois Tick Foil (C). Desmodium laevigatum (Nutt.) DC., Smooth Tick Foil (C). Desmodium paniculatum (L.) DC., Panicled Tick Foil (C). Desmodium rotundifolium (Michx.) DC., Prostrate Tick Foil (C). THE FLORA OP LINN COUNTY. 91 Gleditschia triacanthus (L.), Honey Locust (C). Lathy rus palustris (L.), Marsh. Vetchling (C). Lathy rus venosus (Muhl.), Veiny Pea (C). Lespedeza capitata (Michx.), Kound-headed Bush Clover (C). Medicago sativa (L.), Alfalfa (C). Melilotus officinalis (L.) Lam., Yellow Melilot (C). Petalostemon candidum (Michx.), Tall White Prairie Clover (B). Petalostemon multifiorum (Vent.) Rydb., Round-headed Prairie Clover (B). Petalostemon purpureum (Vent.) Rydb., Violet Prairie Clover (B). Bohinia pseudo-acacia (L.), Common Locust (C), escape. Strophostyles helvola (L.) Britton, Trailing Wild Bean (C). Strophostyles pauciflora (Benth.) Wats., Small Wild Bean (C). Strophostyles umhellata (Muhl.) Britton, Pink Wild Bean (C). Tephrosia virginiana (L.) Pers., Goats Rue (C). Trifolium hyhridum (L.), Alsike Clover (C). Trifolium pratense (L.), Common Red Clover (C). Trifolium procumbens (L.), Low Hop Clover (C). Trifolium refiexum (L.), Buffalo Clover (B). Trifolium stoloniferum (Muhl.), Running Buffalo Clover (C). yicia americana (Muhl.), American Vetch (C). Yicia caroliniana (Walt.), Carolina Vetch (C). Vida sativa (L.), Spring Vetch. MALVACEAE. Abutilon theophrasti (Medic.), Velvet Leaf (C) ; common. Callirhoe involucrata (T. & G.) Gray, Purple Poppy Mallow (C). Hibiscus militaris (Cav.), Halberd-leaved Rose Mallow (C). Hibiscus trionum (L.), Flower-of-the-hour (C). Malva rotundifolia (L.), Common Mallow, Indian Cheese (C). MENISPERMACEAE. Menispermum canadense (L.), Moon Seed (C). NAJADACEAE. Potamogeton perfoliatus (L.), Clasping-leaved Pond Weed (C). Potamogeton pectinatus (L.), Fennel-leaved Pond Weed (C). Potamogeton americanus (C. & S.), Long-leaved Pond Weed (C). Potamogeton foliosus (Raf.), Leafy Pond Weed (C). NYCTAGINACEAE. Oxybaphus nyctagineus (Michx.) Sweet, Four 0 ’clock (C); common. 92 IOWA ACADEMY OP SCIENCE. NYMPHACEAE. Gastalia tuberosa (Paine) Greene, Pond Lily (C). Nymphaea adventa (Ait.), Yellow Pond Lily (C). OXALIDACEAE. Oxalis filipes (Small), Slender Yellow Wood Sorrel (C). Oxalis stricta (L.), TJpriglit Wood Sorrel (C) ; common. Oxalis violacea (L.), Violet Wood Sorrel (C). ORCHIDACEAE. Aplectrum liyemale (Mnhl.) Torr., Putty Root (C). Arethusa htdbosa (L.), Arethusa (B). Corallorrhiza maciilata (Raf.), Large Coral Root (C). Cypripedium candidum (Mnhl.), Small Lady’s Slipper (C). Cypripediiim hirsutum (Mill.), Showy Lady’s Slipper (B). Cypripedium parviflorum (Salisb.), Smaller Yellow Lady’s Slip- per (C). Cypripedium parviflorum puhescens (Willd.) Knight, Downy Lady’s Slipper (C). Habenaria bracteata (Willd.) R. Br., Long-bracted Orchis (C). Habenaria dilatata media (Rydb.) Ames, Green-flowered Orchid (C). Habenaria lacera (Michx.) R. Br., Ragged Fringed Orchid (B). Habenaria peramoena (Gray), Fringless Purple Orchid (B). Habenaria psycodes (L.) (Sw.), Purple-fringed Orchid (B). Orchid spectabilis (L.), Showy Orchid (C). Pogonia ophioglossioides (L.) Ker., Snakemouth (B). Pogonia trianthophora (Sw.) BSP., Nodding Pogonia (C). Spiranthes cernua (L.) Richard., Lady’s Tresses (C). Spiranthes vernalis (Engelm. & Gray), Lady’s Tresses (B). ONOGRACEAE. Circaea intermedia (Ehrh.), Enchanter’s Nightshade (B). Epilobium coloratum (Mnhl.), Purple-flowered Willow Herb (C). Gaura coccinea (Pursh.), Scarlet Gaura (B). Oenothera biennis (L.), Common Evening Primrose (C). Oenothera fruticosa (L.), Sundrops (C). Oenothera rhombipetala (Nutt.), Evening Primrose (C). Oenothera speciosa (Nutt.), White Evening Primrose (B). PORTULACAOEAE. Claytonia virginica (L.), Spring Beauty (C) ; abundant. THE FLORA OP LINN COUNTY. 93 POLYGALAOEAE. Polygala cruciata (L.), Cross-leaved or Marsh Milkwort (B). Poly gala senega (L.)j Seneca Snakeroot (C). Poly gala sanguinea (L.), Field or Purple Milkwort (C). PONTEDERI ACE AB . Pontederia cordata (L.), Pickerel Weed (C).' PRIMULACEAE, Dodecatheon media (LO^ Shooting Star (C) ; abundant. Lysimackia numm.itlaria (L.), Moneywort (B) ; introduced, escape. LysimacMa quadrifolia (L.), Loosestrife (B). Lysimackia tkyrsifiora (L.), Tufted Loosestrife (C). Steironema ciliatum (L.) Eaf., Fringed Loosestrife (C). Steironema lanceolatum (Walt.) Gray, Lance-leaved Loosestrife (C). POLEMONI ACE AE . Polemonia rcptans (L.), Bluebell, Hairbell (C) ; abundant. Phlox bifida (Beck.), Clawed Phlox (C). Phlox divaricata (L.), Broad-leaved Phlox (C) ; abundant. Phlox macidata (L.), Wild Sweet William (C). Phlox paniculata (L.), Garden Phlox (C). Phlox pilosa (L.), Wild Sweet William (C). Phlox procumbens, Phlox (C). Phlox subulata (L.), Moss pink (B). PAPAVERACEAE. Sangiiinaria canadensis (L.), Bloodroot (C) ; abundant. POLYGONAOEAE. Fagopyrum esculentum (Moench.), Buckwheat (C). Polygonum acre (HBK.), Water Smartweed (C). Polygonum aviculare {Ij.) , Yard Knotgrass (C). Polygonum douglasii (Greene), Douglas Smartweed (C). Polygonum dumetorum (L.)‘, Hedge Buckwheat (C). Polygonum erectum (L,), Erect Knot Grass (C). Polygonum hydropiper (L.), Common Smart Weed (C). Polygonum longistylum (Small), Long-styled Persicaria (C). Polygonum orientale (L.), Prince’s Feather (C) ; escape. Polygonum prolificum (Small) Kobinson, (C). Polygonum ramosissimum (Michx.), Bushy Knotweed (C). Polygonum' sagitt at um (L.), Arrow-leaved Tear Thumb (C). 94 IOWA ACADEMY OP SCIENCE. Polygonum scandens (L.), Climbing False Buckwheat (C). Polygonum tenue (Michx.), Slender Knotweed (C). Polygonum virginianum (L.), Virginia Knotweed (C). Rumex acetosella (L.), Field Sorrel (C). Rumex altissimus (Wood), Pale Dock (C). Rumex hritannica (L.), Great Water Dock (C). Rumex crispus (L.), Yellow Dock (C). Rumex ohtusifolius (L.), Bitter Dock (C). Rumex patientia (L.), Patience Dock (C). Rumex verticillatus (L.), Swamp Dock (C). PHRYMACEAE. PJiyrma leptostachya (L.), Lop Seed (C). PLANTAGINACEAE. Plantago aristata (Michx.), Large-bracted Plantain (C). Plant ago lanceolata (L.), English Plantain (C). Plantago majo7^ (L-)? Common Plantain (C). Plantago media (L.), Hoary Plantain (B). Plantago rugelii (Dene.), Engel’s Plantain (B). ROSACEAE. Agrimonia gryposepala (Wallr.), Tall Hairy Agrimony (C). Ainelanchicr canadensifi (L.), Medic., Service Berry (C) ; common. Crataegus coccinea (L.), Rough Thorn (C). Crataegus crus-galli (L.), Hawthorne (C). Crataegus macracantha (Lodd.), Long-spined Thorn (B). Crataegus mollis (T. & G.) Scheele, Red-fruited Thorn (C). Crataegus punctata (Jacq.), Large-fruited Thorn (C). Crataegus tomentosa (L.), Pear Thorn (C). Fragaria virgiyiiana (Duchesne), Wild Strawberry (C) ; common. Geum canadense (Jacq.), White Avens (C). Physocarpus opulifolius (L.), Maxim., Ninebark (C). Potentilla anserina (L.), Silverweed (B). Potentilla arguta (Pursh.), Glandular Cinquefoil (C). Potentilla canadensis (L.), Five Finger (C). Potentilla fructicosa (L.), Shrubby Five Finger (C). Potentilla monspeliensis (L.), Rough Five Finger (C). Potentilla palustris (L.), Scop., Marsh Five Finger (B). Potentilla pentandra (Engelm.) Wats., Five-stamened Five Finger (C). Pminus americana (Marsh.), Wild Plum (C) ; common. THE FLORA OF LINN COUNTY. 95 Prumis angustifolia (Marsh.), Plum, escape. Primus instititia (L.), Blackthorn (C). Primus pennsylvanica (L. f.). Wild Red Cherry (C). Primus serotina (Ehrh.), Rum Cherry (C). Prunus virginiana (L.), Choke Cherry (C). Pyrus baccata (L.), Siberian Crab (C). Rosa acicularis (Lindl.), Prickly Rose (C). Rosa blanda (Ait.), Smoth Wild Rose (C). Rosa - Carolina (L.), Swamp Rose (C). Rosa humilis (Marsh.), Low or Pasture Rose (C). Rosa setigera (Michx.), Climbing or Prairie Rose (C). Rosa virginiana (Mill.), Dwarf Rose (C). Rosa woodsii (Lindl.), Low Wild Rose (C). Rubus canadensis (L.), Low Running Blackberry (C). Rubus frondosus (Bigel.), High Bush Blackberry (C). Rubus idaeus aculeatissimus (C. A. Mey.) Regal & Tiling. Rubus villosus (Ait.), Dewberry (C). Spiraea salicifolia (L.), Meadow Sweet (C). Spiraea salicifolia (Variation), (C). Spiraea tomentosa (L.), Hardback (B). RXJBI A.CE AE . Cephalanthus occidentalis (L.), Button Bush (C). Galium aparine vaillantii (DC.) Koch., Cleavers (C)., Galium asprellim (Michx.), Rough Bedstraw (C). Galium circaezans (Michx.), Wild Liquorice (C). Galium concinnum (T. & G.), Shining Bedstraw. Galium parisiense (L.), Wall Bedstraw (C). Galium tricorne (Stokes), Rough-fruited Corn Bedstraw (C). Galium triflorum (Michx.), Sweet-scented Bedstraw (C). Houstonia caerulea (L.), Innocence (B). Houstonia patens (Ell.), Small Bluets (C). Houstonia minima, Bluet (C). RHAMNACEAE. Ceanothus americanus (L.), New' Jersey Tea (C). RANUNOULACEAE. Actaea alba (L.), Mill., White Baneberry (B). Anemone cylindrica (Gray), Long-fruited Anemone (C). Anemone nemorosa (L.), Anemone, (C). Anemone parvi flora (Michx.), Northern Anemone (C). 96, IOWA ACADEMY OP SCIENCE. Anemone patens wolfgangiana (Bess.) Koch., Basque Flower (C). Anemone canadensis (L.), White Anemone (C). Anemone quinquifoUa (L.), Wood Anemone (C). Anemonella thalictroides (L.), Spach., Kue Anemone (C) ; common. Aquilegia canadensis (L.), Wild Columbine (C) ; common. Caltha palustris (L.), Marsh marigold (C) ; common. Clematis virginiana (L.), Virgin’s Bower (B). Clematis viorna (L.), Leather Flower (C) ; common. Delphinium exaltatum, Tall Larkspur (C). Delphinium penardi (Huth.), Prairie Larkspur (C). Delphinium tricorne (Michx.), Dwarf Larkspur (C). Hepatica triloha (Chaix.), Hepatica (C) ; common. Hepatica triloha acutifolia, Liverwort (B). Myosurus minimus (L.), Mousetail (C). Ranuncidus ahortivus (L.), Small-flowered Crowfoot (C) ; abundant. Ranunculus acris (L.), Tall Crowfoot (C). Ranunculus aquatilis capillaceus (DC.), White Water Crowfoot (C). Ranunculus hulbosus (L.), Bulbous Buttercup (C). Ranunculus delphinifolius (Torr.)^ Yellow Water Crowfoot (C). Ranunculus delphinifolius terrestris (Gray) Farwell, Large Water Crowfoot. Ranuncidus fascicularis (Muhl.), Northwestern Buttercup (C). Ranunculus pennsylvanicus (LF.), Bristly Crowfoot (C). Ranunculus purshii (Kichards.), Yellow Water Buttercup (C) ; rare. Ranunculus recurvatus (Poir.), Hooked Buttercup (C). Ranunculus septentrionalis (Poir.), Swamp Buttercup (C). 'Thalictrum dasycarpum (Fisch. & Lall.) , Stinking Meadow Rue (C) . Thalictrum dioicum (L.), Early Meadow Rue (C). Thalictrum polygamum (Muhl.), Tall Meadow Rue (C). RUTACEAE. Zanthoxylum americanum (Mill.), Northern Prickly Ash (C). SAXIFRAGACEAE. Heuchera hispida (Pursh.), Hairy Alum Root (C). Mitella diphylla (L.), Bishop’s Cap (C), common. Parnassia caroliniana (Mx.), Grass of Parnassus (B). Parnassia palustris (L.), Northern Grass of Parnassus (B). Parnassia parviflora (DC.), Small-flowered Grass of Parnassus (B). Ribes aureum (Pursh.), Missouri or Buffalo Currant (C). Ribes cynosbati (L.), Prickly . Gooseberry (C). Ribes floridum (L’Her.), Wild Black Currant (C). THE FLORA OP LINN COUNTY. 97 Bibes gracile (Mx.), Wild Gooseberry (C). Rihes oxyacanthoides (L.), Smooth Gooseberry (C). Bihes rotundifoUum (Mx.), Eastern Wild Gooseberry (C). Saxifraga micranthidi folia (Haw.) Britton, Lettuce Saxifrage (B). Saxifraga pennsylvanica (L.), Swamp Saxifrage (C). SulUvantia suUivantii (T. & G.) Britton, Sullivantia (B). SANTAIiACEAE. Comandra iimbellaia (L.), Nutt., Bastard Toad Flax. STAPHYLEACEAE. Stapkylea trifolia (L.), American Bladder Nut (C). SALICAOEAE. Populus deltoides (Marsh.), Cottonwood (C). Salix petiolaris (Sm.), Slender Willow (C). Salix tristis (Ait.), Dwarf Willow (C). SCROPHULARIACEAE. Castilleja coccinea (L.) Spreng., Scarlet Painted Cup (C). Castilleja sessiliflora (Pursh.), Hairy Painted Cup (C). Gerardia purpurea (L.), Purple Gerardia (B). Gerardia tenuifolia (Vahl.), Slender Gerardia (C). Gratiola virginiana (L.), Clammy Hedge Hyssop (C). Linaria cymbalaria (L.) Mill., Coliseum Ivy (B). Linaria vulgaris (Hill), Butter and Eggs (C). Mimulus ringens (L.), Monkey Flower (C). Pedicularis canadensis (L.), Lousewort (C). Scrophularia leporella (Bicknell), Hare Figwort (C). Scrophularia marilandica (L.), Heal-all (C). V erbascum blattaria (L.), Moth Mullein (C). Verbascum lychnitis (L.), White Mullein (C). Verbascym thapsus (L.), Common Mullein (C). Veronica longifolia (L.), Speedwell (B). Veronica virginica (L.), Culver’s Boot (C). SOLANACEAE. Batura stramonium (L.), Stramonium (C). Datura tatula (L.), Purple Thorn Apple (C). Physalis ixocarpa (Brotero), Tomatillo (B). Physalis lanceolata (Mx.), Prairie Ground Cherry (C). Physalis pubescens (L.), Low Hairy Ground Cherry ((^). 7 98 IOWA ACADEMY OP SCIENCE. Physalis suhglabrata (Mackenzie and Bush), Philadelphia Ground Cherry (C). Solanum carolinense (L.), Horse Nettle (C). Solatium dulcamara (L.), Bittersweet (C). Solanum nigrum (L.), Common Nightshade (C). Solanum rostratum (Dunal.), Buffalo Bur (C). Solanum tul)erosum (L,), Common Potato (C) ; escape. ; TYPHACEAE. Typha latifolia (L.)? Common cat-tail (C). THYMELAECEAE. Dirca palustris (L.), Leatherwood (C) ; rare. XJMCBEI/I/IEERAE. ■ Angelica villosa (Walt.) BSP., Pubescent Angelica (C). Carum carvi (L.), Caraway (C). Chaerophyllium procumhens (L.) Crantz, Spreading Chervil (C). Cicuta maculata (L.), Spotted Cowbane (C). i Conioselinum chinense (L.) BSP., Hemlock Parsley (C). i Conium maculatum (L.), Poison Hemlock (C). Cryptotaenia canadensis (L.) DC., Honewort (C). Heracleum lanatum (Mx.), Cow Parsnip (C). i Osmorhiza longistylis (Torr.) DC., Smooth Sweet Cicely (C). Thaspium harhinode (Mx.) Nutt., Meadow Parsnip (C). Zizia cordata (Walt.) DC., Heart-leaved Alexanders (C). UTRICACEAE. Boehmeria cylindrica (L.) Sw., False Nettle (C). Cannabis sativa (L.), Hemp (C). Humulus lupulus (L.), Common Hop (C). Laportea canadensis (L.) Gaud., Wood Nettle (C). ' ' Pilea pumila (L.) Gray, Clearweed (C). JJlmus racemosa (Thomas), Rock Elm (C). TJlmus americana, Elm (C). TJrtica urens (L.), Small nettle (C). VITEAGEAE. Vitis cordifolia (Mx.), Frost or Chicken Grape (C). VIOLACEAE. Viola blanda (Willd.), Sweet White Violet (C). Viola fimbriatula (Sm.), Ovate-leaved Violet (B;). I THE FLORA OP LINN COUNTY. Viola palmata (L.), Early Violet (C). Viola pedata (L.), Bird-foot Violet (C). Viola pedatifida (G. Don.), Cut-leaved Violet (C). Viola piibescens (Ait.), Downy Yellow Violet (G). Viola rotundifolia (Mx.), Yellow Violet (C). Viola sagittata (Ait.), Arrow-leaved Violet (C). Viola scahriuscula (Schwein.), Smooth Yellow Violet (C). Viola sororia (Willd.), Wood Violet (C). VERBENEACEAE. Lippia lanceolata (Mx.), Fog-fruit (C). Verbena angustifoUa (Mx.), Narrow-leaved Vervain (C). Verbena stricta (Vent.), Hoary Vervain (C). Verbena urticaefolia (L.), White Vervain (G). Botanical Laboratory, Coe CoiiLEGE, Cedar Bapids. v/ -;-' ■-r -■■iCvs ’ :V'.- , ' * <■ ,fcV': ' >■' I' Vi'V,/ r' i ■ , i ..fw. Kt; :-,%v ;. \' '.’'•^r,. ‘. v'* , ■' :';;S'!^:t:.C:-',,4',. <- myt-'y-- \'-A‘ ■ '., ''j' '.v,i:;: SUNPLECKS. 101 ‘‘SUNFLECKS.” BY W. H. DAVIS. On Sunday, June 28, 1908, between 9 :27 a. m., and 12 :41 p. m., there occurred a seven-eighths eclipse of the sun. Thinking that I might procure some eclipse pictures, I loaded my plate-holder with 5 inch by 7 inch Standard Orthonon plates. While on my way to the spot chosen for photographing the eclipse, I noticed the eclipse was fast appearing and many small eclipse images were visible in a pool of water under some trees. I hurried to photo- graph this phenomenon but on my way for another camera, observed many eclipse images on the walk before my door. Plate VI, figure 1, shows some of those eclipse images as they appeared on the walk during the seven-eights eclipse. I then photographed the eclipsed sun by the aid of another holding my camera after focusing. I used the front com- bination of a Turner-Peich anastigmat lens of eight and one-half inch focus ;'stop, U. S., 64; speed, 1-100 second through a potassium bicromate solution ray-filter. • At the same time, I managed to photograph some of the maple leaf facies with the interleaf spaces directly above the eclipse images, all of which are shown in Plate V. After the eclipse had passed, I photographed the same walk show- ing the normal sun images as showm in Plate VI, figure 2. While the eclipse was on the sun, I held a cardboard, fastened to a pole, over some of the interleaf spaces and thus blocked the eclipse images, showing that the inter-leaf spaces acted similar to a pinhole in a camera, thus throwing an image of the sun on the walk, at one time eclipsed, at another, unobstructed and bright. If a leaf containing worm holes is placed in a blocked window, on a bright day, a sun image will be thrown on the floor. I have seen clouds pass over this sun image thus formed. I have seen sun images formed under elm leaves punctured with worm holes, or by fungi, vary- ing from one-eighth to one-fourth inch. The eclipse images were due to the interleaf spaces acting as ‘‘pin- holes.” The same cause produces the sun images which we see so often under trees and in the shade during the summer months. Their sizes depend upon the size and the height of the interleaf spaces above the ground. These sun images occur abundantly under deciduous trees, under shrubs, frequently under conifers and sparingly under herbs. 102 IOWA ACADEMY OF SCIENCE. They are usually absent on the forest floor underneath very dense forest but occur among the upper branches. They seem to be found most abundantly under shade trees during the summer months of June, July and August. This seems to furnish proof that interleaf spaces and openings in leaves throw sun images in the shade underneath themselves. These I have termed sun images, contrary to the old term which was probably copied from the German, Der Sonnenfleck and spoken of in English as ‘‘sunfleck.” This name would imply a ‘‘fleck” which is a dot, spot, streak of color, dapple or a patch, — a sun spot — and not an image. Clements — Kesearch Methods in Ecology, p. 60, — speaks of taking the “sunflecks” into account when taking photometric measure of the forest floor. 'Here he puts the word “sunflecks” in quotation marks, but in his bibliography, gives no references to it. Sach — The Physiology of Plants, p. 302 — says: “Of course this limit of the intensity of light cannot be exactly given ‘in the absence of suitable photometric methods and when Pringsheim makes circumstantial statements concerning behavior of cells containing chlorophyll in the focus of a lens, or in the sun’s image, as he terms it, these purely pathological processes have about as much physiological value as if, for any reason whatsoever, a so-called sun’s image were allowed to act on the retina of the eye through a burning glass, “In the absence of photometric measurements of general value, I pass over these statements also.” Pringsheim — Jahrbiicher, Vol. 12, I review with these brief results. Pringsheim used a “burning” glass throwing very strong lights on many algae and leaves to see the effect of light on plastidsi, etc. Some chloroplastids were made functionless, lost their green; others retained their function but lost their green, etc. He also observed the move- ment of plastids and other phenomena. His experiment was not for the purpose of illustrating the action of “sunflecks” on chloroplastids and chlorophyll but the succession of strong and weak light — daylight and darkness. However, the effect of sunflecks would be similar to his experiment for they bring about the same conditions. The following is a table showing the frequency of sun eclipses. References : Chamberlain — Astronomy — ^Yols. I, II. World Almanacs, — 1871 to 1912. Todd’s Astronomy. There can be no less than two annual eclipses of the sun and no more than five. One of the first eclipses photographed occurred July 28, 1851. SUNFLECKS. 103 DATE OP ECLIPSES OP THE SUN VISIBLE AT SOME PLACE ON THE EARTH. 585 B. C., May ■'2 8 — Herodotes records, most celebrated. 557 B. C., May . Xenopbon records. 1842 A. D., July 18. *1851 A. D., July 28 — Clouds beautiful, Dr. Bush’s first photograph. 1858 A. D., Aug. 1 — First instance of a successful corona. 1869 A. D., Aug. 7. *1870 A. D., Dec. 22 — Syracuse photo. 1871 A. D., Dec. 16. 1873 A. D., April 1. 1875 A. D., April 5. 