-. ■ s/-

'^^iiiij

V.c^i

IV ^

TRANSACTIONS

OF

THE ACADEMY OF SCIENCE
OF ST. LOUIS.

VOL. XXI.
JANUARY, 1912, TO DECEMBER, 1912.

PUBLISHED UNDER DIRECTION OF THE COUNCIL.

ST. LOUIS.
NIXON-JONES PRINTING CO.

■»• < .

CONTENTS.

PAGE.

Table op Contents iii

List op Oppicers v

List op Members. Revised to December 31, 1912 vi

1. Patrons.,

2. Honorary Members.

3. Active Members.

Abstract of History xviii

Record. January 1, to December 31, 1912 xxii

Papers Published, January 1, to December 31, 1912 :

1. Henry Ellsworth Ewing. — The Origin and Sig-

nificance of Parasitism in the Acarina. —
Plates I-VII.— Issued June 18, 1912. ....... 1

2. Geo. A. Lindsay. — The Annual Rainfall and Tem-

perature of the United States. — Plate VIII. —
Issued June 19, 1912 71

3. Francis E. Nipher. — The Nature of Electrical

Discharge — Positive Column Effects in a
Metal Conductor. — Plate IX. — Issued July
3, 1912 79

4. Title Page. Prefatory Matter and Index of

Vol. XXI. Record January 1, to December
■ 31, 1912.— Plate A.— Issued May 5, 1913.

List op Authors 89

General Index 90

Index to Genera 93

LIST OF OFFICERS, 1912.

President Edmund A. Engler.

First Vice President Francis E. Nipher.

Second Vice President Arthur E. Ewing.

Recording Secretary M. E. Hard.

Corresponding Secretary George T. Moore.

Treasurer H. E. Wiedemann.

Librarian Wm. L. R. Gifford.

Curators Julius Hurler.

Philip Rau.
Joseph Grindon.

Directors Otto Widmann.

Adolf Alt.

MEMBERS.

1. Patrons.

Bixby, William. Keeney Kingshighway and Lindell Bis.

Eliot, Henry Ware 4446 Westminster PI.

tHarrison, Edwin

Mallinckrodt, Edward 26 Vandeventer PI.

McMillan, Mrs. Eliza 25 Portland PI.

McMillan, William Northrop . . . Century Bldg.

2. Honorary Members.

Arrhenius, Prof. Svante University of Stockholm,

Sweden.
Bahlsen, Prof. Dr. Leopold .... University of Berlin, Germany.
Kitasato, Prof. Shibasaburo .... University of Tokyo, Japan.
Lewald, Geh. Oberreg. Rath

Theodor Berlin, Germany.

Limburg, Stiruni, Graf Berlin, Germany.

Orth, Geh. Rath Dr. Johann . . . University of Berlin, Germany.

Ostwald, Prof. Wilhehn University of Leipzig, Germany.

Ramsay, Sir William Royal Institute, London,

England.

Rutherford, Prof. Ernest University of Manchester,

England.

Springer, Frank U. S. National Museum,

Washington, D. C.

Trelease, William St. Louis, Mo.

Waldeyer, Geh. Rath Prof. Dr.

Wilhehn University of Berlin, Germany.

Wassermann, Prof. Dr. A University of Berlin, Germany.

Wittmack, Geh. Reg. Rath

Prof. Dr. L University of Berlin, Germany.

t Deceased.

Members. vii

3. Active Members.

Alleman, Gellert^ Swarthmore College,

Swartlimore, Pa.

Allen, George L 26 Westmoreland PI.

Alt, Adolf 316 Metropolitan Bldg.

Altheimer, Benjamin Melrose Apartments.

Ameiss, F. C 3804 Olive St.

Am merman, Charles McKinley High School.

Armbruster, Wm. J 3622 Shenandoah St.

Bagby, Julian^ New Haven, Mo.

Bain, Samuel McCutchen^ University of Tennessee,

Knoxville, Term.

Baker, Robert H.^ University of Missouri,

Columbia, Mo.

Baldwin, Roger N 3739 Windsor PI.

Barck, Carl Humboldt Bldg.

Barnard, George D Vandeventer and Laclede Aves.

Barroll, Joseph R 4603 Berlin Ave.

Baumgarten, Walter Humboldt Bldg.

Beckwith, Thomas^ Charleston, Mo.

Beede, J. W.^ 822 Hunter Ave.,

Blooinington, Ind.

Bemis, S. A Fourth and Poplar Sts.

Berninghaus, J. A Central National Bank.

Bessey, Charles Bdwin^ University of Nebraska,

Lincoln, Neb.

Bessey, Ernst A.^ Michigan Agricultural College,

East Lansing, Mich,

Blair, V. P Metropolitan Bldg.

Blankinship, Joseph William^ .2329 Carlton St., Berkeley, Cal.

Blewett, Ben Ninth and Locust Sts.

Bock, George W 2904 Allen Ave.

Borgmeyer, Charles J St. Louis University.

Bostwick, Arthur E 70 Vandeventer PI.

Bradshaw, Preston J Liggett Bldg.

Brandenburger, Louis A 3614 Cleveland Ave.

Brandenburger, W. A 1406 Syndicate Trust Bldg.

1

Non-resident.

viii Trans. Acad. Sci. of St. Louis.

Branner, J. C.^ Stanford University, Cal.

Brannon, Melvin A.^ University of North Dakota,

Grand Forks, N. Dak.

Brennan, Martin S 6304 Minnesota Ave.

Brimmer, George G 6900 Michigan Ave.

Britton, F. H.^ Kirk wood, Mo.

Brock, James E Mississippi Valley Trust Co.

Brockman, F. W 3710 N. Grand Ave.

Brookings, Robert S 6510 EUenwood Ave.

Brown, Daniel S.^ Brownhurst, Kirkwood, Mo.

Buehler, H. A.^ Rolla, Mo.

Burg, William 4439 Washington Boul.

Busch, Adolphus Busch PI.

Busch, Aug. A Biisch PI.

Bush, Benjamin Franklin^ Courtney, Mo.

Butler, William M Yeatman High School.

Cale, George W., Jr 12 Lennox PI.

Campbell, James A Mermod Jaccard Bldg.

Carleton, Murray 1135 Washington Ave.

Carpenter, George 0 12 Portland PI.

Carr, Peyton T 62 Vandeventer PI.

Carter, Howard^ Webster Groves, Mo.

Carver, George Washington^ . . . Tuskegee, Ala.

Caspari, Charles E 4060 Westminster PI.

Catlin, Daniel Security Bldg.

Chambers, C. 0 Missouri Botanical Garden.

Chappell, W. G Buckingham Club.

Chenery, Winthrop Holt Washington University.

Christie, Harvey L 5544 Cabanne PI.

Clarke, Enos^ Kirkwood, Mo.

Clopton, Malvern B Humboldt Bldg.

Colnon, R. S 506 Merchants' Laclede Bldg.

Conzelman, Theophilus 5260 Washington Boul.

Cook, Abraham 4208 Pine St.

Cook, Francis E 5510 Gates Ave.

Cook, Isaac T Chemical Bldg.

Cook, Jerome E 4254 Lindell Boul.

Craig, Moses Missouri Botanical Garden.

Cramer, Gustav Care Cramer Drj^ Plate Co.

Crandall, George C 3674 Lindell Boul.

Crawford, Hanford 4442 Lindell Boul.

Members. ix

Crecelius, Elyse C 1110 Dillon St.

Curley, Francis E. A 6143 Berlin Ave.

Curtis, William S Washington University.

Dameron, Edward CaswelP .... Clarksville, Mo.

Danforth, Charles H Washington University,

Medical Department.

Davis, H. N 56 Vandeventer PI.

Davis, John D 815- Merchants' Laclede Bldg.

Dewey, Lyster H.^ 4612 Ninth St., N. W.,

Washington, D. C.

Dieckmann, Charles A 2816 Potomac St.

Diehm, Ferdinand 6175 Kingsbury Boul.

Doan, George P 42 Portland PI.

Dock, George Washington University,

I - .■ |p Medical Department.

Dorsett, Walter B Linmar Bldg.

Dougan, Lewis M 3955 Botanical Ave.

Drosten, F. W 3521 Victor St.

Drushel, J. A Teachers' College.

Duggar, Benjamin F Missouri Botanical Garden.

Duncan, John H Humboldt Bldg.

Duncker, Charles H 3636 Page Ave.

Ebeling, A. W.^ Warrenton, Mo.

Eberle, E. G.^ 416 Jackson St., Dallas, Texas.

Eimbeck, August F.^ New Haven, Mo.

Eliot, Edward C 5468 Maple Ave.

Emerson, John B Syndicate Trust Bldg.

Emmel, Victor E Washington University,

Medical Department.

Engler, Edmund Arthur Washington University.

Ericson, Eric John 1420 Clara Ave.

Erker, Adolph P 608 Olive St.

Espenschied, Charles 3500 Washington Ave.

Evers, Edward 1861 North Market St.

Ewing, Arthur E 5956 Cabanne PI.

Fawcett, H. S.^ Whittier, Cal.

Ferriss, James H.^ Joliet, 111.

Filley, John D 40 Westmoreland PI.

Fischel, Walter 5284 Westminster PI.

X Trans. Acad. Sci. of St. Louis.

Fischel, Washington E Humboldt Bldg.

Fish, E. R 2449 E. Marcus Ave.

Floyd, B. F.^ Gainesville, Fla.

Fordyce, John R.^ 2223 Louisiana St.,

Little Rock, Ark.

Fordyce, S. W 21 Washington Terrace.

Francis, David R 4421 Maryland Ave.

French, George Hazen^ Carbondale, 111.

Frerichs, Frederick W 4320 Washington Boul.

Frick, John Henry ^ Warrenton, Mo.

Fruth, Otto J 3060 Hawthorne Boul.

Fry, Frank R 4609 McPherson Ave.

Fuhrniann, Richard H 3221 California Ave.

Fullgraf, Charles W 7077 Pernod Ave.

Funkhouser, Robert Monroe. . .4354 Olive St.

Garman, Harrison^ Lexington, Ky.

Geeks, Frank 3453 Magnolia Ave.

Geitz, H. A.i 17 West End Ave.,

Rockaway Park, Long Island,

N. Y.

Gifford, William L. R Mercantile Library.

Gill, Charles M Teachers' College.

Gillette, C. P.^ Fort Collins, Colo.

Glasgow, Frank A 3894 Washington Ave.

Goldstein, Max A 3858 Westminster PI.

Goltra, Edward F 4416 Lindell Boul.

Goodman, Charles H 4500 Olive St.

Gratz, Benjamin Rialto Bldg.

Graves, William W Metropolitan Bldg.

Green, John 2670 Washington Ave,

Greene, F. C, Jr.^ Rolla, Mo.

Greer, E. 0 2750 Park Ave.

Greger, Darling Kennett^ Westminster College,

Fulton, Mo.

Gregg, Cecil D 405 North Second St.

Grindon, Joseph 3894 Washington Ave.

Gundelach, William J 4937 Forest Park Boul.

Gundlach, John H 3615 North Broadway.

Guthrie, Robert J Pierce Bldg.

Guy, William E 10 Portland PI.

Members. xi

Haarstick, Henry C St. Louis Union Trust Bldg.

Hall, Fred B 4330 Morgan St.

Hall, Robert A Washington University.

Hambaeh, Gustav" Herford, Westphalia, Germany.

Hard, M. E.^ Kirkwood, Mo.

Harder, Ulrich 8015 Florissant Ave.

Harms, L. A. P.^ Kirkwood, Mo.

Harris, James Arthur^ Station for Experimental Evo-
lution, Cold Spring Harbor,
Long Island, N. Y.

Hartmann, Rudolph 3859 Flora Boul.

Heeker, Frederick^ Argyle Bldg.,

Kansas City, Mo.

Held, George A International Bank.

Hendrich, Walter F 6228 Washington Boul.

Herf , Oscar Pierce Bldg.

Hidden, Edward Commonwealth Trust Bldg.

Hill, Charles Van Dyke Third National Bank Bldg.

Hoffman, Philip 3657 Delmar Ave.

Hoke, William E 304 North Third St.

Holman, C. L 716 Locust St.

Houwink, J. J Delmar Bldg.

Hughes, Charles Hamilton Metropolitan Bldg.

Hughes, Marc Ray Metropolitan Bldg.

Hume, H. Harold^ Glen St. Mary, Fla.

Hurter, Julius 2346 South Tenth St.

Huttig, Charles H Third National Bank.

Ilhardt, William K Euclid and Delmar Aves.

Irish, Henry C Commonwealth Trust Bldg.

James, George Oscar Washington University.

Jensen, L. P Busch PI.

Johnson, Albert L.^ Mutual Life Insurance Bldg.,

Buffalo, N. Y.

Jonas, Ernest 465 North Taylor Ave.

Jones, Breckinridge 45 Portland PL

Jones, Robert McKittrick 6 Westmoreland PL

Kammerer, Alfred L Tower Grove and Flad Aves.

* Elected a life-member January 3, 1882.

xii Trans. Acad. Set. of St. Louis.

Keiser, Edward H Washington University.

Kennett, Luther M 3507 Lucas Ave.

Kessler, George E Security Bldg.

Kessler, J. J 224 South Vandeventer Ave.

Keyes, Charles R.^ 944 Fifth St., Des Moines, la.

King, Goodman 78 Vandeventer PI.

Kinsella, W. J 4422 Lindell Boul.

Kirchner, Walter C. G 1127 North Grand Ave.

Klem, Mary J 3133 Nebraska Ave.

Knapp, H. P Eighteenth and Olive Sts.

Knight, H. F 4433 Westminster PI.

Knight, S. S 6700 Manchester Ave.

La Brie, Joseph Damas^ 504 Keith & Perry Bldg.,

Kansas City, Mo.

Lang, George, Jr 3648 South Broadway.

Langsdorf , Alexander S Washington University.

Larkin, E. H 3600 North Broadway.

Lawver, Albert Briggs 5715 Clemens Ave.

Leavitt, Sherman^ Illinois College, Jacksonville, 111.

Lee, James S City Hall.

Letterman, George W.^ AUenton, Mo.

Le Van, W. C.^ 116 Taylor Ave., Kirkwood, Mo.

Le\\ds, E. G.^ University City, Mo.

Lichter, John J 1740 Simpson PI.

Loeb, Hanau Wolf Humboldt Bldg.

Loeb, Leo St. Louis Skin and Cancer Hos-
pital.

Luedde, William H Metropolitan Bldg.

Lukens, C. DeWitt 4908 Laclede Ave.

Lutz, Frank J Josephine Hospital.

Mack, Charles Jacob 113 North Broadway.

Mallinekrodt, Edward, Jr Mallinckrodt Chemical Works.

Mardorf, W. C 2136 South Grand Ave.

Markham, George Dickson 4961 Berlin Ave.

Mason, Silas C.^ R. F. D. No. 1, Bethesda, Md.

Matthews, Leonard 5447 Cabanne PI.

Mauran, John Lawrence 1620 Chemical Bldg.

McBride, W. J.^ Haskell & Barker Car Co.,

Michigan City, Ind.
McCourt, Walter Edward Washington University.

Members. xiii

McCubbin, J. B Metropolitan Bldg.

McCulloch, Richard 3869 Park Av.

McLeod, N. W Lumberman's Bldg.

McMaster, LeRoy Washington University.

Meier, Theodore G 5220 Washington Boul.

Mesker, Frank 421 South Sixth St.

Michael, Elias Rice, Stix Dry Goods Co.

Mitchell, E. T.^ 7730 Jeanette St.,

New Orleans, La.

Monell, Joseph T 3454 Halliday Ave.

Moore, George T Missouri Botanical Garden.

Moore, Philip N Merchants' Laclede Bldg.

Moore, Robert 61 Vandeventer PI.

Morrison, Gilbert B McKinley High School.

Morse, Sidney^ University City, Mo.

Mudd, Harvey G 408 Humboldt Bldg.

Mueller, Ambrose^ Webster Groves, Mo.

Mumford, Frederick B.^ Columbia, Mo.

Nagel, Charles 3726 Washington Boul.

Nasse, August 2323 Lafayette Ave.

Nauer, Albert R 4634 Nebraska Ave.

Nicolaus, Henry 2149 South Grand Ave.

Nipher, Francis E Washington University.

Nisbet, Fritz 611 Locust St.

Noel, Alexander H 1323 Geyer Ave.

Nolker, William H Fifteenth and Pine Sts.

Norvell, Saunders LaSalle Bldg,

Ohlweiler, W. W 4026a Shenandoah Ave.

Olshausen, Ernest P 1115 Rutger St.

Opie, Eugene L Washington University,

Medical Department.

O'Reilly, Andrew J 1720 Pierce Bldg.

O'Reilly, Robert J 27 Washington Terrace.

Padberg, Aloys J 3900a Easton Ave.

Palmer, Ernest Jesse^ 321 S. Allen St.,

Webb City, Mo.

Pammel, Louis Hermann^ Ames, Iowa.

Pantaleoni, Guido 15 Lennox PI.

Parker, George Ward 501 Liggett Bldg.

xiv Trans. Acad. Sci. of St. Louis.

Parker, L. S.^ Jefferson City, Mo.

Payne, E. G Teachers' College.

Perkins, Albert T 401 North Fourth St.

Pettus, Charles P 33 Westmoreland PI.

Pettus, W. H. H 4373 Westminster PI.

Pitzman, Julius 1900 South Compton Ave.

Plant, Frederick S 802 North Main St.

Plass, Ada E 3248 Copelin Ave.

Post, Martin Hayward 5371 Waterman Ave.

Priest, Henry Samuel New National Bank of Com-
merce Bldg.

Prynne, Charles Martyn Century Bldg.

Pyle, Lindley 6116 Washington Boul.

Randolph, Tom 7 Kingsbury PL

Rassieur, Leo Fourth and Market Sts.

Rathmann, Charles G 3886 Hartford St.

Rau, Philip 4932 Botanical Ave.

Ravold, Amand 5248 Vernon Ave.

Reber, H. Linton Kinloch Bldg.

Reber, Maxime 301 New City Hall.

Reed, George M.^ 809 Virginia Ave.,

Columbia, Mo.

Reller, A. H 24 Gast PI.

Robarts, Heber Box 634.

Roever, William Henry Washington University.

Rolfs, F. M.^ Mountain Grove, Mo.

Rolfs, Peter H.^ Gainesville, Fla.

Rosenwald, Lucian^ 412 Delaware St.,

Kansas City, Mo.

Rowse, E. C Chemical Bldg.

Ruf, Frank A 5863 Cabanne PI.

Rusch, Henri City Hall.

Sampson, C. L 3029 Eads Ave.

Sampson. Francis A.^ Columbia, Mo.

Sargent, Charles Sprague^ Jamaica Plains, Mass.

Sauer, William E Humboldt Bldg.

Scanlan, Philip C 4450 Lindell Boul.

Schisler, Edwin 2600 South Grand Ave.

Schlueter, Robert E 909 Park Ave.

Schlueter, W. H.^ Kirkwood, Mo.

Members, xv

Schnell, L. W 4541 Varrelmann St.

Schramm, Jacob Missouri Botanical Garden.

Von Schrenk, Hermann Tower Grove and Flad Aves.

Schuricht, A. G 3236 Lafayette Ave.

Schwarz, Ernest 6310 Newstead Ave.

Schwarz, Frank 1813 Lafayette Ave.

Schwarz, Henry 440 North Newstead Ave.

Schwarz, Herman^ 720 Clark Ave.,

Webster Groves, Mo.

Schweyer, George 4252 Blaine Ave.

See, Thomas Jefferson Jackson^ . Naval Observatory,

Mare Island, Cal.

Selby, Augustine Dawson^ Wooster, Ohio.

Senter, Charles Parsons 1 Beverly PI.

Sexton, L.J Madison School.

Shaffer, Philip A Washington University,

Medical Department.

Shahan, William E 5234a Von Versen Ave.

Shannon, James I St. Louis University.

Shapleigh, Alfred Lee 3636 Delmar Ave.

Shapleigh, John B Humboldt Bldg.

Sheldon, F. E Chemical Bldg.

Shepley, John F 50 Vandeventer PI.

Shimek, B.^ Iowa City, Iowa.

Shoemaker, William Alfred. . . .4386 Westminster PI.

Simmons, E. C Ninth and Spruce Sts.

Simmons, Wallace D Ninth and Spruce Sts.

Skinker, Thomas K Pierce Bldg.

Sluder, Greenfield 3542 Washington Ave.

Smith, D. S. H 4388 Westminster PL

Smith, George M Washington University,

Medical Department.

Smith, Herbert A.^ 1948 Stewart Ave.,

Kansas City, Kan.

Smith, Irwin Z 87 Vandeventer PI.

Smith, Jared G.^ Kealakekua, Hawaiian Islands.

Spencer, H. N 2725 Washington Ave.

Standley, Paul C.^ Division of Plants, National

Museum, Washington, D. C.

Starkloff, H. M 3623 Cleveland Ave.

Starr, John E.^ 50 Church St., New York City.

Staudinger, B 3556 Lindell Boul.

xvi Trans. Acad. Sci. of St. Louis.

Stelzleni, G. M 1215 North Grand Ave.

Stennett, W. H.^ 203 Linden Ave., Oak Park,

Cook Co., 111.

Stevens, Charles D 5352 Vernon Ave.

Stevens, Wyandotte James 4448 Olive St.

Stinde, George C 5146 Waterman Ave.

Stix, Charles A Stix, Baer & Fuller Dry Goods

Company.

Stoeker, George J 2833 South Kingshighway Bl.

Strecker, John K., Jr.^ Baylor University, Waco, Tex.

Sultan, Fred W 112 North Second St.

Summa, Hugo Metropolitan Bldg.

Suppan, Leo 2648 Russell Ave.

Taussig, William 3447 Lafayette Ave.

Terry, Robert James Washington University,

Medical Department.

Thaeher, Arthur 5185 Lindell Boul.

Thomas, John R 4128 Washington Boul.

Thomasson, Hugh W Grand and Delmar Aves.

Thompson, Charles Henry Missouri Botanical Garden.

Thompson, Frank C 522 Big Bend Road,

Webster Groves, Mo.

Thompson, Henry C, Jr 4642 Cook Ave.

Thurman, John S 521 North Taylor Ave.

Timmerman, Arthur H 6400 Plymouth Ave.

Tittmann, Harold H 5024 Westminster PI.

Todd, Charles A 3723 Dehnar Ave.

Tuholske, Herman 465 North Taylor Ave.

Turner, Charles H Sumner High School.

Turner, Wilson P. H 411 OUve St.

Tuttle, Daniel S 74 Vandeventer PL

Van Ornum, John Lane Washington University.

Vickroy, Wilhelm Rees 2901 Rauschenbach Ave.

Walbridge, C. P Fourth and Market Sts.

Waldo, C. A Washington University.

Wallace, G. W.^ 532 Lee Ave.,

Webster Groves, Mo.

Walsh, Julius S Fourth and Pine Sts.

Watts. Millard F 5740 Cabanne PI.

Members. xvii

Weichsel, Hans 6400 Plymouth Ave.

Wells, Rolla 4228 Lindell Boul.

Werner, Louis Fullerton Bldg.

Wheeler, H. A 3437 Lucas Ave.

Whelpley, Henry Milton 2342 Albion PI.

Whitaker, Edwards 300 North Fourth St.

Whitelaw, George G 5825 Gates Ave.

Whitelaw, Oscar L 409 North Second St.

Whitten, John Charles^ Columbia, Mo.

Widmann, Otto 5105 Von Yersen Ave.

Wiedemann, H. E 1105 Holland Bldg.

Wielandy, Paul J Sixteenth and Locust Sts.

Wiener, Meyer 3854 Westminster PI.

Wiggins, Charles 32 Vandeventer PI.

Wilson, M. E Washington University,

Winkelmeyer, Christopher 4585 West Pine St.

Wislizenus, Frederick A Washington University.

Witt, Thomas D 4374 Laclede Ave.

Wolfner, Henry L 4563 Forest Park Boul.

Woodward, Calvin Milton 3013 Hawthorne Boul.

WoodAvard, Walter B Woodward & Tiernan Ptg. Co.

Wright, George M 4457 Westminster PI.

Zahorsky, John 1460 South Grand Ave.

Zellweger, John 1900 Adelaide Ave.

ABSTEACT OF HISTORY.

ORGANIZATION.

The Academy of Science of St. Louis was organized on
the 10th of March, 1856, in the hall of the Board of Public
Schools. Dr. George Engelmann was the first President.

CHARTER.

On the 17th of January following, a charter incorporat-
ing the Academy was signed and approved, and this was
accepted by a vote of the Academy on the 9th of February,
1857.

OBJECTS.

The act of incorporation declares the object of the
Academy to be the advancement of science and the estab-
lishment in St. Louis of a museum and library for the
illustration and study of its various branches, and pro-
vides that the members shall acquire no individual prop-
erty in the real estate, cabinets, library, or other of its
effects, their interest being merely usufructuary.

The constitution as adopted at the organization meet-
ing and amended at various times subsequently, provides
for holding meetings for the consideration and discussion
of scientific subjects ; taking measures to procure original
papers upon such subjects; the publication of transac-
tions ; the establishment and maintenance of a cabinet of
objects illustrative of the several departments of science
and a library of works relating to the same; and the
establishment of relations with other scientific institu-
tions. To encourage and promote special investigation
in any branch of science, the formation of special sections
under the charter is pro\dded for.

Abstract of History. xix

MEMBERSHIP.

Members are classified as active members, correspond-
ing members, honorary members and patrons. Active
membership is limited to persons interested in science,
though they need not of necessity be engaged in scientific
work, and they alone conduct the affairs of the Academy,
under its constitution. Persons not living in the city or
county of St. Louis who are disposed to further the
objects of the Academy, by original researches, contribu-
tions of specimens, or otherwise, are eligible as corre-
sponding members. Persons not living in the city or
county of St. Louis are eligible as honorary members by
virtue of their attainments in science. Any person con-
veying to the Academy the sum of one thousand dollars
or its equivalent becomes eligible as a patron.

Under the By-Laws, resident active members pay an
initiation fee of five dollars and annual dues of six dollars.
Non-resident active members pay the same initiation fee,
but annual dues of three dollars only. Patrons and
honorary and corresponding members are exempt from
the payment of dues. Each patron and active member
not in arrears is entitled to one copy of each publication
of the Academy issued after his election.

Since the organization of the Academy, 1,314 persons
have been elected to active membership, of whom, on
December 31, 1912, 378 were carried on the list. Six
patrons, Mr. Edwin Harrison, Mrs. Eliza McMillan, Mr.
William Northrop McMillan, Mr. Henry W. Eliot, Mr.
William Keeney Bixby and Mr. Edward Mallinckrodt,
have been elected. Elections to honorary membership
number 19 (page vi), and 226 persons (Vol. X., p. xii)
have been elected to corresponding membership.

OFFICERS AND MANAGEMENT.

The officers, who are chosen from the active members,
consist of a President, two Vice-Presidents, Recording
and Corresponding Secretaries, Treasurer, Librarian,

XX

Trans. Acad. Sci. of St. Louis.

three Curators and two Directors. The general business
management of the Academy is vested in a Council com-
posed of the olTicers.

The office of President has been filled by the following
well-known citizens of St. Louis, nearly all of whom have
been eminent in some line of scientific work: George
Engelmann, Benjamin F. Shumard, Adolphus Wislizenus,
Hiram A. Prout, John B. Johnson, James B. Eads, Wil-
liam T. Harris, Charles V. Riley, Francis E. Nipher,
Henry S. Pritchett, John Green, I\Ielvin L. Gray, Ed-
mund A. Engler, Robert Moore, Henry W. Eliot, Edwin
Harrison, Adolf Alt, Calvin M. Woodward, and William
Trelease.