1878 A. D., July 29. 1882 A. D., May 17. 1883 A. D., May 6. 1885 A. D., Sept. . . 1886 A. D., Aug. 29. 1887 A. D., Aug. 19. *1889 A. D., May . . — In U. S. but rained most places. 1901 A. D., May . . — Invisible. 1901 A. D., Oct. . . 1902 A. D., Nov. 10-11, May 7 — Invisible. 1902 A. D., April 8. 1903 A. D., May 28. 1903 A. D., Sept. 20 — Invisible. 1904 A. D., May 16 — Invisible. 1904 A. D., Sept. 9 — Invisible. *1905 A. D., May 5. 1905 A. D., Aug. 30 — Visible in Eastern United States. 1906 A. D., Feb. 25 — ^Invisible. 1906 A. D., July 21 — Invisible. 1907 A. D., Jan. 13 — Invisible. 1907 A. D., July 10 — Invisible. *1908 A. D., June 28 — Visible. 1909 A. D. 1910 A. D. 1911 A. D. 1912 A. D. 1840 to 1900 — ^Three important eclipses where one-half or more of sun was eclipsed and only two universally visible , in tropics. During the last twelve years two eclipses of account, a three-fourths and a seven-eighths, one in the Eastern United States only. Less than fifty per cent of these eclipses occurred when leaves were on the trees. Deduction from this table: ♦Visible in U. S. 104 IOWA ACADEMY OP SCIENCE. 1. In the last seventy years only five important eclipses, four visible in U. S. and three when leaves were on the trees. 2. The eclipse period here has been about six hours out of seventy years, one-half to total eclipse period, about two hours out of seventy years. Thus little chance has been given to observe the eclipse images. Botanical value of sun images. — One of the greatest factors (if not the greatest) in photosynthetic assimilation is sunlight, and a variation in sunlight causes a variation in photosynthesis. It varies from zero on a dark night to a maximum in sunlight on a dark day, providing other conditions are suitable. In Plate VI all gradations of light intensity can be observed in the sun images; some are as bright as the sunlight; some scarcely can be seen as they approach the intensity of light in the shade. Therefore, it is safe to state that the intensity of sun images varies from bright sunlight to the surrounding shade. By placing a sheet of solio paper across the negative and printing several sheets with recorded times it takes the sun images to print, each having an equal intensity thereon, the intensities can be found. Taking sunlight as 1, recording one set of data, I found them to be 1 to 1-10, but this needs accurate experiment taken with a photometer. Clements — Eesearch Methods, p. 60, states concerning the readings of light intensity: “A very satisfactory place of reading intensity of light is to take readings in two or more spots where shade appears to be typical and to make a check reading in a ‘sunfleck,’ a spot where sunlight shows through.’^ He gives no figures to show such measure- ments, he only suggests a method for measurement. It is very easily seen from Plate VI, that the area of the sun images exceeds the shaded area, so the former must be of great consequence to the shade plants” in carrying on photosynthesis, both in area and light intensity. They might have much to do with the survival of many species growing underneath forest and shade trees. Trees with overlapping and exceedingly dense foliage, I have noticed, have very scant ground vegetation save mosses and ferns. It is generally conceded that leaves “absorb” the green and violet rays of white light. The light received by the shade plants is more or less screened, and composed of red and yellow rays; of course, much reflected and refracted light is received by them not of equal actinic composition. The sun images distribute the white light to the shade plants. SUNFLECKS. 105 The angles at which the sun images strike the plant must have some effect on the light intensity. A table given by Clements is as follows: 90 degrees has an intensity of *1.00 80 degrees has an intensity of .98 40 degrees has an intensity of .64 10 degrees has an intensity of .17 So an image on June 21 would have greater intensity than one on September 21. The path of an image per one day is an arc, and on the following day the arc is north or south of that of the previous day, depending on whether the sun is increasing or decreasing its declination. So the sun image would make a series of concentric arcs, distributing sunshine on the shade plants in a new area for each day, of course, for a short duration. It is possible for one plant to receive the sunlight from several images in one day and hundreds in a season. Eeflected light is of great value to shade plants, but is it enough? By putting a number of leaves on solio paper, and obtaining ‘Jeaf prints” something of the light absorbing power of leaves can be deter- mined. This should also be checked with a photometer, which is preferable. Leaves of Capsella hursa-pastoris allow rays to pass through readily and print quickly, while Rosa Carolina and Hepatica triloha are difficult to print through. Maple leaves are very difficult to print through, which shows that they absorb a great amount of the actinic rays, blues, greens and violets, but allow the reds to pass through Eeliotropism. — ^As the stimulus of the sun images is greater than the reflected light stimulus in the shade, there must be some heliotropic movement, but just what, I cannot say as I have made no experiments. CMoroplastids. — The following facts are conceded as generally true: See Sach and Yohst — As light largely determines the shape, size and number of chloro- plastids : (b) Chloroplastids in the shade are generally hemispherical, those in the sunlight are plane. (c) The position of the chloroplastids depends largely on the light. (d) Light has a great effect on the movement of foods from cell to cell in a plant. (e) Chloroplasts tend to place themselves at angles to different light and parallel to rays of sunlight. 106 IOWA ACADEMY OF SCIENCE. The sun images must have an effect upon each of the above conditions as they vary the condition from shade to bright sunlight. Just what, remains for experimentation. Clements, E. S. — Relation of Leaf Structures to Physical Factors, p. 84. ‘‘Reduced light, besides decreasing the palisade and sponge tissues in amount, shortens and broadens the palisade cells and extends the sponge cells in a horizontal direction. The extreme of this tendency is to be seen in Sparganium which has exactly reversed the long axis of the palisade cells. By this means, the chloropastids are placed in a favorable position to utilize the weak light. The thinning of the leaf comes from the mobility of the chloroplastids. ” So light in a sun image followed by shade must reduce the thickness of leaves after it passes over them. Schimper — Plant Geography. “Many herbs growing on the ground of the virgin forests are pro- vided with wonderful markings on their foliage, in the way of white, silvery, golden, or red spots; E. g. Begonia. Amarantacese. Orchid- aceas. ’ ’ M. Mobins — Pringsheim’s Yahrbuch, V. 18, p. 530. Established hereditary traits more than cause for flecks. Stahl considered these “flecks’^ as devices for increasing transpiration. Suggestions : Could sun images cause the mottling of leaves with darker colors? With lighter colors? With bright colors? Could they cause darker red spots on apples, and darker color on other fruit ? This result is assigned to the sun shining through leaves, etc. Perhaps they cause certain portions of fruits to ripen more quickly than others. What effects, if any, would they have on seed germination in the shade or on the forest floor? Would these sun spots have a direct effect on the soil itself? Could all plants exist in the shade without these sun images — as those under conifers, which receive reflected light? Possible zoological values. — It is a known fact that horned owls perch among trees during the day and are mottled with white spots so that one looking at an owl in a tree, during a summer day, “looks through the owl” as the spots imitate the apparent openings between leaves. Perhaps sun images may be the prime factors of this color pattern, the pattern of the owl corresponding to that of the sun images among the branches. The same is true of many other song birds, such as thrush, whip-poor-will, quail, etc. SUNPLECKS. 107 In the tropics, most favorable conditions are found for sun images and there are found many spotted animals, leopard, giraffe and most of the cat tribe. Strangely enough, the young of the Virginia deer is spotted. The habitat of these animals is under trees or under limbs where sun images are abundant, and where the images are projected during the day. The deer lie rather quietly among them and thus show some relation between the two. Fishes living in shaded streams and along shady banks sometimes bear white spots or silvery markings similar to sun images, as for example, perch, pickerel, pike, minnows, etc. These spots are very com- mon among reptilia and amphibia; small ones occur on toads and frogs, salamanders and snakes. Animals dwelling in a habitat void of sun spots are not spotted ; the polar bear, reindeer, walrus, etc., are examples. The intensity of light is not enough at high latitudes to make sun images of consequence even if other conditions did prevail. It is diffi- cult to name a spotted animal that spends its time in open areas. In conclusion: I think sun images are of great importance and need much experimentation to establish their exact values in the plant and animal kingdom. References : Todd — Astronomy. Chamberlain — Astronomy, Vols. I, II. World Almanac — 1871-1912. Yohst — Plant Physiology, p. 460 — Gibson. Sach — Plant Physiology, p. 302. Strassburger — A Text book in Botany. Clement — Research Methods in Ecology. Clement, Miss E. S. — ^Leaf Structure and Physical Factors. Schimper— Plant Geography. Stahl — Plant Geography. Pringsheim — Jahrbiicher, Vol. 12, 1878. Ernest Seton-Thompson — ^Wild Animals of North America. Deschanel — Natural Philosophy, Part IV : Light. Iowa State Teachers’ College, Cedar I’alls, Iowa. ''W?- ' :-i'H . J \ •,,; I , ';■;■■ • ■' Wr' .ri;.',' ■ '• . i!\v^ ' '.■ [ - . ■"'['- ' f’'.;:;,- i*"- ■ ' ■ v.’> ;: -:;H'f ;" ' ,■•■. ■'■ri.-: ’ ••'.‘■!V I ' vn'ri: 'i- ■ >:, f' >'.? r ■ -Ji " ' .' ' r ■ ■ ■■ V,- ;!>■ ..nn^ V - ' *■ ••■ ■ ' .:' n‘ ."i*--.'..'.,' . ,.' .■■■'•>■■*’ f-i-. ,rr'" •f f.v ' ir V :V; . . ; , Plate VI. Fig. 1. — Eclipse images shown on sidewalk. Fig. 2. — Normal images on sidewalk. SYCAMORE BLIGHT. 109 SOME OBSERVATIONS ON SYCAMORE BLIGHT AND ACCOMPANYING FUNGI. J. P. ANDERSON. Last spring (1913) the Sycamore blight (Gnomonia veneta (Sacc. & Speg.) Kleh.) was very prevalent and destructive in the vicinity of Ames. All the large trees along Squaw creek looked as though the young foliage and growth had been killed by frost except a few tufts in the extreme tops of the trees. Young trees several years planted suffered somewhat, hut none to the extent that the large trees did. About one-half of these young trees showed some traces of the disease. During August the effects of its ravages were noted in eastern Nebraska and at Lamoni, Decatur county, Iowa. Doctor Pammel also reported it as destructive in Madison county, and in Decatur county at Leon. The extreme destructiveness of the disease aroused considerable in- terest in it, and at the suggestion of Dr. L. H. Pammel, head of the Department of Botany at the Iowa State College at Ames, the writer undertook an investigation and he here wishes to acknowledge the help and suggestions received from Doctor Pammel. The plan was to make this investigation a thorough one hut owing to a change of plans this could not he done. A few observations are hereby submitted hoping that they may be of interest to mycologists. It is to be hoped that at least part of the work originally planned may be carried out later. In making plate cultures for the purpose of isolating the fungus many other fungi occurred, including species of Penicilhcm, Mucor, Asper- gillus, Monilia, Macrosporium, Alternaira, Coniothyrium, CepJialothec- ium, and several unidentified forms. CepJialothecium roseum proved very troublesome on all material kept in the damp chambers. Conio- thyrium mixtum Fuckl., Cytospora platani Fuckl. and Massaria platani Ces. are found very commonly on twigs that have been killed by the blight. These will each receive brief consideration later in this paper. Gnomonia veneta (Sacc. & Speg.) Kleb. Plate VII, Figs. 1-4. According to Edgerton^ there are four conidial forms^and an ascigerous stage connected with this fungus. The conidial forms are as follows: 1. The conidia may be borne in acervuli under the cuticle on short conidiophores. Long known as Gloeosporium nervisequm (Fuckel) ^ Sacc. 110 IOWA ACADEMY OP SCIENCE. 2. The conidia may be borne in acervnli under the epidermis on long conidiophores. This has been known as Gloeosporium platani (Mont.) Oud. 3. The conidia may be borne in pustules on the twigs, being then known as Myxosporium valsoideum (Sacc.) All. and Discula platani (Peek) Sacc. 4. Pycnospores may be borne in cleistocarpous pycnidia on old leaves on the ground. This stage has been named Sporonema platani Baumler, and Fusicoccum veronense C. Massalongo. The acervnli on the leaves are found in the summer and fall. The fungus attacks the leaf veins and from these spreads out into the sur- rounding tissue. The acervnli are 100 to 300/^ in diameter. The spores are generally described as 10 to 14x4 to but the spores examined from leaves gathered in the fall and from cultures on agar were quite constant in size and about 10x4%m. The spores from material gathered in the spring showed more variation, but the average size was about the same. The fungus attacks the petioles as well as the leaves and twigs. It seems probable that the mycelium travels down the petiole and from there enters the young stem. When the leaves fall the twigs of the current season’s growth may appear perfectly healthy. But later, and especially toward spring, the presence of the disease is manifest. These diseased twigs may remain alive and send out young leaves, but when the leaves are about one-third grown they wither and die quite suddenly, owing to the cutting off of the source of supplies for growth. This is what gives the trees the appearance of blight and gives rise to the popular name. The twig figured in Plate Yll, Pig. 4, is very typical, although many twigs show a much more extensive diseased area. In many cases a large portion of the twig is thus diseased. This Myxo- sporium or Discula stage may be found at any season of the year and is the one causing most destruction, as the annual loss of the greater part of the young foliage every spring cannot help but seriously weaken the tree. The pycnidial or sporonema stage develops during late winter or very early spring on leaves that have been kept moist over winter. The stroma bearing the conidia continues to grow until it has surrounded the developing spores. As observations were discontinued about the first of the year, this stage was not observed. The ascigerous stage was not ob- served for the same reason, i The ascigerous stage develops on the fallen leaves that have wintered in the open. The perithecium is described as being subglobose, or slightly flattened, 150 to 200/^ in diameter, with the upper side elongated into a SYCAMORE BLIGHT. Ill beak. Asei tog clavate 48 to 60x12 to 15/", generally bent at right angles near the base. Ascns 8-spored ; spores hyaline, 14 to 19x4 to 5/", straight or slightly arcuate, unevenly 2-celled, the upper being several times as long as the lower one. For further literature on this interesting species, the reader is re- ferred to the excellent papers by Edgerton^ Klebahn , and Von Tavef. Coniothyrium mixtum Fuckel. Plate VII, Figs. 5 & 6. What appears to be t]jis species was found to be quite common on twigs of the sycamore killed by the blight. It is also found on twigs killed by other causes. The pycnidia vary from 150 to 250/" in diameter, are nearly globose to much depressed, with a rather thick hymenium and short conidiophores. Spores are produced in abundance, fulgineous, appearing brown when in masses ; about 7x4x4/". , Cytospora platani Fuckl. ; ' Plate VII, Figs. 7-12. • ; I have placed the forms examined promiscuously in this species, al- though the spores are about 50 per cent longer than the measurements given by Saccard!0^ While this fungus is common on twigs of sycamore killed by blight, it is .relatively more abundant on young trees that have died from the effects of transplanting. The stroma, as ordinarily found, are from 1 to 3 mm. in diameter. At first they are entirely covered by the epidermis, but later break through. When placed in a' damp chamber the spores are forced out in light yellow, wormlike masses.. At first the pycnidia are subglobular or slightly angular in outline, with, the hymenium bearing conidiophores on all sides. Later the pycnidium enlarges, becomes very irregular and with a conical beak. The spores are decidedly allantoid, 10 to 12x3 to 4/", and produced in vexy great abundance. ^ Massaria platani Ces. . ^ Plate VIII. i This fungus is common near the base of sycamore twigs killed by the blight. It is not universally present and it is not probable that the two have any organic connection. Around Ames I have found the Massaria on one-third to one-half of the blight-killed branches. It seems never to develop far from the live wood, which indicates that it requires con- ^Edgerton, C. W. The physiology and development of some anthriacnoses. Bot, Gazette 45; 367-408, 1908. ^Klebahn, H. Untersuchungen iiber einige Fungi imperfecti und die zugehorigen Ascomycetenformen. Jahrb. Wiss, Bot. 41; 515-558. 1905. ^Tavel, Franz von. Contributions to the history of the development of the Pyrenomycetes. Jour. Myc. 5; 53-58, 113-123, 181-184. 1889. '‘Saccardo, P. A. Syllage Fungorum 3; 267. 112 IOWA ACADEMY OF SCIENCE. siderable moisture. It may be seen as black dots underneath the epi- dermis of the twig. These dots are one-half to one millimeter in diameter. Sometimes they are very thickly placed, and at other times quite scat- tered. When closely placed they may be connected by fungus hyphae so as to almost appear to be in a stroma. The larger ones are perithecia, while the smaller ones are pycnidia. The specimens examined conform exactly with the description given by Saccardo-^, but differ considerably from the description given by Ellis and Everhart.® The perithecia are depressed globose, three-fourths of a millimeter or more in diameter. Asci ^8-spored, 240x42 to 60/*. Spores 55 to 60 x about 20/*, 5-septate, inequilaterally didymous, the upper and larger portion being 3-septate, the lower portion uniseptate. The spores are brown and surrounded by a hyaline gelatinous envelope. Paraphyses abundant, filiform. The pycnidial stage has been known as Render sonia desmazierii Mont. The pycnidia are smaller than the perithecia, being scarcely one-half millimeter in diameter. They are also much flatter, the diameter being 3 to 4 times the height. The conidia are dark colored, 3-septate, 40 to 45x14 to 16/*. Under favorable conditions, such as exist in a moist chamber, both conidia and ascospores are exuded in black masses. I have found both forms in the same mass, which indicates that the pycinidium may, under favorable conditions, be transformed into a perithecium by enlargement, thickening of walls, and the arising of paraphyses and asci in the place of conidiophores. While evidence on this point is not conclusive, it is further supported by the fact that a twig, on being examined, showed only pycnidia, while after being in a damp chamber a few weeks most of the bodies proved to be perithecia. These perithecia seemed to occupy the positions previously occupied by the pycnidia. .. Ellis and Everhart® give all the measurements too small to apply to any of the specimens examined. They also speak of the ascospores as being 3 to 6 (mostly 3 to 5) -septate. All of the fully mature ascospores examined were uniformly 5-septate, while all the mature conidia were 3~septate. Both are olive-brown in color. The ascospores and conidia germinate by sending out a germ tube from one or more of the cells, most often from one end cell. The mycelium is at first light brown, later becoming dark brown and much branched. Attempts to isolate the fungus were unsuccessful for the reason that the mycelium is slow growing and the plates were over- run by rapid growing fungi. One unidentified form of very rapid grow- ^Saccardo, P. A. Syllag-e Fun^orum 2; 6. «Ellis, J. B., and Everhart, B. M. North American Pyrenomycetes, 403. SYCAMORE BLIGHT. 113 ing fungus made more growth in one hour while under obserration than Massaria did in two days. Botanical Laboratory, Iowa State College, Ames. DESCRIPTION OF PLATES. Plate VII. Gnomonia veneta (Sace. & Speg.) Kleb. (Gioeosporium nervisequm (Fckl.) Sace.) Fig. 1. Portion of the under surface of a leaf of sycamore {Flat anus occidentalis) showing pustules of the fungus. Leaf gathered October, 1913. Slightly enlarged. Fig. 2. Section through a pustule, x 150. Pig. 3. Spores, x 550. Ihg. 4. Myxosporium stage on twig. A leaf sear is shown where young growth had started but had been killed by the fungus. X 1%. Coniothyrium mixtum Fuckl. Fig. 5. A pycnidium. x 150. Pig. 6. Spores, x 550. Cytospora platani Fuckl. Pig. 7. Portion of a twig showing stromata and the wormlike spore masses being pushed out of some of them, x 1%. Pig. 8. Stroma with wormlike spore mass. Somewhat enlarged. - Pig. 9. A stroma more enlarged. Pig. 10. Section of a stroma with three pycnidia, only a portion of one pycnidium being shown, x 150. Pig. 11. A large, irregular pycnidium. A cone-shaped beak is arising from the center, x 150. Pig. 12. Spores, x 550. Plate VIII. Massaria platani Ces. Pig. 1. Several perithecia growing close together and connected by fungus threads and almost appearing as if in a stroma. X 12. The small body at the right is a young pycnidium. Pig. 2. A perithecium. x 65. 8 114 IOWA ACADEMY OP SCIENCE. Fig. 3. A young ascus. x 150. Fig. 4. Nearly mature ascus. x 150. Fig. 5. A fully mature ascus. x 150. Fig. 6. A young ascospore. x 550. Fig. 7. Nearly mature ascospore. x 550. Fig. 8. Fully mature ascospore. x 550. Fig. 9. A {Hendersoma desmazierii Moni.) . x 150. Fig. 10. Two mature conidia. x 550. Fig. 11. Two conidia germinating, x 275. All drawings are original. / .- ‘ V:;' '. . “r-. • .'- v-^ *' V >. •• Plate VII. Drawings of Sycamore blight and other fungi. Plate VIII. Massaria platani. WEED SURVEY OF STORY COUNTY. 115 WEED SURVEY OF STORY COUNTY, IOWA. BY L. H. PAMMEL AND CHARLOTTE M. KING. The matter of the distribution of weeds is one of interest, not only to the phytogeographer, but to the farmer and horticulturist as well. Our alien flora, though Iowa is not an old state, is a large one. In 1879 Dr. Gray prepared a list of the predominant weeds of Eastern North America.^ In a discussion of weed migration in The Weed Flora of Iowa, I made a comparison of weeds and alien plants in Iowa. In counting the weeds of Iowa I find that 172 of that list occur in Iowa. This list can be augmented by the addition of a great many more. We are safe iu saying that not far from twenty per cent of our Iowa plants are alien. Dr. Fernaldf states that only twenty-three per cent of the New England plants are native. In a paper which follows this, ‘‘Intro- duced Plants of Clear Creek Canon, Colorado, ’ ’ it will be seen that more than eighty-five per cent are indigenous. In other words, in spite of various disturbances, such as modern traffic, the burning of the forests, etc., a large per cent of species must be considered as indigenous. A few weeds like the Russian thistle, because of the xerophytic character, have been able to occupy large areas. The case in Iowa is, however, far different. There are comparatively few plants of the native prairie that can overcome the difficulties of cultivation. It is true that the plants of the native prairies were plants of the sunshine, but the plants were firmly rooted in the sod, and, though they do well when protected, they cannot compete with European weeds and alien plants, even where cultivation has not occurred; but grass, timothy, and other alien plants have crowded the goldenrod, aster, etc., leaving little in the way of native vegetation. There are some notable exceptions, as that of the morning glory {Convolvulus sepium), arti- choke {Helianthus tuberosus and H. gross erraf us) , the greater ragweed {Ambrosia trifida), milkweed {Asclepias syriaca), and others. Our weed flora is not fixed, new weeds are not only coming in, but some of these newcomers are crowding out some of the old familiar weeds. The common prickly lettuce {Lactuca scariola var. integrata) is today being crowded out in Story county by the Lactuca scariola. The quack grass {Agropyron repens) in our meadows is crowding the foxtail {Set aria viridis). This has occurred in comparatively recent times. *See L. H. Pammel “Weed Flora of Iowa” p. 714 — references will be found here. Tl. c. 116 IOWA ACADEMY OF SCIENCE. Quack grass in parts of Iowa has occurred for more than twenty-five years. It has occurred in the vicinity of Ames for twenty-seven years, and there are places in Iowa where, no doubt, it has occurred for forty years. During the last few years Johnson grass {Andropogon Hale- pensis) has been reported as persisting in Fremont county; there may also be other localities in the state. It is certainly true that with the purchase of certain kinds- of agricultural seed (sweet clover) Johnson grass is spreading in the state. Much of it, of course, will not survive the severe winters. However, there is always a potentiality in plants. A very good illustration of this is the horse nettle, which, undoubtedly, is a weed of southern United States, and yet, today, this weed occurs pretty close to the northern border of this state. Qua;Ck grass was, un- doubtedly, widely distributed in northern Iowa with awnless brome grass {Bromus inermis). We have been interested in making a study of the weeds of fields in Iowa, under different conditions, with the view of determining the effect of different kinds of field treatment on the abundance of weeds. Let us take a few typical Iowa fields in Story county, near Ames. We know that there is an antagonism between the roots of the different plants ; there is also an antagonism brought about through root secretions, e. g., toxins; moreover, different crops infiuence weed growth by shading. There are weeds, of course, that are confined to special types of soils. It is certain that the geologists, as well as the soil men, can get many valuable suggestions from the plant covering. We should use these data more than we do. There are certain geological outcrops marked by definite types of plants. Does not the presence of the sheep sorrel always indicate a gravelly or sandy soil? The data below were gathered by members of a class in weeds. Their names appear on the maps accompanying this paper. The first field is the Osborne farm, located on the banks of Squaw creek. The oat field was in corn the previous season, and not well tilled, as evidenced from the weeds found on it. The figures represent per- centages or abundancce of the weeds in different parts of the field: Artichoke {Helianthus tuherosiis) 1-5, bull thistle {Cirsium lanceolatum) less than 5, Canadian lettuce {Laciuca canadensis) 5-10, curly dock (Bumex crispus) below 5, dandelion {Taraxacum officinale) 5-10, five- finger {Poientilla monspeliensis) 5-10, foxtail {Set aria glauca) 10-15, field thistle (Cirsium discolor) below 5, field sorrel of yellow sorrel {Oxalis corniculata) 5-10, pepper grass {Lepidium virginicum) 15-25. There were some thirty-five different species of weeds found. In some places some species were more predominant than others. WEED SURVEY OF STORY COUNTY. 117 The corn field, comprising some thirty acres, had been in clover meadow for five years previous. Here twenty-two species of weeds occurred in different parts of the field. Quadrats in different parts of the field gave the following figures in regard to the predominant weeds : Milkweed {Asclepias syriaca) below 5, sour dock {Bumex crispus) below 5, tickle grass {Panicum capillare) below 5, smartweed {Polygonum pennsylvanicum) below 5, sheep sorrel {Bumex acetosella) 5-10, sandy soil, northern nut grass {Cyperus esculentus) 5-10, field thistle {Cirsium discolor) below 5, small ragweed {Amtrosia artemisiifolia) 5-10, pigeon grass {Set aria glauca) 10-15, green foxtail {Set aria viridis) 5-10. An ecological study was made of another field, a portion of the College Dairy Farm. First an oat field : Pigeon grass {Setaria viridis) 43.9, crab grass {Digitaria sanguinalis) 17.5, lamb ’s-quarter {Cheno- podium album) 6.5, the other percentages need not be enumerated; they appear on the map. In the pasture the following weeds appeared: Dandelion 56, small ragweed 2.5, sandbur {Cenchrus trihuloides) 3.5; only fourteen different weeds were found in this field. In another field, the Harper farm, of sixty acres, a part was devoted to corn, a part to pasture, and a third area was in meadow. The weeds observed in the meadow, near the small drainage depression, were: Artichoke {'Helianthus tuberosus) 80, Stachys aspera 15, morning glory {Convolvulus sepium) 3, timothy {Phleum pratense) 2; on the flat leading to the depression: Prickly lettuce 25, red clover {Trifolium pratense) 25, morning glory 15, timothy 15, pigweed {Amaranthus retro- flexus) 10, velvet weed {Abutilon Theophrasti) 5, stink grass {Eragrostis major) 5. The weeds in the meadow on the flat varied according to the sources of the weeds, cultivation, and treatment. The south end of the meadow had 40 per cent covered with morning glory, 30 with timothy, 20 with clover, 4 with knotweed {Polygonum ramosissimum) , 3 with dandelion {Taraxacum officinale), and 3 with sour dock {Bumex crispus). The middle portion of the field had 30 per cent of timothy, 65 of northern nut grass {Cyperus esculentus), 5 of clover. Along the north end of the field were a great deal of volunteer oats, 30 per cent, 30 of morning glory, 35 of northern nut grass, 5 of clover. In the corn field there were some striking differences in the character of the weed flora. In two of the quadrats there were very few weeds, almost a clean field. However, in one of the quadrats the growth of corn was seriously interf erred with by Muhlenberg’s smartweed or devil’s shoestring {Polygonum Muhlenbergii) 25 per cent, Spanish needle {Bidens frondosa) 5. In the pasture there were present dande- 118 , IOWA ACADEMY OP SCIENCE. lion {Taraxacum officinale) 10 per cent, blue vervian {Verhena stricta) 25. The railroad is an important factor in the dissemination of weeds. Mr. H. L. Eels and Mr. H. J. Shutts determined the weed flora of the Chicago and North Western railway for a little more than one-half mile between Ames and Ontario. Brome grass {Bromus inermis) along parts of the right of way occupied 50 to 75 per cent. This was, of course, planted to hold the banks, and is a most useful grass, since it excludes such weeds as sweet clover {Melilotus alba), small ragweed, squirreltail, curled dock, smooth dock, and many others which were common on the right of way not planted with brome grass. Near the west end of the right of way of which this was a study from 25 to 75 per cent of the space was occupied with sweet clover, next to the ballast. Beyond this zone there was pigweed {Amaranthus retro flexus) below 5, Indian' hemp {Apocynum androsaemi folium) below 5, three-seeded mercury {Acalypha virginica) below 5, Iowa tumble 'weed {Amaranthus graecizans) below 5. Next to the fence there was cup plant {Silphium perfoliatum) below 5, sedge {Carex) 5-10, Spanish needle {Bidens fron- dosa) below 5, tickle grass {Panicum capillar e) below 5, burdock {Arctium major) below 5. Botantcai; Laboratory, Iowa State College, Ames. A- ^ nS t \r> ,0 $ . I H 1 e ti I O aA s^ / k y o cj> n ^ I Vj s V -sP ^ o / (y / I Q 5 HJ 5 - 4^1 I ^ K V ^ ^ I ^ 4P l«!l^|5S ^i|!irk>!!|' >. k c Qj A IP tl' ^ s ^ I i h- 1 I? I V tjN Tl S? r^ ::« 1 1|4 ^ i Plate XII, Weeds of Rookwood farm. Ch a V 3 ^ 0) ^ I ^ i ^ <3 K s - V ^ V Hi; >5 ^ \ S' r^‘ r^ IV 5^ rv,> S ^ K K. r 'v S ^ <:/) H) \ S^ s ■S Si S V 'Si ? .tv (A 1^ s -1^ 'i Plate XIV. Weeds of fields at Iowa State College. § ^ ■■ K § 1^ ^ ^ 5 > Ni- V, ^ il^ 'S ll ^ '5 ^ 1'^ § 'w ^ §1:;:' ^ •• jr t 5i ^15 --sv >.5 I! Spi5§ Ssl? \ ^ measurements were made by means of the well known Kohlrauseh method. The bridge wire was carefully calibrated according to the method of Strouhal and Barus. During the latter part of the work we were fortunate in securing a new Kohlrauseh roller bridge of the type devised by Washburn. All of the measuring flasks, * burettes, weights and resistance boxes bore the certifleate and stamp of the Bureau of Standards, or of the Eeichsanstalt. Four glass-stoppered conductivity cells with sealed-in electrodes were used. The two cells of large resistance capacity were standardized against a 0.02 N potassium chloride solution at 25° C. This solution was prepared from twice recrystalized Kahlbaum’s ‘^C.P.’’, potassium chloride and conductivity water, having a specifle conductance of 1.2X10'®, and the specific conductance of the solution was taken as 2.768X10"^. With the cell constants thus obtained the molecular conductivity of a 0.002 N potassium chloride solution was obtained at 25°C. The value of A-goo found was : Cell *2=147.64 ; cell *3=147.60. The constants of the tv^-o cells of small capacity were then determined against the 0.002 N solution, and the constants of all four cells checked against a 0.01 N acetic acid solution at 25°. The temperatures chosen for the work were 0°, 25°, and 35° or 50° C. The zero-bath consisted of clean, finely crushed ice, moistened with dis- tilled water. Large water thermostats, electrically heated and elec- trically controlled, gave temperatures constant to 25°±.01, 35°±.02 and 50°±.02, respectively. An attempt was made to use only those salts which are very soluble in the solvent used, in order to get the greatest possible range in con- centration, but unfortunately the number of typical salts are few. The salts used were either Kahlbaum’s C. P. (best grade), or they were specially prepared. In every case they were carefully purified and dehydrated by the methods recommended for the individual salts and preserved in glass-stoppered weighing bottles over phosphorus pentoxide. The solubility of each salt at 25° was approximately determined and a convenient maximum normality chosen. Whenever possible, the mother solution was made up by direct weighing and then diluted to the con- ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 137 centrations desired, the utmost care being taken to prevent contact with the moisture of the air. SOLUTIONS IN ANILINE. The aniline used was of an especially good grade from Merck. It had been allowed to stand over fused potassium hydroxide for several weeks. It was then decanted into a clean dry distilling flask and dis- tilled; only the middle portion passing over at 181°-182°C. (uncorr.) was collected. This portion was then further purified according to the method of ITantzsch. The aniline was refluxed for ten hours with a quantity of pure anhydrous acetone, the acetone was distilled off and the middle portion collected. It was finally twice redistilled from pure, powdered zinc. When first distilled the aniline was practically color- less; its specific conductances at 0°, 25° and 35° were .9X10“^? 2.4X10'® and 8.2x10"^, respectively. In spite of all precautions taken in its purification, the aniline gradually darkened on standing, but no notice- able change in the specific conductance was to be observed. Owing to the extremely high resistances it was found impossible to work satisfactorily with solutions more dilute than 0.005 N, while in some cases 0.01 N is the highest dilution measurable. SILVER NITRATE TABLE I.— MOLECULAR CONDUCTIVITY. V. XO" X25‘> X35« 200 .182 .372 100 .159 .349 ".423 40 .156 .338 .414 20 .194 .407 .494 10 .299 .650 .738 4 .464 .869 1.418 2 .725 1.984 2.600 TABLE II.- -TEMPERATURE COEFFICIENTS. V. ^25 \ ^35 ^^0 ^35 ^^25 Xo. 25 x„. 35 O 'P^ 100 .049 .048 .021 40 .047 .047 .022 20 .044 .044 .021 10 .047 .046 .021 4 .055 .057 .026 2 .069 .078 .031 138 IOWA ACADEMY OF SCIENCE. ANILINE HYDROBROMIDE. TABLE III. — MOLECULAR CONDUCTIVITY. V. X0« X25'> XSS® 200 .159 .306 .311 100 .124 .213 .230 40 .109 .183 .185 20 123 .199 .199 10 .170 .263 .264 4 .361 .556 .564 2, * .971 1.009 TABLE IV.- -TEMPERATURE COEFFICIENTS. XO® X X X X V. t\ M tJ /\\J ^35 ''•35 ''25 Xo. 2 5 1 Xo. 35 X25. 10 1 200 .037 .027 .001 100 .029 .025 .008 40 .027 .019 .008 20 .025 .017 .000 10 .022 .016 .000 4 .022 .016 .001 2 * * .003 ANILINE HYDROCHLORIDE. TABLE V.— MOLECULAR CONDUCTIVITY. V. X0“ X25« X35° 1 40 .051 .085 .098 20 .048 .079 .088 10 .056 .087 .095 4 .095 .143 .154 2 * .265 .286 TABLE VI. — TEMPERATURE COEFFICIENTS. X V. Aos Ao ''35 ''0 ''35 ''25 Xq. 2 fc) Xo. 35 X05. 10 40 .026 .025 .014 20 .025 .024 .012 10 .021 .019 .009 4 .020 .017 .007 2 * * .008 ♦Solidified. ELECTRICAL CONDUCTIVITY OF SOLUTIONS. 139 MONO-ETHYL-ANILINE HYDROCHLORIDE. TABLE VII.— MOLECULAR CONDUCTIVITY. V. XO" X25‘> XSS® 100 .064 .112 .119 40 .048 .092 .102 20 .021 .079 .093 10 .053 .084 .089 4 .083 .125 .134 TABLE VIII. —TEMPERATURE COEFFICIENTS. V. ^25 ^^0 ^35 ^^0 ^35 '^25 Xo. 25 Xo. 35 X25. 10 100 .030 .024 .006 40 .037 .032 .011 20 .109 .097 .018 10 .023 .020 .007 4 .020 .018 .007 MERCURIC IODIDE. TABLE IX.— MOLECULAR CONDUCTIVITY. V Xo X25 X35 10 .0033 .0076 .0097 2 .0014 .0036 .0046 1 .0012 .0032 .0046 TABLE X.— TEMPERATURE COEFFICIENTS. V. X25 — ^0 Xss" — ^Xo X35 -X25 Xo. 25 Xo. 35 X25. 10 10 .053 .053 .027 2 .063 .066 .025 1 .069 .084 .043 .40 IOWA ACADEMY OF SCIENCE. AMMONIUM SULPHOCYANIDE. TABLE XI.— MOLECULAR CONDUCTIVITY. V. ^0 ^25 ^33 100' .187 .2588 . .312 40 .130 .251 .2919 20 .1647 .313 .3669 10 .267 .506 .8063 4 .647 1.271 1.502 TETRAETHYLAMMONIUM IODIDE. TABLE XII.— MOLECULAR CONDUCTIVITY. V. Xo X25 X25— Xo Xo. 25 200 .910 2.021 .0488 100 .850 1.910 .0498 40 .964 2.195 .0510 20 1.234 2.842 .0521 10 1.689 3.943 .0534 4 2.244 5.631 .0603 2 2.650 6.849 .0633 1 1.801 5.445 .0809 0.8 1.334 4.477 .0942 SUMMARY OP THE RESULTS IN ANILINE SOLUTIONS. As might be expected from the nature of the solvent, all of the salts used give poor conducting solutions. In respect to the molecular con- ductivity these salts may be divided into three classes. In the first class, which includes by far the larger number, are silver nitrate, aniline hydrobromide, aniline hydrochloride, ifiethylaniline-hydrochloride, ammonium sulphocyanide and lithium iodide. With these the molecular conductivity decreases with dilution in the concentrated regions, passes through a minimum 'and finally increases normally with further dilu- tion. Mercuric iodide, whose molecules usually exhibit a great ten- dency to polymerize, gives values for. the molecular conductivity which apparently increase normally with the dilution. For tetraethyl- ammonium iodide, on the other hand, the molecular conductivity first increases with the dilution to a maximum, then decreases rapidly, passes through a minimum and finally again increases normally with the dilution. The behavior of tetraethylammonium iodide is similar to ELECTRICAL CONDUCTIVITY OF SOLUTIONS. 141 that found by Franklin and Gibbs^® for solutions of silver nitrate in metliylamine. Of the salts studied tetraethylammonium iodide gives the best and mercuric iodide the poorest conducting solution. The effect of temperature varies with the nature of the dissolved salt. The temperature coefficients of the molecular conductivity of solutions of silver nitrate, aniline hydrochloride, and aniline hydrobromide de- crease with dilution in the concentrated regions and pass through a minimum in those solutions which give the minimum value for the molecular conductivity. Methylaniline hydrochloride, on the contrary, gives a maximum temperature coefficient in that concentration which gives the minimum molecular conductivity. Although but three con- centrations of mercuric iodide were studied, the temperature coefficients show a distinct increase with increasing dilution, while for tetraethyl- ammonium iodide the temperature coefficients decrease throughout with increasing dilution, the decrease being most rapid . in the regions of greatest concentration. SOLUTIONS IN QUINOLINE.