MEETINGS.

The regular meetings of the Academy are held at its
building, 3817 Olive Street, at 8 o'clock, on the first and
third Monday evenings of each month, a recess being
taken between the meeting on the first Monday in June
and the meeting on the third Monday in October. These
meetings, to Vv^hich interested persons are always wel-
come, are devoted in part to the reading of technical
papers designed for publication in the Academy's Trans-
actions, and in i^art to the presentation of more popular
abstracts of recent investigation or progress. From time
to time public lectures, calculated to interest a larger
audience, are provided for in some suitable hall.

The following dates for regular meetings for the year
1913 have been fixed by the Council :

Jan

Feb

Mar

April

May

June

Oct

Nov

Dec

6

3

3

7

5

2

3

1

20

17

17

21

19

20

17

15

Abstract of History. xxi

LIBRAEY.

After its organization, the Academy met in Pope's
Medical College, where a creditable beginning had been
made toward the formation of a mnseiim and library,
until May, 1869, when the bnilding and museum were
destroyed by fire, the library being saved. The library
now contains about 18,500 books and 16,000 pamphlets,
and is open during certain hours of the day for consulta-
tion by members and persons engaged in scientific work.

PUBLICATIONS AND EXCHANGES.

Twenty-one octavo volumes of Transactions have been
published since the organization of the Academy, and
widely distributed. Two quarto publications have also
been issued : one from the Archaeological Section, being
a contribution to the archaeology of Missouri, and the
other a report of the observations made by the Washing-
ton University Eclipse Party of 1889. The Academy
now stands in exchange relations with 422 institutions or
organizations of aims similar to its own.

MUSEUM.

After the loss of its first museum, in 1869, the Acad-
emy lacked adequate room for the arrangement of a
public museum, and, although small museum accessions
were received and cared for, its main effort, of necessity,
was concentrated on the holding of meetings, the forma-
tion of a library, the publication of worthy scientific mat-
ter, and the maintenance of relations with other scientific
bodies.

The Museum is at present located on the third floor
of the xVcademy Building and has in it a number of
specimens illustrating the various branches of natural
science, among which may be mentioned the Yandell Col-
lection of fossils, a collection of some 600 exotic butter-
flies, a collection of Mound Builder pottery and skulls
from near New Madrid, Mo,, and a collection of 25
meteorites. Our material forms but a nucleus of a
museum which the Academy hopes to establish — a
museum which we trust will be of benefit to the public
and to the educational institutions of the city.

xxii Trans. Acad. Sci. of St. Louis.

EECORD.

Fkom January 1 to December 31, 1912.

The following list of papers were presented at the
meetings during this period:

January 2, 1912 :

A. S. Langsdorf. — Graphical Methods for Con-
structing the Characteristic Curves of Electric
Motors.

January 15, 1912:

A. E. EwiNG. — Sanninoidea exitiosa (Say) and San-
ninoidea opalescens (Hy. Edw.). Borers which
infest the peach tree root; examples of the in-
sects from the egg to the imago ; description of
the life history and the resulting tree destruc-
tion.

February 5, 1912 :

G. O. James. — Mechanical Flight.

February 19, 1912 :

C. H. Turner. — Experimental Study of Color Vision
and Pattern Vision of Bees.

(Published in Biological Bulletin, Vols. XIX and XXI.)

H. M. Whelpley. — Miniature Indian Baskets.

March 4, 1912 :

C. A. Todd. — A Problematical Geological Phenom-
enon in Colorado.

H. T. A. Hus. — Inheritance in Capsella.

F. E. Nipher. — Effect of a Sudden Draining of Neg-
ative Corpuscles from Matter.

March 18, 1912 :

E. J. Terry. — A Grove of Deformed Trees.

C. A. Waldo. — The Problem of Coal Exhaustion.

H. M. Whelpley. — Miniature Flint Arrows.

Record. xxiii

April 1, 1912 :

J. L. Van Ornum. — The Permeability of Concrete

and Methods of Securing Impermeability.
G. 0. James. — The Application of the Relativity
Law of Gravitation to the Motion of the Peri-
helion of Mercury.

(Published in Astronomical Journal, Vol. XXVII, 1912.)

F. E. NiPHER. — Effect of a Disruptive Discharge

Through a Fine Wire.
C. A. Waldo. — Multiplication Tables of Russian

Peasants.

April 15, 1912:

A. S. Langsdorf. — Transient Electrical Phenomena.
C. H. Turner. — Results of Recent Experiments on

the Homing of Ants.
A. E. BosTwicK. — Atomic Theories of Energy.

(Published in The Monist, October, 1912.)

Wm. H. Roever. — A Mechanism for Illustrating
Lines of Force.

May 6, 1912:

J. F. Abbott. — The Water Boatmen, an Unexplored
Corner of the Insect World.

C. M. Gill. — Recreation Studies in Estes Park, Col-
orado.

Fred Hecker. — Microscopic Studies of Living Or-
ganisms and Their Growth Rate.

May 20, 1912 :

A. S. Pearse. — Fiddler Crabs.

(Published in Philippine Journal of Science, Vol. 7, No. 3,
1912.)

Phil Rau. — The Life History of the Devil Horse

( Stagmomantis Carolina ) .

(Published in Transactions of The Academy of Science of
St. Louis, Vol. XXII, No. 1, 1913.)

June 3, 1912 :

F. E. NiPHER. — Electric Waves in Solid Conductors.
R. J. Terry. — The Development of the Cranium in

Mammals.
J, L. Van Ornum. — The Effect of Fatigue Tests and

of Moisture Upon the Elasticity of Concrete.

xxiv Trans. Acad. Sci. of St. Louis.

October 21, 1912:

G. 0, James. — On the Contingence of the Physical
Theory and the Problem of the Geologic Past.
G. 0. James. — Notice of the Death of Poincare.

November 4, 1912 :

F. E. NiPHEE. — Geissler Tube Effects in Solid Con-
ductors.

(Published in Transactions of The Academy of Science of
St. Louis, Vol. XXI, No. 3, 1912.)

M. E. Hard. — Mushrooms Found in the Vicinity of
St. Louis.

November 18, 1912:

J. F. Abbott. — Permeability of Animal Membranes.

(Published in Biological Bulletin, February, 1913.)

C. H. Turner. — The History of an Orphan Colony

of the Paper-Making Wasp, Polistes pallipes.

(Published in Psyche, December, 1912.)

H. M. Whelpley. — Indian Miniature Axes and Celts.

December 2, 1912 :

Wm. H. Roever. — The Design and Theory of a Mech-
anism for Illustrating Certain Systems of Lines
of Force and Stream Lines.

(Published in Zeitschrift fiir Mathematik und Physik,
1913.)

D. L. Harris. — Experimental Work on the Etiology

of Rabies and the Mechanism of Anti-Rabio Im-
munity.

(Published in Series of Articles in Journal of Infectious
Diseases, Vols. V, VIII, X, XI, 1908-12.)

December 16, 1912 :

LeRoy McMaster. — A Review of the Address of
Dr. E. A. Schaefer, on the Chemical Origin of
Life, before the British Association for the Ad-
vancement of Science.

(Published in Chemical News, London, Vol. CVI, Nos. 2754

and 2755.)

A. E. EwiNG.— The Plum Curculio; its Food, Abil-
ity to Stand Cold, Inability to Stand Drought,
Longevity.

Record. xxv

Meeting of January 2, 1912.

The Academy of Science of St. Louis met in the Acad-
emy Building, 3817 Olive Street, at 8 p. m., January 2,
1912; President Trelease in the chair; attendance 18.

The President delivered his address as President of
the Academy for the year 1911.^

The Treasurer's report for the year 1911 was sub-
mitted.^

The report of the Curators for 1911 was read.^

The report of the Librarian for 1911 was presented.®

The report of the Entomological Section was sub-
mitted.'^

The Nominating Committee reported the results of the
election of officers for 1912, as follows :

President E. A. Engler

First Vice-President P. E. Nipher

Second Vice-President A. E. Ewing

Recording Secretary M. E. Hard

Corresponding Secretary Geo. T. Moore

Treasurer H. E. Wiedemann

Librarian Wm. L. R. Gifford

Curators Julius Hurter

Joseph Grindon
Philip Rau

Directors Otto Widmann

Adolf Alt

Professor A. S. Langsdorf explained graphical meth-
ods for constructing the characteristic curves of electric
motors. These methods involve only straight lines and
circles.

January 15, 1912.

President Engler in the chair; attendance 18.

Dr. A. E. Ewing presented an illustrated account of
" Sanninoidea exitiosa (Say) and Sanninoidea opales-
cens (Hy. Edw.). Borers which infest the peach tree

' Transactions, Vol. XX, page xxxi.

* Transactions, Vol. XX, page xxxiii.
" Transactions, Vol. XX, page xxxiv.

• Transactions, Vol. XX, page xxxiv.
' Transactions, Vol. XX, page xxxiv.

XX vi Trans. Acad. Sci. of St. Louis.

root ; examples of the insects from the egg to the imago ;
description of the life history and the resulting tree de-
struction."

After describing the varieties of the S. exitiosa and the difference
between them and the S. opalescens, giving the history of the insects
and Beutenmueller's classification, examples were exhibited of the
eggs on the bark of the tree, on the gum from the base of the tree,
on leaves from the lower limbs of trees, and one on a trumpet vine
leaf that grew a foot from the base of a tree, all of which were ob-
served as they were laid and immediately collected, the collection hav-
ing been made at the Mountainboro orchard, Mountainboro, Alabama,
and at Gadsden, Alabama, between the first and the fifth of Septem-
ber, 1911. The exit of the larvae from these eggs was observed to be
from seven to nine days, the time of the one laid on the trumpet vine
was eight days.

For four successive seasons the life period of the insect had been
carefully noted at Mountainboro, and it was found to confirm for
northern Alabama the observations of Porter, Starnes and Shermau
for Georgia and North Carolina, and shows that in the Southern Alle-
ghany peach belt pupation begins about the first of August and the
moth appears the last week in the same month. In 1908, August 4th,
as many full grown borers were captured in this orchard of 15,000
trees as there were cocoons, the total number being 1,100. August
7th, 300 cocoons were captured and as many borers destroyed. In
this same orchard 8,500 cocoons were taken from the trees between
the 20th and 24th of August, in 1910. Two hundred of these cocoona
were placed in a wire cage on a southern covered porch. From these
25 moths emerged previous to September 5th, 46 between the 5th
and the 8th, inclusive, 29 between the 9th and the 13th, and after this
only two, one male the 16th, and another the 21st. The remainder
failed to develop.

Observations on the moths in the cage were that their activity de-
pends greatly upon the temperature; with it below 70° F. they are
very quiet, and very active when it is above 80° F. At night they
sleep with their antennae spread rather wide, some with the wings
moderately spread, usually, however, with the wings near the body
as when at rest, and the male with the tip of the abdomen strongly
turned upward. When awake and alert the antennae were erect and
near together as if indicating the facial expression of the insect. At
night they took no notice of an electric light right above them when
it was turned on and off. Thus caged they lived only three or four
days.

The 28th of August, 1911, fifty infested trees were examined. From
the half of the cocoons the moths had escaped. During the examina-
tion only one borer was found which had not yet begun its cocoon.
Throughout the orchard the moths were numerous, and in greater
numbers from the first to the fifth of September. On September 13th

Record. xxvii

only one moth was found, although a careful outlook was kept during
the middle of the day, the time when the imago is most active.

An exhibition was made of the larvae at numerous ages, from the
emergence from the egg to the time of spinning the cocoon, together
with an example of their destructive work on the tree, and numerous
mounted examples of the male and female moth of the S. exitiosa
type.

Also a cocoon was shown filled with the larvae of Bracon mellitor
(Say), and others filled with the cocoons of this ichneumon, the
parasite having been found in from one to two per cent of the S. ex-
itiosa cocoons examined.

Particular stress was laid upon the fact that only black and white
drawings of the insects were given in the various state and national
bulletins which were distributed throughout the country for the in-
struction of the orchardist, and lantern slides were shown from the
plates of Beutenmueller in which there were at least 75 other exam-
ples of Sesia, which in black and white would readily be confused
with this one by the laity. To be of any real value to the people all
government bulletins dealing with insects should contain exact col-
ored plates of the insects described in order to be Intelligible to those
not familiar with entomology. As an example, the owners and the
foreman of the Mountainboro orchard did not know the 8. exitiosa
until they saw it emerge from the cocoon, although all of them had
carefully read all the important government bulletins on the subject,
particularly those of Slingerland, Marlatt, and Starnes, and they had
owned and cared for the orchard for more than ten years. As the
moth flies only in mid-day it was unquestionably often seen by them
without being recognized.

The death of Mr. Samuel Cupples was reported.

Febkuary 5, 1912.

President Engler in the chair; attendance 25.
Dr. G. O. James addressed the Academy on the sub-
ject of "Mechanical Flight."

Dr. James divided the history of mechanical flight into four peri-
ods: the legendary, leading up to the Renaissance; the heroic, ending
with the XVIII century; the scientific, extending through the XIX
century, and finally the industrial, beginning with the present cen-
tury.

Passing over the first two divisions, the scientific period began in
1809, when Sir Geo. Cayley published the first complete mechanical
theory of the aeroplane, in which he put clearly in evidence the funda-
mental principle of sustention obtained by velocity. This memoir, pub-
lished in Nicholson's Journal, passed almost unnoticed until unearthed
some sixty years later by Penaud. Following Cayley there was a long
period of unfruitfulness. At the close of the Franco-Prussian War

xxviii Trans. Acad. Sci. of St. Louis.

interest in heavier than air flying machines was revived. Pgnaud con-
structed the first toy aeroplane with the propeller in the rear and
driven by a rubber band. This apparatus flew for an appreciable time,
utilizing motive energy which it carried with it, and this property dif-
ferentiates very sharply the experiment of Penaud from those of his
predecessors in which was realized only a fall more or less retarded by
the resistance of the air.

The German Lilienthal followed Penaud, and from 1891 to 1896
studied the equilibrium, manoeuvering and landing of gliders, falling
to his death on his two thousandth flight, August 9, 1896. In this
country the French engineer Chanute and the American Langley had
meanwhile been experimenting and developing the laws of aerody-
namics, Langley's v.ork going as far back as 1887 and continuing to
his unsuccessful attempts at flight in 1903. In 1891 he published the
results of his researches and definitely stated that it was possible to
construct machines which would give such velocity to inclined sur-
faces that bodies indeflnitely heavier than air could be sustained
upon it, and moved through it with great speed. For sixteen years,
Langley continued his efforts to attain mechanical flight, and this long
period of fruitful scientific achievement closed with failure due pri-
marily to lack of funds. Langley died February 27, 1906, about two
years before the Wright brothers astonished the world by their feats
in sustained flying in 1908.

Turning then to the mechanical principles underlying flying. Dr.
James discussed the distribution and action of forces on an aeroplane
in uniform horizontal flight in still air. If a uniform horizontal wind
is blowing, whatever be its velocity, the machine behaves exactly as
in still air except that its velocity relative to the ground is the result-
ant of its velocity in still air and the velocity of the wind. The effect
is exactly as if the machine flew in a volume of still air enclosed in
a great spherical envelope while at the same time this envelope is
carried along by the wind.

If the velocity of the aeroplane in still air is greater than that of
the wind the machine may move in any desired direction relative to
the ground, while if it is less it will be forcibly carried in the direc-
tion of the wind.

The mechanical theory of the behavior of the aeroplane in flight is
built on the hypothesis that "the normal thrust on the sustaining
plane is proportional to its area, the square of its velocity and to the
sine of the angle of attack." By mathematical deductions follows the
interesting result that the power expended is inversely proportional to
the velocity and directly proportional to the angle of attack, and the
advantages of a small angle of attack are evident. In this discussion
the passive resistances have been neglected and the power necessary
to drive the machine against these increases with the velocity so that
there is a minimum angle of attack and a maximum speed for a given
machine and motor.

Passing now to the question of stability, there are three types of
oscillations of an aeroplane which must be guarded against; rolling.

Record. xxix

pitching and gyration. After discussing these phases the speaker
passed to the future of the aeroplane.

That mechanical flight is possible is evident, but it is equally evi-
dent that the aeroplane even yet is at the mercy of the wind and one
of the most important advances of the future is some method of real-
izing certain stability of flight so that inequalities in air conditions
and variations in skill on the part of the aviator shall have but negli-
gible effect. It is desirable that the stability may be rendered auto-
matic while at the same time the machine is not deprived of all sen-
sitiveness but remains easy to manoeuver. Stabilization must be at-
tained by mechanical methods which call into play the stabilizing
devices at will by a mechanism of transmission. Theoretically either
pendular or gyroscopic masses may be used and brought into effective
play by the transmitting device.

It has already been pointed out that the speed required for susten-
tion depends on the angle of attack and increases as this angle de-
creases, while the power required to drive the sustaining plane
against the air resistance decreases with this angle. Theoretically
then at least, a given motor might drive an aeroplane at any desired
speed however high by flying it "close to the wind." Practically this
is not the case because of the passive resistances developed by mov-
ing the accessory parts of the machine through the air at high veloc-
ity. The resistance to flight offered by the sustaining planes is for
high velocities only a small fraction of the total resistance, and it
is very difficult to get even an approximate idea of the value of the
passive resistances. They are very considerable even for trains and
automobiles and for the greatest velocities actually attained by these
they absorb nearly all the driving energy. The problem of velocity
is then much the same for high speed machines whether they are
designed to move on the ground or through the air. Their principal
parts are the motor and its accessories, including the full reservoirs,
and the problem is essentially one of building a motor which will
develop sufficient power to drive itself, including the full tanks and
the rigid frame which carries it, against its own resistance.

The power of a motor is roughly proportional to its weight and a
motor of 100 horse power is capable of moving at 100 kilometers per
hour. A motor of 800 horse power, homothetic to the first and mak-
ing the same number of strokes per second will have a volume eight
times as great and hence a surface four times as great. The power
required to move this at the same velocity as before is then quadru-
pled, but since the power is now eight times as great as formerly
the velocity may be increased. How much? The passive resistances
are proportional to the square of the velocity and hence the power
required to overcome them is proportional to the cube of the velocity
and also to the resisting surface. But this resisting surface has been
quadrupled and hence the new velocity is only the cube root of two
times the old and cannot exceed 126 kilometers per hour. To raise
it to 200 kilometers per hour would require — on the same theory —
a 50,000 horse power motor. Very little is to be gained by increasing

XXX Trans. Acad. Sci. of St. Louis.

the power of the motor once its weight is such that the weight of the
pilot and its accessories is small in comparison, and large machines
cannot expect to make greater speed than moderate sized ones.

The architecture of the aeroplane is then seen to be the important
point for future investigation and machines with bodies so constructed
as to offer a minimum resistance for a given weight are the racing
planes of the future.

The death of Mr. Ernest E. Buckley was reported.

February 19, 1912.

President Engler in the chair ; attendance 36.

Dr. Chas. H. Turner addressed the Academy on ''Ex-
perimental Study of Color Vision and Pattern Vision of
Bees."

To those whose interest in the interrelations of insects and flowers
has been stimulated by the work of Spengel, Darwin, Mueller, Robert-
son and others, the most logical theory that has yet been proposed to
account for the colors and color patterns of flowers is the one which
asserts that colored flowers are for the purpose of causing the cross-
fertilization of plants.

This theory was held by practically all serious students until a
short time ago, when a reaction set in and a number of men came to
feel that, although the theory is plausible, there is not sufficient exper-
imental evidence to establish it. This change of view was brought
about by two things: first, the advent of the tropism theory of the
physiologists, and second, deductions based on morphological studies
of the insect eye.

After a discussion of these two conceptions, Dr. Turner described
a series of experiments which he had made. Dr. Turner argued that
if bees can distinguish colors and color patterns it should be possible,
first, to train bees to collect from artifacts of a certain color, if such
artifacts contain something of value to the insect; second, once hav-
ing learned to collect from such artifacts, the bees should be able to
select artifacts of that color under each of the following conditions;
■when the artifacts of that color pattern contain the thing of value
and none of the others do, when the artifacts of that color pattern
and some of the others contain the thing of value, when none of the
artifacts contain the thing of value.

Dr. Turner conducted two sets of experiments; one, to determine
if bees can distinguish between plain colors and the other to test the
ability of bees to distinguish between color patterns.

In the experiments of the first summer Dr. Turner found that
without a doubt bees can discriminate between solid colors, and his
experiments the second year proved conclusively that, after a bee
had learned, by experience, that artifacts bearing a certain color
pattern contained a more copious supply of easily obtained honey
than ordinary flowers, it would select artifacts bearing that color
pattern from those marked in a different way. This was true: first,

Record. xxxi

when several of the artifacts to be selected were scattered among a
number of plain artifacts of the colors used in making the color
pattern; second, when the artifact to be selected was scattered among
several other artifacts, some of which were plain and some of which
were marked with patterns unlike that of the artifact to be chosen;
third, when the only difference between the artifacts was that one
was marked with transverse and the other with longitudinal stripes;
fourth, when the artifacts to be selected contained the honey and the
others did not; fifth, when honey was to be found not only in the
artifact to be selected, but in some of the other artifacts also; sixth,
when none of the artifacts contained honey.

Dr. H. M. Whelpley spoke on ''Miniature Indian Bas-
kets."

Dr. Whelpley exhibited two specimens made by the Pomo Indians,
which were viewed by means of simple microscopes. The foundation
of the baskets is from the white leaf willow (Salix argyrophylla) and
is sewed with California sedge {Car ex tarharae). The baskets are
made in pattern black and white, the black being from the root of
the California sedge.

The larger basket is .ISx.lO inches, with the opening .06 inches
across and weighs 1/4 grain. The smaller basket is .10x.04 inches,
with an opening .04 of an inch across, and weighs 1/20 grain. Both
baskets are woven in the same manner as large baskets and care-
fully patterned.

The Pomo Indians, located in northern central California, are
noted for their basketry which is unrivaled in North America, for
workmanship, beauty and variety of design. The women are the
weavers but the smaller basket was made by a man, who is one of
the few men weavers among the Pomo Indians.

Dr. Geo. 0. James was elected to membership.

The death of Dr. Enno Sander, an honorary member
of the Academy, and for forty-eight years its Treasurer,
was reported.

Makch 4, 1912.

President Engler in the chair; attendance 48.
Dr. Chas. A. Todd addressed the Academy on *' A Prob-
lematical Geological Phenomenon in Colorado."

The remarkable arrangement of rocks, which Dr. Todd discussed,
is found in the northeastern mountainous district of Colorado, in the
region known as Estes Park, near Fern Lake.

After describing the topography of the region, Dr. Todd described
the particular locality. It is a conical pit, the sides of which slope
at an angle of about 45°. Its length is roughly 600 feet, its width
200, and its depth about 50. Adjoining and blended with this oblong
pit at its eastern end is a circular pit of the same general character.

xxxii Trans. Acad. Sci. of St. Louis.

The walls are of distinct masses of broken granite rock, chiefly
cubical, the largest near the top of the wall, the smallest at the bot-
tom. The edges of these rocks are as sharp as though freshly broken
out of a quarry.

What was the origin of these pits? Two theories have been ad-
vanced. One, that it is a great "blow out," i. e., volcanic in nature;
the other, that it is simply a glacial deposit.

As to the theory of volcanic origin, the fact that the fragments tend
to be cubical, are sharp angled, the largest lying in the highest
places, and the whole structure of the pit being so regular in plan,
would strongly suggest a violent local upheaval, due, say, to super-
heated steam, since there is nothing in the immediate neighborhood
to imply volcanic action accompanied by eruption of lava or ash.
Still, close to the Park is Specimen Mountain, which is said to abound
in pumice. In the canyon four miles distant huge blocks of rock
encumber the valley, having the appearance of having been thrown
down from the bordering mountains all at the same time. If by an
earthquake, it may have opened a crevice close to Fern Lake, letting
water into the depths to be suddenly converted into steam that burst
through the granite crust and left these pits to mark the site of the
explosion.

As to the second theory, that of glacial deposit, there is much in its
favor. The pits are directly over the course of a glacial stream, at
its lower end is the beginning of a great moraine.

At first glance the pits will call to mind the so-called "kettle holes,"
so common on the site of moraines. But if the theory of the origin
of kettle holes is correct, then our Estes Park cavities can hardly be
so classified. For it is supposed that the ice carrying upon its surface
the debris that is to form the moraine melts in such a fashion as to
cause the transported rock, sand, etc., to slide off and down, gradu-
ally forming a ring or oblong with the unmelted ice in the center as
a core. This core finally melting, a hollow is left — the kettle. The
sides fall in under the wash of rains or from the weight of the loose
material, so as to form slopes that may meet to make hollow cones or
troughs.

Now, in the Estes Park pits we have these configurations, but in-
stead of a loose, movable material, the walls are of angular rock
masses firmly jammed together and altogether incapable of any such
sliding movement.

So far the only solution of this mystery seems to be through a stout
derrick and some dynamite, backed by a good working squad, but in
the wilderness such aids to research are not readily at hand.

Dr. H. T. A. Hiis spoke on ''Inlieritance in Capsella.''^

" When Dr. Hus read this paper he left it an open question whether
new forms of Capsrlla were to be looked upon as hybrids or as muta-
tions sensu de Vries. Subsequent observations have enabled Dr. Hus
to explain new forms as the result of hybridization.

Record. xxxiii

Professor F. E. Nipher discussed his recent work on
the effect of a sudden drainage of negative corpuscles
from matter.

Maech 18, 1912.

President Engler in the chair; attendance 32.
The following donations to the Museum were re-
ported :

J. A. Drushell. . . 5 species of Ordovician Brachiopods,

2 species of Ordovician Bryozoa.
Mary J. Klem..A section of a fossil tree trunk from Veedersburg,

Indiana.

The following report of the committee, appointed by
the President to write a memorial to the late Dr. Enno
Sander, was read and ordered spread on the records of
the Academy.

The Academy of Science of St. Louis wishes to place upon record
Its great appreciation of the valuable service which has been rendered
to it by Dr. Enno Sander.

He became a member during the first year of its history, fifty-five
years ago. For nearly fifty years he served as its Treasurer. Much
of its success is due to the attention which he gave to its financial
affairs. In his death the Academy loses a valued supporter.

(Signed) FRANCIS E. NIPHER,
WM. TRELEASE,
ADOLF ALT.

Dr. Eobert J. Terry spoke on "A Grove of Deformed

Trees."

A grove of four or five hundred small persimmon trees in St.
Louis County has suffered from the ravages of a beetle which has
been identified as Oncideres cingulata. Limbs varying in diameter
from 5 to 15 mm. are girdled and the ends fall to the ground. All
the trees, old and young, have been attacked. The girdling is done
in the fall, mainly in September and October. During this time the
larger trees present scores of branches bearing dead leaves and the
ground is strewn with fallen branches often laden with fruit. Small
trees have, in some instances, lost several or all of their main limbs
in one season, in others been divided so near the ground that only
a short stump of the tree remains. The work is indeed a most com-
plete pruning; but the operation evidently does not consider the
future symmetry of the persimmon tree. Buds on the truncated limbs
develop an excess of branches the following spring, some of which in
turn are cut away at some future time. The highest latent buds of the

xxxiv Trans. Acad. Sci. of St. Louis.

seedling stump, which at first grow out at an angle, later assume
a more or less vertical direction and are adapted to the supporting
functions of the trunk. Many of these secondary trunks were found
girdled. There is no tree in the grove that does not present crooked
trunk and limbs. The deformities in some cases are extreme. Most
of the trees are as a consequence dwarfed, although able to make
some advance in growth. Some trees only a meter and a half tall
bore fruit in 1911.

A few beetles have been observed working. The girdling was be-
gun on the upper side of the branch and was made % mm. wide and
about 3 mm. deep. Most of the limbs fall, within a few days after
the girdling. A small proportion remain throughout the following
winter. On every severed branch, near the distal ends of the twigs,
one or more small deep excoriations of the bark were found. That
the beetle makes similar abrasions of the bark of twigs of the honey
locust is known from observations on Oncideres in captivity. Limbs
recovered from the ground in winter in some cases presented no evi-
dence of the propagation of the beetle, whereas in others more or less
of the wood has been destroyed under the bark along one side of the
branch, extending from the distal end proximally. The cavity never
quite reached the proximal severed end. Larvae which are now being
studied were discovered in some of the tunnels.

Professor C. A. Waldo then addressed the Academy
on "The Problem of Coal Exhaustion."

"Miniature Flint Arrows" was the subject of a short
paper by Dr. H. M. Whelpley.

Dr. Whelpley illustrated his remarks with over two thousand
specimens, varying in length from .06 to 1 inch. In form they rep-
resent all of the common types of ordinary arrows and were evidently
made by the same process of pressure chipping. Specimens have
been found in England, Spain, Belgium, India, Palestine, Egypt and
the United States. These artifacts belong to the Neolithic age. It has
been suggested, but without evidence, that they were made by a pygmy
race of human beings. It is also claimed that they were barbs for har-
poons, tattooing instruments, fish snags or drills for skin and shell
work.

Dr. Whelpley concluded that the medium size and larger miniature
arrows, such as are very plentiful along portions of the Missouri and
Meramec Rivers, were used as arrow heads. The most minute ones he
considers examples of skill in flint chipping, the same as the minia-
ture baskets made by the Pomo Indians today are merely examples of
skill in basketry.

April 1, 1912.

President Engler in the chair; attendance 25.
The Corresponding Secretary reported that he had
attended the celebration of the one hundredth anniver-

Record. xxxv

sary of the founding of the Philadelphia Academy of
Natural Science as the representative of the Academy.

Professor J. L. Van Ornum spoke on "The Permea-
bility of Concrete and Methods of Securing Impermea-
bility."

Professor Van Ornum reviewed the methods practicably applicable
to prevent dampness in rubble masonry foundation walls; that is, by
drainage or by an impervious coating of their exterior, or by both. He
then referred to the general use at present of concrete foundation
walls for important structures and the necessities for securing their
impermeability. This may be attained by constructing an impervious
diaphragm of a bituminous material; by an efficient surface coating,
preferably on the outside; by carefully securing a maximum density
by propeiiy proportioning the components of the concrete; or by mix-
ing with the concrete certain colloidal (or other) substances to secure
this result. The latter two methods have been experimentally investi-
gated in successive years as thesis work by H. P. McFarland, P. C.
Grace, S. Johnson, and W. K. Begeman. Their results agree in gen-
eral with those of others in concluding that, for any usual conditions,
the patented mixtures sold for this purpose vary in effectiveness
from very poor to very good; and that proper proportioning of the
constituents of the concrete to attain a maximum density, such as is
desirable to secure a maximum strength, will also effect practical
impermeability; but they differ from the conclusions of some others
in the fact that they found no advantage to result from the incorpo-
ration of such a material as hydrated lime in the richer mixtures.

The apparatus designed by the students for these experiments,
which gave pressure up to foi'ty pounds per square inch, was planned
to eliminate certain features of the experimental devices of other
tests which seemed objectionable to them; particularly in eliminating
tensile stresses from the specimens tested, with the resulting ten-
dency to form cracks. It is such development of the student's initi-
ative and his responsibility in adapting his methods to conditions so
as to secure the desired results which constitute the most valuable
experience in the work of graduation theses.

Dr. Geo. 0. James then addressed the Academy on
"The Application of the Relativity Law of Gravitation
to the Motion of the Perihelion of Mercury."

Professor F. E. Nipher gave a preliminary account of
work he has been doing on the effect of a disruptive dis-
charge through a fine wire.

Plante discovered that the wire buckles. He ascribed the phenom-
enon to rapid vibrations of more or less elastic matter, brought about
by the propagation of the "electric movement."

Professor Nipher is experimenting on a very delicately suspended
wire, with a view of determining whether the longitudinal thrusts

xxxvi Trans. Acad. Sci. of St. Louis.

are balanced under all circumstances. He suggests that the forces
which cause positive and negative ions in discharge through gases
and liquids to move in opposite directions are active in a metal con-
ductor.

Professor C. A. Waldo gave an interesting demonstra-
tion of how the Russian peasants can multiply any two
numbers, provided they know how to multiply and divide
by two.

For example, it is desirable to multiply 69 by 49. Divide 69 by 2
and multiply 49 by 2. Continue this process as indicated:

69 49

34 98

17 196

8 392

4 784

2 1568

1 3136

Then cancel in the second column all numbers opposite even quan-
tities in the first. Add the remaining figures, which will give 3381.
Multiply 69 by 49 according to the regular method and the result will
be the same, 3381.

Mr. Albert Briggs Lawver was elected to membership.

April 15, 1912.

President Engler in the chair; attendance 65.
Professor A. S. Langsdorf addressed the Academy on
'' Transient Electrical Phenomena."

The speaker showed that in most mechanical systems there is
stored a certain amount of energy, this energy being potential in
the case of stationary systems and kinetic in the case of moving
systems. When such a system changes from one condition to an-
other, the amount of the energy stored in it also undergoes a change
in magnitude, and this increase or decrease of energy must take
place in a finite time. The period during which the change of
energy occurs is the transient period. In some cases the energy is
stored in only one form, as for instance, kinetic energy (a moving
train being an example), and this energy must be gradually dissi-
pated in bringing the train to rest. In other systems the energy may
exist in two forms, potential and kinetic, as for instance, in a pen-
dulum, and in such a case the dissipation of the stored energy may
take place by an oscillation of the system.

Electrical circuits are in many respects analogous to the above
forms of mechanical systems. Energy may be stored in one form
only, such as magnetic energy only, or electrical energy only, or it

Record. xxxvii

may be stored in both forms simultaneously. In the first case, that
is, single energy circuits, the dissipation of energy is gradual; in
the second case the dissipation of energy takes place by means of
an oscillating current.

There was then discussed the question of the oscillating currents
that may be produced in a transmission line, and it was shown that
the oscillation may give rise to excessive and dangerous voltages and
currents which must be guarded against to prevent a breakdown.
Following this, the speaker discussed the conditions obtained in a
transformer at the moment of switching such a device on to a live
circuit, and it was shown that a transient condition existed for a short
period during which very excessive currents might be produced in the
transformer windings.

Finally, the short circuit conditions in large alternating current
generators were described, showing that dangerous rises of voltage
accompanied by a rush of current could occur, and the measures em-
ployed to prevent this condition were explained.

Dr. Chas. H. Turner gave an illustrated account of
''Results of Recent Experiments on the Homing of

Ants."

On account of the remarkable complexity of their behavior ants
have been studied by many investigators. For convenience these
students may be divided into four groups.

The first school, of which Bethe is the most noted member, claims
that ants are mere machines that respond to certain stimuli, always
with the fixed actions or set of actions. The most complex activities
of ants are but unconscious mechanical responses to diverse stim-
uli. In other words the life of these creatures is a round of mechan-
ical responses to tropisms. For them there is no content of con-
sciousness. Heliotropism, galvanotropism, stereotropism, polarized
trails, etc., explain all of their behavior. They do not learn. All re-
flexes may not be possible at birth, because the physical mechanism
is not yet perfected; but, once the mechanism has responded, there-
after under the same conditions, it always responds to the same stim-
ulus in the same manner.

The second school, to which may be assigned Pieron, admits that
reflex actions, some of which are connate and some of which are de-
ferred, do not fully explain the habits of ants. According to it, the
so-called instincts of these creatures are decidedly plastic. They
profit by experience; but not by associating present sensations with
revived sensations, nor by inference, nor by any of the higher forms
of rational thought, but by what Morgan, Thorndike and others have
called the method of trial and error.

The third school, to which belong Emery, Forel, Lubbock, Was-
mann and others, holds that ants have elementary feelings, elemen-
tary ideas, and even what the English have called association of
ideas, but that they do not have rational thoughts and emotions.

xxxviii Trans. Acad. ScL of St. Louis.

The fourth school, which includes L. Buchner, Huber, MacCook,
Romanes and others, Insists that the difference between human con-
sciousness and that of ants is one of degree and not of kind.

About ten years ago Dr. Turner began a series of experiments on
the behavior of ants, the aim of which was to see which of these
sets of men was right. Some of the results of these studies were pub-
lished in 1907. The purpose of this evening's paper was to discuss the
bearing of those experiments on the homing of ants and compare with
them the published results of experiments on the same subject con-
ducted by two independent workers, Cornetz of Algeria and Santsci
of Tunis. The experiments of these two men were performed during
the years 1909-1911.

From a series of experiments Dr. Turner came to the following con-
clusions:

1. The movements of ants are not tropisms and ants are not
guided by a homing instinct.

2. In their wanderings, ants are influenced by olfactory, topochem-
ical, optic, auditory, kinesthetic and tactile stimuli.

3. Ants have fairly definite impressions of direction in both hori-
zontal and vertical planes, and also impressions of distance.

4. Ants have associative memory and in their home-goings they
display marked individual variations.

Cornetz's experiments made in the field on ants in Algeria lead him
to the following conclusions:

1. There is no homing instinct, for ants that are carried away
from home cannot find the way back.

2. Ants are not lead home by the odor trail, because an ant never
returns to the nest along the path by which it left it.

3. Ants have memory of location and persistent sensory ideas of
direction and these have been acquired independently of vision, touch
or smell.

From field observations and field experiments on ants of Tunis Dr.
Santschi arrived at the following conclusions:

1. Among ants we find two kinds of trails; in one kind the ants
are guided largely by odors and topochemical sensations, in the other
they are guided by perceptions that are based largely upon visual
sensations.

2. Among the Tapinomas and, perhaps, other harvesting ants, the
trails are started by odors secreted intentionally by a single worker.

3. Such an intentionally scented trail is utilized by workers that
do not slavishly follow it, to teach other workers the way to the food.

4. This trace of odor is not sufficient to fully explain the behavior
of the ants guided by it.

5. As a rule orientation among ants is a complex phenomenon
based upon a variety of sense stimuli; the predominant stimulus de-
pending upon the species and the condition under which it is operat-
ing.

Record. xxxix

6. Odors, topochemical sensations, visual sensations, direction of
the rays of light, tactile sensations, auditory sensations form an idea
which serves as a flexible guide to behavior.

The final conclusion of all these experiments Dr. Turner summed
up as follows:

Ants are much more than mere reflex machines; they are self-act-
ing creatures guided by memories of past individual experience.
These associative memories are usually complexes of sensations con-
tributed by several different kinds of sense organs and include an
awareness of distances and of direction.

Dr. Arthur E. Bostwick read a paper on ''Atomic The-
ories of Energy."

A theory involving some sort of a discrete or discontinuous struc-
ture of energy has been put forward by Prof. Max Planck of the
University of Berlin. The various aspects of this theory are dis-
cussed and elaborated by M. Henri Poincare in a paper entitled
"L'Hypothese des Quanta," published in the Revue Scientifique (Paris,
Feb. 21st).

A paper in which a discontinuous or "atomic" structure of energy
was suggested was prepared by the speaker some flfteen years ago,
but not published. In the light of present radical developments in
physical theory this paper has historical interest. Planck's theory
was suggested by thermodynamical considerations, while in this
paper the matter was approached from the standpoint of a criterion
for determining the identity of two portions of matter or of energy.
A brief abstract of the paper is as follows:

"Physicists are divided into two opposing schools, according to the
way in which they view the subject of energy, some regarding It as
a mere mathematical abstraction and others looking upon it as a phys-
ical entity, fllling space and continuously migrating by definite paths
from one place to another.

"While we now believe that a material body can by no possibility
Increase continuously in mass, but must do so step by step, the min-
imum mass of matter that can be added being the molecule, we believe
on the contrary that the energy possessed by the same body can and
may increase with absolutely perfect continuity, being hampered by
no such restriction.

"At first sight both matter and energy appear non-molecular in
structure. But we have been forced to look upon the gradual growth
of a crystal as a step-by-step process, and we may some day, by
equally cogent considerations, be forced to regard the gradual in-
crease of energy of an accelerating body as also a step process, al-
though the discontinuity is as invisible to the eye in the latter case
as in the former.

"Modern views of the identity of matter seem closely connected
with modern views of its structure, and the same connection will
doubtless hold good for energy."

xl Trans. Acad. Set. of St. Louis.

The speaker read a letter addressed to him in criticism of this
paper by J. Willard Gibbs, in which the writer adduced certain gen-
eral objections to any atomic theory of energy.

In conclusion, after commenting on Prof. Gibbs's views in the
light of later developments, Dr. Bostwick presented in abstract Poin-
care's discussion of Planck's theory, which is that a physical system
is susceptible only of a finite number of distinct states; it leaps from
one of these to the next without passing through any continuous
series of intermediate states. The universe leaps suddenly from one
state to another; but in the interval it must remain immovable, and
the divers instants during which it keeps in the same state can no
longer be discriminated from one another; we thus reach a concep-
tion of the disdontinuous variations of time — the atom of time.

Professor Wm. H. Roever exhibited and explained "A
Mechanism for Illustrating Lines of Force. ' '

The mechanism consisted essentially of two wheels with radial
spokes (about 8 inches in diameter) which could be made to rotate
in nearly coincident planes and thus render visible the loci of the
intersections of the spokes. In the Transactions of the Academy, Vol.
VII, No. 9, p. 201, Professor Roever has shown for what fields of force
the systems of curves exhibited by this mechanism are the lines of
force.

May 6, 1912.

President Engler in the chair ; attendance 45.

The gift of a volume of ' ' Globus ' ' and one of ' * Natur-
wissenschaftliche Rundschau" from Dr. Edward Evers
was announced.

Professor James F. Abbott gave an interesting account
of "The Water Boatmen, an Unexplored Corner of the
Insect World."

Mr. Chas. M. Gill gave an illustrated lecture on ''Rec-
reation Studies in Estes Park, Colorado."

Mr. Frederick Hecker read a paper on ''Microscopic
Studies of Living Organisms and Their Growth Rate."

Dr. William Trelease was unanimously elected an
Honorary Member of the Academy.

May 20, 1913.

President Engler in the chair; attendance 62.

The following gifts to the museum were announced:

Dr. Joseph Grindon — Three Colubris from Guadeloupe, West In-
dies.

Record. xli

Dr. Wm. Trelease — Four rosaries made from seeds by the Alaska
Indians. Two pouches of sealskin (the hair seal or blubber seal),
made by the Alaskan Coast Indians. An Aleutian waterproof jacket
and belt, made of seal intestine. Relaxed by wetting these are
worn, the belt tightened about the waist and about the rim of the
bidarka or kayak — a skin boat.

Dr. A. S. Pearse gave an illustrated talk on "Fiddler
Crabs."

Mr. Pliil Rail read a paper on "The Life History of
the Devil Horse (Stagmomantis Carolina)/^

The death of Mr. J. J. Cole was announced.

June 3, 1912.

President Engler in the chair; attendance 25.

Dr. Wm. Trelease presented to the Academy a paper
weight — the original punch for the Engelmann medal on
the occasion of the semi-centenary of the Academy.

Professor P. E. Nipher addressed the Academy on
"Electric Waves in Solid Conductors."

Dr. Robert J. Terry presented some results of his
work on "The Development of the Cranium in Mam-
mals."

Professor J. L. Van Ornum spoke on "The Effect of
Fatig-ue Tests and of Moisture Upon the Elasticity of
Concrete. ' '

Six years ago the Civil Engineering Department of Washington
University made an extensive investigation of the effects upon con-
crete of repeated loadings, the number of repetitions generally run-
ning well into the thousands. Pertinent to the discussion of this
evening, that of "The Effect of Fatigue Tests, and Moisture Upon
the Elastic Properties of Concrete," are conclusions then reached
that, if the intensity of the repeated load exceeded about half the
ultimate strength of the concrete, the Modulus of Elasticity con-
tinually decreased after the first repetition until it became exceed-
ingly small just before failure; and if the repeated load was less
than the intensity just mentioned, the modulus decreased at first
but rapidly approached a constant value of about two-thirds the
maximum, and the failure of such specimen did not occur. These
experiments were of service in enabling a satisfactory fixing of
the equivalent elastic limit or yield point of concrete and so arrive
at safe working stresses in design.

The particular experimental investigations now reported by Pro-
fessor Van Ornum, as abstracted from a graduation thesis of a year

xlii Trans. Acad. Sci. of St. Louis.

ago, all involved loads below the yield point of the concrete, which
had an age of seven years, instead of a month, which is the usual
age at which tests have been made. Repetition on the dry speci-
mens not only verified the previous conclusion as to its capacity to
safely endure an indefinite number of repetitions, but unexpectedly
indicate that repeated loadings did not lower the Modulus of
Elasticity materially below its early high value, which was perhaps
ten per cent greater than at an age of one month. When saturated
for a few days preceding the experiments, the Modulus had a value
of about sixty per cent of the value when dry, and repetition of load-
ing in this case also did not materially change its first value.

Mr. Herbert A. Smith was elected to membersliip.

October 21, 1912.

President Engler in the chair ; attendance 32.

Dr. Geo. 0. James addressed the Academy '*0n the
Contingence of the Physical Theory and the Problem of
the Geologic Past. ' '

After reviewing the theories of Helmholtz, Mach and Enriques on
the Principle of Causality, Dr. James stated that so far as descriptive
representation of the present is concerned, it malies no difference
whether or not we admit that pushing precision of measurement
further and further we shall ultimately come to a point where
there ceases to be accord between observation and theory, and be-
yond which it cannot be again established. Even adhering to this
conception of the contingent nature of the world of experience, we
may still assert that the results of observation agree with those of
theory to within errors which can be assigned. Experience alone,
however, does not justify us in concluding that successive approxi-
mations will make these outstanding errors as small as we please,
although this has long been the scientific conception. Admissible
or not, this conception must be referred to some postulate of knowl-
edge— the causal postulate as formulated by Enriques, for instance —
and becomes a metaphysical question.

On the other hand, we may ask ourselves what we lose by denying
this exactness to the laws of nature, and reasoning on the basis of
the existence of an approximate physical theory only, which need
never become rigorously exact no matter how large be the circle of
phenomena taken into consideration, nor how precise the observa-
tions.

Painleve's assumptions are:

1st. It is possible to adopt for all time and for all phenomena
such a measure of length and such a measure of time that the
principle of causality will be true always and everywhere.

2nd. It is possible to adopt for all time and for all measurements
of the universe, such a system of reference that the laws of mechanics
will be true always and everywhere.

Record. xliii

This is the admission of a rigorous solution for the general prob-
lem of celestial mechanics, of which Anding's statement: "The
problem of celestial mechanics is the representation of the motions of
the heavenly bodies by means of the Newtonian Law of Gravitation,
while at the same time the constants entering that representation,
and the system of reference and the time are so determined as to
give the best possible representation," is too narrow in that he as-
signs the law of attraction, and so fixes the form of the equations of
motion.

The existence postulate of the planetary problem may be written:
"It is possible to choose for the Solar system measures of length and
time, a set of masses, a system of reference and a law of force, such
that the behavior of the system is representated."

Does such a choice exist? The question may be stated in two
essentially different ways:

A. Does a choice exist such that the resulting equations repre-
sent the behavior of the system to within errors less than the prob-
able errors of observation in the neighborhood of a given epoch?

B. Does a choice exist such that the resulting equations rigorously
represent the behavior of the system for all time?

An affirmation of B may be termed the Postulate of Causality, and
a denial of B, but an affirmation of A, the Postulate of Contingence.
It will be of interest to inquire into the answer to A by examining
the degree of approximation attained in the representation of the
motions of the solar system.

Using mean solar time, the masses of theoretical astronomy, the
trihedron of the fundamental catalogue, and the Newtonian law of
attraction, we find that the outstanding differences for the following
are:

1. Mercury: A secular perturbation in the longitude of the
perihelion of 41" a century.

2. Venus: A secular perturbation in the longitude of the node of
10" a century.

3. Mars: A secular perturbation in the longitude of the peri-
helion of 8" a century.

4. Moon: A difference of about 5" a century between the theo-
retical and observed values of the acceleration of the longitude.

5. Encke's Comet: A shortening of about 2i/^ hours in its 3.3
year period at each revolution.

Various attempts at modifying the planetary theory proving un-
satisfactory, Seeliger in 1906 so modified the solar system itself
as to remove the difference in the motions of Mercury, Venus and
Mars.

So far as Encke's Comet is concerned, it is now recognized that
the presence of a resisting medium in the neighborhood of the sun,
as first assumed by Encke himself, is not an adequate explanation
of the variation in its period and it remains one of the outstanding
problems.

xliv Trans. Acad. Sci. of St. Louis.

The disagreement in the observed and theoretical motion of the
Moon has led to an attempted modification of the measure of time,
and to the substitution of an inertial time gaining nine seconds
a century on the mean solar time. This would remove the difference
in the Moon's longitude.

The truth of A is established through experience quite inde-
pendently of B, and so far as a representation of the behavior of the
solar system throughout historic time is concerned, the Postulate of
Contingence is sufficient. What then is the positive content of the
postulate of causality which makes its retention essential to the
existence of science? It is this:

The Postulate of Causality builds the program according to which
we must envisage the geologic past, and prescribes the confines
within which expectation places the future.

Without it neither would exist for us. Affirming B is equivalent
to postulating the existence of a geologic past and a future accessible
to us through a physical theory satisfying the requirements of A.
The present planetary theory adequately represents the behavior of
the solar system throughout historic time, but extended into the
geologic past, it pictures a system without observational control.
The past is constructed on the assumption of a permanent planetary
theory, and if this theory does not possess permanence the past cer-
tainly furnished no means of detecting it.

Once the Postulate of Causality is replaced by a mere contingent
coherence of phenomena, the past ceases to be and the mental horizon
lies entirely in the world of experience. The data of that world
may be ordered in any way that fits it, and the complex of rela-
tions connecting such data is controlled solely by the resulting errors.
The problem is to make these as small as possible by continuous ad-
justment, and experience itself furnished no ground for belief that
these outstanding errors themselves constitute an ordered group.
They stand always, a chaotic totality, between the physical theory
and the world of experience, preventing us from regarding that
world as subject to law in the sense that relations are rigorously
satisfied by its phenomena. Suppose then that we replace this world
of experience by a fictitious world governed by a causal principle and
osculating the world of experience during the present. This fictitious
world will possess both a past and a future rigorously reducible from
its present, and the postulate of causality identifies the past and the
future of this fictitious world with the past and future of the world
of experience, and so creates both for the world of experience.

Does a past or future created in accordance with the Postulate of
Causality possess reality? The older point of view, which regarded
empirical verification as a proof of reality, which nevertheless did
not cease to exist even when all connection between the external
world and its representation was broken, has given way to a mod-
ern conception of reality of which invariance is the criterion, but re-
gards this invariance as relative and approximate.

Record. xlv

Notice of the Death of Poincare.

Dr. James then read the following :

Mr. President and Members — It seems fitting that on
this, the first meeting of the Academy since Spring, we
should express our recognition of the loss which science
has suffered in the death of M. Jules Henri Poincare,
Member of the Institute of France and Professor of
Celestial Mechanics in the Sorbonne.

M. Poincare died in Paris on July 17 of an embolism after a two
weeks' illness, and on July 19 after the religious ceremonies at
the Church of Saint-Jacques-du-Haut-Pas, the funeral procession
passed to the cemetery of Montparnasse, where lie also his friends
Tisserand and Callandreau, who preceded him by but a few years.

Eulogies were delivered by M. Claretie, Director of the French
Academy; by M. Lippmann, President of the Academy of Science; by
M. Plainleve, of the Institute; by M. Appell, Dean of the Faculty of
Science, and by M. Bigourdan, President of the Bureau of Longitudes.

M. Poincare was born at Nancy, April 29, 1854, received the de-
gree of Doctor of Science from the University of Paris in 1879, and
in 1881, at the age of 27, was offered the chair of Mecanique Physique
by the Faculty of Science. In a period of 30 years he occupied suc-
cessively the chairs of Mechanics, Mathematical Physics, Mathemati-
cal Astronomy and Celestial Mechanics.

In 1887, at the age of 33, he was elected to the Academy of Science,
and in 1908 to the French Academy. He became a member of all the
National Academies of Science of the world of the first class before
he was 40, the only scholar ever accorded that honor.

In 1885 he was awarded the Poncelet prize, and in 1896 the Regnaud
prize, both by the French Academy of Science. In 1889 he received
the King Oscar II prize, in 1900 the gold medal of the Royal
Astronomical Society, in 1901 the Sylvester medal, in 1904 the
Lobachevsky prize, in 1905 the first award of the Boylai prize, and in
1909 the gold medal of the French Association for the Advancement
of Science.

His memoirs and papers exceed fifteen hundred, and his published
volumes cover almost the entire field of mathematical physics and
astronomy.

In celestial mechanics alone his work would suffice for his glory.
In 1887 King Oscar of Sweden established an International Con-
gress of Mathematics, and it was the great medal of gold which was
adjudged to Poincare in 1889 for his study of the mechanical stability
of our universe.

Year after year this intellectual giant attacked new problems and
opened up new solutions for those that had long baffled the ablest

xlvi Trans. Acad. Sci. of St. Louis.

minds. Whatever he touched yielded to the mai-velous power of that
great thinker, until all France knew that there lived among them
a man capable of comprehending and adding to the accumulated
knowledge of all time, un "cervcau consultant" of human science.
The scientific world envied France his possession, and nations with
no reason to love her bowed down before the genius of her son, and
accorded her respect because of him.

His was a life of profound and uninterrupted meditation — medita-
tion despotic and pitiless, which stoops the shoulders and furrows the
brow. Too soon he exhausted the body which he inhabited.

Toward the end of this magnificent intellectual career, which was
the admiration and envy of the world, he turned the power of his
mind to certain philosophic questions, profoundly conscious that na-
ture was at last about to break him who had wrested so many
secrets from her. The foundations of science trembled under his
hands, but his was ever a constructive criticism, and he labored
for truth, the high goddess whose servant he was.

A great thinker is dead, one of the greatest of all time. For him
life was but a short episode between two eternities of death, thought
but a gleam in the midst of a long night, but through the centuries
science will bear the impress of the mighty mind of Henri Poincare.

A motion was carried that the Academy record in its
minntes the death of M. Poincare and that Dr. James'
paper be inckided in full in the record.

The Corresponding Secretary was requested to convey
to Mrs. Russell Sage the appreciation of the Academy
for her gift of $250,000 for the purchase of Marsh Island
to be used as a reservation for the protection of bird life.

The death of Dr. W. J. McGee, a Corresponding Mem-
ber, was reported.

November 4, 1912.
President Engler in the chair ; attendance 35.
Professor F. E. Niplier addressed the Academy on
''Geissler Tube Effects in Solid Conductors."