=^« Schuchardt’s chemically pure, synthetic quinoline was allowed to stand over fused potassium hydroxide for several weeks and then twice redistilled. Only that portion passing over at 227-229° C. was used in the work. In order to make the effect of the temperature greater, the molecular conductivities were determined at 50°, instead of at 35°, as in the case of aniline. The specific conductivities of the quinoline at 0°, 25° and 50° were found to be 1.6X10"^? 2,2X10"® and 7.4X10"®, respec- tively. , • Eough determinations of the solubility of many salts in quinoline showed that only a very few are sufficiently soluble to make work with them worth while. Of these the three chosen are aniline hydrobromide, silver nitrate and cobalt chloride. 251oc, cit. 26The work with solutions in quinoline was performed by Mr. E. H. Conroy. 142 IOWA ACADEMY OF SCIENCE. ANILINE HYDROBROMIDE. TABLE XIII.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 1,000 .596 .918 1.319 500 .480 .760 .988 200 .340 .528 .666 100 .267 .416 .527 20 .207 .324 .412 5 .264 .464 .642 TABLE XIV. —TEMPERATURE COEFFICIENTS. V. t! X50 Xo X50 ^X25 Xo. 25 Xo. 50 X25. 2 5 1,000 .0216 .0243 .0175 500 .0236 .0212 .0151 200 .0221 .0192 .0105 100 .0233 .0195 .0107 20 .0266 .0198 .0109 5 .0303 .0286 .0153 SILVER NITRATE. TABLE XV. — MOLECULAR CONDUCTIVITY. V. Xo X25 X50 1,000 2.327 500 2.158 3'254 4101 200 1.951 3.115 4.005 100 1.669 2.574 3.178 20 1.443 2.273 2.842 10 1.397 2.246 2.896 5 1.270 2.275 3.197 . TABLE XVI. — TEMPERATURE COEFFICIENTS. V. Xo-, ^Xo X50 Xq X50 X05 Xo. 25 Xo. 50 X25. 2 5 500 .0204 .0180 .0104 200 .0239 .0210 .0114 100 .0217 .0181 .0094 20 .0231 .0194 .0100 10 .0244 .0215 .0116 5 .0317 .0303 .0162 ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 143 COBALT CHLORIDE. TABLE XVIL— MOLECULAR CONDUCTIVITY. V. Ao A25 A50 266.6 .1042 .1933 .3110 500 .253 .464 .599 1,000 .293 .499 .653 TABLE XVIII.— TEMPERATURE COEFFICIENTS. V. 1 1 ° Asq-' Aq A50 A25 Ao. 25 Ao. 50 A25. 2 5 266.6 .0342 .0398 ' .0245 500 .0334 .0274 .0116 1,000 .0281 .0246 .0123 In view of the fact that quinoline has a higher dielectric constant than aniline, we should expect that solutions in it should give higher molecu- lar conductivities. This is found to be true for silver nitrate and aniline hydrobromide. The minimum of molecular conductivity is dis- placed toward the region of higher concentration and the molecular conductivity increases rapidly with the dilution. The temperature coefficients pass through a minimum, but at dilutions which are greater than those which give the minimum molecular conductivity. Owing to the rather slight solubility of the cobalt chloride, only three concentra- tions of this salt were studied. In these the molecular conductivity increases with dilution, while the temperature coefficients decrease under the same conditions. SOLUTIONS IN PYRIDINE.2^ Merck’s best grade of pyridine was allowed to stand over fused potassium hydroxide for several months, then decanted and twice redis- tilled. Only the middle portion passing over at 115°-116.1" and 745 mm. was retained for the work. Its specific conductances at 0°, 25° and 50° were found to be .57X10“^ .74X10"'^ and 1.2X10"'^, respectively. Lincoln^® found the specific conductance of the pyridine which he used to have the much higher value of 7.6X10"'^. Those salts which do not show hygroscopic properties were weighed directly, transferred to a certified volumetric fiask and made up to 2TThe data for the pyridine solutions are taken from a thesis begun by Mr. E. X. Anderson. Since the completion of the thesis appeared doubtful, it was thought advisable to include the data in the present paper, 144 IOWA ACADEMY OF SCIENCE. volume, but for those salts which do absorb moisture the method of weighing by difference was used. The pyridine was added directly to the flask from a specially devised filling apparatus, whose open ends were always protected by phosphorus pentoxide tubes. The dilute solu- tions were made by diluting the mother solution, the utmost care being taken to prevent contact with the moisture of the air. SILVER NITRATE. TABLE XIX.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 1 1.05 1.53 2.01 2 14.77 19.38 23.28 10' i *20.68 25.38 27.25 20 1 22.38 27.05 29.17 100 1 27.80 34.49 37.92 500 i 37.31 47.63 55.10 TABLE XX.- —TEMPERATURE COEFFICIENTS. \ X x X X ^x V. A50 Aq A50 A25 Xq. 25 0 0 Xos. 2 5 1 .0149 .0133 .0121 2 .0125 .0114 .0081 10 .0091 .0064 .0029 20 .0084 .0061 .0031 100 .0096 .0073 .0040 500 .0111 .0095 .0063 The values for here given agree very closely with those given by Lincoln^^ for the same salt at 25°. The molecular conductivity increases at first very rapidly with slight changes in dilution in the concentrated regions and then more slowly at higher dilutions. The temperature coefficients show a very rapid decrease in the concentrated solutions. It will be seen that the molecular conductivities at first increase very rapidly with slight increase in dilution, and then less rapidly, with further dilution for all three temperatures. The temperature coef- ficients show distinct minima, the effect of temperature upon the con- ductivity being greatest in the concentrated solutions. Although solutions of silver nitrate in pyridine possess a relatively high molecular conductivity, Walden and Centnerszwer^® have found that the molecular weights of silver nitrate in dilute solutions of ^ pyridine are normal, while in the concentrated solutions the molecular weights are greater than normal, thus indicating association. By the 2«J. Physical Chem., 3. 457, 1899. 28Z. physik. Chem., 321, 1906. ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 145 same method Schmujlow^® found that this salt is apparently non-ionized, but, since transference experiments made by Neustadt and Ahegg^^ + showed that both the Ag ion and the NO3 radicle migrated toward the cathode, it was assumed that, if ionization does take place, it does so according to the equation, _j_ - 2AgN03==Ag3N03+N03 It is obvious that if the amount of polymerization just compensates for the effect due to ionization, the total number of dissolved particles will be the same as they would be if neither polymerization nor ionization had occurred. The molecular weights obtained by the boiling point- method should be normal. As the concentration is increased, on the other hand, polymerization rapidly increases, while the degree of disso- ciation decreases, a result which is interpreted by some to indicate the presence of polymerization and the absence of ionization. That the J_ simple Ag ions are also present even in the concentrated solutions is not to be doubted. LITHIUM CHLORIDE. The pure salt was heated at 160° for several days, it was frequently pulverized in a hot agate mortar and the heating continued until the tendency to cake had ceased. It was then transferred to a weighing bottle and heated to constant weight. TABLE XXI. — MOLECULAR CONDUCTIVITY. V. Ao 1 ^25 ^50 0.58 .143 .199 .239 1.6 .218 .264 .282 2 .254 .290 .299 10 .279 .322 .346 100 .519' .573 .613 1,000 1.47 1.600 1.680 TABLE XXII. — TEMPERATURE COEFFICIENTS. \ \ •X A \ V. A50 Aq ^50 ^25 Xo. 25 Xo. 50 X25. 2 5 0.586 .0160 .0135 .0079 1 .0083 .0058 .0028 2 .0056 .0035 .0012 10 .0061 .0047 .0030 100 .0041 .0036 .0028 1,000 .0037 .0029 .0020 f. anorgan. Chem., 15, 1897. ®iZ. Physik. Chem., 69, 436, 1910. 10 146 IOWA ACADEMY OF SCIENCE. Lithium chloride is at best a very poor conductor and is but slightly dissociated at all dilutions and temperatures. In other solvents it shows a high tendency to polymerize and doubtless does so in pyridine solutions. The molecular conductivities do increase gradually with increasing dilution throughout the whole range of concentration. The values found by Laszczynski and Gorski®^ for the same solution are about four times larger, due, perhaps, to the presence of traces of moisture. The tempera- ture coefficients decrease with dilution throughout, the greatest changes being in the most concentrated solutions. LITHIUM BROMIDE. The anhydrous salt was prepared in a manner similar to that used for lithium chloride. TABLE XXIII. — MOLECULAR CONDUCTIVITY. V. Xo X25 X50 0.977 * 1.29 1.65 2 "98" 1.72 1.98 10 2.29 2.44 2.40 100 5.43 5.34 4.89 1,000 13.68 14.15 13.58 10,000 24.80 28.70 29.9 TABLE XXIV.— TEMPERATURE COEFFICIENTS. X X X X X X V. A50 Aq A50 A25 Xo. 25 Xo. 50 X25. 2 5 0.97 .0109 2 '.0298 .0202 .0061 10 .0026 .0009 -.0006 100 -.0007 -.0020 -.0034 1,000 .0013 -.0001 -.0016 10,000 .0063 .0041 .0017 ♦Solidified. For all temperatures the molecular conductivity increases steadily throughout with increasing dilution, but not at all dilutions with a rise in temperature, there being at certain dilutions a decrease in conduc- tivity with increase in temperature. The temperature coefficients are in all except the most concentrated solutions very small. They pass through minima of negative value. 32Z. Elektrochem., //, 290, 1897. ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 147 LITHIUM IODIDE. This salt, after several months’ standing over phosphorus pentoxide, was heated for nearly one week at 150°. TABLE XXV. — MOLECULAR CONDUCTIVITY. V. ^25 ^50 1 4.40 . 7.04 9.82 2 7.79 10.98 13.82 10 • 12.76 16.40 18.62 100 18.34 23.35 25.98 1,000 27.10 35.99 42.65 10,000 31.20 44.4 50.50 inf. (31.2)* (44.9) (50.5) * Extrapolation. TABLE XXVI.— TEMPERATURE COEFFICIENTS. V. X25 Xq 1 1 0 ^50 ^25 Xq. 2 5 Xo. 50 Xor,. 2 5 1 .0224 .0246 .0158 2 .0164 .0155 .0103 10 .0114 .0092 .0054 100 .0109 .0083 .0045 1,000 .0131 .0115 .0074 10,000 .0169 .0124 .0055 From Table XXV it will be observed that lithium iodide is a good conductor. The molecular conductivity increases very rapidly for slight dilution in the concentrated regions and then more slowly, but steadily up to a maximum at ten thousand liters. The temperature coefficients pass through a minimum at a dilution of one hundred liters. SODIUM IODIDE. TABLE XXVII.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 1.33 .11* .70 .84 5 10.00 11.14 11.20 10 14.56 16.15 15.80 100 21.66 23.81 22.87 1,000 32.99 39.53 41.28 10,000 42.20 56.70 63.20 TABLE XXVIII.— TEMPERATURE COEFFICIENTS. V. X25 X50 Xq X50 ^Xor, Xo. 25 Xq. D 0 X25. 25 1.33 .2084* .1279* .0076 5 .0046 .0024 .0002 10 .0044 .0017 -.0009 100 .0040 .0011 -.0016 1,000 .0079 .0050 .0018 10,000 .0137 .0099 .0046 Solid phase present. 248' IOWA ACADEMY OF SCIENCE. Sodium iodide solutions in pyridine are good conductors at all dilu- tions, except those near the point of saturation, where the molecular conductivities are very small at all temperatures. By extrapolation ^ inf. was found to be 43.3 at 0°. Laszczynski and Grorski®^ obtained 44.32 for the value of x inf. at 18°. For 25° and 50° no limiting values of the molecular conductivity could be found; at these temperatures the con- ductivity continues to increase with dilution more rapidly than at 0°. The temperature coefficients exhibit well defined minima with negative values appearing for temperatures between 25° and 50°, POTASSIUM THIOCYANATE. The sample was recrystallized from absolute alcohol, washed with the alcohol and dried at 95°. This salt differs from the others that have been studied in that its solubility in pyridine decreases as the tempera- ture rises. TABLE XXIX. — MOLECULAR CONDUCTIVITY. V. K ^25 ^50 7. 5.97 7.12 7.75 14 7.20 8.45 9.00 70’ 11.40 13.36 14.54 140 14.17 16.77 18.14 1,400 27.32 33.70 38.31 14,000 42.86 58.51 71.30 inf. 46.5^ — — TABLE XXX. TEMPERATURE COEFFICIENTS. V. , . : ^25 ^0 ^50 ^0 , X50 X25 K 25 Xo. 50 . X25. 2 5 7 . .0077 . .0060 ; .0035 14 ' .0069 .0050 ' .0026 70 .0070 .0055 .0035 140 .0073 .0056 .0033 1,400 , .0093 , .0081 .0055 14,000 ' .0146 j .0133 ! .0087 *By extrapolation. Apparently the conditions which tend to produce a decrease in solubility with rise in temperature are those which have to do with rapid increase in conductivity at higher temperatures.. The temperature co- efficients here also pass through a minimum. 331oC. cit. ELECTRICAL CONDUCTIVITY OF SOLUTIONS. 149' AMMONIUM THIOCYANATE. The anhydrous salt was prepared in the same manner as was the potassium salt. TABLE XXXI. — MOLECULAR CONDUCTIVITY. V. ^0 ^25 X50 .33 2.10 4.46 7.43 1 8.21 11.70 15.12 2 10.45 13.76 16.53 10' 11.96 14.56 16.29 100 17.00 20.33 22.18 1,000 33.57 41.80 47.76 TABLE XXXII.— TEMPERATURE COEFFICIENTS. 1 1 X \ X X X X V. ^25 ^0 A50 Aq A30 Aos Xo. 25 Xn. 50 X25. 2 0 CO .0451 .0508 .0266 1 .0170 .0169 .0117 2 .0127 .0116 .0081 10 .0087 .0072 .0048 100 .0078 .0061 .0036 1,000 .0098 .0085 .0057 The molecular conductivity curves for ammonium thiocyanate are peculiar in that they rise rapidly with slight increase in dilution, then rise slowly for a considerable change in dilution, and finally increase rapidly as the dilution is further increased. The values for are con- siderably larger than those found by Laszczynski and Gorski. Working up to dilution of 2080 liters, these men calculated the value of x inf. at 18° to be 40.22. In the curves for the above tables it is clearly seen that the 0° curve gives promise of a limiting value for x^, but the 25°- and 50°-curves give no signs of such a behavior. The initial rapid increase in the molecular conductivities and decrease in the temperature coefficients are undoubtedly due to a rapid decrease in the viscosity of the concentrated solutions with slight increase in dilution. The concentrated solutions here used are very viscous. 150 IOWA ACADEMY OP SCIENCE. MERCURIC CHLORIDE. TABLE XXXIIL— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 .5 .009* .036 .045 1 .019 .025 .030 2 .016 .021 .025 10 .016 .021 .027 100 .037 .061 .067 1,000 .130 .260 .400 TABLE XXXIV. — TEMPERATURE COEFFICIENTS. V. X25- — \ Xso Xo X50 X25 Xq. 2 0 Xo. 50 X25. 25 .5 .1176* .0793 .0104 1 .0106 .0119 .0076 2 .0126 .0105 .0065 10 .0126 . .0141 .0119? 100 .0260 .0162 .0038 1,000 .0400 .0415 .0215 MERCURIC BROMIDE. TABLE XXXV.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 .5 .012* .034 .043 1 • .020 .026 .032 2 .018 .023 .026 10 .017 .023 .028 100 .031 .047 .053 1,000 .130 .280 .290 MERCURIC IODIDE. TABLE XXXVI.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 .66 •» .013 .018 1 .009 .013 .018 2 .008 ,012 .015 10 .013 .019 .024 100 .069 .102 .117 1,000 .266 .364 .448 *Solid phase present. ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 151 The conductivities of the mercuric halide salts are extremely poor. With increase in dilution the molecular conductivity varies but little and only begins to show an appreciable increase at a dilution of one hundred liters. All three of the salts show faint but distinct minima in the molecular conductivity. Since the molecular conductivities are so small, any slight errors in them will be highly magnified in the temperature coefficients. The values of the latter are all of the same order of magnitude as those given for mercuric chloride and all three salts give minima for temperature coefficients. The value for for mercuric iodide are much smaller than those obtained by Lincoln^^ at 25°. COPPER CHLORIDE. Kahlbaum^s C. P. cupric chloride was heated for several hours in a current of pure dry hydrogen chloride at 160°, then heated in a current of dryjiydrogen, and cooled in a current of the latter; lastly, it was quickly transferred to a weighing bottle and further heated in an air- bath at 160°. TABLE XXXVII.-— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 25 .053 .062 .074 50 .066 .076 .086 100 .088 j098 .111 200 .130 .146 .171 500 .203 .216 .216? 1,000 .302 .365 .410 TABLE XXXVIII.— TEMPERATURE COEFFICIENTS. V. X25 Xq X50 Xo X50 X25 Xo. 25 Xo. 50 X25. 2 5 25 .0073 .0082 .0076 50 .0059 .0059 .0052 100 .0045 .0053 .0055 200 .0050 .0063 .0068 500 .0027 .0014 .0000 1,000 .0084 .0072 .0049 The molecular conductivities for all temperatures increase steadily with increase in dilution. While more or less irregular, the temperature coefficients exhibit a minimum value in the dilute regions. 3Uoc. cit. 152 IOWA ACADEMY OP SCIENCE: Kohlsckuetter^^ states that cnpric chloride dissolved in pyridine gives a blue solution, and since its molecular weight, as determined by the boiling point method, is normal, its color may be attributed to that of the undissociated cupric chloride. Naumann^® has also observed this blue color in his work and assumes it to be due to the presence of the complex, CuCl2.2Pyr. All of the cupric chloride solutions used in this work gave a beautiful, deep green color without the least indication of a bluish tint and, furthermore, the solutions remained green for several months. On the other hand, in making one of the trial solubility tests an attempt was made to weigh the salt directly. The salt absorbed moisture so rapidly that this was impossible. Although it was noticed that the edges of the salt mass had taken on a greenish blue color, it was quickly transferred and dissolved in pyridine and, as might be expected, the solution was perfectly blue. When, however, the salt was quickly weighed by difference, a deep green solution was always ob- tained. It is evident, therefore, that the blue solutions reported by Kohlschuetter and Naumann owe their blue color to traces of water. COPPER NITRATE. A .IN solution of silver nitrate was treated with an excess of finely divided, reduced metallic copper and allowed to stand until the solution gave no test for silver. TABLE XXXIX.— MOLECULAR CONDUCTIVITY. V. ^0 1 X25 X50 10 9.68 12.94 • 14.96 20 5.00 7.21 8.88 40 8.57 11.60 14.16 100 12.08 16.43 20.43 1,000 16.41 23.88 29.71 10,000 19.42 27.24 35.71 TABLE XL.- —TEMPERATURE COEFFICIENTS. \ X X X X ^x V. ^25 ^0 A50 Ao ^50 ^2C Xo. 25 Xo. 50 X25. 2 5 10 .0135 .0109 .0062 20 .0176 .0155 .0093 40 .0142 .0131 .0088 100 .0144 .0138 .0097 1,000 .0158 .0162 .0119 10,000 .0161 .0168 0124 Copper nitrate gives far better conducting solutions than does the chloride. 37, 1153, 1904. 36Ber., 37, 4609, 1904. ELECTRICAL CONDUCTIVITY OF SOLUTIONS. 153 COBALT CHLORIDE. The pure salt was first partially dehydrated by long standing over phosphorus pentoxide and then successfully treated according to the method employed for copper chloride. The final product was of a pale blue color. Reitzenstein^^ prepared the compound CoCls-^Pyr. Pearce and Moore^® found that within their respective temperature limits we may have the three compounds, CoCls.bPyr, CoCl2.4Pyrj and CoCl2.2Pyr. Cobalt chloride, dissolved in pyridine gives a red solution at 0°, a violet at 25°, and a deep purple at 50°. These color changes at different temperature are doubtless closely associated with changes in the amount of pyridine combined with the salt, since the colors of the solid phases in contact with the saturated solutions at these temperatures are aproxi- mately the same as those of the solutions. TABLE XLI.— MOLECULAR CONDUCTIVITY. V. Xo X25 X50 10 .009* .012 .021 20 .015 .015 .022 40 .021 .020 .024 100 .042 .045 .041 1,000 .220 .230 .310 10,000 .600 1.00 TABLE XLII.— TEMPERATURE COEFFICIENTS. V. X2S Xq X50 Xq X50 X25 Xo. 2 5 Xo. 50 X25. 2 5 10 .0148* .0393 .0319* 20 .0019 .0101 .0174 40 -.0021 .0028 .0082 100 .0028 -.0005 -.0036 1,000 .0018 .0082 .0139' *Solid phase present. Cobalt chloride in pyridine solutions gives at best exceedingly poor conducting solutions. By some its solutions are considered as non-con- ductors. Consequently, slight errors are highly magnified. The results obtained show a continuous increase in molecular conductivity with dilution for all temperatures. Lincoln’s values for Vy at corresponding 3‘Ann. Phys. Chem., 839. 3SAmer. Chem. Jour., 50, 231, 1913. 154 IOWA ACADEMY OF SCIENCE. dilutions are very much higher than the values here given. The tempera- ture coefficients, although subject to error, show definite minima at which negative coefficients are observed. As is evident from table XLII, the effect of temperature is greater between 25° and 50° than at the lower temperatures. This is, no doubt, due to the greater instability of the solvated ions at higher temperatures. CADMIUM NITRATE. The solution of the pure salt was prepared by displacing the silver of a .IN solution of silver nitrate by means of pure metallic cadmium. TABLE XLIII.