Professor Nipher gave a verbal account of work supplemental to
that published in his last paper (Transactions Academy of Science of
St. Louis, Vol. XXI, No. 3). This work has reference to the longi-
tudinal creeping of a copper wire through which spark discharges
are passed.

Mr. M. E. Hard gave a brief talk on ''Mushrooms
Found in the Vicinity of St. Louis," illustrating his re-
marks with fresh specimens.

Messrs. Robert A. Hall and W. H. Schlueter were
elected to membership.

Record. xlvii

No\^MBEK 18, 1912.

President Engler in the chair ; attendance 31.
Professor James F. Abbott addressed the Academy on
^'Permeability of Animal Membranes."

The "Fiddler Crabs" of the genus Uca accommodate themselves
readily to immersion either in fresh or salt water, or to life in the
open air.

This is due to a special mechanism for storing water in a capacious
gill-chamber. When the gill-chamber is opened and rinsed out, they
do not live longer than four hours in pure distilled water. Under
such circumstances they gain in weight by the absorption of water,
and lose salts to the surrounding medium by diffusion. They will
live indefinitely in a mixture of NaCl and KCl of much lower concen-
tration than that of sea water, although either salt is toxic by itself
in the same concentration.

Dr. C. H. Turner gave a short talk on ' ' The History of
an Orphan Colony of the Paper-Making Wasp, Polistes
pallipes."

A colony of this wasp, consisting of nine capped cells containing
pupae and fifteen open cells containing larvae, had been deprived
of its "widow mother" and transferred to an insectary. This paper
was a discussion of some incidents in the life of the wasps that
emerged from the cells of that nest. The following conclusions were
reached :

1. These wasps, which had never seen their mother nor associ-
ated with other wasps, performed all of the ordinary activities of
such wasps except egg-laying and paper-making.

2. Large larvae that had nearly completed their larval, after
fasting for eight days, then feeding on honey for two days and on
their normal diet for the remainder of their larval life, spun normal
cocoons and emerged normal wasps. Young larvae when submitted
to this treatment died. Two large larvae after fasting for eight days
and feeding on honey for two days, wove normal cocoons and
emerged normal wasps. This result was a surprise, for Fabre's
experiments on several different wasps (not of this species) has
caused the belief that hymenopterous larvae that feed on insect food
will die if fed honey.

3. After being restricted to a honey diet for several days, these
wasps became cannibals, upcapping a pupal cell and feeding on the
contents of the pupa.

4. From the first the wasps were so tame that they would ac-
cept honey or insect food when offered them on glass rods, steel
spatulas or the fingers.

5. Lepidopterous larvae captured for food are not stung. Grasp-
ing the caterpillar with her forelegs, the wasp rotates it on its longi-
tudinal axis and gradually elevates the insect while she malaxates
the posterior end until her jaws are filled with a ball of pulpy

xlviii Trans. Acad. Sci. of St. Louis.

matter. The remainder of the insect is then dropped. This is quite
unlike what Belt found to be the case in Polistes carnifax.

6. Several of the small larvae died. The wasp that was acting
as nurse would enter the cells and attempt to feed these dead wasps.

7. The behavior of these wasps indicated that, in finding their
way home, they were guided in part by associative memory.

"Indian Miniature Axes and Celts" was the subject
of a talk, illustrated with lantern slides and specimens
by Dr. H. M. Whelpley.

stone axes of utility range from four to six pounds and those of
hematite from one-half to four pounds. Ordinary axes occur not weigh-
ing more than three ounces. Miniature axes form a class by themselves
in weight below one-half ounce. The usual miniature ax weighs
about one hundred grains. They are similar in shape to ordinary
axes. The workmanship is usually very good. They are generally
made of granite or hematite and are found where axes of utility
occur. The purpose for which they were made is problematical. It
has been suggested that they were toys for children, ornaments,
amulets for medicine men or examples of expert workmanship.
They are usually found on village sites or picked up in the field.
Fraudulent miniature axes are more plentiful than genuine. They
are usually made from material which is readily worked and sel-
dom equal the genuine article in finish.

Of four hundred stone celts in Dr. Whelpley's collection, 74 per
cent weigh between four ounces and two pounds. Three hundred
and fifty hematite celts in the same collection average about two
ounces each. Miniature celts, like miniature axes, are separated
from those of normal size by a wide line of demarcation in weight
and size. Scarcely any normal celts occur below three ounces or
hematite celts below one-half ounce in weight. Miniature celts
weigh about one hundred grains each. They are not faked to the
same extent as are miniature axes. The comments on shape, work-
manship, material, distribution, use and conditions of finding minia-
ture axes also apply to miniature celts.

It has not been suggested that miniature axes and celts were
made by a race of dwarfs. Such claim has been made to explain
miniature flint arrows. The speaker estimated that miniature axes
and celts occur in about the proportion of 1 to 5000 of those of nor-
mal size.

Messrs Benjamin M. Duggar and LeEoy McMaster
were elected to membership.

December 2, 1912.

President Engler in the chair; attendance 25.

Professor Wm. H. Roever read a paper entitled "The
Design and Theory of a Mechanism for Illustrating Cer-
tain Systems of Lines of Force and Stream Lines."

Record. xlix

In this paper, which includes the theory of the mechanism exhibited
at the meeting of April 15, 1912, it is shown that not only for radial
spokes, but also for spokes in the form of logarithmic spirals, the
mechanism illustrates lines of force. By having several pairs of
wheels with different systems of logarithmic spirals (in particular,
of radial lines) it is possible, in virtue of the device for obtaining
different angular velocity ratios, to obtain a great number of dif-
ferent systems of curves, each of which may be regarded as lines
of force or stream lines in five or six different branches of mathe-
matical physics. It is possible, by making time exposures, to obtain
well-defined photographs of these systems of curves. This possibility
adds to the usefulness of the mechanism. The mechanism and pho-
tographs of some of the systems of curves were exhibited.

Dr. D. L. Harris read a paper on ''Experimental Work
on the Etiology of Rabies and the Mechanism of Anti-
Rabio Immunity."

Professor W. H. Roever, Mr. Frank Schwarz and Dr.
R. J. Terry were elected a committee to nominate officers
for the year 1913.

December 16, 1912.

President Engler in the chair; attendance 32.
The following report of the Nominating Committee
was read:

St Louis, Mo., Dec. 16, 1912.
The Academy of Science,

St. Louis, Mo.

Gentlemen: The nominating committee, appointed at the meet-
ing of December 2, 1912, begs to submit the following nominees for
oflBces for the year 1913:

For President Edmund A. Engler.

For First Vice-President Francis E. Nipher.

For Second Vice-President Arthur E. Ewing.

For Recording Secretary J. A. Drushel.

For Corresponding Secretary Geo. O. James.

For Treasurer ,H. E. Wiedemann.

For Librarian Wm. L. R. Gifford.

For Curators Julius Hurter, Philip

Rau, Hermann von
Schrenk.
For Directors Adolf Alt, H. M. Whelp-
ley.
Respectfully submitted,

(Signed) Wm. H. Roeveb,
Frank Schwaez,
Robert J. Terry.

1 Trans. Acad. Sci. of St. Louis.

Professor LeRoy McMaster gave a review of the ad-
dress of Dr. E. A. Schaefer, on the '' Chemical Origin of
Life," before the British Association for the Advance-
ment of Science.

Dr. A. E. Ewing gave some of the results of his inves-
tigations on the plum curculio : its food, ability to stand
cold, inability to stand drought, longevity.

A series of experiments with the plum curculio, conducted during the
summers and the winter of 1908 and 1909, showed that the fruit of the
plum or of the peach tree is not essential to the life of the adult being,
45% of the insects that survived the winter living until the last of
May, 20% until the middle of June, 10% until the first of July and 3%
until the first of August, although in captivity and fed only on fresh
plum and fresh peach leaves. While they always showed a strong
preference for plum and peach leaves, they also ate apple leaves, celery,
cabbage and bits of Irish potato vines. Quince, willow and rose vine
leaves were eaten sparingly. Attempts were made to eat the pear leaf,
but the epidermis seemed to be too tough. The leaves of the maple,
black and v.'hite mulberry, haw, wild and cultivated cherry, wild plum,
raspberry, grape vine and honeysuckle were not touched. Fresh slices
from winter apples and also dried peaches were readily eaten, and dried
peach and cultivated plum leaves after having been moistened in
water.

For a single, apparently thoroughly satisfying meal a curculio was ob-
served to cut a hole 1.5x4.5 mm. in size in a fresh, green plum leaf in
two and one-half hours. The action of the snout, as seen under a hand-
glass, was similar to that of the head of a sheep or a cow while grazing.
The accompanying halftone (Fig. 1) shows the peach leaves eaten by
18 curculio from September 20 to 26, 1909, while in captivity in a
Mason jar. The companion halftone (Fig. 2) shows the control leaves
which were in an adjoining jar.

During the winter a number of curculio were kept in jars covered
with tarlatan, near a window in the celler, where the temperature
was never below 50° F. They continuously fed on moistened dried
peach and plum leaves and slices from fresh winter apples and bits from
dried peaches, though not with the avidity as in the case of the
fresh leaves of the spring and summer.

The ability to stand cold was evidenced by the following experiment:
A tin can, five inches in diameter and eight inches deep, capped with
fine copper wire mesh, was filled to five inches with earth and sunk five
inches in the ground in the back yard, numerous fine holes having been
punched in the sides and bottom to admit moisture and to prevent
the entrance of ants. In this can twenty-five curculio were placed
November 1st, 1908, together with a handful of dried plum leaves and
several slices of dried peaches. On the 7th of the following March,
which was a bright warm spring day, ten of the curculio were found
alive among the leaves. These were removed from the can. On the

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate A.

FIG. 1. PEACH LEAVES EATEN BY 18 CURCULIO FROM SEPT. 20th TO 26th, 1909,
WHILE IN CAPTIVITY IN A MASON JAR.

FIG. 2. CONTROL PEACH LEAVES WHICH WERE IN AN ADJOINING JAR FOR
THE SAME LENGTH OF TIME AS THOSE IN FIG. 1.

Record. li

4th of April, 1909, a further very careful examination was made and
fourteen others were found aliva, in all twenty-four out of twenty-flve
that had survived the winter. The weather report shows thai in Janu-
ary, 1909, the temperature ranged as follows: Sixth, 2 degrees; 7th, 1
degree; 10th, 9 degrees; 11th, 5 degrees, 12th, 3 degrees, 29th, 7 degrees;
30th, zero; 31st, 1 degree below zero, which would have frozen the
ground to a depth greater than five inches. This refutes the idea,
which obtains in our Southern states, that the insects are killed
by the cold. What really takes place is that the fruit is killed by the
cold and this destroys the nesting place for the insect, the result of
which is one or two years of sound fruit. It is of further interest
that the plum leaves in the can were full of holes, as if they had been
fed upon during the warm days of the winter and spring when the cur-
culio were not torpid.

One of the jars in the cellar was permitted to become dry as the
Winter progressed. The curculio in the jar all died, although it was the
hibernating season. This lack of ability to stand drought is the prob-
able explanation of why the fruits from the Pacific Coast are free from
the pest.

It is shown above that a considerable percentage of the curculio that
have successfully passed the winter will live till June or July. In this
series of experiments one lived until September 12th, and in another
series, conducted during the summer of 1910, one survived until August
21st, an evidence that the curculio of the preceding year are in the
orchard until after the usual season for gathering the peach crop.

lii Trans. Acad. Sci. of St. Louis.

EEPORTS OF OFFICERS.

Treasurer's Report.

Receipts.

Balance from 1911 $ 26.84

Dues from members 2,002.00

Rent from tenant societies 610.00

Telephone (Engineers' Club) 10.00

Academy's Transactions sold 50.50

Interest on balance .71

H. E. Ewing (toward printing paper) 33.06

Income from endowment fund 788.76

Total receipts for the year $3,521.87

Expenditures.

Salaries $1,380.00

Water license 24.61

Gas, electric light and power 118.11

Fuel '. 324.93

Telephone 54.25

Printing 822.12

Current expenses 329.78

Fire Insurance (5 years) 120.00

Total expenditures for the year 3,173.80

Balance December 31, 1912 348.07

$3,521.87
Respectfully submitted,

(Signed) H. E. Wiedemann,

Treasurer.

Librarian's Report.

The Librarian reported that the accessions to the library for the year
1912 by exchange with 114 home and 308 foreign societies amounted to
589 volumes and 263 pamphlets, by donation 71 volumes and 110
pamphlets, and by purchase 4 volumes.

The Transactions for the year were sent to 114 home and 308 foreign
societies.

Curators' Report.

The Curators reported that during the year donations were received
from:

J. A. Drushel. — Five species of Ordovician Brachiopods and two spe-
cies of Ordovician Bryzoa.

Joseph Grindon. — Three Colubris from Guadeloupe, West Indies.

Mary J. Klem. — Fossil tree trunk from Veedersburg, Indiana.

Wm. Trelease. — Four rosaries made of seeds by Alaska Indians. Two
pouches made of sealskin by Alaska Indians. Aleutian waterproof
jacket and belt made of seal intestine. Paper weight of the original
punch for the Engelmann medal of the fiftieth anniversary.

Transactions of The Academy of Science of St. Louis.

VOL. XXI. No. 1.

THE ORIGIN AND SIGNIFICANCE OF PARASITISM

IN THE ACARINA.

HENRY ELLSWORTH EWING.

Issued June 18, 1912.

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LIBRARY
NEW YORK
BOTANICAL,

GARDEN

THE ORIGIN AND SIGNIFICANCE OF PARASI-
TISM IN THE ACARINA.*

Henry Ellsworth Ewing.

In the study of the origin and significance of parasi-
tism in the Acarina one is confronted by conditions ex-
tremely complex, on account of the great variety in the
forms met with and the complicated symbiotic relations
involved. In the preparation of the present paper the
writer made many and extended field observations of
these minute creatures, covering a period of several
years; and these have been supplemented by laboratory
experiments.

In my treatment of the subject of parasitism in the
Acarina special attention will be given to three aspects
of the question:

The causes leading to the origin of the parasitic habits,
and the subsequent development of these habits.

The analysis and classification of the various aspects of
parasitism.

The significance of distribution according to host spe-
cies.

In regard to the first of these aspects, altogether too
little has been done by the way of scientific research,
and scarcely nothing in the Acarina. In this country
Professor H. Osborn has studied the origin and develop-
ment of the parasitic habit in epizoic insects.

In regard to the second aspect it appears that as yet
CM we are without a very complete and analytical classifica-

cn

,— J • Presented by title to The Academy of Science of St. Louis, Febru-

,.^ ary 19, 1912. Presented to the faculty of the Graduate School of Cor-

Q_ nell University for the degree of Doctor of Philosophy, June, 1911.

K (1)

2 Trans. Acad. Sci. of St. Louis.

tion of the various kinds of parasitism, notwithstanding
the fact that the various symbiotic and other relation-
ships involved in the habits of parasites have received
the serious attention of parasitologists for years. It
might be mentioned, however, that a few years ago Stiles
compiled a list of the various kinds of parasites,^ as
recognized by different workers, and tabulated them ac-
cording to the basis upon which they were made.

In regard to the third point, the significance of dis-
tribution according to host species, much more has been
done, but scarcely anything in the Acarina ; although here
there is perhaps, one of the very best groups in which
to study it. Professor Kellogg of Stanford University
has made an extensive study of the distribution accord-
ing to host species in the Mallophaga.

The chief work upon this paper was done in the Ento-
mological Laboratory of Cornell University, and in its
preparation I have become indebted to several persons,
but especially to Professor Comstock, and to Dr. W. A.
Eiley, who has made an extensive study of parasitism.
Professor V. L. Kellogg has also made suggestions which
have been especially valuable, since he has made a thor-
ough study of somewhat similar problems in the Mallo-
phaga, and Dr. E. H. Wolcott of the University of Ne-
braska has supplied me with valuable data in regard to the
habits of the ' ' "Water Mites. ' '

Definition of Paeasitism.

But few terms exist in the biological literature of such
common usage as the term parasitism, yet few are so dif-
ficult of definition or so incapable of proper limitations.
Many attempts have been made to define parasitism; but
as our knowledge has been extended we have been com-
pelled to recognize more and more its complexity; until
today perhaps no two naturalists could agree upon the

' Stiles, C. W. ParaEitisra. Proc. Ent. Soc. Wash. S : 6.

Eiving — Significance of Parasitism in Acarina. ■ 3

same limits of its definition. Used in the broader sense
Meguin lias described as parasites^ those which live at
the expense of others which are living. Simple as this
definition is, the scope of its interpretation is so great
that it appears almost useless, for it might well be said
that nearly all organisms live at the expense, directly
or indirectly, of other living organisms. Leuckart would
include as parasites^ all those creatures that inhabit a
living organism, and obtain nourishment from its body.
This definition, which is perhaps as good as any, is ob-
jected to by many who claim that a parasite need not
necessarily ''inhabit a living organism"; or in other
words a definite host relationship is not necessary in
order to establish parasitism; for example, many para-
sites only visit the forms subject to their attacks at feed-
ing times, and certainly do not inhabit them. Another
objection may be raised to this definition because the
statement of obtaining "nourishment from its body" is
hardly clear or sufficient. Some epizoa live upon the
excretions, or the secretions, or the food taken into their
hosts, yet I do not see how it could be said that they
obtained their nourishment from the body of the forms
they attack. So with equal impunity every definition
offered in the past may be criticised and rejected.

I cannot hope, therefore, to give a definition of para-
sitism that will meet with general acceptance. But I
believe that the special forms of parasitism can be sat-
isfactorily defined.

It is only in recent years that the varied nature and
complexity of the factors involved in parasitism have
been realized. Prominent parasitologists as Leuckart,
Kiicheumeister, Cobbold, Megnin, and Neumann, did
great and extensive work on the life histories of para-
sites. Many specialists in the various groups of parasitic

' M§gnln, P. Les Parasites et les Maladies ParasitaireS'. Paris, 1880,
'Leuckart, K. G. F. R. The Parasites of Man. Translated from the
German by W. E. Hoyle. Edinburgh, 1886.

4 Trans. Acad. Sci. of St. Louis.

organisms have studied the aspects of parasitism and
helped settle many questions in regard to their nature,
significance and ecological relations. From the results of
these various workers and from my own observations, I
have been able to obtain a large amount of data in regard
to the various biological aspects presented in the dif-
ferent states of symbiosis which have been included un-
der the term parasitism.

Although numerous and various kinds of symbiosis
have been considered under parasitism by others, for the
purposes of this paper the writer has decided to limit the
use of the term as follows :

It must predicate the actual subsistence of one form
upon the bodily tissues or the physiological products of
the bodily tissues of another living organism.

A host relationship will not be necessary in order to es-
tablish parasitism.

The organism affected by the parasite is not necessarily
injured by the same.

Limiting the term in this way, the following classifica-
tion of parasites can be made. This classification is in
a nature theoretical to the extent that in a few phases
of parasitism given, examples appear to be as yet want-
ing, but no doubt that more extended observation in the
plant and animal kingdom will reveal all or most of
them.

A Classification of Pakasites.'*

Taking into account the nature and habits of the para-
sites themselves.

Depending upon whether the parasite is a plant or an animal.
Phytoparasites.
Zooparasites.

*In giving this classification of the different kinds of parasites many
■of the kinds are not designated by special names; the writer preferring
to define the kind of parasite given rather than inflict upon the general
student of biology any new technical terms, thus overloading a termla-
vology already rather unwieldy.

Ewing — Significance of Parasitism in Acarina. 5

Depending upon the nature of the food eaten.

Those living upon the bodily tissues.
Those living upon live tissues.
Those living upon dead tissues.

Those feeding upon partially digested food.

Those living upon blood of the species affected.

Forms feeding on secretions. '

Forms feeding on excretory products.

Forms living upon the eggs of the species affected.

Forms living on spermatozoa.
Depending upon adaptation to the parasitic life.

Facultative parasites.

Obligatory parasites.
Depending upon the stage of degeneration of the locomotor organs.

With wings.

Without wings.

Capable of walking when off the host.

Incap.;.bl€ of walking when detached from host.

Without legs.

Taking into account the nature and habits of the organ-
isms attacked.

Depending upon whether the organism attacked Is a plant or an
animal.

Photophsgous parasites.
Zoophagous parasites.
Depending upon the free state, or the stage of parasitism of the
organism affected.
Primary parasites.
Secondary parasites.
Tertiary parasites.
Depending upon the conditions Imposed by the life of the host.
Hydroxenous parasites (with an aquatic host).
Geoxenous parasites (with a terrestrial host).
Aeroxenous parasites (with an aerial host).
Depending upon the number of hosts.
Monoxenous parasites.
Heteroxenous parasites.
Bixenous.
Trixenous.
Tetraxenous.
etc.

Taking into account the interrelations of the parasites

and organisms affected.

Depending upon the position of the parasites In relation to their
hosts.

6 Trans. Acad. Sci. of St. Louis.

Endoparasites.

Living in the passages or cavities of the body where
there is a direct communication with the outer world.

Living free inside of the body cavity but not in con-
nection with the outer world.

Imbeddpd in the tissues of the host.

Ectoparasites.

Cuticolata, living on the skin.
Villicolata, living on hairs.
Plumicolata, living on feathers.

Depending upon the duration or time of parasitism.
Erratic parasites.
Periodical parasites.
Nocturnal.
Diurnal.

During a definite stage or stages in the life cycle of the
species attacked.

During the egg stage.
During the fetal stage.
During Immature stage or stages.
During the adult stage.
Permanent parasites.
Depending upon symbiotic relationship.

Mutuallsts (where the relationship Is beneficial to both para-
sites and host).
Commensals (where the relationship Is beneficial to the para-
site, and neither beneficial nor injurious to the host).
True parasites (where the relationship is beneficial to the
parasite and injurious to the host).
Depending upon the blood relationship of the parasite to the host.
Host or organism affected not related to the parasite.
Host or organism affected closely related to the parasite,
perhaps belonging to the same family, but not of the same
species.
Organism affected of the same species as the parasite itself.
Host the opposite sex.
Host the male.

Host the female, parasite the male.
Host one of the parents, but parasite not fed by special
•secreting glands or nourished in the uterus of the
female.

The father the host.

The mother the host. ,

Host one of the young of the parents.

Ewing — Significance of Parasitism in Acarina.

The Zoological Position of the Acarina,

The Acarina consist of a more or less natural group
of the class Arachnida. The saclike form of the body, the
absence of a distinct head, the possession of four pairs of
legs, the usually very incomplete metamorphosis, as well
as the structure and relationships of the internal organs,
are only a few points which demonstrate their undoubted
position in this class. The absence or incomplete de-
velopment of many of the special senses, the loss of
many specialized structures found in a high grade of de-
velopment in some of the other groups of Arachnida,
as well as the frequent assumption of a parasitic life, all
point toward a line of degenerate descent from the an-
cestral stock of the class to which they belong. It must
be remembered, however, that in some respects they show
a development of specialization that is perhaps not ex-
celled by any of the various groups of the arachnids.

The nearest affinity of the order appears to be with the
Phalangidea, yet in some respects they are more nearly
related to the Solpugida. This relationship of the Aca-
rina to the Phalangidea has been most clearlv shown bv
the discovery and study of some of the smaller tropical
phalangids. Some of these phalangids are exceedingly
mitelike in general appearance, and a careful study of
them brings out other points of relationship. Among
these characters might be mentioned their smallness,
the shortness of the legs and their reduced number
of segments, the more nearly saclike shape of the body,
the length of the palpi, and the form of the body. But
many of the characters of the Acarina may be used to
demonstrate their affinity with the more common of the
Phalangidea. These may be listed as below: —

A general similarity in the sliape of the body, especially in the
breadth and frequently depressed condition of the abdomen.

The possession of a segmented abdomen by several forms of the
Acarina, showing probably a homologous state to that of the Phalan-
gidea.

8 Trans. Acad. Sci. of St. Louis.

T&e possession of median eyes In some of the mites, suggesting the
condition found in the Phalangidea.

The close similarity of the typical chelate chellcera of the mites to
those of the Phalangidea.

The possession by the two groups of very similar internal organs,
especially those of reproduction, and digestion.

The similarity of habitB existing between many of the free-living
Acarjna and the Phalangidea.

The relation of the Acarina to the Solpugida is best
brought out by the study of the species of the genus
Rhagida, belonging to the family Eupodidae. There is a
remarkable resemblance of these mites to solpugids.
This is shown in the general shape of the body, the form
and shape of the legs and the palpi, but more especially.
in the size and shape of the chelicerae. These are of
enormous size as in the solpugids, being equal to a fourth
or fifth of the total length of the body. They are greatly
swollen, and the movable digit works vertically as in the
solpugids. An investigation of their internal anatomy
has shown that it is among the most primitive of the
Trombidoidean type.

Of the various groups of the Acarina which have been
suggested as being most nearly related to the primitive
stock, the genus Opilioacarus^ has attracted most atten-
tion of late. The genus is represented by four species
found in the following countries: Algeria, Italy, Ara-
bia, and South Am^erica. These mites have a segmented
abdomen, leg-like palpi, chelate chelicerae, two pairs of
eyes; while the tracheae open by means of four dorsal
stigmata. The possession of a segmented body is cer-
tainly a marked primitive character, but it must be re-
membered that some of the well-known groups possess
a more or less segmented body, for example the Tarson-
emidae and some of the Tetranychidae. The possession
of leglike palpi as well as chelate chelicerae are even

'For a figure of one of these species and a short discussion of the
systematic characters see: Oudemans, A. C. A Short Survey of the
More Important Families of Acari. Bull. Ent. Research. 1 : 105. 1910.

Ewing — Significance of Parasitism in Acarina. 9

typical of several of the well-known groups of mites, the
chelate chelicerae being the most common type in the
Acarina. The most curious fact in regard to this genus^
the phylogenetic significance of which is much in doubt, is
the possession of four dorsal stigmata. This character is
so different from that of any of the other known Acarina
that the genus has been raised to the rank of a suborder
by some acarologists.

The Eange of Paeasitism in the Acarina.

In order to determine the origin and significance of
parasitism in the Acarina it is necessary to study the
range of parasitism within the order, to determine the
relationships between the parasitic and the free-living
forms.

This study can only be tentative at this time ; for only
a small proportion of the acarid fauna of the world is
known. The results of such a study are shown in tab-
ular form below, and in the further notes regarding sep-
arate families that follow the table.

10

Trans. Acad. Sci. of St. Louis.

TABLE I.

Table of Habits of Mites.

Family

Feee

Semi-
paeasitic

Parasitic

Only laevak
parasitic

eupodidab
Bdellidae
Cheyletidae

Caeculidae
Tetbany-

CHIDAE

Erythbaei-

DAE

Rhyncholo-

PHIDAE
rsOMBIDIIDAE

Hydrachni-

DAB

Halacabidae

ixodidae

Argasidae

Debmanys-

8IDAE

Gamasidae

All genera
All genera
Cheyletus

Caeculus
only genus

Caligonus

Erythraeus

Anystis

Some of the
genera

Iphlopis

Epicrlus
Greeniella
Macrocheles
(mostly)
Celaenopsis
Megisthanus
An:ennopho-
ru3

Cheyletiella

Bryobia
Raphignathus
Neophyllobius
Tenuipalpus

Laelaps

Myobia
Harpyrhyn-

chus
Psorergates
Picobia
Syringo-

philus

Tetranychus
Stigmaeodes
Stigmaeus

Gekobia

Atax

All genera
All genera
All genera

Haemogama-

SU3

Raillietia

All genera

All genera
All genera

except Atax
Most of the

family

Ewing — Significance of Parasitism in Acarina. 11

TABLE I. — Continued.
Table of Habits of Mites.

Family

Free

Semi-
parasitic

Parasitic

Only larvae
parasitic

Gamasidae

Podocinum

Liroaspis
Zercon

Seiodes

Seius

Gamasus

Ueopodidae

Glyphopsis

Polyaspis

Uroseius

Dinychus

Uropoda

Cilliba

(some spe-
cies)

Obibatidae

All genera

-

NOTHRIDAE

All genera

HOPLODEEMI-

All genera

DAE

Pediculoidi-

Pediculoides

Pediculoides

DAE

(mostly)
Siteroptes

Pigmeo-
phorus

(in part)
Podapolipus

Tarsonemi-

DAE

Tarsonemus
(In part)
Dlsparipes

Tarsonemus
(in part)

Tarsonemus
(in part)

Tyroglyphi-

Most of the

Histiostoma

Histiostoma

DAB

genera

(in part)

berghi

LlSTBOPHOEI-

All genera

DAE

Analgesidae

All genera

-

Canestbini-
dae

Hemlsar-
coptea

Most of the
family

Saecoptidae

All genera

Cytoleichi-

All genera

DAE

Demodecidae

All of family

Eeiophyidae

All genera

Unplaced

Opilioacabi-

DAE

12 Trans. Acad. Sci. of St. Louis.

FuKTHEK Notes Eegaeding the Separate Families.

EupoDiDAE. — This Is a small family of mites which live in dark, damp
places. They are predaceous and of very agile movements.

Bdellidae. — A small family of mites of medium size. They live among
dead leaves and rubbish, but may be found on trees under bark.
All are predaceous. The mouth-parts are very large, the palpi may
be raptorial.

Chetletiuae. — The genus Chcylctus is free and predaceous, and its
members are found under dead vegetation and under dead bark,
etc. Cheyletiella Is found upon furred animals, but It Is doubtful
if It lives at all from their tissues, but rather, simply preys upon
other parasites present. The parasitic genera are found upon both
birds and mammals.

Caecltlidae. — Only a few forms are included in this family, and little
or nothing is known of their habits. They are found In moss and
rubbish where there is plenty of moisture.

Tetraxychidae. — All the members of this group are plant feeders.
Where the attacks of a single Individual or several generations of
the same species are confined to a single food plant (hence host
plant) the species is called parasitic. In several cases there Is a
strong tendency for individuals to attack a single plant, yet they
may leave the same; these species may be called semi-parasitic.

Ebythraeidae. — The two free genera include predaceous forms which
run about plants. The parasitic genus includes forms parasitic on
reptiles.

RHYNCHOLOPHinAE. — Rather large acarlds, the adults of which are found
running over the leaves of various plants and the bark of trees.
The adults are predaceous.

Tkombidiidae. — Some of the mature forms of this group constitute the
largest known free-living Acarlna. Although the larvae are para-
sitic, the mature forms are predaceous.

Hydrachmdae. — The largest family of the order. They are aquatic, and
with but few exceptions, are free in the adult state. The larvae
are parasitic on aquatic insects.

Halacaridae. — Includes marine forms. All the adults are free and feed
upon minute vegetation. Some cf the larvae are free and some
are parasitic.

IxoDiDAE. — Includes most of the ticks. All are parasitic, but usually
leave their hosts in order to molt. They are haematophagous, and
do not show nearly as great a stage of degeneration as some of the
other parasitic groups.

Abgasidae. — A very small family, including some forms of ticks which
have not degenerated as much as the true ticks. They are noc-
turnal, haematophagous parasites.

Ewing — Significance of Parasitism in Acarina. 13

Debmanyssidae. — Parasitic mites, but the habit of parasitism is evi-
dently not of very long standing, since some of the members ara
yet facultative parasites, and few species show any noted symptoms
of degeneration.

Gamasidae. — As far as habits are concerned this group Is very hetero-
geneous. Most of the species are free and predaceous; however,
many species live in various degrees of symbiotic relationships
with certain insects, especially the ants. Some of these are pure
scavengers, others live upon the salivary secretions with which
the ants cover their eggs, while others feed upon food regurgitated
by the ants. At least two genera are true parasites, while semi-
parasitic species are found in the genera composed mostly of frea
species.

Ukopodidae. — Most of the members of this group are predaceous In their
adult state. In the nymphal state they are frequently found at-
tached to various arthropods for the purpose of transportation. A
few forms are parasitic when mature.

Obibatidae. — Free-living forms. They are found in dark, moist places,
where they live upon fungi or small bits of decaying matter.

NoTHEiDAE. — A large family. They are especially characterized for their
hard, chitinous integument. They live under bark and under logs
where It is moist and feed upon small vegetable organisms and
rotten wood.

Hoplodermidae. — A very small group of vegetable feeders of similar
habits to the preceding family.

Pediculoidiuae. — The members of this family are very small and con-
stitute a very heterogeneous group. Some of the members are
plant feeders, others will make sporadic attacks upon animals, and
a few are real parasites.

Tabsonemidae. — Contains two well represented genera, one of which Is
plant feeding and one which has free as well as parasitic forms
and intermediate stages.

Tyboglyphidae. — This is a small family in species, but large In number
of Individuals. They are atracheate creatures, blind and live as
scavengers. Individuals of the genus Histiostorna are taking up
parasitic habits.

Listbophobidae. — This Is probably not a natural group, but the forms
included in it have been so placed because of a similarity of habit.
They are parasitic upon small mammals.

Analgesidae.— A very large family. They live in the plumage of birds,
feeding upon epidermal scales, excreted matter, etc. About 400
species are known.

Canestrinidae. — Only a few species represented and these are parasitic
on insects. Hemisarcoptes is hardly a true parasite as yet.

14 Trans. Acad. Sci. of St. Louis.

Saecoptidae. — A very important family composed of ttie itch mites.
They live in the skin, and in a few cases in the internal organs of
other animals. Here degeneration reaches its limit.

Cytoleichidae. — Only two species known. They live In or upon the
skins of fowls, or in the air passages of the same.

Demodecidae. — Includes but one genus, Demodex, which occurs in the
hair follicles of mammals. The body is vermiform and the legs
are reduced to stumps.

Eeiophyidae. — Consists of several genera of vermiform Acarina which
live upon plants. Most of them produce galls or other malforma-
tions of leaves.

Opilioacaridae. — Habits unknov.-n and systematic position uncertain.

Paths of Evolution from the Feee-living to the Para-
sitic Forms.

In our study of the origin of parasitic forms from
free-living types two facts appear pre-eminently impor-
tant; first, no great or sudden change in the nature of
the food must be encountered; and, second, there should
be but a gradual change in the environmental conditions.

A study of the way in which parasitism has arisen in
many of the larger natural groups of the animal king-
dom, has shown us that it has followed at least several
well defined courses. Of these several lines of descent,
as we may call them, the first of which I will treat, and
which is the simplest of all, is the origin of parasitism
in predaceous groups of animals. In such cases it is
evident that often there would be little and frequently
no change whatever in the nature of the food, in the
transition from the predaceous to the parasitic life.
\Vhat is yet more significant of the gradual transition
from the predaceous habit, is that forms now exist that
are actually on the border line between the two and
might equally well be called predaceous or parasitic, ac-
cording as to whether they attack forms smaller or larger
than themselves. This point might be illustrated in the
case of some of the leeches, which may attack forms
larger than themselves and thus be parasitic, or attack
forms smaller than themselves, in which case they might
be called predaceous. The same might be said of some

Eiving — Significance of Parasitism in Acarina. 15

of the blood-sucking members of the family Pentato-
midae in the insects. In these cases all that is necessary
to establish the parasitic habit is that the preying form
shall more frequently attack larger animals than itself
and in such a way as not to overpower these or hold
them captive while feeding from their substances.

Another road over which we find the parasitic habit
developing is in groups which are scavengers. In these
groups the free individuals frequently live upon small
bits of dead plant or animal tissues and when they first
begin to take on parasitic tendencies they generally con-
fine their attention to essentially the same kind of food
material, which is found in the dead cutaneous or ex-
cretous products of the organism to be parasitized. In
these cases, as in most cases of parasitism, the parasites
themselves are small and likewise descended from small
forms. A good illustration of this method of the origin
of the parasitic habit is shown in the origin of para-
sitism in the Mallophaga. The Mallophaga are small,
flat, apterous insects that live chiefly on the barbules of
feathers and on dead cutaneous cells. A study of their
development and structure*' has established a very close
relationship between them and the Corrodentia, or book-
lice. These free-living insects live on small bits of or-
ganic matter which they find under logs, bark, etc. That
parasitic forms have been evolved from these or from
forms of similar habits appears to be evident. Here
again we find the change of the kind of food is but slight
and also the environmental conditions are entirely satis-
factory for those forms which should, perhaps at first
by accident, find themselves transferred to the plumage
of birds.

Yet a third way in which zoophagous parasitism may
have originated is in forms which live on plant juices.
The structure of their mouth-parts is such as to be al-

• Kellogg, V. L. New Mallophaga, II. Proc. Cal. Acad. Sci. II. 6;
431-471. 1896.

16 Trans. Acad. Sci. of St. Louis.

most as well adapted for sucking the blood of animals as
the juices of plants. Mr. Tucker^ has recently made some
careful observations on several species of plant-bugs in
regard to their attacks on man. He found that several
of these, particularly some of the Jassidae, or leafhop-
pers, would at times attack human beings and cause them
much annoyance. In doing so they really did feed on
the blood of the individuals bitten. In regard to the
attacks of Empoasca mall Le B. he states: "From the
time my attention was first attracted by feeling the bite
until the insect desisted, a trifle over four minutes
elapsed according to my watch. The first insect was then
captured, and after being crushed on a white sheet of
paper a faint bloody streak was produced, which proved
beyond any doubt that the specimen had actually en-
gorged itself with blood."

In the Acarina we find the parasitic liabit developed
independently from several groups of free-living forms,
but in each case I think that its method of development
has been over one of the three roads indicated above.
By a study of Table I the following classification of the
free-living Acarina can be made, all of them falling into
one of three classes. These classes are as follows:

I. Free-living predaceous forms: usually provided
with eyes and prehensile organs; possessing a delicate
sense of touch and being very agile in movements. To
this class belong:

The Eupodidae and Bdellldae.

Caeculidae (Habits doubtful but probably predaceous).

Of the Cheyletidae, the genus Cheyletus.

Some of the Halacaridae.

Most of the Gamasidae.

Many of the Uropodidae.

II. The free-living scavengers. These forms, as a
rule, are less highly specialized than the predaceous
forms (a correlation with their mode of life). They

^ Tucker, E. S. Random Notes on Entomological Field Work. Can.
Ent. 43:29-31. 1911.

Ewing— Significance of Pafasitism in Acarina. 17

usually are blind, without prehensile organs, atracheate,
and are more or less sluggish. To this class belong:

A few of the Gamasidae.

The Orlbatidae, Nothridae and Hoplodermidae. (Many of the species
of these families live partially on small vegetable organisms, as fungi,
but en the v/hole they are to be regarded as scavengers.)

Practically all the Tyroglyphidae.

III. The free-living phytophaga. The phytophaga, as
a rule, have piercing mouth-parts. They possess the spe-
cial senses developed to a moderate degree, while the
palpi have become reduced. In their movements they
are not as agile as the predaceous forms. To this class
belong :

Some of the Tetranychidae.

A few of the Oribatidae and Nothridae.

Some of the Pedlculoididae and Tarsonemidae.

From these three classes of free-living forms, or from
their ancestral types of very similar habits and of some-
what similar structure, there arose the various grotips of
our present day, living, parasitic Acarina. To show how
this process probably took place, and how many and
what kind of lines of descent there are in the parasitic
forms, will be the next object for our consideration.

Standing in close relation to the free-living forms of
the first class, either as genera of the same families or
as closely related families, or groups of genera or fam-
ilies, we have the following apparently natural groups :

The parasitic Cheyletidae.

Families of the trombidoidean type with parasitic larvae (Rhyncholo-
phidae, Trombidiidae, Hydrachnidae, Halacarldae [mostly]).

Ixodidae, Argasidae, Dermanyssldae and some genera of the Gamasi-
dae.

A few parasitic forms of Uropodidae.

In a similar manner the following groups of parasitic

Acarina are allied to the free-living forms of the second

group, the scavengers:

Some of the Gamasidae (?).
Canestrinidae and Sarcoptidae.
Listrophoridae (in part).
Analgesidae.

^o

18 Trans. Acad. Sci. of St. Louis.

One zoophagous parasitic group, showing affinity to the
plant feeding free forms, is known:
The parasitic Pedlculoldidac.

Very many facts could be brought together, showing
that each of the four phylogenetically separate sub-
groups of parasitic forms included in the first group of
parasites indicated above has been evolved from pre-
daceous ancestors; but, owing to the limits of space, only
two of the subgroups will be considered here, the para-
sitic Cheyletidae and the parasitic Peritremata, exclud-
ing those few forms found in the Uropodidae, which
evidently had a separate origin.

The parasitic Cheyletidae both in habits and in their
superficial external characters appear to be related to
the Sarcoptidae and the Analgesidae, and have been
placed with such forms by some authors; but the follow-
ing structural characters will, I think, show that their
affinity with the Cheyletidae should not be disputed:

They possess tracheae, hence these must have been either evolved
from tracheate ancestors, or the tracheal system must have been evolved
independently in forms of parasitic habits. The latter alternative Is
something almost entirely beyond our belief, since it is in contradiction
to the common influence of parasitism; and If so, would represent a
process so exceptional in the history of arthropod evolution as to be
only duplicated in an extremely few Instances, covering vast periods of
geological time.

The absence of anal suckers and tarsal suckers, and the possession
of almost normal tarsal claws allies them with the Cheyletidae rather
than the Analgesidae.

In the case of the gefius Harpyrhynchus the enormous size of the
palpi, so similar to those of the free Cheyletidae certainly establishes
the affinity of these forma with the Cheyletidae.

Passing to a study of the habits of the Cheyletidae, the
steps in the origin of parasitism in this family become
more clear.

The free-living Cheyletidae are very small creatures,
many of them being not more than half a millimeter in
length. Their palpi are enormously developed (PI. Ill,
Fig. 8), and instead of working vertically, as is true of

Ewing — Significance of Parasitism in Acarina. 19

practically all the other free-living Acarina, they move
horizontally. Thus it can be seen how these organs alone
are excellently adapted for clinging to a host; as a
Jnatter of fact they are perfectly typical of the adhering
forms of palpi as we find them in the parasitic trombi-
doidean larvae (PL V, Fig. 20). Next, we actually know^
of some species of the genus Cheyletiella which live upon
the backs of fur bearing animals. Here they apparently
feed only upon the other parasites present, but the con-
ditions are perfect for the development of the parasitic
habit. All that is necessary is that the normal food sup-
ply be cut short; then, according to the law of the sur-
vival of the fittest, only those individuals will live that
are able to sustain themselves for a while, at least, upon
another diet. Since they are already accustomed to the
animal juices of smaller forms, it is but a slight step for
them to take in order to be able to digest the juices of
mammals. Perhaps those individuals which first partook
of these juices only did so for a very short time and
perhaps from some wound upon the animal.

In the case of the parasitic Peritremata (the poultry
mite, blood-sucking bird mites, ticks, etc.), not only can
we trace the anatomical homologies of the different
groups step by step as we pass from the free-living to the
parasitic groups, but we can also trace in a parallel man-
ner the development of the parasitic habit.

Among the free-living Gamasidae it is a frequent oc-
currence to find species which live in association with
other animals. Mention here will only be made of a few
cases. Some of these forms use their pseudohost only
for the purpose of transportation. Many species, as
Macrocheles moestus Banks, live in association with
other animals, acting somewhat as scavengers. I have
frequently observed such cases in the rearing of insects
and also in my experiments upon inoculations with para-
sites upon some of the higher animals. In some cases,
as with species of Antennophorus, the mites come in as

20 Trans. Acad. Sci. of St. Louis.

symbia for a share of the food of the host; again, as in
Oolaelaps odphilus, they feed on the saliva with which
ants coat their eggs or their young. As a very gradual
step from these symbiotic relationships, we find several
facultative or semiparasitic forms, which may be para-
sitic for a while, but which can yet maintain themselves
without a host. An excellent example of this class is
the common chicken mite, Dermanyssus gallinae (Eedi)
(PI. I, Fig. 2). In favorable circumstances, as in the
moist droppings from the roost, they can maintain them-
selves almost indefinitely. In the Argasidae we find spe-
cies which are very similar to the Dermanyssidae both
in habits and structure. They are nocturnal, but may be
regarded as obligatory parasites. However, here the
parasitic habit has not developed to the extent that it
has in the Ixodidae, as has been well established by Nut-
tall.^ In the true ticks, Ixodidae, the parasite is firmly
attached to a single place on its host, hence is a sta-
tionary or fixed parasite. However, in most cases it
leaves the host to molt. For a sketch of the degenera-
tive processes accompanying this progress in the devel-
opment of the parasitic habit see the explanation for
Plate I.

In considering the second groups of parasitic Acarina,
those most nearlj^ related to the free-living scavengers,
we must regard them as representing at least four dif-
ferent and phylogenetically distinct lines of descent. The
ways in which each separate line arose from scavenger
ancestors is practically the same, so only one line will be
considered.

The small family Canestrinidae and many, if not all
of the Sarcoptidae, may be regarded as descending from
an ancestral type very similar to some of our living Ty-
roglyphidae, as the species, Monieziella entomopliagiis
(Laboulbene). This form (see PI. II, Fig. 4), as well
as most of the members of the family, is a true scav-

«Nuttall, G. H. F. On the adaptation of ticks to the habits of their
hosts. Parasitology. 4:46-67.

Eiving — Significance of ParasHlsm in Acarina. 21

ecger. The members of tlie Tyroglyphidae live on refuse
matter of various sorts, but especially on decaying ani-
mal matter and upon sores of animals, etc. The species
just mentioned differs from most the members of the
family in that it is always associated with a certain
species of insect, in this case the Oyster Shell Scale.
Here it feeds, not on the live scale insects, as was once
supposed, but only on the dead insects and the old Qgg
shells. However, there is a form present in association
with the same scale insect, and which has been much
confused with the mite just mentioned, which does live on
the fresh eggs of the scale, and I have observed it occa-
sionally attacking the scale insects themselves. This is
Eemisarcoptes mains (Shimer), (PI. HI, Fig. 5); which,
as the name indicates, may be regarded as the connecting
link between the true Sarcoptidae and the scavenger free
forms.

Among the scavenger types the first steps toward para-
sitism are perhaps the constant association of the mite
with some other particular species of animal, as is the
case of Monieziella entomophagus Laboulbene. The next
step in the case of the origin of parasitism among the
Canestrinidae and Sarcoptidae was perhaps the change
of diet from dead tissues to that of live tissues as found
in fresh eggs. Then began a partial life on some fresh
animal food and finally a complete parasitic form was
evolved.

In the Analgesidae, of course, the change of diet by
forms taking up the parasitic habit would be very slight.
Here the ancestral type was probably the same as that
of the Canestrinidae, that is, was similar to our present
day Tyroglyphidae. In this connection, I may mention
that I have discovered a species of Tyroglyphidae that is;
repeatedly found upon the plumage of birds. Mr. W. R.
Thompson, a specialist in the group, has also confirmed
my observations. In the case of this species, Glycypha-
gus spinipes Koch, there is but little doubt that these mites

22 Trans. Acad. Sci. of St. Louis.

get on the birds while they are roosting or sitting upon
the nest and, finding plenty to eat, remain for long periods
of time with the same bird. This might be called acci-
dental parasitism, but since it is so frequently met with
I would be inclined to call it semi-parasitism. After
several generations, through the action of natural selec-
tion, we would have evolved forms that would feed upon
little else except the excretious material or dead epi-
dermal scales of the birds; and finally a form would ap-
pear that would be wholly parasitic.

The parasites of the third class, those that have arisen
from plant feeding ancestors, all belong to a single group,
the parasitic Pediculoididae. One of our most common
parasitic species is Pedicidoides ventricosus Newp. This
species is remarkably similar to the plant feeding species
of the same genus, so much so that it has been frequently
confused with them even by well trained entomologists.
This species has recently been extensively studied by
"Webster^ who has shown that it is changing its habits
of feeding upon insects and now is a serious parasite
of man himself.

But it is among the plant feeding forms themselves
that we have seen the beginnings of the development of
the parasitic habits.

Some of these, as Tarsonenms intectus, frequently have
attacked man among other animals and have caused him
very serious trouble. Here the step in the change of diet
is much greater than is usually the case, but the mouth-
parts are extremely well adapted for the new life as a
parasite.

The Significance of Distribution According to Host

Species.
Two methods of attack have been employed in study-
ing the significance of the distribution of the parasitic
Acarina according to host species. The first of these

■ Webster, F. M, A predaceous and supposedly beneflcla! mite, Pedl-
.ciiloides, becomes noxious to man. Ann. Ent. i>oc. Amer. 3: 15-3i). 1910-

Ewing — Significance of Parasitism in Acarina. 23

is by means of the statistical method, lists of the parasites
with more than one host species having been prepared. In
some groups a complete list of all the known parasites with
the host or hosts of each is given. The second method is
by experimentation by means of which data were ob-
tained; in regard to the ability of the parasites to move
about when detached from their hosts, in regard to the
length of time a parasite can live when detached from its
host when either with food or without food, the habits of
the parasites themselves, and lastly and most important
of all, transfers of the various parasites from their normal
hosts to various other hosts.

In the following pages of this chapter the different
groups of the parasitic forms will be taken up separately;
the list of species with their hosts being given first, after
which follow the deductions obtained from a study of
these lists, together with what experimental evidence I
have secured.

The first group with which we will occupy our atten-
tion is that of the parasitic Cheyletidae, a list of them
being given with the hosts of each.

A List of the Parasitic Cheyletidae and Theib Hosts.

MYOBiA Hey.

M. lemnina (Koch) — Arvicola arvalis Pall.
M. caudata Banks — Little brown bat.

M. musculi Schrank — Mus musculus, M. silvatlcus L., M. rattus.
M. irevihamata Haller — Mustela vulgaris.
M. pantopus Troues. — Synotus barbastellua.
M. heteronycha Berl. & Troues. — Phyllorhina tridens.
M. poppei Troues. — Vesperugo abramus.

M. chiropteralis Michael— Rhinolophus hipposideros. Vesperngo plpls-

trellus.

PICOBIA.
P. heeri Guzzoni.

SYRINGOPHILUS Hcl.
8. Upectinatus Heller— Phoenopepla nitus Sev.

psorergates sty.
p. simplex Tyrrell— Mus musculus, Arvicola agrestls.
P. simplex var. musculinis.

24 Trans. Acad. Sci. of St. Louis.

HARPYEHYXCHUS Meg.
H. longipilus Banks — Loxia curvirostra minor (Brehm.).
H. nidulans Megnin— Alauda arvensis Linn., also en grosbeak sp. (?)
H. brevis Ev/ing — Coccothraustes vespertina (Coop.).

The parasitic members of the Cheyletidae form a very-
small and probably heterogeneous group. The five dif-
ferent genera are morphologically rather widely sepa-
rated and each is markedly specialized. These genera
are certainly not in the least allied to the atracheate
parasitic forms which in all probability arose from atra-
cheate free-living types. For the present, on account of
convenience, we will consider them taken together as a
group.

Two of the genera Myohia and Psorergates are found
on mammals, the former attached by their highly spe-
cialized clasper-legs to the bases of the hairs, the latter
in little cavities or cells just beneath the skin. Two of
the other genera, Picobia and Syringopliilus, live inside
of the quills of the feathers of birds; while the genus
Harpyrhynchus is found forming tumors in the skins
of birds.

Of the thirteen species known in this group all are
confined either to a single host species or to very closely
related host species. These extremely narrow limits in
their distribution are due chiefly to one of two things;
either the development of a highly specialized clinging
apparatus or to semi-endocolous habits. Thus the mem-
bers of Myohia have the highly specialized claspers for
grasping a single hair; and it would be impossible for
them to hold on to a hair very much smaller or very
much larger than those of their host.

Of course the members of the genera Picobia and
Syringopliilus, living inside the quills of birds, would
have only rare chances for their transference from one
host to another. Likewise the members of Psorergates
and Ilarpyrliynclius which are almost endocolous would
not be easily transferred from one host to another.

Etving — Significance of Parasitism in Acarina. 25

I made an attempt to inoculate our common striped
ground squirrel, Spermophilus 13 — lineatus with Myohia
musculi from a mouse. The parasites took hold at first
and caused the ground squirrel much annoyance, but
could not establish themselves and soon disappeared.

A List of Some Trombidium Larvae and Their Hosts.

In considering the larvae of the Rhyncholophidae,
Trombidiidae, Hydrachnidae and Halacaridae, it seemed
that the data in regard to all of them and their distribu-
tion were so inadequate that it was decided to give lists of
species and hosts for only two of the best known genera.
These records are taken chiefly from Oudemans.

ALLOTHROMBIDIUM Bei'leSC.

A. fuliginosum (Herm.) — Aphis tiliae L., A. sambuci L., A. jaceae L.,

A. evonymi F., A. rosae L., A. fabae, A. ribis.
A. poriceps Oudms. — Specimens have been taken upon Homo, but tha

true host or hosts are unknown.
A. inexspectatiim Oudms. — Host unknown.
A. italicum Oudms. — Acridium, Mantis, Gryllotalpa.
A. tectocervix (Oudms.) — Host unknown.

A. striaticeps Oudms. — Found on Homo as an accidental host. Its true

host unknown.

TROMBIDIUM Fabricius.

T. grannlatuTTi Oudms. — Host unknown.

T. muscae Oudms. — Musca domestica, Vesperugo piplstrellus, V. sero-
tinus, Plecotus auritus.
1'. WicTimanni Oudms. — Found upon Goura sp.
T. russicum Oudms. — Upon a bat; host probably accidental.
T. inopinatum Oudms. — Crossopus fodiens (Pall.). Talpa europaea L.
T. meridionale Oudms. — True host unknown.
T. berlesei Oudms. — Hirundo riparia.
T. vandersandei Oudms. — Found on the legs of Homo In New Guinea.

Although the list of species of these Trombidium lar-
vae is not large, and doubtless a more careful search
would add several more hosts for each species, yet from
these data I think we can draw the conclusions ; that they

26 Trans. Acad. Sci. of St. Louis.

are not as a rule restricted to a single host species, also
that their normal hosts are always closely related forms,
usually species of the same genus or of closely related
genera.

In regard to the fuller biological significance of the
distribution of the Trombidium larvae and the parasitic
larvae of related forms, Rhyncholophidae, Hydrachnidae,
and Halacaridae, several interesting facts were brought
to light. First, some of these larvae may sustain them-
selves for long periods of time when detached from a
host. Thus I found that the larvae of one of our com-
mon hydrachnids remained alive for sixty-four days in a
watch glass without any hosts. In this case I believe
that these small creatures lived partially upon minute
organisms found in the water, but no doubt these various
larvae can live for several days without food. This I
found to be the case with the larvae of Microtromhidium
muscarum Riley, the larvae of our common house-fly
mite, which lived for five days in confinement without
food.