— MOLECULAR CONDUCTIVITY V. ^0 ^25 ^50 10 .141 .160 .122 20 .322 .348 .288 40 .402 .433 .340 100 .694 .733 .630 1,000 2.370 2.310 2.440 10,000 7.400 8.600 9.800 TABLE XLIV.— TEMPERATURE COEEFFICIENTS. \ \ •\ X \ X V. ^25 Aq -^50 ^25 ^25* 2 5 50 X25. 25 10 .0052 -.0028 -.0095 20 .0033 -.0021 -.0070 40 .0031 -.0031 -.0086 100 .0023 -.0018 -.0056 1,000 -.0010 .0006 .0023 10,000 .0065 .0065 .0056 Solutions of cadmium nitrate would be classed as poor conductors ; the values of increase with dilution throughout. For the concentrated solutions increase of temperature above 25° produces a rapid decrease in conductivity and, as the temperature coefficients show, this decrease is greater between 25° and 50° than between 0° and 25°. An explanation for this phenomenon will be given in the discussion. SUMMARY OF THE RESULTS IN PYRIDINE SOLUTIONS. The molecular conductivities of fourteen salts and their temperature coefficients have been determined in pyridine solutions. These salts may be divided into two classes, the strong and the weak. Among the former ELECTRICAL CONDUCTIVITY OF SOLUTIONS. 155 are silver nitrate, lithium iodide, sodium iodide, potassium and am- monium thiocyanates and copper nitrate. The values for of these salts are very small in the most concentrated solutions, but they increase rapidly with slight initial dilutions and then more slowly with further increase in dilution. All of them give minima in the temperature coef- ficients, except copper nitrate whose temperature coefficients seem to in- crease steadily with dilution. The weak salts are lithium chloride, lithium bromide, the three mer- curic halides, copper chloride, cobalt chloride and cadmium nitrate. Only the mercuric salts give minimum values for ; the molecular con- ductivity of the others increases slowly with increasing dilution. All hut one of the salts of this group give minimum values for the tem- perature coefficients; those of lithium chloride decrease with dilution. Negative temperature coefficients have been found for solutions of sodium iodide, lithium bromide, cobalt chloride and cadmium nitrate. DISCUSSION. The molecular conductivity of a solution of an electrolyte is dependent first upon the nature of the solvent and primarily upon its dielectric constant, or specific inductive capacity. According to the Nernst- Thomson rule, the dissociating power of a solvent will be greater, the greater is its dielectric constant. Walden^® has found that the dielectric constants of solvents of feeble ionizing power are increased by dissolving in them certain binary salts. The amount of this increase depends upon the constitution of the salt used. According to him salts may be divided into two classes, the strong and the weak. Strong salts exhibit a great tendency to ionize and possess large dielectric constants, while in a weak salt both of these are small. The degree of ionization of a salt depends both on the ionizing power of the solvent and the tendency of the salt to ionize. As both of these factors increase with the dielectric constant, the highest degree of ionization will be found in a system where both the solvent and the solute possess large dielectric constants. The molecular conductivity also depends upon the degree of dissocia- tion of the electrolyte, the nature of the ions, their speeds and the viscosity of the solutions. The degree of dissociation depends upon the magnitude of the electroaffinities of the ions formed. It will also be more or less affected by the degree of solvation of the molecules and ions present, since, doubtless, the energy of the simple and polymerized 39Bull. Accad. Sci. St. Petersburg-, 1912, 305-332. 156 IOWA ACADEMY OF SCIENCE. molecules, as well as the electroaffinities of the ions must he somewhat modified by combination with the solvent. If degradation of energy accompanies an increase in electroaffinity, then, as Sachanov^® states, the electroaffinity of the ions must increase with solvation and, for a given electrolyte, will he greater, the more dilute is the solution. The speeds of the ions, if they have the power of combining with the solvent, must also he greatly affected by solvation; the greater the amount of solvation, the greater will be their mass, or volume, and, therefore, the smaller will be their migration velocities. Since, accord- ing to the Law of Mass Action, the degree of solvation of the ions must increase with increasing dilution, the effect of solvation upon the ionic velocities will be greatest in the most dilute solutions. The stability of the solvated ions (also molecules) decreases with rise in temperature. If we consider solutions which are dilute with respect to a given ion, we should expect to find the effect of temperature to in- crease with dilution. That this is true may be seen from a study of the temperature coefficients given in this paper. According to Noyes and Coolidge^^, the molecular conductivity of aqueous solutions for a given concentration, increases steadily with rise in temperature up to 306°, the increase being due chiefly to a steady decrease in viscosity. The rate of decrease in dissociation of the salt is small between 18° and 100°, but becomes much larger for higher tem- peratures. This decrease is evidently due to a change in the nature of the solvent, i. e., a decrease in its degree of association and, hence, in its dissociating power. If the formation of ions depends to any extent upon the power of these ions to combine with the solvent, an increase in temperature should be accompanied by a decrease in ionization and likewise in molecular conductivity. It has been noted that lithium bromide, sodium iodide, cobalt chloride and cadmium nitrate in pyridine give negative tem- perature coefficients. For lithium bromide the value of x for a .01 N solution decreases slowly from 0° to 25° and then more rapidly up to 50°, while the same values for the other three salts increase up to 25° and then decrease with rise in temperature. All of these show a tendency not only to form polymeric molecules in pyridine, but also the power to form pyridine-solute complexes. The effect of temperature on these solvates is clearly indicated by the color changes in the cobalt chloride solutions. These salts also have the power to form complex ions which, doubtless, also have a great tendency to form solvates. It will be ob- 4®loc. cit. physik. Chem., 46, 823, 1903. ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 157 served also that these negative temperature coefficients are those of minimum value. They are likewise found in those concentrations in which the concentration of the complex ions is least and hence most highly solvated. The effect of temperature upon the unstable solvent-ion complexes will therefore he greatest at this point. If, again, the for- mation of these ions depends upon their power to combine with the solvent, then the degree of ionization should decrease with rise in tem- perature. This assumption agrees perfectly with the results obtained. It was for a time believed that the molecular conductivity of an electrolyte in solution must increase with dilution. Then appeared the above cited work in organic solvents which, in the minds of some chemists, completely overthrew the whole electrolytic dissociation theory. In practically all of these cases the molecular conductivity was found to decrease with increasing dilution. Unfortunately, these investigators seem to have stopped too soon. Had they but continued their work at greater dilutions, they would probably have found that in very dilute solutions in these solvents the molecular conductivity behaves normally as in aqueous solutions. This has been found to be true for solutions in aniline, quinoline and pyridine, without exception. There are also solutes which in these three solvents show increase in conductivity throughout the whole range of dilution. The three solvents chosen are but slightly, if at all, associated and they have small dielectric constants, viz., aniline=7.31^2, quinoline== 8.8^^, pyridine— 12.4^^. The ionizing power of the solvents and the conductivity of their solutions increase from aniline to pyridine. Salts dissolved in them give, for the most part, low molecular conductivities and exhibit a great tendency not only to polymerize, but also to combine with the solvent. It is probable that there are present at all dilutions to a greater or less extent both the simple and polymeric molecules and their ions, as well as the solvated forms of each. We may represent the condition of equilibrium existing in a solution by the following scheme: Li.Sj+Br.Sp—LiBr.Ss— (LiBr)o.S4=Li.Si+LiBr2.S5, wffiere Si, Sg, S3, etc., represent the number of molecules of combined solvent. The two molecular forms are in equilibrium with each other and also with their respective ions*. Unfortunately, we have no means of arriving at any conclusions as to the complexity of the solute in these solvents, except by the boiling- ^‘^Turner: Z. Physik. Cbem., 3-5, 385. 3 900. ^^Schlundt : J. Physical Chem., 5, 157, 1901. 158 IOWA ACADEMY OF SCIENCE. point method and this is not applicable in the very dilute solutions. The assertion that simple molecules predominate in the dilute solutions is supported by experiments upon the molecular weights of alcohol, acetic acid and phenol in benzene. The molecular weights are smallest in the dilute regions and increase rapidly with increase in concentration, e. g.. Concentration percent. Mol. Weight found. Mol. weight Theory. Alcohol .161 46 46 32.50 318 Phenol .34 144 94 26.8 252 Acetic acid .465 110 60 22.8 153 Most of the salts used in this work show by the boiling-point method either normal molecular weights or slight association. That these solu- tions contain ions is obvious from the fact that they conduct electricity. It is obvious also that the phenomena of ionization, polymerization and solvation may all exist at the same time and still give normal molecular weights, since the effect due to polymerization of the solute molecules under the conditions need only be just sufficient to counteract the effects due to ionization and solvation. Keturning to our equilibrium equation, it is evident that, if we begin with the most dilute solutions and increase the concentration, there will be a repression of the simple ionization with the formation of simple molecules. The molecular conductivity in the dilute solutions should, and does, decrease with increase in concentration. With the increase in concentration of the simple molecules there is an accompanying increase in the number of the more easily ionizing polymerized molecules. Normally, the molecular conductivity of any salt, whether simple or complex, should decrease wdth increase in concentration, whereas in many solvents the reverse is true. One way of explaining this phenomenon seems to have been overlooked, one which at least seems logical and in harmony with the facts. Let us take a solution of a salt at a dilution which is far beyond that dilution which just gives complete dissociation or maximum molecular conductivity. If now we begin to remove the solvent (say, by evapora- tion) the molecular conductivity calculated for the successively increas- ing concentrations will remain constant up to that concentration which first gives the maximum molecular conductivity. If, however, we should ELECTRICAL CONDUCTIVITY OP SOLUTIONS. 159 start with that initial great dilution and, while removing solvent, add the ions of the salt sufficiently rapidly, we should find for each succes- sively greater concentration an increase in the molecular conductivity until that concentration is again reached which first gives the maximum value. After this the molecular conductivity must again decrease with increase in concentration. Since the amount of polymerization of the solute molecules need only he very small in order to compensate for the effect due to ionization, as determined by the boiling-point method, we can not be far wrong in assuming that the polymerized molecules are highly dissociated and that their ionic product, + ~ Li.S,XLiBr,.S,==K, is relatively very large. Furthermore, according to Walden’s views upon the dielectric constant, the dissociation should increase with in- crease in the concentration of the salt. We may consider, there- fore, that those dilutions which give minimum values of molecular con- ductivity are far beyond the dilution at which the polymerized molecules are completely dissociated. Normally, the molecular conductivity of these should remain constant with removal of solvent until that con- centration is reached which just gives the maximum value for the molecular conductivity of the polymerized solute. With the increase in concentration of the highly dissociated polymer there is an abnormally rapid increase in the number of ions with the result that, from the minimum on, the molecular conductivity increases with concentration. If it is possible to exceed the ionic product which the ions of the polymerized molecules would give at the concentration giving the maxi- mum molecular conductivity, then from this point on the molecular con- ductivity should decrease with further increase in concentration. Starting then with the most concentrated solutions, the molecular conductivity should first increase with dilution to a maximum, due to an increase in the dissociation of the solute and a decrease in the viscosity of the solution. From the maximum the molecular conductivity decreases abnormally, due to a rapid decrease in the number of ion- forming molecules which in its effect more than counterbalances the effect due to increase in dissociation. At the minimum the influences due to the two kinds of molecules and their respective dissociations just balance each other. From the minimum on the molecular conductivity continues to increase with further dilution due to the ionization of the simple salt. IOWA ACADEMY OP SCIENCE. 160 A curve representing such a phenomenon would have a maximum in the concentrated regions, a minimum at higher dilutions and, if com- plete dissociation is possible, a second maximum at infinite dilution. The data for the molecular conductivity of tetraethylammonium iodide in aniline, when plotted, give exactly this form of curve. The same may be said for the data obtained by Franklin and Gibbs for solutions of silver nitrate in methylamine.^^ They, however, explain the phenomenon as due tg the autoionization of the salt. If, on the other hand, it is not possible to exceed the value for the ionic product at complete dissociation, the molecular conductivity should continue to increase with the concentration up to the concentration of the saturated solution. This should be true unless, perhaps, the viscosity of the solutions at these very high concentrations should be great enouglr to cause a decrease in conductivity. All of the most concentrated solu- tions in the solvents studied possess a relatively high degree of viscosity, yet for all, with the single exception of tetraethylammonium iodide, the molecular conductivity increases along with the viscosity as the concen- tration is increased. Silver nitrate is the only salt that has been used in all three solvents ; aniline hydrobromide has been used in aniline and quinoline. While these two can scarcely be considered as a basis for comparison, a study of their molecular conductivities brings out one or two interesting points. It will be observed that as the dielectric constant of the solvent increases the dilution at which the value of the molecular conductivity is a minimum is displaced toward solutions of higher concentration. The tendency for molecular conductivity to increase with concentration, like- wise, becomes less. If this tendency is due to the presence of easily dissociating polymeric molecules, then we can say that the tendency of a solute to polymerize in different solvents becomes greater, the smaller the dielectric constant of the solvent. In the dilute solutions the molecu- lar conductivity and, hence, the dissociation of the solute, for a given normality, increases with the dielectric constant of the solvent. In so far as these salts and solvents give us a clue, w^e are justified in saying that the Nernst-Thomson rule does hold for dilute solutions in solvents, with low dielectric constants. This work will be continued with solutions in other organic solvents.. Physical Chemistry Laboratory, The State University op Iowa, Iowa City. •^loc. cit. MERCURIC IODIDE AND ANILIN. 161 EQUILIBEIUM IN THE SYSTEM: MERCURIC IODIDE AND ANILIN. E. J. FRY AND J. N. PEARCE. Those who have worked with anilin have no doubt observed its ex- traordinary high solvent power upon many of the inorganic salts. Like ammonia it also has the power of combining with salts to form stable crystalline compounds containing from one to as high as six molecules of anilin of crystallization. Among the large number of crystalline compounds which have been prepared are CoCL.2C6H,N, Cu.Ch.2CJl,^, Cu2Br2.2CGH7N, Cu2l2.2C6H7N“. Tombeek^ produced the corresponding compounds of the chlorides, bromides, iodides, and nitrates of zinc and cadmium and magnesium nitrate. He also prepared similar compounds of zinc, cadmium, magnesium, nickel, cobalt, and copper sulphates, all of which combine with two molecules of anilin, except nickel sulphate, which crystallizes with six molecules, and cobalt sulphate, which crystallizes with four molecules of anilin. Grossman and Hunter^ pre- pared the compounds of the thiocyanides of cadmium, cobalt, nickel, iron, manganese, and zinc, each combining with two molecules of the base. Upon further treatment of the addition compounds thus formed with thio-cyanic acid double thio-cyanides corresponding to the formula Cd (Ph.NH3)2 (SON) 4 were obtained. The dichromates of co- balt, nickel, copper, cadmium, zinc, and manganese, each with four molecules of anilin, were prepared by Parravaus and Pasta^. Fran- quoise® contributed the compound Hgl2.2C6H7N. The usual method of preparing these compounds has been to treat alcoholic solutions of anilin with the salt, or vice versa. No reference to compounds made by direct combinations of anilin with the inorganic salts was found. Only one system containing anilin and an inorganic salt has been « studied quantitatively. This was worked out by Menchutkin^ for the system magnesium bromide and anilin. These two substances react with the liberation of much heat and produce three compounds. The tempera- iLippmann and Vortmann, Ber,, 12j 79, 1889. 2Saglier, C. r., 106, 1422-25. 3C. r., m, 961; 126, 967. ^Z. anorgan. Chem., ^6, 361, 1903. ^Gazzetta, 87, ii, 252-264, 1907. 6J. Pharm. Chem. VI, 21-24, 1906. '^Gazzetta, 37, i, 252-264. 1907. 11 162 IOWA ACADEMY OF SCIENCE. ture-solubility equilibrium curve consists of three branches, viz., Mg‘Br2.6C6H7N in equilibrium with its saturated solution at all tempera- tures up to 103°C; that of MgBr2.4C6H7N between 103° and 237° C; and probably the compound MgBr2.2C6H7N or MgBr2.C6H7N at still higher temperature, but owing to decomposition the investigation could not be carried higher than 250° C. or 260° C. OBJECT. Owing to the relatively high solubility of mercuric iodide in anilin at ordinary temperatures, the dimorphic nature of the solid mercuric iodide and the power of dhe two to form crystalline compounds, it was thought worth while to make a careful study of this system over the maximum possible range of temperature. For this purpose the regular solubility method was used. MATERIALS. Kahlbaum’s anilin ‘‘I” was dehydrated over fused potassium hydroxide for two weeks and carefully distilled, only that portion pass- ing over at 180°-182° C. (uncor.) being collected for the work, while the first and last portions were rejected. The mercuric iodide was precipitated from a saturated solution of chemically pure mercuric chloride by means of an equivalent weight of pure potassium iodide. The precipitate was allowed to settle and then washed by decantation, using large volumes of distilled water, until all traces of chlorine were removed. It was then transferred to a large Buchner funnel, washed with distilled water, sucked dry, and finally spread upon porous plates and thoroughly dried. APPARATUS. The solubility determinations were made in an apparatus similar to the one used by Pearce and Moore.^ For all temperatures between 0° C. and 42.9° C. an electrically heated and electrically controlled water thermostat was used ; a cooling coil for running water was added for all temperatures below that of the room. In this way temperatures constant to within a few hundredths of a degree could be kept for any desired period of time. For temperatures above 42.9° C. the saturation tube was immersed in the vapor of a boil- ing liquid whose boiling point was approximately equal to the tempera- ture desired. The tube containing the motor-driven spiral was inserted through a tightly fitting cork into a large boiling vessel containing the ^Amer. Chem. Jour., 50j 220, 1913. MERCURIC IODIDE AND ANILIN. , / 163 * liquid and this was fitted with a long vertical condenser to prevent the loss of the boiling liquid by evaporation. The liquid was maintained at the boiling temperature by means of an electrically heated platinum spiral. In order to prevent variation in the temperature, due to radia- tion, which increases with rise in temperature, the whole apparatus, excepting the condenser, was inclosed in an asbestos case fitted with a glass door through which the temperature readings could be taken. In order to still further prevent loss of heat by radiation, the inside of the case was heated by means of incandescent electric lights. By this means even the highest temperatures could be held constant to within ±.05° C., any variation being due to changes in barometric pressure only. For temperatures below 0° C., the saturation tube and stirrer were trans- ferred to a larger tube, which was surrounded by a freezing mixture of salt and ice. These temperatures could likewise be kept constant for four to six hours by the careful addition of salt and ice. All tempera- tures were read on a certified mercury thermometer passing through the ’ cork and kept at the same level as the material in the saturation tube. All thermometers used were graduated in 0.1° C., permitting estima- tions accurate to ±.05° C. Repeated tests showed saturation to be complete in about one and one- half hours. In most cases, however, a much longer time was allowed for saturation, except at the three highest temperatures, where, owing to decomposition, the time had to be limited somewhat. After saturation was complete the stirrer was stopped, the solid phase was allowed to settle for a few minutes and a sample of the liquid phase was removed by a small tube covered at one end by a double thickness of muslin. In order to prevent solidification within the tube, the latter was heated to a temperature slightly higher than that of the saturated solution. All samples were run at once into dry glass-stoppered weighing bottles and kept in dry desiccators at room temperatures until analyzed. The difficulties in the analysis of either phase of the system are readily appreciated by one familiar with the extremely volatile nature of the iodide and its inertness in the ordinary acids. The complications are still further increased by the difficulties of eliminating the easily oxidized anilin and its oxidation products. Three possible methods for the determination of the mercury seemed available. An attempt was made to dissolve out the anilin with dilute hydrochloric acid and to weigh the mercuric iodide directly, but the iodide was found to be appreciably soluble in the anilin hydrochloride formed. Likewise, the electrolytic method was found to be unsatisfac- tory, owing to the formation of anilin black at the anode. This was de- 164 IOWA ACADEMY OF SCIENCE. posited upon the surface of the mercury and exposed platinum and could not be removed. The method finally adopted was to dissolve the sample in a solution of acetic acid containing an excess of potassium iodide and to precipitate the mercury as the sulphide by passing in hydrogen sulphide to complete precipitation. This method proved very satisfactory and was used in all determinations. Samples taken at the three highest temperatures seemed to be more difficultly soluble, and complete transformation to the sulphide was accomplished by placing the solid mass in the acetic acid-potassium iodide solution and passing in hydrogen sulphide for two or three hours until portions of the filtrate gave no test for mercury on further treat- ment with hydrogen sulphide. The precipitate was transferred to a weighed Gooch crucible, washed with water and dried. The free sulphur was removed by carbon bisulphide in an electrically heated extraction apparatus of the form recommended by Treadwell and Hall.^ The quantities of acetic acid or potassium iodide added did not seem to affect the speed of transformation of mercuric iodide to sulphide, but the physical nature of the precipitate seemed to be a little better, if the solution was heated slightly before being filtered. However, the nature of the mercuric sulphide precipitated from the anilin solutions made it necessary to do all drying at temperatures below 70° C. to avoid loss due to the volatilization of mercuric sulphide. In order to test the effect of temperature upon the extent of volatilization of the sulphide, weighed Gooch crucibles containing the pure dry sul- phides were heated for intervals of one to three hours at 70°, 80° and 110 ° C., the temperature recommended by Treadwell and Hall.’^® TABLE I. HgS One hour at 110° C. Two hours at 110° C. 1.4352 gr. 1.4201 ’ 1.2784 . 2.3076 2.2321 2.0375 HgS Two hours at 80° C. Three hours at 80° C. .5412 .5378 .5300 .6879 .6765 .6685 HgS One hour at 70° C. Three hours at 70° C. .1311 4311 .4311 .4432 .4432 .4432 .2054 .2054 .2054 .1802 .1801 .1801 ^Analytical Chemistry, Vol. II, 3d Ed., 169. ^'’loc. cit. MERCURIC IODIDE AND ANILIN. 165 By observing these precautions, results were obtained which leave little to be desired as to the accuracy of the method. Analyses made on known weights of mercuric iodide in anilin gave results for mercuric iodide averaging to within less than .01 per cent. TABLE II. ANALYSIS ON KNOWN WEIGHTS OF Hgla. Gr. taken Gr. found .4325 .4323 .2936 .2930 .5872 .5872 Eesults of analyses are found in table III and are graphically repre- sented by the curve, Plate XIX. TABLE III. Temp. ° C, Sample HgS HgL Gr.Hgl. per 100 Gr. of Anilin Mean ^6.5 4.0110 .3910 .7636 23.52 23.61 -6.5 3.7128 .3667 .7162 23.10 -6.5 3.8273 .3719 .7264 23.42 .4 1.6667 .2054 .4012 i 28.72 28.69 .4 2.8167 .3214 .6277 28.68 .4 1.5798 .1802 .3519 28.66 17.8 2.8032 .4311 .8420 42.94 42.83 17.8 2.8818 .4432 .8670 42.80 17.8 2.8667 .4396 .8586 42.81 21.10 3.0095 .4937 .9867 47.43 47.55 21.10 2.7408 .4543 .8848 47.67 26.9 3.7408 .6842 1.3365 55.58 55.47 26.9 2.7353 .4987 .9707 55.35 30.1 3.5303 .6927 1.3530 62.14 62.05 30.1 3.3077 .6478 1.2650 61.96 36.2 2.4979 .5512 1.0770 75.76 75.80 36.2 2.9044 .6456 1.2610 76.03 36.2 3.1347 .6879 1.3435 75.72 42.9 3.2802 .8204 1.6025 96.60 96.49 42.9 3.4225 .8604 1.6805 96.47 42.9 3.5057 .8812 1.7210 96.40 48.8 3.6347 1.0447 2.0480 - 128.4 128.1 48.8 3.6440 1.0509 2.0530 128.0 48.8 3.8001 1.0901 1 2.1290 127.9 166 IOWA ACADEMY OF SCIENCE. TABLE III— Concluded. Temp. ° C. Sample HgS Hglo Gr.Hgl, 1 per 100 Gr. . of Anilin - Mean 63.6 2.4242 .7680 1.5000 162.9 163.8 63.6 2.0912 .6652 1.2990 164.0 ' 63.6 2.1322 .6833 1.3350 163.6 1 70.82 7.4980 2.4870 4.8580 -■ 184.0 - 184.1 70.82 7.4982 2.4890 4.8.600 184.2 1 76.2 4.3407 1.4910 2.9120 1 202.5 201.8 76.2 3.6806 1.2586 2.4590 j 201.2 77.35 .7988 .2779 .5428 : 211.45 211.5 77.35 .7902 .2747 .5365 i 211.60 95.9 1.5092 .5500 1.874 246.8 246.7 95.9 1.5092 .5497 1.072 246.5 1 97.2 4.1847 1.4658 2.863 216.2 214.9 97.2 4.0332 1.4095 2.7525 214.3 97.2 3.7170 1.2950 2.5292 213.0 1 99.1 4.2948 1.4540 2.8400 220.7 221.0 99.1 3.7840 1.3339 2.6055 221.5 99.1 4.6574 1.6415 1.4514 221.0 105.9 1.1751 .4179 .8343 239.5 239.1 105.9 1.5432 ! .5566 1.0870 i 238.3 105.9 2.4114 I .8707 1.7010 1 239.4 111.0 4.3550 1.6221 3.0960 245.9 245.0 111.0 4.4086 1 1.6030 3.1310 , 245.2 111.0 4.8830 i 1.7470 3.4120 1 243.5 115.7 2.2389 i .8456 1.6520 ! 281.8 281.8 115.7 1.3955 1 .5274 1.0300 j 281.8 137.2 .6997 .2648 .5172 284.9 285.2 137.2 .1893 .0720 .1490 286.5 j 181.1 .9820 .3763 .7350 297.6 ! 297.9 181.1 2.4612 .9823 1.9180 298.3 1 The freezing point of pure anilin has been found to he — 8° hence that part of the curve between — 8° and ■'-11.8° represents the freezing point curve for solution in equilibrium with solid anilin. At — 11.50° C. solid anilin and the compound Hgl2.2C6H7N separate out in the form of a eutectic mixture. This point was determined three times by determining the cooling curve of the saturated solution. In a freezing point tube fitted with a thermometer and stirrer and surrounded Lucuis, Ber. V, 154-155, 1872. MERCURIC IODIDE AND ANILIN. 167 by an air jacket was placed the saturated solution. The whole was surrounded by a freezing mixture of salt and ice and gently stirred until a slight under-cooling was obtained. The temperature then quickly rose to — 11.6° C., where it remained constant until the entire mass solidified and then fell slowly to the temperature of the bath, which was kept at a temperature of — 16°. The points obtained were — 11.5°, — 11.55°, — 11.4°, the mean being — 11.483°. Beginning with the eutectic point, the solubility increases gradually to 10°, then more rapidly to 42.9°. The white crystalline solid in equi- librium with the saturated solution has the composition Hgl2.2C6H7N. These crystals have parallel cleavage and parallel extinction, and melt at 58.6°. They are third or fourth system crystals, but it was impossible to determine exactly which. At 42.9° we have a quadruple point repre- senting an equlibrium between Hgl2, Hgl2.2C6H7N, saturated solution and anilin vapor. The solubility curve rises rapidly with the rise in temperature up to approximately 108°, the solid phase in equilibrium being red mercuric iodide. At approximately 108° we have another quadruple point, the solids being the red and yellow mercuric iodides in equlibrium with saturated solution and vapor. The transition point from red mercuric iodide to yellow mercuric iodide is apparently lowered by the influence of the solvent from 126° to 108°. This is in accord with the work done by J. H. Kastle,^^ in which he finds that the transition point of the iodide is affected by the solvent used. An insoluble greenish yellow solid begins to appear at this point and the solution assumes a violet permanganate color. From 108° the increase in solubility with rise in temperature is but slight up to approximately 200°, where the substance passes into a state of fusion, and the decomposition of the anilin prevented the investiga- tion being carried further. The entire mass solidified into a sort of pasty solid on being allowed to cool. The solid in equilibrium with the solu- tion above 105° is yellow mercuric iodide. The insoluble solid coming in at 108° and above was isolated, thor- oughly washed with distilled water and alcohol. It is a greenish yellow, flaky, micalike solid having oblique extension angles and no cleavage, belonging to the fifth or sixth system; it is insoluble in water, alcohol, hot anilin, or the ordinary acids, but dissolves in potassium cyanide, liberating metallic mercury. It will precipitate silver iodide from strong acid solution of silver nitrate and was found to contain 35.7 i2Am. Chem. Jour., 22-473, 1899. 168 IOWA ACADEMY OF SCIENCE. pel" cent of iodine and 56.9 per cent mercury, corresponding very closely to a compound of the composition C6H5N.Hg2l2, which would contain 34.02 per cent iodine and 53.77 per cent mercury. SUMMARY. A complete curve representing the conditions of equilibrium between mercuric iodide and anilin has been plotted for temperatures between —11.48° and 199.9°. The region of stability of the three solids Hgl2.2C6H7N, red mercuric iodide, and yellow mercuric iodide, has been established. Sixteen solubility measurements of mercuric iodide in anilin are given, all in duplicate and mostly in triplicate. A new compound corresponding to the formula CeH^N.Hgglg has been identified and described. The compound Hgl2.2C6H7N has been made by direct combination of mercuric iodide and anilin. A method for the determination of mercuric iodide as mercuric sul- phide in the presence of an easily oxidized organic solvent has been tested. Physical Chemistry Laboratory, The State University op Iowa, Iowa City. Plate XIX. Curve showing conditions of equilibrium between mercuric iodide and anilin. ^''-.K -i £?r* ‘ . '.vl? :y/U ’.‘j *- ' ''“ •'" - : '"■"'u'r‘' • '-i r>V/ -'n ^ ■' , .^4 r .u-' 'H: r'i '. ‘ ’ 'v~ :. ' V*.. 'A .V- 4 ■= I'l* RECENT PROGRESS IN GEOLOGY. 169 SOME EVIDENCE OF EECENT PKOGEESS IN GEOLOGY. • GEORGE F. KAY. (Abstract.) In a recent publication by President Van Hise it was stated that the data of geology have become so numerous that they are almost un- manageable. With this view all geologists will agree. Not many de- cades ago it was possible for a geologist to have a reasonably full and satisfactory knowledge of his own science, and, also, to be fairly familiar with the related sciences. Now it is impossible for any geologist to learn all the important facts about all the branches of his own science. Not only is this true, but no geologist can know all the discovered facts of the world, or even of his own country, concerning that branch of geology in which he may be a specialist. The inability of any person to be thoroughly familiar with the whole field is impressed by the fact that during the last ten years more than 12,000 papers have been published on different phases of American geology alone. However, it is possible and necessary that the geologist be familiar with the leading facts and many of the details of that branch of the science in which he has specialized, and, moreover, that in his science as a whole he be acquainted with the tendencies which indicate the lines along which the greatest progress has been and is being made. During the last decade great progress has been made in all branches of geology. To illustrate this progress reference is made in this paper to some of the outstanding publications in general geology, economic geology and petrology. No reference is made to the advances in other branches of geology. GENERAL GEOLOGY. 1. Without doubt one of the greatest influences upon geological thought during the last decade has been the development by Chamberlin and his associates of new and fundamental conceptions of the early stages of the earth’s history. These new conceptions have greatly- changed our former interpretations of the early atmospheres and hydro- spheres of our earth, the oldest rocks, vulcanism, diastrophic movements, climates, glaciation, the early life of the earth, and many other features. 2. The critical study of sediments has been of great assistance in 170 ’ IOWA ACADEMY OF SCIENCE. the interpretation of past climates. It has been recognized that several of the geological formations belong not to marine deposits, as was for- merly thought, but to the continental class of deposits. 3. There have been great advances in stratigraphic geology. For example, the researches of Van Hise and Leith and of others have greatly advanced our knowledge of the Pre-cambrian systems of rock. The work of Bailey Willis and others has been of great value in the correlation and unification of the rock systems throughout the world. 4. The study of radio-activity in relation to the interior heat of the earth has become, in recent years, of great interest to the geologist. 5. The development of physics and chemistry has stimulated new modes of attack in experimental geology. 6. As a result of the investigations of the earthquake commission^ our knowledge of earthquakes has been greatly extended. 7. Our knowledge of the geology of the western states has been greatly increased as a result of the new duties placed upon the United States Geological Survey in the classification of the public lands. ECONOMIC GEOLOGY. 1. In recent years it has come to be recognized as never ’before that chemical work is absolutely essential in connection with the detailed study of ore deposits. Already some excellent researches have been made by Stokes, Sullivan, Wells, and others of the chemical laboratory of the United States Geological Survey, and by Arrhenius, Vogt, Kohler, and others. But the future will see much of this chemical work done on a more systematic basis than has characterized the investigations up to the present time. One of the most interesting illustrations of the great value of experimental chemical work in the correlation of problems con- nected with ore deposits has been given by W. H. Emmons in a publica- tion entitled, ‘‘The Agency of Manganese in the Superficial Alteration and Secondary Enrichment of Ore Deposits in the United States.” 2. The chemical study of ore deposits has influenced the interpreta- tions of the genesis of ores. Whereas there were several conflicting but strongly advocated theories regarding the deposition of ores, there now is general agreement. It is now considered by all that some important types of ore deposit are. undoubtedly the result of precipitation from meteoric waters, and that many which were formerly thought to belong to this class have been precipitated from magmatic waters. Concerning this latter method of origin, the work of Doctors Day and Shepard of the Geophysical Laboratory in collecting gases unmixed with air from the crater of Kilauea is of fundamental importance. These investigators RECENT PROGRESS IN GEOLOGY. 171 have demonstrated the presence in these gases of large amonnts of water, thns furnishing direct evidence of a process which many students of ore deposits have for a long time believed to be of fundamental importance, namely, the potency of magmatic waters in contact metamorphism and the formation of mineral veins. 3. Great advancements have been made in the study of ore deposits as a result of microscopic study of rocks and ores. There is now an appreciation of the necessity of microscopic study and the unreliability of observations which are not supported by such testimony. In this con- nection it is well to refer to the recent application of metallographic methods of study to polished sections of ore. These methods of study are clearing up many points previously uncertain in the history of certain ore deposits and promise to be fully as important in future work on ore deposits as the study of thin sections has become to the petro- grapher. 4. Lindgren, in a paper on Physical Conditions and Ore Deposition, has made an important contribution to the literature of ore deposits. He shows clearly that there is an intimate relation between the mineral content of an ore deposit and the physical conditions under which the deposition occurred. He has shown that by a study of the mineral asso- ciations in an ore deposit it is possible to diagnose whether the deposit was formed, under igneous conditions, pegmatitic conditions, contact metamorphic conditions, in the zone of cementation, in the zone of weathering, or under physical conditions which differ from all of these. In his text book on mineral deposits Lindgren has described ore deposits which were formed under each of the conditions mentioned above. 5. In the year 1904 a monumental work was published by Yan Hise on the subject of metamorphism. In this he applied the laws of physical chemistry to the outer zones of the earth and showed that the principles of metamorphism have a direct bearing upon ore deposits; in fact, he contended that the deposition of most ores is but a special case of meta- morphism which is of exceptional interest to man. 6. During the past few years a distinct advance has been made in the United States in publishing monographs of the important ore de- posits of the United States. The geologist makes a thorough study in his particular field and records his results with great detail, thus allow- ing others to judge wliether or not his conclusions are justified. In this connection it is necessary to mention only the excellent monographs issued by the United States Geological Survey on the iron ores of the Lake Superior region, on the copper deposits of Arizona, and on the gold and silver deposits of the West. 172 IOWA ACADEMY OF SCIENCE. PETROLOGY. 