I made several attempts to inoculate other forms than
the normal hosts with the larvae of Microtromhidium
muscarum (Riley) and M. locustarum Walsh, but was
unsuccessful. The larvae soon fell from the forms on
which they were placed and apparently never did firmly
fasten the beak into their integument. I was somewhat
surprised at this for in some cases the alien species used
was very closely related to the normal host. I thought
that it might have been because of mechanical reasons,
or because that once having a square meal the appetite
no longer acted as a sufficient incentive for obtaining a
second attachment. However, I found this was not true,
at least with Microtromhidium muscarium Riley, as I
got this species to change its attachment from one in-
dividual of its host species (the house fly) to another
very easily.

In regard to the experiments made in attempts to
get a suitable host for two hydrachnid larvae, I will

Emng — Significance of Parasitism in Acarina. 27

state that after trying many insects, mostly aquatic
forms from the same pool from which the mothers of the
larvae were obtained, I was unable to get any of them
to attach. In some cases the aquatic insects were con-
fined in a small jar in the water of which hundreds of
larvae swarmed, yet after days of confinement not a
single larva was attached. These results are similar
to many others obtained by different workers.

The reason why these larvae will thrive only upon a
single host species or upon a few closely related host spe-
cies appears to be physiological differences in the nature
of the two diets met with. That they will frequently at-
tack many different kinds of animals, vertebrates as well
as invertebrates, is well known. Thus man himself is
attacked by probably several species. Yet in all these
cases the mites do not thrive but soon perish.

It may be suggested that it is because the larvae do
not have a chance to meet with a larger range of host
species that they are so limited in their distribution, but
I have carefully investigated the habitats and surround-
ings of several of our American species, and find that
such is not the case. Grass sweepings made in the vi-
cinity of Ames, Iowa, where there were thousands of the
larvae of Microtrombidium locustarium Walsh present,
contained representatives of many orders of insects, but
these larvae were only found on a few closely related
species of grasshoppers.

A List of the North American Ixodoidea and Their

Hosts.

Argasidae.
ARGAs Latreille.

A. hrevipes Banks — Cereus giganteus.
A. miniatus Koch— Chickens, cattle, quail.
A. reflexiis Fabricius — Pigeon.

A. persicus (Oken)— Fowls, ducks, geese, turkeys, ostriches, quail, wild

doves, canaries, man, cattle.

28 Trans. Acad. Sci. of St. Louis.

ORXITHODOKOS Kocll.

0. coriaceus Koch — Cattle, man.

0. megnini Dug^s — Cattle, horses, man, ass.

0. marginatus Banks — West Indian bat.

0. talaje Guerin — ^lan.

0. turicata Duggs — Hogs, man, cattle, llama, horse, tortoise, gopher.

IXODIDAE.

CERATixoDEs Neumann.

C. putus Cambridge — On several migratory sea birds.
C. signatus Birula — Cormorant.

IXODES Latreille.

1. cngustus Neumann — Neotoma occidentalis, Sciurus hudsonius doug-

lasi, Tamias townsendi, Lepus dalli, "Mouse."

7. arcticus Ostorn — Seal.

I. biKnneus Koch — Tufted titmouse, hermit thrush, "Chipping bird,"

Californian birds.

7. californicus Banks — Gray fox, black-tall deer.

7. cooki^i Packard — Lutra, Mustela vison, Spermophilus, weasel, porcu-
pine, marmot, pocket gopher, dog, cat, sheep, robin.

7. dentatiis Neumann — Rabbit.

7. diversifossus Neumann — Raccoon.

7. Tiexagonus Leach — Erinaceus europaeus, Mustela ermlnea, M. vulgaris,

M. putorius, M. furo, Lutra vulgaris, Meles taxus,
Lepus cuniculus, Myopotamus coypu, Sciurus sp.,
Canis vulpes, C. familiaris, Ovis aries, Sus scrofa.
Homo sapiens.

J. marxi Banks — Red squirrel, fox.

I. pratti Banks — Prairie dog, skunk (?), rock squirrel (?).

7. ricinus Linnaeus — Bos taurus, Ovis aries, Canis familiaris, Cervus

elaphus, C. capreolus, C. dama, Capra hircus,
Equus caballus, Homo sapiens, Fells concolor,
Genetta sp., Lepus europaeus, Erinaceus euro-
paeus, Mustela putorius, M. erminea, Meles taxus,
]Mus decumanus, "Mouse," Myoxus sp., Talpa
europaea, ground squirrel.

7. scapularis Say — Dogs, man. cattle, sheep, deer.

I. sculpttia Neumann — Rook squirrel.

7. aequalis Banks — California ground squirrel.

7. uriae White (?)

7. canisuga — Canis familiaris, C. vulpes, Cotile riparte, Mustela furo,
Meles taxus, Sciurus, Talpa europaea, Equus caballus,
Ovis aries.

Ewing — Significance of Parasitism in Acarina. 29

I. ruhidus — Bassaris astuta.

7. bicornis — Fells concolor, F. onca, Homo sapiens.

I. texanus — Grey squirrel, Procyon lotor,

HAEMAPHYSALIS Koch.
H. chordeilis Packard — Nighthawk, turkey, killdeer (?).
H. leporis-palustris Packard — Rabbits, quail, lark.

EHIPICEPHALUS Kocll.
R. texanus Banks — Dogs, horses.

MAKGAROPus Karscli.

M. mmulatiis Say — Cattle, rabbit, porcupine, man (?), moose (?), sheep,

horses.

AMBLYOMMA Kocll.

A. amcricanum Linnseus — Cattle, man, horses, hogs, dogs, goats, panther,

wolf, some of the small mammals.
A. cajennense Fabricius — Cattle, horses.
A. maculatum Koch — Cattle, horses, dogs, fox, man.
A. tuberculatun Marx — Gopher, tortoise.

DERMACElSrTOR Kocll.
D. albipictus Packard — Moose, wapiti, beaver.
D. bifurcattis Neumann — Wild cat.
D. nigrolineatus Packard — Deer.
D. nitena Neumann — Horses.

D. occidentalis Neumann— Deer, California ground squirrel.
D. parumapertus Neumann— Man, chicken (?), jack-rabbit.
D. variabilis Say— Man, dogs, cattle, various smaller animals.
D. venuatus Banks — Man, horse, and several small mammals.

Of all the groups of the parasitic Acarina the Ixodoi-
dea, or ticks, have the widest distribution among host
species. Single species of the ticks have been reported
from hosts not only belonging to different families, but
to different orders and even classes. For example,
Ixodes ricinus Linn, has been found upon sheep, goats,
cattle, horses, deer, dogs, cats, fox ferrets, hedgehogs,
hares, rabbits, bats, birds, man and ground-squirrels.

Such a wide spread distribution of the different species
as is presented in the ticks is unique in the Acarina. It

30 Trans. Acaa. Sci. of St. Louis.

is true that in the Analgesidae we may have a single
species found on hosts belonging to different families, or
even in a few cases to different orders, but never are
these forms found on other hosts than birds. That a
single species like Ixodes ricinus Linn, has been found
on such widely separated hosts as bats, birds, hedgehogs
and man shows that they possess most of the characters
necessary for a wide host distribution. Perhaps the most
important point in this regard is their peculiar adhering
apparatus. This consists of a strong, dartlike hypos-
toma with prominent recurved teeth. This structure, as
can easily be seen, is capable of being inserted with about
equal ease into the skin of a mammal, a bird, or a reptile ;
this is in marked contrast with the clinging apparatus of
Myohia, which can only be used upon a single mamma-
lian hair, and that of a definite size. Then the ticks pos-
sess good walking legs, have a very tough skin, are re-
sistant to temperature changes when off a host. Being
blood suckers, they can engorge themselves with blood,
drop to the ground and live for months upon this meal.
Again the females are enormously prolific, laying in
some cases as high as 10,000 eggs. These eggs usually
hatch upon the ground and the young are given oppor-
tunities to find various hosts, each for himself. In clos-
ing my remarks about this group it might be safe to say
that almost every condition necessary for a great range
in distribution among host species has been fulfilled in
regard to it.

A List of the Species of Listrophoridae Which Have
Been Recorded from More than One Host Species,
Together w^ith Their Hosts.

listrophokus Pgst.

L. gihbus Pgst. — Lepus cuniculus, L. tlmidus L.

L. mustelae M^gn. — 'Mustela valgaris Erxl., M. erminea L., M. putorlus

L., also on pole cat.
L. leuckarti Pgst. — Paludicola terrestris (L.), P. amphiblus (L.), Arvlc-

ola arvalls (Pall.), Mus sylvatlcus L.

Ewing — Significance of Parasitism in Acarina. 31

MYcoPTEs Clap.

M. ienax Michael— Arvlcola arvalls (Pall.), Mus sylvaticus L.

TRiCHOEcius Can.

T. brevipes (Can. & Trt.)— Arvicola arvalls (Pall.). Also on rats.

SCHIZOCARPUS Trt.
8. mingaudi Trt.— Castor fiber L., C. canadensis Kuhl.

This little group of mammal-infesting parasites is of
particular interest to us because of its extremely narrow
limits of host distribution, and the factors which cause
the same. Up to the present, eighteen species have been
described and of these only four are found upon hosts
belonging to different genera, twelve are known from only
a single host species, and none is found upon hosts be-
longing to different families.

They are very small forms and are all unique in one
respect, i. e., in the possession of some specialized ap-
paratus for clinging to the hairs of mammals (PL V,
Fig. 19). They feed, as do the Analgesidae, upon the
oily secretions of the skin and on old epidermal cells.

What are the factors which cause such very limited
host distribution? It can not be on account of their diet
for it is the same as that of the Analgesidae, the mem-
bers of which may have a very wide distribution among
host species. It can not be on account of the habits of
the hosts, for they are frequently more or less gregare-
ous, and besides have other habits, as that of burrowing
and nesting in close proximity to other species, which
would offer splendid opportunities for a very wide dis-
tribution of the parasites. This point is proved bj^ the
fact that these same hosts have other external parasites
that do have a wide host distribution.

As a solution of the question I think that there can
be little doubt but that these forms have such very nar-
row host limits because of mechanical reasons pertain-
ing to their attachment to a hair. The special apparat-

32 Trans. Acad. Sci. of St. Louis.

uses which have been developed consist, of either a high
specialization of the front pairs of legs into chitinous
claspers shown on PL V, Fig. 19, in the development of
the maxillary lip so as to form two curved, shovellike
claspers, or in the special modification of the hind group
of legs into clasping structures. A careful examination
of these clasping organs shows that they can only be used
upon a hair of almost a definite diameter and even of a
definite shape. A hair much larger than those of the
accustomed host would frequently be too large even to
permit the presentation of the claspers, while a hair
much smaller could not be held tightly at all.

A List of the Analgesidae Found upon Moee than One
Host Species, Together with the Names of Their

HOSTS.^*^

Pterolicheae.

FEEYANA Hallcr.

F. gracilipes Trt. & Megn. — Grus antigone (L.), Ephippiorhynchus sene-

e galensis (G. Shaw).

F. pelargica Trt. & Megn. — Ciconla ciconia (L.), C. nigra (L.), Euxe-

nura maguarl (Gm.).
F. anserina Trt. & M^gn. — Anser anser (L.), Cygnus olor (Gm.), Chea

hyperboreus (Pall.).
F. anatina (C. L. Koch) — Anas acuta L., A. crecca L., A. querquedula

L., Mergus serrator L., Fuligula fuligula
(L.), Nettapus auritus (Bodd.). Other
■water birds.
F. leclerci Trt. — Loblvanellus senegalus (L.), L. indicus (Bodd.).
F. caput-medusae Trt. — Sula bassana (L.), and other species of tha

genus.
F. gigas Trt. — DIomedea nigrlpes Audub., and on related species.

PTEROLicHUs Robin.

p. hijuilatus (Haller) — On species of Strigidae.

P. denticulatus M^gn. & Trt. — Pyrrhula cruentata (WIed), and Amer-
ican parrots.
P. canestrinii Trt. — Ara macao (L.), A. canga, A. severa (L.).

^" The followino; list has been compiled chiefly from Canestrini's mono-
graph of the family published in 1S99. Des Tierreich, Lieferung 7.

Ewing — Significance of Parasitism in Acarina. 33

p. venustissimus Trt. — Conurus canicularis (L.), and other species of

Conurus.
P. squatarolae (Can.) — Charadrius squatarola (L.), C. pluvialls L.
P. charadrii (Can.) — Charadrius hiaticula L., C. alexandrinus L., C.

curonicus Gm., Totanus hypoleucus (L.), and
other marsh birds.
P. obtusus Robin — Caccabls rufa (L.), C. saxatilis (Meyer), Perdix

species.
P. ornatus Megn. & Trt. — Upon parrots.
P. ardeae (Can.) — Botaurus stellaris (L.). Other species of fam. Ardei-

dae.
P. gracilis Trt. — Megapodius forsteni Temm., M. freycineti Temm., Aepy-

podius bruijni (Oust.).
P. delibatus Robin — Corvus corone L., C. cornix L., C. corax L., C. frugi-

legus L., C. scapulatus Daud., Corvultur albi-
collis (Lath.). Other related species of Corvi-
dae, and species In Vulturidae.
P. musophagi Trt. — Schizoris africana (Lath.). Tauracus buffoni

(Vieill.).
P. uncinatus Megn. — Steganura paradisea (L.). Other Fringillidae.
P. nisi (Can.) — Accipiter nisus (L.), CIrcaetus gallicus (Gm.), Buteo
buteo (L.), Pernis apivorus (L.), Circus pygarus
(L.).
P. intermedins Megn. & Trt. — Upon diurnal birds of prey.
P. bicaudatus (Gerv.) — Struthio camelus L., Rhea americana (L.).
P. cuculi M6gn. & Trt. — Cuculus canorus L., and upon related genera la

Europe and America.
P, biemarginatus M6gn. & Trt. — Capito auratus Dumont, and on other

species of Capitonidae.
P. rhamphastinus Megn. & Trt. — Pteroglossus aracari (L.), Rhamphas-

tus dicolorus L. Other species of
Rhamphastidae.
P. circiniger M6gn. & Trt. — Rhytidoceros plicatus (Forst.), Cranorrhi-

nus leucocephalus (Vieill.). Other spe-
cies of Bucerotidae.
P, attenuaius Megn. & Trt. — On species of Bucerotidae.
P. ninnii (Can.) — Numenius arquatus (L.), N. tenuirostris Vieill.
P. limosae (Buchh.) — Species of Limosa, Totanus fuscus (L.).
P. limosae var. selenura Megn. & Trt. — Symphemia semipalmata (Gm.),

Limosa lapponica (L.).
P. totani (Can.)— Totanus calidris (L.), T. pugnax (L.), Tringa alpiaa

L.
P. proctogamus Trt. — Fulica atra L., Porphyrio caeruleus (Vand.).
P. bucJiholzi (Can.)— Limosa limosa (L.), Charadrius squatarola (L.).
P. buchholzi var. hastigera Megn. & Trt.— Tringa alpina L., Microsar-

cops cinereus (Blyth).

34 Trans. Acad. Sci. of St. Louis.

p. buchholzi var. fascigera Megn. & Trt. — Totanus calidrls (L.)f Tringa

canutus L., Arenaria Inter-
pres (L.).
P. colymbi var. major Mfgn. & Trt. — Colymbus cristatus L., Urlnator

septentrionalis (L.),
P. vexillarius M6gn. & Trt. — On Buceros species.
P. vexillarius var. homophylla M6gn. & Trt. — Upon Buceros species.
P. vexillarius var. minuta Megn. & Trt. — Lophoceros melanoleucus

(Lcht.), L. erythrorhyn-
chus (Temm.).
P.cultrifer Robin — Apus apus (L.), A. melba (L.),
P. onychophorus var. fauna Trt. — Brachypteraclas pittoides Lafr., B.

crossleyi (Sharpe).
P. bracJiiatus Trt. — Lorius doraicella (L.), Loriculus sclaterl Wall.,

Trlchoglossus haematodes (L.).
P. brachiatus var. crassior Trt. — Trlchoglossus novaehollandiae (Gm.),

Glossopslttacus concinnus (G.
Shaw), Loriculus sclateri "Wall.
P. chiragricus M6gn. & Trt. — Pezoporus formosus (Lath.), Platycercus

flaveolus J. Gd., P. elegans (Gm.).
P. velifer Trt. — Nymphicus cornutus (Gm.), Pyrrhulopsis personata (G.

R. Gray), Platycercus flaveolus J. Gd.
P. flavettei Trt. — Nestor notabilis J. Gd., N. meridionalis (Gm.), Pse-

photus xanthorrhous Bp., Microglossus aterrimus
(Gm.).
P. casuarinus Trt. — Calcopsitta atra (Scop.), Eos rubiginosa (Bp.).
P. eurycnemis Trt. — Ara macao (L.), Pyrrhula ferruginea (St. Miill.).
P. bisiibulatus Robin — Caccabis rufa (L.), Perdix perdix (L.).
P. bimucronatus Trt. — Upon Lagopus species.
P. aquilinus Trt. — Aquila chrysaetus (L.), A. pomarina Brehm., Hallae-

tus species.
P. aquilinus var. milvulina Trt. — Milvus milvus (L.), Haliastur Indus

girrenera (Vieill.).
P. calcaratus Trt. — On many species of Bucerotidae.
P. curtus Trt. — Megapodius freycineti Temm., Aepypodius bruljnl

(Oust.).
P. guadratus Trt. — Aepypodius bruijni (Oust.), Talegallus cuvieri Less.
P. tritiventris Trt. — Upon Ara and Conurus species.
P. panoplites Trt. — Poeocephalus gulielmi (Jard.) and related species.
P. fissiventris Trt. — Penelopides manillae (Bodd.), Rhytidoceros plicatus

(Forst.), Anthracoceros malabaricus (Gm.) and
related species.
P. filrstenbergi (Buchh.) — Buceros rhinoceros L., Ortholophus leucolo-

phus (Sharpe), Anthracoceros malabaricua
(Gm.), Hydrocorax hydrocorax (L.).

Ewififf' — ■Significance of Parasitism in Acarina. 35

p. pterocolurus Trt. — Anthracoceros convexus (Temm.), Penelopides ma-

nillae (Bodd.).
P. pegasus Trt.— Anorrhirus galerltus (Temm.), Rhytidoceros plicatus
(Forst.), Hydrocorax hydrocorax (L.). Various spe-
cies of Bucerotidae.
P. pegasus var. retusa Trt. — Anthracoceros malabarlcus (Gm.), Anorrhl-

nus galeritus (Temm.).

xoLOPTEs Can.

X. claudicans (Robin) — ^Coturnix coturnix (L.), Perdix perdlx (L.),

Caccabis rufa (L.).

FALCULIFEK Raill.

F. rastratus (Buchti.) — Lophophaps plumifera (J. Gd.), Goura coronata

(L.). On European species of Columbidae.
F. cornutus (Trt.) — Cyanocorax violaceus Du Bus.

CHILOCERAS Trt.
C. cervus Trt. — Caloenas necobarica (L.), Butrygon terrestris (G. R.
Gray).

C. taurus Trt. — Carpophaga pinon (Q. & G.), C. goliath G. R. Gray.

BDELLORHYNCHUS Trt.
B. polymorphus Trt.— Anas crecca L., A. clypeata L., Erismatura leuco-

cephala (Scop.), and other water birds.

Dermoglypheae.

THECARTHRA Trt.
T. longitarsa (M6gn. & Trt.)— Charadrius squatarola (L.), C. pluvia-

11s L.
T. theca (Megn. & Trt.)— Sterna caspia Pall, and related species.

DERMOGLYPHUS Megll.
T). minor (Norn.) — Gallus domesticus, Meleagris gallopavo L., Numida

meleagris L.

D. elongatus (M6gn.)— Gallus domesticus, Serinus canarius (L.), and

Ploceidae.
D. major (Trt.)— Eutoxeres aquila (Bourc), Phaethornis longlrostria

(Less. & Delattre).
D. pachycnemis (Trt.) — Struthio camelus L., Rhea amerlcana (L.).
D. pteronyssoides (Trt.)— Gallinago nigripennis Bp., Aulacorhamphus

caeruleicinctus (Orb.).
D. paradoxus Trt.— Pyrrhula leucotis (Lcht.), Conurus aeruginosus

(L.), Chrysotis farinosa (Bodd.).

36 Trans. Acad. Sci. of St. Louis.

SPHAEROGASTEA Tl't.

S. thyJacodes Trt. — Totanus littoreus (L.), Tringa subarquata (Guld.).
S. monstrosa (Trt.) — Eclectus pectoralis (St. Miill.), Trichoglossus

cyanogrammus Wagl.

( Analgeae.

PTERONYSSUS Robill.
P. gracilis (Nitzsch) — Upon species of Picus.

P. chiasma Trt. — Pteroglossus aracari (L.) and other Rhamphastidae.
P. obscurus Berl. — ^Chelldonarla urblca (L.), Clivicola riparia (L.).
P. truncatus Trt. — Sturnus vulgaris L., Lamprotornis sp.
P. truncatus var. subtruncata Trt. — Mainatus javanensis (Osb.), Calor-

nis panayensis (Scop.).
P. integer Trt. & Neum. — Muscicapa grisola L., Parua crlstatus L.
P. conurus Trt. — Pogonorhynchus bidentatus (G. Sliaw), Barbatula leu-

colaema Verr.
P. quadratus Haller — Picus viridicanus Wolf, Sylvia atricapilla (L.).
P. pufpni (Buchh.) — Dromas ardeola Payk., Sterna sp., Larus sp., Puf-

finus sp., Procellaria sp.
P. abbreviatus (Buchh.) — Buceros rhinoceros L. and related species.
P. lyrurus Trt. & Neum. — Rhytldoceros plicatus (Forst.), Anorrhinus

galeritus (Temm.). Other Bucerotldae.
P. elephantopus Trt. & Neum. — Rhytldoceros plicatus (Forst.), Anorrht-

nus galeritus (Temm.). Other Bucer-
otldae.
P. spinosus Trt. 6 Neum. — Upon Bucerotldae.

ANALGES NitzSCh.

A. chelopus (Herm.) — Corvus sp., Parus sp., Motacllla sp.

A. bidentatus Gleb. — Accentor modularis (L.), Acrocephalus arundina-

ceus, Anthus sp.
A. passerinus (L.) — Passer sp. and related genera.
A. corvinus Megn. — Corvus corone L. and other Corvldae.
A. mucronatus (Buchh.) — ^Panurus blarmicus (L. ). Other Parldae.
A. pachycnemis Gleb. — Accentor modularis (L.), Picus species.

PROTALGES Trt.

P. affinis Trt.— Pterophanes teramlncki (Boiss.), Aglaeactis cuprlpenula

(Bourc. ft Muls.).
P. longitarsus Trt. & Neum. — Petasophora iolata J. Gd., Eulampls jugu-

laris (L.).
F. attenuatus (Buchh.)— Aslo otus (L.),Fam. Strigldae.

Emng — Significafice of Parasitism in Acarina. 37

p. accipitrinus Trt. — Falco tinnunculus L. and other diurnal birds of

prey.
P. curtus Trt. — Platycercus elegans (Gm.) and related species.
P. lorinus Trt. — Lorius garrulus (L.), L. domicella (L.) and related

species.
P. larva Trt. — Species of Pslttacidae.

M^GNiNiA Berl.

M. cuhitalis (Megn.) — Meleagrls gallopavo L., species of Phasianidae.
M. cuhitalis var. ginglymura (Megn.) — Upon Phasianidae, Anatidae,

Corvidae.
M. columhae (Buchh.) — Columba domestica and other Columbidae, Se-

rinus canarlus (L.).
If. picimajoris (Buchh.) — Picus viridls L., Dendrocopus major (L.),

other Picidae.
M. hirsuta Trt. — Conurus solstitialis (L.), C. canlcularis (L.), C. nen-
day (Vieill.), Galea melanocephala (L.), Pyrrhura
plcta (St. Miill.), P. leucotis (Lcht.), Brotogerya
chlril (Vieill.).
If. velata (M6gn.) — Upon Anatidae.

Jlf. aeguinoctialis Trt. — Phaethon aethereus L., P. rubricaudus Bodd.
M. gallinulae (Buchh.) — Gall inula chloropus (L.), Ortygometra por-

zana (L.), Rallus aquaticus L., Vanellus
vanellus (L.), Coturnix coturnix (L.).
M. aestivalis var. suhintegra Berl. — Chelidonaria urbica (L.), Clivlcola

riparia (L.).
M. psoroptopus Trt. — Dichoceros bicornis (L.), Anthracoceros mala-

baricus (Gm.).
M. magnifica Trt. — Upon Paradiseldae.

PTERALLOPTEs Trt. & Megn.

p. megnini var. falcinelli (Trt.) — Plegadis falcinellus (L.), Platalea

leucorodia L.
P. hipartitus (Trt.) — Anthracoceros convexus (Temm.), A. malayanua

(Raffl.) and other Bucerotldae.
P. corrugatus (Trt.) — Ortholophus leucolophus (Sharpe), Anthracoceros

malayanus (Raffl.), Cranorrhinus corrugatus

(Temm.).
P. elytTirura (Trt.) — Upon species of Bucerotldae.

XOLALGES Trt.

X. analginus Trt. — Dendroecia aestlva (Gm.), Elainea martinica (L.),

other Rhamphastidae.

38 Trans. Acad. Sci. of St. Louis.

Pkoctophyllodeae.
ALLOPTEs Can.

A. norneri Trt.— Cyanolesbia mocoa (Del. & Bourc.) and other Trochili-

dae.
A. aviculocaulis Trt. — Eutoxeres aquila (Bourc), Phaethornis longiros-

tris (Less. & Delattre), other Trochilidae.
A. intermedius (Trt. & Neum.) — Elainea martinica (L.), Loxigilla noc-

tis (L.).
A. trogontis (Trt.)— Trogon collarls (Vieill.), Harpactes orrhophaeus

(Cab. & Heine), other Trogonidae.
A. hemiphyllus (Robin)— Fringilla coelebs L., F. montifringilla L..

Emberiza calandra L., other Fringillidae.
A. pteronyssoides Trt. — Pipra aureola L., P. erythrocephala L., other

Tyrannidae.
A. dielytra Trt. — Pipra erythrocephala L., P. aureola L.
A. minutus Trt. — Phaethon aethereus L., P. rubricaudus Bodd.
A. phaethontis (Gm.) — Phaethon rubricaudus Bodd., P. aethereus L.,

Fratercula arctica (L.).
A. crassipes (Can.) — Limosa limosa (L.), Totanus pugnax (L.), Tringa

alpina L., Sterna minuta L. and other Scolopaci-
dae and Laridae.
A. crassipes var. curtipes Trt. — Haematopus ostralegus L., Totanus

macularius (L.).
A. crassipes var. minor Trt. — Alca torda L., Fratercula arctica (L.), Uria

grylle (L.), Larus ridibundus L.
A. bisetatus (Haller) — Sterna hirundo L., S. cantiaca Gm., Stercorarius

parasiticus (L.), Tringa alpina L.

ALLANALGES Trt.
A. gracilipes (Trt.) — Lanlus excubitor L. etc.

PROCTOPHYLLODES Robin.
P. glandarinus (C. L. Koch) — On Fringillidae.
P. armattts (Banks) — On Fringillidae, Turdidae, Mniotiltidae.
P. ampelidis (Buchh.) — Bombycilla garrula (L.), Accentor modularls

(L.), Anthus, Fringillidae, Laniidae, Corvl-
dae, etc.
P. truncatus Robin — Passer domestlcus (L.), P. montanus (L.).
P. arcuaticauUs Trt. — Acanthis sp.
P. stylifer (Buchh.) — Upon Parldae.

TROUESSARTIA Can.

T. corvina (C. L. Koch) — On Corvidae.

T. appcndiculata (Berl.) — Clivicola riparia (L.), Apus apus (L.).

T. bifurcate (Trt.)— Upon Sylviidae.

Eiving — Significance of Parasitism in Acarina. 39

PTERODECTES Robill.
p. ortliygometrae (Can.) — Orthygometra pusilla (Pall.). O. porzana

(L.).
P. actitidis (Can.) — Totanus hypoleucus (L.), Tringa sp.
P. edwardsi (Trt.) — Acrocephalus arundinaceus (L.), Sylvia galactodes

Temm.
P. rutilus Robin — ^Chelidonaria urbica (L.) and related species.
P, muticus Banks — Poocsetes granaineus (Gmel.), Sayornis pbcebe

(Lath.).
P. iilo'batus Robin — Anthus trivialis (L.), Alauda arvensis L.
P. gracilis Trt. — Ostinops decumanus (Pall.), Xanthura yncas (Bodd.),

Cyanocorax chrysops (Vieill.).
P. paradisiacus Trt. — Paradisea minor G. Shaw, Sericulus melinus

(Lath.).
P. gracilior Trt.— Topaza pella (L.), Chrysolampis mosquitus (L.),

Lophornis ornatus (Bodd.) and other Trochilidae.
P. mainati var. aculeata Can. — Eurylaemus ochromelas Raffl., Lampro-

colius glaucovirens Ell.
P. trocMlidarum Trt. — Upon Trochilidae, Chrysolampis mosquitus (L.),

Topaza pella (L.), Lophornis ornatus (Bodd.),
Cyanolesbia mocoa (Del. & Bourc).
P. gladiger Trt. — Upon Trochilidae, Chrysolampis mosquitus (L.), Eu-

lampis Jugularis (L.).
P. selenurus Trt. — Cyanolesbia mocoa (Del. & Bourc), Topaza pella

(L.).

PTEROPHAGUS Megll.
P. strictus M6gH. — Upon Columbidae.

Epidermopteae.
HETEROPSORUS Trt. & Neum.

H. pteroptopus Trt. & Neum. — Acrocephalus streperus (Vieill.), Eritha-

cus cyaneculus (Wolf.), Emberiza cir-
lus L., E. schoeniclus (L.).

PACHYLicHus Can.

p. crassus Can. — Erithacus phoenicurua (L.), Dendrocopus medlus
(L.).

MicROLicHus Trt. & Neum.

if. avus (Trt.) — Gallinago major (Gm.), G. nigripennis Bp.. Dendroco-
pus medius (L.), Garrulus glandarlus (L.), Eulam-
pls holosericeus (L.), Passer domesticus (L.).

40 Trans. Acad. Sci. of St. Louis.

The list of the mites recorded from more than one host
species in this group is in itself extremely long, while the
total number of all the species is over 400. The various
genera and species differ greatly in their external mor-
phology and considerably in their internal structure, yet
their food habits are practically the same.

In their distribution according to host species most
of the forms fall into two classes; those confined to a
single host and those found on several closely related
host species. Although over half of the known forms are
at present reported from only a single host, this does not
indicate in the least that most of these have such a re-
stricted host distribution; the reason they have not been
reported from other hosts being that no search has been
made for them on other hosts, or at least no careful and
thorough search for them.

In regard to the Analgesid species it will be noticed
that frequently there is a greater range of hosts than is
usually found in the mite species of other groups excepting
the Ixodoidea. No case, however, is known of one of these
forms being reported from other than a bird host, hence it
is probable that they could not survive upon such forms as
mammals. In the absence of direct inoculation experi-
ments upon mammals it is hard to tell just why this is. In
the Mallophaga, a group of more unity of structure and of
comparatively few individuals, a few bird-inhabiting
forms are found also on mammals. Since the Mallophaga
of the birds live upon the barbules of feathers it is easy to
see that one of them would find insufficient food when
transferred to a mammal ; but this would not be true of the
Analgesidae, for they live upon old epidermal scales and
oily secretions. As far as the diet is concerned I can not
see why these mites could not live upon mammals. It is
my opinion that the reasons are mechanical. In the flatten-
ing of the form of the analgesid body, it has become de-
pressed, not compressed, hence when turned edgeways be-
tween the hairs of a mammal the mite would lose its foot-

Ewmg — Significance of Parasitism in Acarina. 41

ing and either fall off or would be incapable of loco-
motion.

Among the birds themselves it is by far the more usual
thing to find a species of Analgesidae upon closely related
forms, but such is not always the case. For example
Proctophyllodes ampelidis (Buchh.) is found on members
of five different families, four of which are not closely
related; they are the Ampelidae, Mniotiltidae, Fringilli-
dae, Laniidae, Corvidae. Megninia ciihitaUs (Megn.) is
found on three different families, Phasianidae, Anatidae
and Corvidae, each of which belongs to a different order.
Other cases of the same kind exist so that we are forced
to the conclusions that under favorable conditions a spe-
cies may have a very wide range of hosts.

Since quite a number of these species, representing
most of the important genera, are found on widely sep-
arated host species, it may be regarded as an indication
that the reason why other species have not as great a
distribution is simply because they have not had the
chance to be transferred to other hosts. However, of
the two attempts which I made at transference of these
mites from their normal to a foreign host, neither was
successful.

When the members of this family are detached from
their hosts they walk freely about and at a moderate
rate. I tested their vitality under these conditions and
found that frequently they would live for three days.
These two facts make the transference from one host to
another much easier and more probable and doubtless
are great factors in the explanation of the distribution of
many of the species.

Of special interest in regard to their host distribution
are the forms which are found upon the raptorial birds.
Of the ten species of Analgesidae found on the Fal-
conidae, four are known to occur on more than one
host species. Although these four species are distributed
among several hosts none of them are on any birds outside

42 Trans. Acad. Sci. of St. Louis.

of the Falconidae. Thus Pterolichus nisi (Can.) is found
on six host species, but all of them belong to the Falconi-
dae and are closely related.

If these forms are able to adapt themselves to lives
upon rather widely separated hosts, why have they not
done so as have many of the other forms? Since the
hosts are preying birds there would be a good chance
for them to get the mite parasites from the species
preyed upon, but such does not seem to have happened.

Since the members of the Falconidae are non-grega-
rious and solitary in habits, thus making the transfer of
the parasites from one host to another improbable, it is
interesting to see how they became distributed among
several hosts belonging to this family. Doubtless it is
to be explained in the same manner as Kellogg has ex-
plained the host distribution of similar cases in the Mal-
lophaga, ''that the parasitic species have persisted un-
changed from the common ancestor of the two or more
now distinct but closely allied bird-species.

n

A List of the Sarcoptidae Known to Occur upon More
THAN One Host Species, Together with Their
Hosts.

notoedres Raill.

N. notoedres (M6gn.) — Mus rattus L., M. decumanus Pall., Paludicola

amphibius (L.).

PROsopoDECTEs Can.

P. chiropteralis (Trt.) — Rhinolophus ferrumequinum (Schreb.), Vespe-

rugo serotinus (Schreb.).

SARcoPTES Latr.

S. caprae Furstb. — Capra liircus, Ovis aries, Equus caballus, Bos taurus,

Homo.
8. dromedarii '7<>rv. — ^Camelus dromedarlus L., C. bactrlanus L., Lama

glaraa (L.), Giraffa camelopardalls (L.), Antl-
lope bubalis (sp.?).

cnemidocoptes Fiirstb.
C mutans (Robin) — Gallus domesticus and other birds.

Eunng — Significance of Parasitism in Acarina. 43
psoEOPTEs Gerv.

p. equi (Hering) — Equus caballus, E. asinus, E. caballusc^X E. asinusj.

PSORALGES Trt.

P. Wbertus Trt. — Tamandua tetradactyla (L.) and other species of the
same genus.

OTODECTES Can.

0. cynotis (Hering) — ^Canis familiaris, Felis domestica.

In this family over forty species have been described.
Only eight of them have been recorded from more than
one host species, and they are found in seven of the nine
genera comprising the family.

The study of the distribution according to host species
in these itch mites presents a puzzle indeed. Perhaps
no group of the parasitic Acarina has such a large per-
centage of forms restricted to a single host and yet,
strange to say, a few of the species have a distribution
among host species not closely related, for example Sar-
coptes caprae Fiirstb. is found on man, the horse, and
several of the Bovidae,

Several attempts at inoculation have been made by
other workers with various forms of itch mites, and
with results just as perplexing as the distribution of the
species themselves.

I made a very careful attempt at inoculation with
Notoedres notoedres (Megn.) taken from rats, upon our
common striped ground squirrel, Spermophilus 13-lin-
eatus, but the attempt was a failure. Megnin was un-
able to get any successful inoculations with the Sar-
coptidae when placed on other than their normal hosts,
hence he called several of the forms, morphologically
identical, separate physiological species. Yet against
these experiments, it is established that the itch mite of
the dog, Sarcoptes canis, is transferable to man.

44 Trans. Acad. Sci. of St. Louis.

In regard to the factors bearing upon the possibility
of transportation it might be mentioned that these forms
are practically helpless in regard to their locomotion,
yet in regard to duration of life when off a host, I found
that forms would live easily for four days in minute
scrapings. Doubtless under favorable circumstances
they would live much longer. What then are the condi-
tions which cause such a contradictory distribution of
the species'? Some forms have been able to adapt them-
selves to hosts not closely related; others can not live
except upon a single host. I can not give any very sat-
isfactory answer to this question, but merely suggest that
it is because some species have either a much more deli-
cate taste or more delicate digestive systems than other
forms, and for this reason have remained upon a single
host species.

A List of the Eeiophyidae Known to Occuk upon More
THAN One Host Species, Together with Their
Hosts.

Eriophyinae.

eriophyes Sieb.

E. tenuis (Nal.) — Avena pratensis L., Bromus arvensls L., B. erectut
Huds., B. mollis L., Dactylis glomerata L.

E. Jaevis (Nal.) — Alnus glutinosa Gart., A. incana D. C, A. vlridis D. C.

E. irevitarsus (Focken) — Alnus glutinosa Gart., A. Incana D. C, A.

viridis D. C.

E. rudis (typlcus) (Can.) — Betula verrucosa Ehrh., B. pubescens Ehrh,

E. rudis longisetosus (Nal.) — Betula verrucosa Ehrh., B. pubescens

Ehrh.

E. lionotus (Nal.) — Betula verrucosa Ehrh., B. pubescens Ehrh.

B. iJicis (Can.) — Quercus ilei L., Q. Ithaburensis Decne.

E. populi (Nal.) — Populus tremula L., P. nigra L.

E. tetanothrix (Nal.) — Salix fragilis L., S. aurita L.

E. dralae (Nal.)— Alyssum calycinum L., A. hirsutum M. B., Berteroa

incana D. C., Camellna sativa Crantz, Capsella
bursa-pastoris L., Erysimum canescens Rth., Lepld-
ium draba L., Sisymbrium sophia L.

E. rosalia (Nal.) — Helianthemum fumana Mill., H. hirsutum Th., H,

oelandicum Wahlb.

Etving — Significance of Parasitism in Acarina. 45

E. tiliae (typicus) (Pgst.) Nal. — Tilia platyphyllos Scop., T. ulmlfoUa

Scop.
E. tetratrichus (Nal.) — Tilia platyphyllos Scop., T, ulmlfolia Scop.
E. geranii (Can.) — Geranium sanguineum L., Malva alcea L.
E. heteronyx (Nal.) — Acer campestre L., A. platanoides L.
E. macrorhynchus (Nal.) — Acer campestre L., A. platanoides L.
E. macrochelus (Nal.) — Acer campestre L., A. platanoides L., A. pseu-

doplatamus L.
E. hrevirostris (Nal.) — Polygala amara L., P. depressa Wend.
E. peucedani (typicus) (Can.) — Orlava grandiflora Hoffm., Peucedanum

venetum Koch, Seseli glaucum L., S.
hippomarathrum L., Torills Infesta
Koch, Trinia vulgaris D. C.
E. ribis (Nal.) — Ribes rubrum L., R. alpinum L., R. nigrum L.
E. kochi (Nal. & F. Thorn.) — Saxifraga aizoides L., S. mutata L.
E. piri (Pgst.), Nal. — Pirus communis L., P. malus L., Amelanchier vul-
garis Monch., Cotoneaster vulgaris Lindl., C.
tomentooa (Rech.), Sorbus aria Crantz. S. aucu-
paria L., S. torminalis Crantz, S. mongeoti
(Rech.).
E. piri var. variolata (Nal.) — Sorbus aria Crantz, S. aucuparia L., S.

torminalis Crantz.
E. calycobius (Nal.) — Crataegus oxyacantha L., Amelanchier vulgaris

Monch.
E. parvulus (Nal.) — Potentilla argentea L., P. reptans L., P. verna L.
E. similis (Nal.) — Prunus domestica L., P. spinosa L.
E. padi (Nal.) — Prunus padus L., P. domestica L., P. splnosus L.
E. genistae (Nal.) — Genista pilosa L., Sarothamnus scoparius Koch.
E. euaspis (Nal.) — Lotus corniculatus L., Dorycnium pentaphyllum

Scop.
E. plicator (typicus) (Nal.) — Medlcago falcata L.. M. lupulina L.
E. plicator trifolii (Nal.) — Trifolium arvense L., Ervum hirsutum L,
E. ononidis (Can.) — Ononis repens L., 0. spinosa L.
E. anthonomus (Nal.) — Theslum intermedium Schrad., Th. divarlcatum

Jan.
E. alpestris (Nal.) — Rhododendron hirsutum L., Rh. ferrugineum L.
E. laticinctus (Nal.) — Lysimachia vulgaris L., L. nummularia L.
E. fraxini (Karp.) — Fraxinus excelsior L., F. viridis Bosc.
E. eucricotes (Nal.) — Lycium europaeum L., L. mediterraneum Dun.
E. anceps (Nal.) — Veronica chamaedrys L., V. officinalis L.
E. ajugae (Nal.) — Ajuga reptans L., A. genevensls L.
E. salviae (Nal.) — Salvia pratensis L., S. silvestris L., S. verbenaca L.
E. schmardae (Nal.) — ^Campanula rapunculoides L., C. glomerata L., C.

trachelium L., C. rotundifolia L.
E. gain (Karp.), Nal. — Galium aparine L., G. mollugo L., G. silvatlcum

L., G. verum L.

46 Trans. Acad. Sci. of St. Louis.

E. galiobius (Can.) — Galium verum L., G. lucidum All.
E. artemisiae var. subtilis (Nal.)— Artemisia campestris L., A. vul-
garis L.
E. centaureae (Nal.) — ^Centaurea amara L., C. maculosa Lam., C. sea-

biosa L.
E. oleivorus Ashmead — On orange and lemon.

Phyllocoptinae.

PHYLLOCOPTES Nal.

Ph. duUus (Nal.)— Avena pratensis L., Bromus arvensis L., B. errectus

Huds., B. mollis L., B. sterilis L., Dactylls glom-
erata L.

Ph. comatus (typlcus) Nal. — ^Corylus avellana L., C. a. var. fol. lasc.

Ph. reticulatus Nal.— Populus alba L., P. tremula L.

Ph.. magnirostris Nal. — Salix fragilis L., S. purpurea L., S. alba L.

Ph. parvus Nal. — Salix alba L., S. purpurea L., S. sp.

Ph. eurynotus Nal.— Torills infesta Curt., T. anthriscus (L.).

Ph. schlcchtendali Nal.— Pirus malus, P. communis L.

Ph. fockeui Nal. & Trt. — Prunus cerasus L., P. domestica L., P. ma-

haleb L.

Ph. cytisicola Can. — Cytisus nigricans L., C. laburnum L.

Ph. anthoUus Nal. — Galium silvaticum L., G. uliginosum L., G. verum L.

EPITKIMEKUS Nal.

E. salicohius (Nal.) — Salix alba L., S. fragilis L.

E. heterogastcr (Nal.) — Clematis recta L., C. cirrhosa, C. alplna (L.).

E. trilohus (Nal.) — Sambucus nigra L., S. racemosa L.

OXYPLEUEITES Nal.
0. carinatus (NaT.) — Aesculus hippocastanum L., A. rubicunda Lois.

Of about 250 known species of the Eriophyidae I have
listed 59 that have been recorded from more than one host
species. Of these 59, 50 are found only upon species of
the same genus and the remaining 9 are found only upon
closely related genera. Thus Eriophyes tenuis (Nal.) is
found only on members of the grass family, E. drabae
(Nal.) only on members of the mustard family, and E.
piri (Pgst.) Nal. only on related genera of the rose family.

Emng — Significance of Parasitism in Acarina. 47

■When one species is found upon more than one host
it is interesting to note that the malformations produced
may be quite different on the different host species, al-
though frequently they may be very similar.

Since the species of mites in this group have such nar-
row limits in their host distribution it is interesting to
study the causes of it. In the first place is there a ready
means of transference from one kind of a host to an-
other? I think that there can be no doubt but that these
species are easily transferred from the leaves of one
kind of a plant to those of another. In many forests we
find the branches of one tree mingled with those of an-
other or superimposed over those of another, so that dur-
ing a high wind they would be frequently rubbed to-
gether.

Again a tree or bough when falling frequently would
lodge in another, and the mites which it carried would
be transferred to the latter. Since the gall inhabiting
forms always inhabit open galls and since all of the
Eriophyidae travel very well, though they have but four
legs, they would thus be enabled to pass easily from one
host to another when these hosts are in actual contact.

I am inclined to attribute this very limited distribution
of the different species of this group to physiological
reasons. The forms are very small and have a simple
and somewhat degenerate digestive system, hence too
great a change in the nature of the diet could not be en-
dured. In this regard it may be interesting to note that
some of the members of the phytophagous Tetranychi-
dae are well nigh omnivorous. They are hardy forms
and do not have a delicate digestive system.

48

Trans. Acad. Set. of St. Louis.

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Eimng — Significance of Parasitism in Acarina. 51

Adaptive Convergence.

Although the Parasitic Acarina have descended from
many widely separated free-living groups, yet when ex-
amined many of these forms show a remarkable super-
ficial resemblance which at first sight suggests a very
close phylogenetic relationship (See PL III, Figs. 10 and
11). This superficial resemblance is a direct response
of these originally widely separated groups to the same
environmental conditions.

The flattened form of the body has been assumed
by many of the Acarina of parasitic habits, and it is in-
teresting to note that we find a duplication of the same
process in some of the parasitic insects. It is obvious
that a compressed form of the body is an advantage to
those parasites that inhabit fur-bearing animals, as it
enables the parasite to pass easily between the hairs of
its host. Examples of such parasites possessing this
form of body are the fleas, among insects, and the fur-
inhabiting Listrophoridae among the mites.

On the other hand a depressed form of body is an ad-
vantage to those parasites that live upon birds and need
to crawl between the superimposed feathers; this form
offering less resistance to movements and affording bet-
ter footing for the locomotor organs. Familiar examples
of parasites having this form of body are the Mallophaga
among insects and the Analgesidae among mites.

We find the need and the development of the locomotor
organs becoming less and less as we pass from the free
to the occasional, to the semiparasitic, and finally to the
permanent parasitic epizoa; likewise we find a gradual
development of clinging organs. These organs may be
of several kinds, but of special importance are the hooks
or claws. Many of the parasitic groups have these
structures developed for adhering to their hosts. These
may be developed on any or all of the legs as is the case
in the Ixodidae, Argasidae, Analgesidae, Listrophoridae

52 Trans. Acad. Sci. of St. Louis.

and several other groups ; or they may be developed upon
the palpi as in the case of the parasitic Cheyletidae (PL
III, Fig. 10), or the larval parasites of the families,
Trombidiidae, Hydrachnidae or Halacaridae (PL V,
Figs. 18 and 20, and PL VII, Fig. 28); or again they
may be developed upon some other structure of the
mouth-parts as the hypostoma in the case of the ticks.

The possession of stout, backwardly directed spines
or bristles is a characteristic almost universally found
in external parasites inhabiting fur or feather bearing
animals. The fleas, Mallophaga and Pediculidae have
them, and in the Acarina we find them well developed
in members belonging to the Dermanyssidae, Cheyletidae
(PL III, Fig. 10), Analgesidae (PL lY, Figs. 15 and 16,
and PL VI, Figs. 24 and 25), Sarcoptidae (PL II, Fig.
6, and PL III, Fig. 11), and Listrophoridae (PL V,
Fig. 19).

In order to establish the significance of the possession
of these backwardly directed spines, I have made a num-
ber of observations and experiments and from these have
decided that they fulfill chiefly two functions. First, be-
cause they are very stiff and are directed toward the
rear, they aid the possessor of them very materially in
its forward movements. Frequently I have watched fleas
advance themselves very successfully through a mass of
hairs simply by a backward and forward movement of
the body and legs, the spines permitting a free forward
movement of the parts, but blocking a backward thrust
of the legs and thus compelling an advance of the body.
Another advantage of these spines and bristles is in re-
tarding any effort which is made by the host to rid it-
self of its tormentors. Dogs, cats, chickens, and almost
all other infested animals, being much irritated by the
parasites, will make repeated efforts to get free from
them. They do this by scratching themselves with beak
or claw, or by rubbing against some object, or wallowing
in the dust. In these efforts frequently the parasites are
dislodged either from their hold on the skin or the hairs

Eiving — Significance of Parasitism in Acarina. 53

or feathers only to be caught by other hairs or feathers
on account of these long spines and thus are saved from
a complete loss of a host. This fact, I think, would sug-
gest itself immediately to any one who had ever endeav-
ored to pick off these live parasites from their hosts, or
who has watched domestic animals trying to rid them-
selves of them.

The degeneration of the special senses, an almost uni-
versal accompaniment of parasitism, is fully illustrated
in the Acarina. Of the special senses found in the free-
living mites that of touch is undoubtedly the highest de-
veloped; sight is present in some cases, but many of the
free forms are without eyes. It appears to be estab-
lished that many free forms have the faculty of smell
and also that of taste. The possession of the sense of
hearing has never been satisfactorily proved, I believe,
for any of the Arachnida, not even in the spiders, where
stridulating organs are found; so, of course, it is sup-
posed to be wanting in the mites.

All of the special senses which are found in the free
forms show successive stages of degeneration in accord-
ance with the progressive stages of parasitism. In prac-
tically all of the free forms we find special tactile struct-
ures present, in the form of long specially adapted palpi
or front legs, the possession of tactile bristles, or even
special organs developed for this purpose. In the Sar-
coptidae, some of the Cheyletidae, in the Listrophoridae,
and in other groups all these tactile organs have atro-
phied. Although many of the free forms, closely re-
sembling the types from which parasitic forms evidently
arose, have well-developed eyes, these structures appear-
to be universally absent in parasitic forms. Here the
degenerative process has been complete. No evidence^
appears to be obtained that the sense of smell has been
lost or has become weakened in the parasitic forms. But
since the development of this sense in the free forms is
slight, it would be difficult to get reliable data upon its.
decline, if present, in the parasitic forms.

54 Trans. Acad. Sci. of St. Louis.

The degeneration of the locomotor appendages is also
as complete as that of the special senses. We get all
degrees of degeneration from the type of legs found in
the free forms; consisting of from five to seven distinct
segments, clothed with bristles and ending in special
adaptive tarsal appendages, as claws, caruncles, and pul-
villi; to even entirely limbless sarcoptids.^^ Bridging the
space between these two extremes, two common types
of legs might be mentioned, that of the Eriophyidae and
that of the Demodecidae. In the former family the legs
are reduced to four in number; and although they con-
sist of five segments each, they are weak and unable to
sustain the weight of the body (See PL VII, Fig. 29).
In the latter family the legs are of the normal number,
yet are greatly reduced, consisting of only three short,
stumpy segments and scarcely extending beyond the mar-
gins of the body (PL IV, Fig. 14).

All of these changes thus far mentioned, the assump-
tion of a flattened form of body, the possession of back-
wardly directed spines and bristles, of hooks and claws
for adherence, and the degenerative process affecting
the special senses and the locomotor organs, can only
be fully accounted for by the action of natural selection
working in response to similar environmental conditions.
It has resulted in bringing forms descended from widely
different groups to the assumption of a variety of sim-
ilar characters, so that now they appear to be closely re-
lated forms. It illustrates excellently adaptive converg-
ence (Note the similarity of Figs. 10 and 11 on PL III,
and compare with illustrations of living forms. Figs. 8
and 9, probably very similar to the ancestral types of
each).

Divergence and Special Adaptations.

Wliile the assumption of similar parasitic habits has
in many cases resulted in similar adaptations so that
primitively widely divergent forms now are structurally

" TrSgardh, In 1902, discovered some sarcoptids under the elytra of a
species of Pimelia In which the extremities were entirely suppressed.
See Zool. Anzeig. 25: 617-8 (3 figs.).

Ewing — Significance of Parasitism hi Acarina. 55

very similar, on the other hand some forms which phylo-
genetically were closely related, are now structurally
very diverse, because their habits, at least in some par-
ticular aspects, lead to peculiar environmental conditions.
This response, which has resulted in such peculiar spe-
cializations, has often brought about some very highly
evolved types.

Prominent among those forms which exist under pecu-
liar environmental conditions might be mentioned the
gall mites, Eriophyidae (PI. VII, Fig. 29). These mites
live by sucking juices from various plants, but especially
from leaves of trees. Here their attacks have resulted
in the development of various malformations of the
leaves and in many cases in the formation of definite
galls. Not all species, however, cause galls and some
form only a distorted area in the leaf which is densely
covered with small hairs. The ancestors of these forms
evidently were simple plant feeders and probably were
closely related to the "Red Spiders." Certainly there
are many things which indicate their phylogenetic rela-
tionship to this group. As to just what kind of galls
were originally formed by these mites, probably we can
never know; yet there is the significant fact about the
galls now formed by them, that they all have openings
to the exterior through which the mites can pass. The
life in any of these galls with such small openings, or in
those of a pinlike formation, or even among the hairs
on the erineum, requires that the body must be very
narrow in order that the mite may be able to move about.
In response to these conditions we find that these gall-
inhabiting mites have the body enormously lengthened
(PI. VII, Fig. 29), so much so as to suggest a super-
ficial resemblance to the worms.

Again in other groups we find this same enormous
lengthening of the body in response to very different
conditions but each requiring this vermiform structure
of the body. This is true in the case of the Demodecidae,
the "hair-follicle mites." These mites live in the hair

56 Trans. Acad. Sci. of St. Louis.

follicles of man and other mammals. Here evidently
the form of body best adapted is that which these mites
have assumed, the vermiform type (PL IV, Fig. 14).
Perhaps the most beautiful adaptation of this vermiform
body is shown in those mites which inhabit the quills of
bird's feathers. We find it well illustrated in the genera
Picohia and Syringophilus which have this habit (See
PI. V, Fig. 17).

As is true of most external parasites specialization in
the form of clinging or clasping organs may become
highly developed. Besides the claws or hooks, which have
been mentioned, we have several other structures of con-
siderable interest. In the Analgesidae there are devel-
oped upon tarsal pedicels partial-vacuum suckers (See
PI. IV, Figs. 15 and 16), which are very effective as
adhering organs. These forms when placed on a smooth
glass surface adhere so tightly that it is very hard to
lift them off with a sable-hair brush.

The well known development of the hypostoma in the
ticks is also a good example of specialization. Here the
hypostoma becomes greatly developed into the form of
a dart and is provided with many strong recurved teeth.
When this structure is thrust into the skin of the host the
recurved teeth act like the barbs on a fish-hook against
its being withdrawn.