1. Notable advances have been made recently in the physical and chemical investigations of rock minerals and rocks. Some of the most important of these are being carried on in the Geophysical Laboratory of the Carnegie Institution of Washington. Of great significance has been the determination of the value of certain minerals, such as quartz, as a geologic thermometer. As has been stated by Iddings, ‘‘The syn- thetical researches of Day and his colleagues, as well as those of Yogt, Doelter, Morozewitz and others, are carrying forward the earlier work of Daubree, Fouque and Michel Levy, and are establishing the laws of formation of the mineral constituents of igneous rocks. Eecognition of the character of igneous magmas as solutions has opened the way for the application of modern conceptions of physical chemistry to the elucida- tion of the phenomena of crystallization and of genetic relationship among igneous rocks.’' 2. “The Quantitative Classification of Igneous Rocks,” by Cross, Iddings, Pirsson and Washington, is a publication which clearly indi- cates the rapid advance of our conceptions of the classification of igneous rocks. In this classification all igneous rocks are classified primarily on the basis of their chemical composition, and only secondarily accord- ing to their mineral constituents, texture, and other characters. In its application detailed chemical analyses of the rocks are required. For the first time in the history of petrology, the fundamental characteristic of the rock, namely, its chemical composition, has been recognized as the basis of classification. 3. The recent publication of text books by Iddings, Daly, Johannsen and others will be of great service to all who are interested in the study of rocks and will stimulate research in petrology. Geological Laboratory, State University of Iowa, Iowa City. EARTH MOVEMENTS AND DRAINAGE LINES. 173 EARTH MOVEMENTS AND DRAINAGE LINES IN IOWA. JAMES H. LEES. It is well known that several systems of drainage lines have been impressed upon the surface of the present state of Iowa, only to be successively wiped out by the hand of time. Not to mention possible earlier ones, a well marked drainage system was cut into the Saint Louis and older strata prior to Des Moines time. Upon the (relative) subsidence of the land during Des Moines time the valleys were filled and drainage lines obliterated to the farthest limits of deposition of Coal Measures rocks. Differences of nearly 400 feet in the altitude of the Saint Louis surface near Des Moines give evidence of the vigor of the erosive forces and the lapse of time during which degradation was active. At least some of the Coal Measures outliers of eastern Iowa may occupy depressions cut during this period, and, as Doctor Calvin^ pointed out, the land surface of that time probably stood higher than at present, since the base of the Coal Measures sandstones of the Iowa City outlier is sixty feet below present river level. Beyond the eastern limits of the Des Moines strata the drainage systems doubtless con- tinued for a long time, though at times sluggish and ineffective as erosive agents. The Paleozoic era closed with extensive crustal movements, which initiated the formation of the Appalachian mountains in the east and excluded the sea from the continental interior. The sluggish streams of Carboniferous times must have been invigorated by these movements and new lines incised into the recently elevated Carboniferous rocks. This system of drainage persisted until, and, in eastern Iowa, through Upper Cretaceous times, but whether any of its elements survive to the present time is of necessity uncertain. An age somewhat greater than that of the Saint Louis limestone has been claimed for the prototype of the Mississippi^ along the Iowa border and buried channels have been noted by numerous writers on Iowa geology.^ These channels are usually referred to post- Cretaceous uplift and erosion, and, while it is possible that some of them may have been re-incised in Cretaceous and pre-Cretaceous valleys, the fact that pre-Tertiary drainage was toward Uowa Geol, Surv., Vol. VII, p. 94, 1897. 2Fultz, F. M; Iowa Acad. Sci., II, p. 39, 1895. ^Gordon, C. H.; Iowa Geol. Surv., Ill, 237-255, 1895;. Bain, H. F.; Iowa Acad. Sci., II, pp. 23-26, 1895. Others might be cited. IOWA ACADEMY OF SCIENCE. X74 the southwest renders it unlikely that any great proportioii of this system should be perpetuated in the present southeastwardly trending lines. It is possible that such valleys as the lower part of Oneota or Upper Iowa river valley may represent remnants of this old pre-Tertiary drainage system. The main purpose of this paper, however, is to attempt an explanation for certain incongruities in the topography and drainage of eastern Iowa. It was pointed out many years ago by McGee^ and later empha- sized by Calvin® that the streams of this region do not flow down the slope of the surface, but at practically a right angle. It may also be noted that in general these streams flow parallel to the strike of the underlying rocks and not with or against the dip. There is, however, probably no genetic relationship here. The anomalous courses of the Mississippi tributaries are probably due to the following course of events. During Upper Cretaceous time western, and perhaps a part of eastern, Iowa was under the sea, while the land area of the state was subject to prolonged erosion and so by the close of the period was re- duced to base level. The slow-moving rivers wandered aimlessly across their broad, flat-bottomed, shallow valleys, miniature editions of the lower Mississippi of today. But the Mesozoic era was closed, as the Paleozoic had been, by marked crustal and mountain-making movements, which again elevated the upper Mississippi valley beyond the reach of the seas. However, at this time the locus of movement was in the west and the Rocky mountains began their growth, the Great Plains were tilted up and a new system of drainage was initiated. The direction assumed by the members of this system was the resultant of two fac- , tors : one, the eastward tilt given the plains between the young Rockies and the axis of the great trough whose eastern rim was, and still is, the Appalachian highlands; the other, the southward slope from the old continental nucleus — the pre- Cambrian shield of Canada. Hence, the Missouri and its tributaries from the west, also the westerly tributaries of the Mississippi, as they worked headward in their development, lengthened out to the northwest. Local factors have varied this scheme, but in general it holds good. The relatively small tributaries of Missouri river in Iowa are probably post-Kansan and owe their some- what peculiar relations in part to a great southwardly-trending ridge of drift which lies immediately to the west of the present so-called divide and through which some of the larger streams have already carved their valleys. The courses of some, at least, of these streams may also ^U. S. Geol. Survey, 11th Ann. Kept., pp. 363-365, 1891. ^lowa Geol. Surv., XIII, pp. 296-299, 1903. EARTH MOVEMENTS AND DRAINAGE LINES. 175 be influenced by the great Sioux island centering about Sioux Falls and Pipestone, which has profoundly affected the history of the im- mediately surrounding regions. This growing system of streams, then, to come back to our local province of eastern Iowa, carved out its valleys upon the Cretaceous peneplain until in many cases these had assumed great proportions and had reached late maturity or old age. A Tertiary base-level was being im- pressed upon the old' Cretaceous plain. Whether the Tertiary peneplain extended merely as a narrow strip along the Mississippi, as urged by Hershey,® or was co-extensive with the great plain of the entire state, as indicated by Calvin,^ may be a moot question, though the evidence seems to point to there being but one peneplain in northeastern Iowa. Hershey based his conclusions partially upon the work of McGee, and some rearrangement of McGee’s geological section has been found necessary by later workers. The valleys of the Driftless Area give a clear picture of the develop- ment of topographic features unmolested by glacial invasions and there- fore show what might have been expected in all of northeastern Iowa had not the advance of the ice sheets terminated the* Tertiary cycle. A study of the topographic maps of the Waukon and Decorah quadrangles, for example, will show Oneota or Upper Iowa river flowing in wide meanders across a dissected plain whose summit hills and ridges rise to a fairly common level. These summits represent the Tertiary pene- plain and the intrenched meanders of the stream are faithful reproduc- tions of the course of the river when it flowed up near the level of the uplands. It is clear that valley and plain alike must have been very mature by the beginning of the Ozarkian interval, that is, near the close of the Tertiary period. Now^, the Ozarkian was a time of elevation of the continent, of differ- ential movements and warpings of the crust, and one of these warpings affected northeastern Iowa and adjacent portions of the adjoining states. The topographic maps of these states seem to indicate that this deforma- tion assumed the shape of a long ridge trending west of south and cul- minating in central and southwestern Wisconsin, southeastern Minne- sota and northeastern Iowa. Southward beyond Dubuque and westward toward Cedar river it declines rapidly. Unfortunately, the area covered by topographic maps is not sufficiently inclusive to render posi- tive assurance to this supposition. The deformation may have been a dome rather than a ridge. In any case, the streams were obliged to '■’American Geologist, XX, pp. 253-256, 1897. ^Op. Cit., XIII, pp. 298-299. 176 IOWA ACADEMY OP SCIENCE. resume downward cutting* in their valleys to prevent being ponded or reversed by the slowly rising land. They succeeded in the effort and now flow in deep canyon valleys whose floors in some cases lie 500, 600 or 700 feet below the hilltops. In fact, the valleys are over 100 feet deeper than this, for they have been fllled to that depth with detrital material dropped by the streams, as will be explained later. But the result of the upwarp is that northern Iowa lies as a great trough, with Cedar river in its axis, rather than as a plain sloping uniformly to the Mississippi, as was seemingly the case during Tertiary time. The master streams, being so largely pre-Ozarkian, or reoccupying pre-Ozarkian valleys, have held the main lines of drainage to their old courses and also have been determining factors in establishing the courses of their affluents. These latter are not widely radiate, but are narrowly digitate, or dendritic, due, perhaps, to preglacial topography, coupled with the directions of glacial advance and consequent form of glacial deposition. The partial filling of Ozarkian-cut valleys was mentioned above. The following cases may be cited. At the mouth of Oneota river wells sunk from an altitude of 650 feet penetrate 130 to 140 feet of alluvial filling before they reach rock. The level of the river here is 620 feet and the actual floor of the valley is 520 feet. Eight miles up Oneota river the floor lies at 560 feet and has been buried 100 feet. At Prairie du Chien the Mississippi bottoms are somewhat more than 600 feet above sea. A deep well sunk for 627 feet pierced 147 feet of valley filling, reaching the rock floor at 480 feet above sea. At Eagle Point, Dubuque, where the flood plain is 600 feet above sea, a well was sunk from this level through 160 feet of alluvium and from the Julien Hotel well, scarcely more than twenty feet higher, there is reported a thickness of 210 feet of loose material. This puts the valley floor at 440 to 410 feet. Most of the deep wells at Clinton strike rock within forty feet of the curb, which latter is about 588 feet above sea level, but one penetrates 205 feet of Quaternary material before bedrock is reached. This seems to indi- cate a very steep wall here, dropping to 380 feet above sea level. Again, the buried valley of the Mississippi west of Keokuk was cut at least as low as 374 feet above sea level, 103 feet below low water at Keokuk. The accompanying cut shows the relative sizes of the fossil and present channels. The same situation holds for the tributaries of the Mississippi. For instance, the Wapsipinicon and Cedar-Iowa valleys were originally less than 400 feet above sea level, though nearly 300 feet of glacial and alluvial material has been dumped into them. In Scott county a buried channel, probably of Mississippi river, named by Norton, Cleona channel. EARTH MOVEMENTS AND DRAINAGE LINES. 177 has likewise been cut lower than 400 feet above sea, though now entirely •obliterated. Low water in the present Mississippi channel at Eoek Island, only a few miles to the east, is 542 feet above sea, and the chan- nel is very shallow and rock-cut. This assemblage of facts points, of course, to the conclusion that at some time in the past, probably during the Ozarkian interval, the lands stood high and that the valleys were being deepened rather rapidly, since the buried channels show very steep walls. Subsequently these valleys were depressed through a sinking of the land surface, or else their outlet was blocked, through a rise of land athwart its lower course or by a change in its course through the agency of an ice barrier. In any case, the result has been the same — ^the partial filling of the existing valleys with detritus and the entire filling of the abandoned ones. It seems likely that two of these causes were active. We know that the Mississippi has been obliged to alter its course by invasions of Fig. 6. Section across present and former channels of Mississippi fiver in Dee County. From Gordon. glacial ice, and that parts of the course, once abandoned, have never been reoccupied, but that, instead, , the river has cut new channels through the hills and is still rock-bound and shallow at these points. This is the cause of the rapids at Eock Island and Keokuk. It will be understood that this change would tend to cause a filling of the channel behind these rock barriers. Whether this cause alone would be sufficient to account for the observed phenomena is perhaps doubtful. But another agency which I believe may be looked upon as one of the causative fac- tors is a depression of the land. During the final withdrawal of the ice sheet at the close of the Wis- consin age a series of great lakes was formed in front of the ice wall. One of the lakes. Lake Agassiz, occupied the depression now drained by Eed and Minnesota rivers, and a group with varying forms and areas filled the basins of the present Great Lakes and spread far beyond their borders. Now, these lakes formed beach ridges, shore lines, wave- cut terraces and other marks, which would naturally be horizontal. But at present these lines depart markedly from horizontality, and, further- 12 178 IOWA ACADEMY OP SCIENCE. more, the lines which were made at various levels are not parallel one to the other. This means not only that there has been a tilting of the land, but that this tilting was going on while the ice was retreating and the glacial lakes were extant. It is not thought probable that the lessen- ing burden of ice is primarily responsible for this,^ and the fact that the ocean invaded the St.. Lawrence and Hudson valleys at this time is evidence against such a cause. The significant fact is that while the land to the north of the Great Lakes was raised several hundred feet above present lake level the area south of Green bay and Saginaw bay, on Lakes Michigan and Huron, respectively, was being so depressed that certain of the shore lines are estimated to be 100 feet below lake level at Chicago.® So the shore lines of Lake Agassiz are 400 feet higher near its northern than at its southern terminus. Whether this change is due entirely to elevation, or to elevation combined with subsidence, cannot, of course, be determined, since there is no such reliable datum here as exists in the Great Lakes. Studies in the correlation of moraines and the deformation of shore lines show that the same class of move- ments was affecting the two regions,^® hence the continuation of the tilting westward from the Great Lakes region to the Mississippi may be considered as somewhat certain. Lowering the valleys and hence the gradients of streams would at once result in lower velocities, diminished carrying powers and a gradual building up of the valley bottoms. This building up would continue until the movement ceased and the streams were aggraded to their base level. Another factor which assisted in filling the valley bottoms was the immense quantities of silt, sand and gravel brought down by the floods from the Wisconsin ice front and carried down the Mississippi valley until decreasing carrying power forced their deposition. The tributary valleys were also aggraded by the backing up of the flood waters with their burden and the release of this burden in the slack waters of the estuaries. Terraces of detritus in the valleys of Mississippi and Oneota and other rivers fifty to sixty feet above present water level still bear witness to the size of the floods and of the loads carried by them and indicate the level at which the mighty stream once flowed. It is to this agent, at least as the artist which put on the last skillful touches, that the great valley owes its rugged headlands and bold, frowning scarps and precipices, while the side valleys still retain the smooth, flowing contours imposed by ages of weathering. ®Taylor, P. B. ; An. Kept. Smithsonian Inst, for 1912, pp. 91-327. ^Chamberlin and Salisbury; Geolog'y, Vol. Ill, p. 481, 1906. ^®Leverett, Frank; Fourteenth Kept. Michigan Academy of Science, 1912, p. 15. EARTH MOVEMENTS AND DRAINAGE LINES. 179 Then, how comes the river to he flowing at its present intermediate level? After the ice melted beyond the margins of the valley, the stream, though much diminished, still was freed from its great burden and was, therefore, able to degrade its channel instead of aggrading it. Further, during the early part of its existence Lake Agassiz was drained into Minnesota and thence into Mississippi river. This volume of water had left its load of detritus in the lake, hence was able to assist in carry- ing away the material which is found choking the valley of the Mississippi. It is possible, of course, that there has been a slight uplift of the entire valley following the disappearance of the ice, but of this we have no positive knowledge. We do know that there have been postglacial uplifts in eastern and northeastern America. In this connection there is another fact of some interest. Some years ago, during our work in Winneshiek county, Doctor Calvin called my attention to the fact that the smaller streams of the region were all cutting into their valley Ailing. The accompanying cut, taken from the report on Winneshiek county,^^ gives a good illustration of the situation. It will be readily seen that, whatever the cause of this re-erosion, it is of recent occurrence and its effects are just now being felt in this region. It may be noted that this photograph here reproduced was taken less than two miles from Oneota river, and, therefore, in a location where any quickening of erosive activity in the master streams would be easily felt in their tributaries. The most reasonable explanation of this phenomenon seems to be its correlation with the formation of the great terraces along the major drainage courses through the degradation of the detrital accumulations within them, as discussed above. The lowering of the water levels in the larger streams would necessitate a readjustment of gradients throughout their basins and a consequent increase in velocities and erosive powers. It may be remarked parenthetically that this increased activity is not confined to northeastern Iowa, but may be observed in other drainage areas. Gullies twenty feet deep and scarcely as wide at the top are being cut into the loess plains of the western slope of the state. Similar instances are occurring elsewhere. The incursion of human civilization and agriculture has been held responsible for this phenomenon, but whether the coincidence is causal, or merely fortuitous, or both, is, as yet, undetermined. Certain it is that there has been, within recent years, a notable depression of the ground water table, and these various changes may be intimately related one to the other. ^Uowa Geol. Surv., XVI, pp. 55, 56, 1906. 180 IOWA ACADEMY OP SCIENCE. Resume. — The streams of northeastern Iowa are strike streams, rather than dip streams. Their southeasterly direction was determined originally by the eastward tilt of the Great Plains and the southerly slope from the old Canadian land nucleus. Later the slope of the area considered was changed by an upwarp extending across southwestern Wisconsin, southeastern Minnesota and into northeastern Iowa. The streams were quickened, cut deep valleys into this ridge and so have held to their courses instead of being changed to other directions of flow. The land was formerly higher than now, as attested by the partially filled valleys of Mississippi and tributary rivers. This filling was aided by fioods from the Wisconsin ice, which dropped great quantities of silt, sand and gravel along the bottom lands. Much of this material has since been cut away, leaving the remnants as terraces along the valley walls. Iowa Geological Survey, Des Moines. Plate XX Fig. 1. — Mississippi bluffs below Fansing. Allamakee county, showing vertical walls fronting the river, but mature side and back slopes. From Calvin. Fig. 2. — Reerosion of an aggraded valley, in the northeast quarter of section 21, Glenwood township, in Winneshiek county. From Calvin, IOWA MOUNTAIN MAKING. 181 IOWA’S GEE AT PEEIOD OF MOUNTAIN MAKING. BY CHARLES KEYES. It is a fact almost too well known to state here that the most important single problem in earth-study with which we have to deal in Iowa is that of exact mapping of the different rocky formations. Unlike the cases in the majority of states, the work in this state is vastly simplified by the fact that there has been apparently little orogenic disturbance in the region, and the geological terranes of fundamental consequence mainly belong to a single geologic era. Calling the problem some- what simple does not by any means signify that the labor of discrimina- tion and tracing of the formation boundaries is easy, or that it is not highly varied. The basis upon which Iowa geologists have to work is almost entirely Paleozoic in age. This general rock-sequence is very complete — as much so, perhaps, as any other Paleozoic section of our continent. In Iowa there are two special conditions which rather severely limit close mapping of the Paleozoic formations. These are the presence every- where over the state of a thick mantle of glacial till, associated with which are heavy deposits of loess, and, in the western half of the state, the occurrence of a great sheet of Cretacic sediments. The difficulties presented by the presence of the glacial deposits are fairly well over- come. In the case of that part of the state covered by the Cretacic for- mations in addition to a great overburden of drift, little or nothing has heretofore been done to elucidate the present structural attitude and the stratigraphic and taxonomic affinities of the underlying terranes. There are, moreover, some of the broader relationships of the several formations that have not been taken into account and this fact makes the various associated problems which have come up still harder to solve. These features are more than state-wide in character. In extent they are really provincial rather than local, and certain of them are of continental proportions. It is to some of these aspects that attention is here briefly directed. By peeling off, as it were, the Cretacic covering in the western one- third of the Iowa area, the entire Mesozoic floor is laid bare, and the Paleozoic formations then constitute the bedrock of the whole state. By what is essentially the same thing, elimination of the glacial and Cretacic 1S2 IOWA ACADEMY OP SCIENCE. coverings is accomplished by plotting the deep-boring records and other data. Part of these are made available through Professor Norton’s recent report on the underground water supplies; but a large portion of the data is derived from sources to which he did not have access. All of these data are checked by the results of recent field-work. In addition, examination of the rocks of neighboring states throws much light upon the problems long regarded as too intricate to be solved witlyn state borders alone. On the general geologic map of Iowa the Paleozoic formations are distributed in relatively narrow belts trending in a northwest direction across the northeastern one-third of the state. Very singularly, it has always seemed, these belts abruptly terminate at the north soon after leaving the state boundary. For many years I have longed to know what becomes of these belts*; and to learn the exact reason of this rather peculiar and unlooked for circumstance. During the past summer I found out. While on the geological excursions which followed the sessions of the Twelfth International Geological Gongress which con- vened in Canada I had special opportunities to examine the Paleozoic sections of Manitoba, and under the guidance of those who had long worked in the field. There the same narrow belting of the same forma- tions occurs and, as farther south, the strike is northwest. The Canadian Paleozoic area is separated in central Minnesota from the Iowan Paleo- zoic field by a broad Pre-Cambric area. These Pre-Cambric rocks form the core of a rather notable arch, the axis of which runs northeast and southwest. This anticline is one of large proportions and extends from the east shore of Lake Superior to South Dakota, where, as a canoe-shaped form, it plunges beneath the post-Paleozoic deposits of the Great Plains region. The exposure of Sioux quartzite constitutes its western nose. It is against the south slope of the sharp Siouan anticline that the belted Paleozoic terranes of northeastern Iowa are upturned and cut off. The eastern margin of the vast Cretacic field crosses the same line so that there is apparently no westward extension of the five groups of formations, if it ever existed, at least on the surface of the ground. On the other, or north, side of the anticline the same belts reoccur, as already stated. Bearing in mind the position of this marked anticline, an arch be- tween the center of which and the limbs there is a stratigraphic interval of more than 5,000 feet, it is obvious that the Paleozoic belts originally did not really terminate against it in southern Minnesota, but rather IOWA MOUNTAIN MAKING. 183 extended over it and were continuous with the Canadian belts. This being the case, it is equally obvious that the Iowan belts should not only not terminate against the arch in eastern or southeastern Minne- sota, but should continue westward along the strike of the arch, but beneath the Cretacic covering. This is found actually to accord with recently observed facts. A cross section (figure 7), drawn to a scale indicates the actual amount of tilting displayed at the present time, with the part originally present, but removed during Mid-Cretacic time, represented by dotted lines. By reconstructing the many well-sections and other deep-boring records, and correlating them in cross section, and then roughly map- ping them on the Cretacic fioor, it is found that all of the five belts actually turn sharply westward in eastern Minnesota and, crossing again into Iowa, extend southwestward into South Dakota and Nebraska. The Devonie and Ordovicic belts appear to pass under Sioux City. At any 84 IOWA ACADEMY OP SCIENCE. rate, they are so steeply upturned in the great truncated arch ‘that their outcrop on the Cretaeic floor is relatively narrow. The areal distribution of these various belts is indicated on the accompanying sketch-map of the state (plate XXI). The boundaries of the formations are located about as accurately as are the similar lines in much of the region nearer the Mississippi river. Several other points incidentally brought out are of great interest. The areal extent of the Missourian series, or Upper Coal Measures, is probably not more than one-half as large as it has been commonly sup- posed to be. On the Missouri river this formation does not appear to extend north of Harrison county. The limestone outcrops in the Boyer valley, between Logan and Woodbine, seem to belong to no other than the familiar basal member of the Missourian series — ^the Bethany lime- stone. Contrary to all previous conceptions, there appears to be but a small part of the present Cretaeic area in Iowa immediately underlain by the Productive Coal Measures, or Des Moines series. The pre- Cretaeic out- croppings appear in a narrow band scarcely a dozen miles in width extending southwest from Fort Dodge to a point on the Missouri river about twenty miles above Council Bluffs. The entire northwestern part of the state thus appears to be without Productive Coal Measures .beneath the Cretaeic beds. A third instructive point suggested by the present inquiry is its bearing upon the age and deposition of the Fort Dodge gypsum, about which there has always been warm controversy. It is conclusively shown by the evidence here presented that if the Oklahoman and Cimarronian beds (so-called Permo-Carboniferous and Permian) of Kansas ever existed so far into Iowa territory as Fort Dodge they were at least 2000 feet above the floor of the gypsum deposits ; and were never con- tinuous with them. It may not be out of place to say a word here on the age of the great Siouan anticline and the physiographic significance of the Cretaeic floor. Since all of the Paleozoic formations take part in the arching, while the Cretaeic rocks do not, it is quite evident that the main move- ment or uprising occurred in Early Mesozoic time. At the beginning of Comanehan deposition (Early Cretaeic), when this part of the continent was land area, the country was again completely baseleveled, the Siouan arch as well as the lower lands. Upon this even plain, worn out on the bevelled edges of the ancient strata, which was then gradually earned beneath sea-level sediments were laid down during Mid Cretaeic times. V IOWA MOUNTAIN MAKING. 185 These are the deposits which cover the northwestern portion of our state and out of which peeps the crestal remnant of the old arch, called by us the Sioux Quartzite area. ' The Siouan mountains were rapid in formation and rapid in decline. At the time of their highest stage they probably stood 3,000 to 4,000 feet above the surrounding country. They were greatly diversified. In the Black hills, the Ozarks, and the Appalachians of today we find their nearest counterparts. With the recognition of a great erogenic interval within the limits of our State there is added to the general geologic column a new sec- tion of very great importance. In the same region new chapters are inserted at the base of the general rock section. These together with other important modifications and intercalated features recently made known renders at this time a revision of previous diagrams particularly instructive. This chart is given below. PALEOZOIC. MESOZOIC CENOZOIC 186 IOWA ACADEMY OF SCIENCE. REVISED GENERAL GEOLOGIC SECTION OP IOWA ROCKS. Periods SUB-P. Series Terranes Thick- ness Rocks Late Recent Alluvium 25 Clays, sands Wisconsin ... 30 Till Peoria 1 Soils Iowa 30 Till Sangamon ._ 1 Soil QUATERNARIC Mid_- — - Illinois 100 Till Yarmouth ... 1 Soil Kansas 200 Till Alton 40 Sands Nebraska 30 Till EARLY— Epicene Dubuque 10 Clays (geest) Late Pliocene Interval Unconformity Riverside 50 Sands TERTTAT?TO Mid Dodg-ft 100 Shales Early.— Eocene-- Interval Unconformity Late Montanan Unrepresent- ed in state. Niobrara 150 Limestones Coloradan Hawarden _. 125 Shales Crill 100 I.imestones Woodbury 150 Shales ORETAr-TP Ponca 25 Sandstones Dakotan Sergeant 75 Shales Nishnabotna. 200 Sandstones Early... Comanchan Interval Unconformity JURASSIC Interval TRIASSIC Interval Late Oklahoman Unrepresent- ed in state. Atchison 300 Shales Forbes 25 Limestones Platte 125 Shales Plattsmouth.. 30 Limestones Missourian Lawrence 100 Shales Stanton 20 Limestones Parkville 100 Shales Thayer 75 Shales Bethany 50 Limestones Mid.. Marais des Cygnes 300 Shales Des Moines... Henrietta 100 Limestones Cherokee 250 Shales Arkansan Interval Unconformity Pella 30 Shales CARBONIC Tennessean.— St. Louis ' 50 Limestones Verdi 100 Sandstones Unconformity Spergen 10 Limestones Warsaw 65 Shales Early... Mississippian. Keokuk _ ... 75 Limestones Burlington — 125 Limestones Chouteau 50 Limestones Unconformity IOWA MOUNTAIN MAKING, 187 REVISED GENERAL GEOLOGIC SECTION OP IOWA ROCKS— Concluded. ERAS Periods SUB-P. Series Terranes Thick- ness Rocks Hannibal 75 Shales Waverlyan Louisiana -— 10 Limestones Saverton 60 Shales Grassy 50 Shales Chattanooga- Unconformity Chemungan-'—- Lime Creek— 125 Shales Lucas - 25 Limestones Coralville 30 Limestones Late 8 6716 can - -. Rapif^ 35 Limestones Solon 25 Limestones Tully Unconformity Fayette 75 Limestones Independence 20 Shales Otis 10 Limestones Coggan - - - 15 Dolomites EARLY--. Oriskanian -- Interval Unconformity Bertram 35 Dolomites Late Gower an Anamosa 60 Dolomites O M LeClaire 70 Dolomites o Monticello 100 Dolomites © STTJTRTC: Niagaran Hartwick 80 Dolomites & Colesburg 30 Dolomites < Sabula 50 Dolomites Early— Al6xandrian..-. Interval Unconformity Brainard 125 Shales Atkinson 40 Limestones Late Maquoketan — Clermont 15 Shales Elgin — 75 Shales Galena 225 Dolomites ORDOVICIC Mid- Mohawkian Decorah 30 Shales Platteville — 100 Tumestones Glenwood 15 Shales Early—. Mmn6sotan St. Peter 100 Sandstones Shakopee 75 Dolomites Late Ozarkian New Rich- mond 25 Sandstones Oneota 150 Dolomites Jordan 100 Sandstones CAMBRIC Mid Groixan. St. Lawrence 50 Dolomites Dresbach 150 Sandstones Hinckly _- — 600 Sandstones EARLY— G6orgian Interval Unconformity Corson Diabases © Late K6ewenawan—. Hull 475 T^’orphvries o Tipton 425 Sandstones o SUPERIORIC Mid Interval Unconformity Split-rock -— 75 ■ 'Elates EARLY— Animikian Sioux - - - 500 Ouartzites o Jasper 30 Conglomerates h SELKIRKIC Interval Unconformity ARCH Unrepresent- HiU— ZOIC ed in state. AZO- 500 Gneisses IC Schists Plate XXI A I ! t EARLY CARBONIC SUCCESSION. 189 SERIAL SUBDIVISION OF THE EARLY CARBONIC SUCCES- SION IN THE CONTINENTAL INTERIOR. CHARLES KEYES. As the taxonomic consideration of the Early Carbonic formations of the American continent has proceeded during the quarter of a cen- tury just passed, complication, rather than simplification, has taken place. Systematic arrangement of the terranes has become less rather than more clearly defined. The recent attempt to amplify one of the subordinate divisional titles so as to cover the whole has been attended by rather incongruous consequences. Small real advancement has re- sulted from mere change in nomenclature. Bureaucratic authority has been unable to take the place of fact, and its dictates have been as un- fortunate, as they have been unsatisfactory and unreal. That present custom is as unsatisfactory as it is inexpressive of actual genetic* relationships between the various terranes represented on the American continent is amply indicated by a number of incidents. For example, Chamberlin and Salisbury^ propose to give the Early Carbonic interval a taxonomic rank righer than it has been the custom to do, and to have it represent a periodical division, thus paralleling it with Car- bonic itself. Cambric or Cretacic. Both Schuchert^ and Ulrich^, in recent arguments, strongly support either restriction of the term Mississippian, as now widely applied in America, or abandonment of it altogether. "They suggest also new subdivision. Were the Early Carbonic rocks of the continental interior reviewed anew today, without reference to any arrangement or subdivision already proposed, it is quite likely that a tripartite scheme would be, without much discussion, adopted. Upon grounds faunal, genetic, lithologic, stratigraphical, structural, diastrophic and paleogeographical, there is close agreement upon at least two major divisional lines. It so happens that these lines also correspond to the early subdivision deliminations. If, without too much disturbance in nomenclature and conception, these subdivisions can be readily used and the various local sections adapted to them, great and permanent advancement in provincial stratigraphy will have been made. This appears possible. ^Text-book of Geology, Vol. II, p. 160, 1906. 2Bull. Geol. Soc. America, Vol. XX, p. 548, 1910. sibid., Vol. XXII, p. 608, 1911. 190 IOWA ACADEMY OP SCIENCE. The two divisional lines which are most striking in the Early Car- bonic sequence of the Mississippi valley are those at the base of the Burlington or Chonteau limestone and at the bottom of the St. Lonis limestone. Both of these lines were pointed out by Owen'^ as early as 1852. Upon strictly fannal grounds, they were especially defined by me^ in 1889. Twm years later Williams® also recognized them and pro- posed new titles for the faunas of these subdivisions thus suggested. In 1892 I again'^ distinctly called attention to the same lines and also another of subordinate importance. Lately SchucherU and Ulrich® pro- pose still another grouping of the formations but draw the line of separa- tion at or near the base of the St. Louis limestone. In the Iowa section, as lately review^ed,^® I do not especially emphasize any subserial grouping. In Anew of the fact that in late years Uvo neAv criteria have come to have a dominant influence in stratigraphic classification and the faunal standard is largely displaced, the conception of rational grouping of terranes is someAvhat changed. These tAvo factors are diastrophic record and paleogeographical distribution. The two division lines here noted happen to be products of both diastrophic movement and paleogeo- graphical limitation. They mark provincial effects, not continental or universal changes. The sections Avhich they limit therefore have a taxonomic rank that is neither higher nor loAver than that of series. The three series thus demarcated are already designated by special names which, with slight modification in scope, may be appropriately retained. The nethermost set of terranes corresponds to the section which in Ohio w^as early defined as the Waverly formation, in Michigan as the Marshall group, in Illinois and loAva as the Kinderhook beds, and in Missouri latterly as the Chouteau section. Since the main and most widely distributed limestone section constitutes the middle series, the term Mississippian is appropriately restricted to it; and this also is very nearly Winchell’s original use of the title. The lately proposed name, Tennessean, for the uppermost series, is useful and valid because the term Ste. Genevieve Avas already preoccupied for one of the subordinate limestones. Little need be said here concerning the Waverly an or the Tennessean series. Regarding the term Mississippian, a AA^ord or two may not be 4Rept. Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 92, 1852. ^•Am Jour. Sci., (3), Vol. XXXVIII, p. 186, 1889. mull. U. S. G. S., No. 80, p. 169, 1891. mull. Geol. Soc. Vol. Ill, p. 263, 1892. Ubid., A^ol. XX, p. 548, 1910. <'Ibid., Vol. XXII, p. 608, 1912. J^Iowa Geol. Surv., Vol. XXII, p. 154, 1913. ' EARLY CARBONIC SUCCESSION. 191 out of place. The formations of the Eocky mountains, which are commonly called by this title, probably represent little more than the Burlington and Keokuk limestones of the continental interior. Hence, the use of the term in a somewhat restricted sense is not out of place and will give rise to but small confusion. As it now appears, the correlation of the Iowa section of Early Car- bonic, with other characteristic sections, is given below: CORRELATION OP EARLY CARBONIC TERRANES. 192 IOWA ACADEMY OP SCIENCE. m o m m tD he .2 ^ i •NvassaNNSi •NVIddlSSISSIW •uteau Li. I Chouteau Li. EARLY CARBONIC SUCCESSION. 193 W m -4-> i=i » O ?H CD § »£