The most varied and interesting cases of specializa-
tion in the form of clinging organs are found in the Vil-
licolata. In the family Listrophoridae we have several
genera represented, all of which have some specialized
apparatus developed for clasping hairs.

In the case of the genus ListropJiorus the underlip is
modified into a large, curved, flexible plate, which can
be brought around a hair so as to clasp it very effect-
ively. In the genus Lahidocarpus the front two pairs
of legs have been entirely changed from their primitive
shape, and each consists of a single, strongly curved chit-
inous plate entirely without appendages (See PI. V, Fig.
19). These appendages when opposed to each other

Ewing — Significance of Parasitism in Acarina. 57

act like a vise upon the partially encircled hair. In
Myocoptes it is the posterior group of legs which is mod-
ified into clasping organs. Here the apical joints, which
are broad and flat, can fold upon the basilar ones like
the blade of a knife into its handle.

Perhaps one of the most significant things that ap-
pears in connection with the evolution of the parasitic
Acarina is the development of marked sexual dimor-
phism. In the free forms from which the parasitic ones
arose there was evidently little or no sexual dimorphism,
yet in some of the Analgesidae, for example, it is very
marked as will be seen by looking at PI. IV, Figs. 15
and 16, and PL VI, Figs. 24 and 25. In most of these
cases the dimorphism consists of an increased size of the
male over the female, and in his possession of special
organs for holding her during pairing. In the genus
Analges these modifications for clasping reach such an
enormous size as to cause some conjecture as to the
factors influencing their development. They consist sim-
ply of an enormous enlargement of the third pair of legs,
but to such an extent that the two legs taken together
may be equal to the total size of the body of the mite
(See PI. VI, Fig. 25). How such enormous structures
if used alone for holding the female during coition could
have been developed through natural selection is a puz-
zle. It may be that the members of this genus are the
descendents of a primitive ancestor which was a mutant.
If this is true this initial variation was out of all reason-
able limits in its magnitude. Again it may happen that
these organs are used by rival males in striving with
each other for the possession of the females, but their
structure hardly suggests it, and besides I am not aware
that in the Acarina any one has ever noticed any rivalry
between the males over the females. I am inclined to
think that these structures have an important, and per-
haps their chief function, as organs for holding on to the
feathers of the host. As the male is the one that hunts
out the female, and is thus much the more active, his

58 Trans. Acad. Sci. of St. Louis.

liability of becoming detached from the host is much
greater than hers. In this regard it is interesting to
note that he has many more enormous bristles than the
female which is in harmony with the suggestion just
given (since I have already shown that such long bristles
in the epizoa frequently keep them from becoming de-
tached from their hosts).

Generalizations Regarding Various Aspects of Para-
sitism IN the Acarina.

As a whole, the order Acarina has not been very ex-
tensively studied in the different parts of the world, but
this statement can hardly hold true in considering the
parasitic forms, for it is concerning these that we know
the most, at least in regard to geographical distribution.
Our knowledge of the ticks and the "Bird Mites" in-
cludes forms from almost every part of the globe. How-
ever, much is yet to be learned in connection with the
distribution and life histories of most of the smaller
groups.

In our study of parasitism in the Acarina it is inter-
esting to note the tremendous range of its various as-
pects. The parasitic forms have originated independ-
ently from several rather distantly separated free an-
cestors. The process of evolution in each separate group
has been going on for vast periods of time, upon hosts
which belong to different classes and even subkingdoms.
These hosts in turn have become evolved, they have as-
sumed different habits and environments. The processes
of degeneration and specialization have wrought great
structural changes, and with them vast differences in
their relation to each other and their hosts. When we
consider all of these things it is not so much to be won-
dered at that in this group we probably find a larger
variation in the different aspects of parasitism than is
presented by any other group of the Arthropoda.

The following classification of the parasitic Acarina is
given, based upon an analytical study of their structure,
habits, food relations, etc. This is simply an applica-

EvAng — Significance of Parasitism in Acarina. 59

tion of the general classification given for all parasites
in the introductory chapter.

A Classification of the Parasitic Acarina Based

Upon the Different Aspects of

Parasitism Presented.

Taking into account the nature and habits of the para-
sites themselves.

Depending upon the nature of the food eaten.
Living upon the bodily tissues.
Living upon live tissues.
Gen. Harpyrhynchus.
Sarcoptidae (itch mites).
Gen. Laminosioptes of the Cheyletldae.
Living upon dead tissues.

Analgesldae (bird mites).
Listrophoridae.

Canestrinidae (?). These forms doubtless live upon
live tissues also.
Feeding upon partially digested food.
Antennopliorus.
Echinomegistus tcTieeleri (?).
Living upon blood.

Parasitic larvae of Rhyncholophldae, Trombldildae,

• Hydrachnidae and Halacarldae.
The ticks, Ixodidae and Argasldae.
Dermanyssfdae.
Haemogaviasus and Raillietia of the Gamasids; CilU-

bano (?).
Some species of Pediculoides.
Some species of Cilliba, a genus of the Uropodldae.
Feeding upon secretlona.

Cytoleichus (?). It probably feeds both upon mucous

secretions and the cellular fluids of Its host.
Demodex. The species of this genus live largely upon

the oil secreted in the hair follicles.
Myobia. Species of this genus feed at the bases of hairs

of mammals upon cutaneous excretions.
Oolaelaps oophiJus. (Lives upon the salivary secretion
with which some ants coat their eggs.)
Living upon eggs.

Genus Hemisarcoptea. It lives upon eggs of scale In-
sects (predaceous?).
Histiostoma berghi, lives In egg capsule of a horse-leech.
Larvae of some of the Halacaridae.

60 Trans. Acad. Sci. of St. Louis.

Depending upon adaptation to tlie parasitic life.
Facultative parasites.

Cheyletiella (?). The species of this genus may not be
parasitic at all, but there is evidence that during
their immature stages they are real parasites.
Some of the Dermanyssidae.
Uropoda (Some species).
Hemisarcoptes.
Obligatory parasites.

All of the other parasitic Acarina not mentioned under
facultative parasites.
Depending upon the state of degeneration of the locomotor organs.
Capable of walking when off the host.
Parasitic Cheyletidae.
GekoMa.
Larvae of Rhyncholophidae, Thombidiidae, Hydrachnldae

and Halacaridae.
Ixodidae, Argasidae, Dermanyssidae and the parasitic

Gamasidae.
Uropoda (some species), 011111)0.
Parasitic Tarsonemidae.
Analgesidae.
Canestrinidae.
Cytoleichidae.
Some of the Sarcoptldae.
Eriophyidae.
Incapable of walking when detached from host.
Many of the Listrophorldae.
Most of the Sarcoptidae.
Without legs.

Pimelobia apoda.

Taking into account the nature and habits of the
organisms attacked.

Depending upon whether the organism attacked is a plant or an
animal.

Phytophaga.

Most of the Tetranychldae.
Tarsonemidae (in part).
Eriophyidae.
Zoophaga.

Parasitic Cheyletidae.

GekoMa.

Larvae of Rhyncholophidae, Trombidiidae, Hydrachni-

dae, Halacaridae.
Ixodidae, Argasidae, Dermanyssidae and parasitic

Gamasidae.
Parasitic Uropodidae.

Ew'ing — Significance of Parasitism in Acarina. 61

Zoophaga.

Tarsonemidae (in part).
Listrophoridae.

Analgesidae, Canestrinidae, Sarcoptidae, Cytoleichidae.
Demodecidae.
Depending upon the conditions imposed by the life of tlie host.
Hydroxenous.

Larvae of Hydrachnidae and Halacaridae.
Gen. Atax.
Geoxenous.

Myobia and Psorergates.
Gekobia.

Ixodidae, Dermanyssldae (in part), parasitic Gamasidae.
Cilliba.

Parasitic Tarsonemidae.
Listrophoridae (In part).
Canestrinidae.
Sarcoptidae (mostly).
Cytoleichidae.
Demodecidae.
Aeroxenous.

Harpyrhynchus, Ptcobia and Syringophilus.
Larvae of Rhyncholophidae and Trombidildae.
Argasidae, Dermanyssldae (in part).
Listrophoridae (in part).
Analgesidae, some of the Sarcoptidae.
Depending upon the number of host species.
"With a single host species.

Parasitic Cheyletldae (in part).
Gekobia (?),
Cilliba (?).

Listrophoridae (In general).
Analgesidae (in part).
Canestrinidae.
Sarcoptidae (in general).
Cytoleichidae (?).
Eriophyidae (in part).
With more than one host species.
Parasitic Tetranychldae.

Larvae of Rhyncholophidae, Trombidildae, Hydrachni-
dae and Halacaridae (in general).
Ixodidae, Argasidae, Dermanyssldae and parasitic

Gamasidae.
Parasitic Tarsonemidae.
Analgesidae (in general).
Sarcoptidae (a few species).
Demodecidae (?).
Eriophyidae (in part).

62 Trans. Acad. Sci. of St. Louis.

Taking into account the interrelations of the parasites
and organisms affected.

Depending upon the position of the parasites in relation to their
hosts.

Endoparasites.

Sarcoptidae (in part).
Cytolelchldae (?).
Demodecidae (?).
Ectoparasites.
Cuticolata.

Harpyrhynchvs, Psorergates.

Gekohia.

Larvae of Rhyncholophldae, Trombidiidae, Hydra-

chnldae, Halacarldae.
Ixodldae.

Parasitic Tarsonemldae.
Sarcoptidae (mostly).
Cytolelchldae (?).
Demodecidae.
Vlllicolata.
Myobia.
Llstrophorldae.
Plumlcolata.

PicoTbia, SyringopMlus.
Analgesldae.
Depending upon the duration or time of parasitism.
Erratic parasites.

Semiparasitic Tetranychidae.
Atax (?).

Some of the Gamasidae and some of the Uropodldae.
Some of the Tarsonemldae.
Hetni.tarcoptes.
Periodical parasites.
Nocturnal.

Argasldae.

Dermanyssidae (In part).
Diurnal.

(Data upon habits In this regard wanting.)

During a definite stage or stages in the life cycle
of the species attacked.
During the egg stage.
Histiostoma berghi.
Eemisarcoptes.
During the fetal stage.
During the immature stage.
Pediculoides ventricosus.
During adult stage.

Eiving — Significance of Parasitism in Acarina. 63

Permanent parasites.

GekoUa (?).

Parasitic Cheyletidae.

Ixodidae.

Listrophoridae.

Analgesidae.

Sarcoptldae.

Cytolelchidae.

Demodecidae.

Eriophyldae.
Depending upon symbiotic relationship.
Mutuallsts.

Some of the Gamasldae.

Many of the Analgesidae.
Commensals.

Picohia, Syringophilus.

Many of the parasitic Gamasldae.

Listrophoridae (In part).

Most of the Analgesidae.
True parasites.

Parasitic Tetranychidae.

GekoMa.

Trombidoldean larvae.

Myobia, Harpyrhynchus, Psorergates.

Ixodidae, Argasldae, Dermanyssldae.

Cilliba (some species).

Parasitic Tarsonemidae.

Some of the Listrophoridae.

Canestrinidae.

Sarcoptldae.

Cytolelchidae.

Demodecidae.

Eriophyldae.
Depending upon the blood relationship of the parasite to the host
Host of organism affected not related to parasite.

Nearly all of the parasitic Acarina.
Host or organism affected closely related to parasite.

Larva of Smaris longiJinealis on Oribata latincisa.
Organisms affected of the same species as the parasite itself.

Host one of the parents.

Rhyncholophus parvisetosus (?).

64 Trans. Acad. Sci. of St. Louis.

SUMMARY.

As TO THE OeIGIN OF PARASITISM IN THE ACARINA.

We have very strong evidence indicating that the i^ara-
sitic habit has originated independently at least eleven
times in the phylogeny of the Acarina.

Among the zoophagous parasites the parasitic habit
has been developed from three different types of free-
living Acarina; (a) predaceons forms, (b) scavengers,
(c) forms living upon the juices of plants.

The chief reason for so frequent occurrence of parasi-
tism in the Acarina is because of their minute size; and
the predaceous, scavenger, or plant-sucking habits of the
free-living forms.

Among our living forms we can to-day trace out all the
stages of advancing parasitism including the occasional
or erratic parasitism, semiparasitism, facultative parasi-
tism, even to the fixed and permanent type, and finally to
endoparasitism.

As is usually the case with other parasites, we generally
find here a gradual increase in the state of degeneration
as we follow the advancing stages of parasitism from its
origin among free types. In the Analgesidae however
this is not true as they are in several respects highly
specialized and have undergone little or no degeneration.

We find in the Acarina a process of degeneration which
in its completeness is seldom obtained in the animal king-
dom. We must remember that the Arachnida are in
many ways a highly evolved group, certainly much more
BO than the Crustacea, yet here we find degeneration
almost equal to that of the classical example of Sacculina.

As TO THE DlSTKIBUTIOX ACCORDING TO HoST SpECIES AND

ITS Significance.

The parasitic Acarina may be arranged into three
classes depending upon their distribution according to
host species: —

Ewing — Significance of Parasitism in Acarina. 65

Those which are confined or limited to a single host species.

Those which may be found upon only closely related host species,
usually species of the same genus or of very closely related genera.

Those which are found upon host species which are very widely
separated from each other, belonging to distantly related families or
«ven to different classes.

Our present distribution of the parasitic Acarina ac-
cording to host species is dependent upon many factors,
some of the more important being :

The nature of the food of the parasite, whether it be blood, living
tissues, cast epidermal cells, etc.

The means by which the parasite attaches itself to its host.

The ability of the parasite to withstand fasting when detached
from its normal host.

The degree of locomotor ability possessed by the parasite when
detached from its normal host.

The ability of the parasite to sustain or partially sustain itself
when detached from its host upon the diet of a free-living species; in
other words a facultative or partially facultative parasite.

The life history of the parasite especially in regard to the number
and methods of its transformations.

The shedding or molting habits of the host or hosts.

The wandering or migration habits of the host or hosts.

The surroundings and the materials of the home or nest for the
young of the host or hosts.

The feeding habits of the host especially in regard to preying or
scavenger habits.

The limits and nature of the geographical distribution of the host
or hosts.

General climatic conditions of the country, especially in regard
to temperature.

Some of the conditions actually found to favor the
greatest distribution among the most widely separated
hosts are:

A blood diet (This enables the parasite to engorge itself with an
enormous amount of food in a short time and then become detached
and live for long periods until a new host is found).

The possession of ambulatory legs.

The possession of a clinging apparatus designed to adhere to the
flesh itself (Special apparatuses for clinging to either hairs, or
feathers, etc., disqualifying their possessors from adhering to hosts
which do not have these).

Oviparous reproduction with a large number of eggs laid when
away from any host.

The ability to withstand great changes in temperature and moisture.

66 Trans. Acad. Sci. of St. Louis. -^

The ticks most completely fulfill tliese conditions, and
are actually found to have the greatest distribution
among the most diversified hosts.

Any one of the following conditions appears to cause
a very restricted host distribution, and in many cases a
restriction to a single host species or even to a single
host individual :

Endocolous habits.

The possession of highly specialized clinging apparatus for holding
on to external growths of the host or hosts.

A delicate and degenerate digestive system (This condition often
gives rise to physiological species in forms which are anatomically
identical).

The inability of the parasite to live off its host because of climatic
conditions.

The inability of the parasite to walk when detached from a host.

The host being one of solitary and monogamous habits.

As TO THE Analysis and Classification of the Various
Types and Aspects of Parasitism.

Although various classifications of the parasites have
been made, and many m^ore will doubtless follow, all of
them may be included in three groups:

Those which take into account the nature and habits of the parasites
themselves.

Those which take into account the nature and habits of the organ-
isms attacked.

Those which take into account the inter-relations of the parasites
and the organisms attacked.

Under each of these three general groups several classi-
fications may be made having for a basis either habits,
morphological characters, or ecological relations; and
these classifications may each in turn be subdivided into
others of a more restricted meaning, having for their
bases these same factors.

Ewing — Significance of Parasitism in Acarina. 67

EXPLANATION OP PHYLOGENETIC TREE.

In the diagram, or phylogenetic tree, given on the opposite page
the writer has shown by the use of a series of symbols (squares,
circles, dashes, etc.) much more than is generally done in such trees.
This is in order to give the habits of these arachnids as they have
been traced in this phylogeny. Thus, although according to this
diagram we have living mites with eight diiferent kinds of feeding
habits, they all have descended from predaceous forms.

As we pass in position from the top of the page to the bottom, we
get a regular decline in the state of evolution. Forms with many
specialized parts or organs and with highly developed functions are
considered highly evolved; those with many similar parts and with
these parts not highly specialized, or those with few parts and with
functions poorly developed are considered as being less highly evolved.

EXPLANATION OF ILLUSTRATIONS.

Plate I. — Steps in the Origin of Parasitism from Predaceous Types.
— Fig. 1. Oamasus clentatus Ewing, dorsal view. This species is
typical of the free living forms of Gamasidae. They are predaceous
in habit and evidently are very similar to the ancestral predaceous
type or types from which the Dermanyssidae, as well as the Argasidae
and Ixodidae, arose. — Fig. 2. Dermanyssus gallinae (Redi), female,
dorsal view. This is the notorious chicken mite of domestic poultry.
As yet it may be considered a facultative parasite as it can maintain
itself indefinitely away from its host if suitable conditions are at
hand. In this stage of parasitism, which is only a step toward the
final one, degeneration and adaptation are well exhibited as may be
seen by comparing this figure with Fig. 1. The legs have become
somewhat shortened, the palpi are much smaller and the body is
much depressed in form, while the chelicerae are modified into long
piercing organs. — Fig. 3. Boophihis annulatus Say. The v.'ell known
Texas Fever Tick. In the Ixodidae the parasitic habit has become
permanent, the parasite, however, leaves its host in most cases in
order to molt. Degeneration and specialization has continued as is
seen in the great reduction of the size of the legs and mouth-parts,
in the fiattened form of the body, and in the enormous development
of the hypostoma which is provided with recurved teeth for the pur-
pose of clinging to a host.

Plate II. — Steps in the Origin of Parasitism from Scavenger Types.
— Fig. 4. Monieziella eiitomophagus (Laboulbone). This mite belongs
to a small family of scavenger mites. It does not live upon live
insects, as the name suggests, and as has been long supposed by most
entomologists, but only chews and sucks the juices of dead insects
and other decaying organic materials. It evidently is very similar to
the ancestral type from which a very large group of our most im-

68 Trans. Acad. Sci. of St. Louis.

portant mite parasites arose. It is found generally associated with
scale insects. — Fig. 5. Hemisarcoptes mains (Shimer). This is the
most efficient of all the natural enemies of the Oyster Shell Scale.
It is hardly a real parasite as yet, but has taken to feeding upon live
eggs of the scale insects and will occasionally attack the mature
insects themselves. The diet upon decaying organic matter has been
entirely forsaken. Degeneration is noticed in the shortening of the
legs and in the reduction of the mouth-parts. Specialization is shown
in the development of suckers situated each on a tarsal pedicel. The
homologues of these suckers can be seen in Fig. 4, where they are
present as a flat padlike tarsal appendage. — Fig. 6. Notoedres notoe-
dres (Megn.). The itch mite of the rat. Here parasitism is firmly
established. Degeneration has continued in the shortening of the
legs, and the shortening or loss of their tarsal suckers, the reduction
of the mouth-parts and a change of the original bodily form. — Fig. 7.
Cnemidocoptes mutans (Robin), dorsal view. The itch mite causing
"Scaly Leg" among chickens; a true parasite. Here the individual
has become so degenerate that only stumps of legs are left which
bear no tarsal appendages. The mouth-parts are very simple while
the body is only a round fleshy mass entirely devoid of hairs except
for a single posterior pair.

Plate III.— Converging Adaptation.— The two small parasitic mites
figured at the bottom of this plate have a very great superficial re-
semblance to each other, and for a long time were supposed to be
closely related forms. The one represented by Fig. 10, is now known
to be closely related to the predaceous Cheyletidae, forms that are
very highly developed; the other, represented by Fig. 11, is on the
contrary most nearly related to the simplest of the free-living Acarina,
the Tyroglyphidae. — Fig. 8. Cheyletus seminivorus Packard. A mem-
ber of the family Cheyletidae. The Cheyletidae possess highly de-
veloped and specialized mouth-parts, an elaborate tracheal system,
have the sense of touch highly developed, and usually possess eyes. —
Fig. 9. Tyroglyphus lintneri Osborn, one of the "Cheese IMites." The
members of the family Tyroglyphidae, the "Cheese Mites," are prob-
ably the most degenerate and the simplest of all the free-living mites.
The mouth-parts while rather prominent are very simple; no tracheae
are present, the sense of touch Is poorly developed, and they are all
blind.— Fig. 10. Harpyrhynchns brevis Ewing. The members of the
genus Harpyrhynchns differ from their predaceous free ancestral
types in the great shortening of the legs, the degeneration of the
mouth-parts, the loss of the eyes, etc. Internally they still have left
a tracheal system, but it is very vestigial.— Fig. 11. Sarcoptes scabiei
De Geer, the itch mite of man. Superficially it resembles the species
of Harpyrhynchus just mentioned. Since its free type was very
simple the degenerative process has been less.

Plate IV.— Diverging Adaptation.— The different types of parasitic
Acarina here figured, though very diverse in their appearance and
structure, apparently have descended from a common scavenger an-

Ewing — Significance of Parasitism in Acarina. 69

cestor which was very similar to our present day cheese mites, a
member of which is represented by Fig. 12. — Fig. 12. RMzoglyphus
phylloxerae Riley, dorsal view. A good representative of the family
Tyroplyphidae "Cheese Mites." This species is found in this country
upon old decaying grain, etc. — Fig. 13. Sarcoptes scabiei De Geer,
male from below. This is the itch mite of man. In the assumption
of a small round form of body, of long stout spines on the legs, and
the rudimentary mouth-parts, it has adapted itself to a life within the
skin of man. — Fig. 14. Demodex folUculorum Simon, ventral view.
This species is taken from the hair follicles of man. Several closely
related forms are found in similar situations in other animals. Ap-
parently it has little resemblance to the itch mite of Fig. 13, yet we
have vei-y strong evidence that the two are closely related. The ex-
treme reduction of the legs and mouth-parts, and the very long drawn
out, wormlike body are all beautiful adaptations for the life in hair
follicles. — Fig. 15 and 16. Megninia magna Ewing, male and female
respectively as seen from below. This species, as well as the other
members of the Analgesidae has adapted itself to a life among the
feathers of birds. Scarcely any degeneration is noticed, but on the
contrary it shows a higher state of evolution than the ancestral type
In the development of very efficient partial-vacuum suckers on the
tarsi, and in the marked sexual dimorphism shown. Phylogenetically
this species is closely related to the two preceding.

Plate V. — Special Adaptations. — Fig. 17. SyringopMlus elongatus
Ewing. The very elongate form of body, found in this and a few other
allied species, is a curious adaptation for living in the quills of bird's
feathers. The affinity of this species with the Cheyletidae, a family the
free-living members of which are highly evolved forms, appears to be
established. — Fig. 18. A Hydrachnid larva. These larval parasites
of the Hydrachnidae, show the palpi modiiied into adhering organs,
being provided with stout claws and working horizontally. In some
species, as in this one, the presence of long hairs on the legs show
an adaptation for locomotion in the water. — Fig. 19. Lahiclocarpus
compressus Ewing. The members of this genus exhibit a remarkable
adaptation in the form of the anterior group of legs, which do not
look at all like legs and which as locomotor organs are useless. These
legs have become reduced to a single segment which is much flat-
tened, strongly curved, and strongly chitinized. The two pairs
oppose each other and when contracted strongly grip a single hair to
which the parasite is attached. — Fig. 20. A Hydrachnid larva. The
last segment of the palpus has been transformed into a strong hook
by means of which the mite clings tenaciously to its host. The
species is chiefly a wader, as is shown by the absence of long hairs
on the legs, in this respect it has not become perfectly adapted to
the aquatic life. — Fig. 21. A dipterous insect with a larva of Rhyn-
cholopJius attached. Shows the exposed position assumed by
many of these parasitic larvae and the great necessity of having good
adhering organs.

70 Trans. Acad. Sci. of St. Louis.

Plate VI. — A Symbion and Commensals. — Fig. 22. Macrocheles
moestus Banks. One of the several species of Gamasidae which live
in symbiotic relationship with ants. This species has been studied
by Prof. S. A. Forbes, who found that the ants paid much attention
to it and would carry these mites about as if they were their own
young. The mite probably lives as a scavenger of the domicile. In
many cases these gamasids will attach themselves to the bodies of
the ants and live upon food regurgitated by their hosts. — Fig. 23.
Pterodectes vinticus Banks. One of the commensals belonging to the
Analgesidae. The members of this genus live among the feathers
of birds where they eat cast epidermal cells and oily secretions. — Fig.
24 and 25. Female and male respectively of Analges passerinus
Linnaeus. Like the preceding species this species lives among the
feathers of birds upon excretory products and dead cells.

Plate VII. — Some types of True Parasites. — Fig. 26. Psoroptes
cuniculi (Delaf.). Male and female in copulation. The species of
this genus infest the skin of mammals where they cause great slough-
ing of the same. They live on the cellular tissues. — Fig. 27. Micro-
tromhidium muscarum (Riley). It is a larval parasite of one of the
harvest mites. The common house fly is its true host from which it
sucks the blood. At times these larvae attack man himself and cause
intense itching. — Fig. 28. Larva of RhynclwlopJiiis. It lives as a
haematophagus parasite upon species of Empoasea. — Fig. 29. Eriophyes
ulmi (Garman). One of the gall mites. The gall mites live upon
the juices of plants. Often their attacks cause various malformations
to appear upon the leaves, some of which are called galls. The vermi-
form shape of the body is an adaptation similar to that of the hair
follicle mites.

Issued June 18, 1912.

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Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate I.

1

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//. £ . L Win_ij clonal d ej.

PARASITISM FROM PREDACEOUS TYPES.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate II.

PARASITISM FROM SCAVENGER TYPES.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate III.

|M4

1 1 L C^V'l'i adn^t. Hi^.

CONVERGING ADAPTATION.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate IV.

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DIVERGING ADAPTATION.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate V.

17

18

A, ^^' :P/ ■# ■ -MA t'M \

20

t-J.F.Ewini^ ad natdcj.

SPECIAL ADAPTATION.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate VI.

24

V -

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23

n.L.Ewiiit] ndnat.dcf.

A SYMBION AND COMMENSALS.

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate VII-

L.Lwinq ailjiaiiltj.

27

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29

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Transactions of The Academy of Science of St. Louis.

VOL.. XXI. No, 2.

THE ANNUAL RAINFALL AND TEMPERATURE
OF THE UNITED STATES.

GEO. A. LINDSAY.

Issfued June 19, 1912.

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ir!-

K

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THE ANNUAL RAINFALL AND TEMPERATURE
OF THE UNITED STATES.*

Geo. a. Lindsay.

A record of the annual temperature and rainfall of var-
ious stations scattered over a large territory, having
wide variations of climate cannot give a very accurate
idea of the mean annual temperature of the whole region,
or of the total volume of precipitation upon its surface.

In ''A Report on Missouri Rainfall"^ for the years
1878-1887 inclusive, Professor Nipher has shown the aver-
age number of cubic feet per second of water in the var-
ious forms of precipitation which fell upon the surface of
the state during those years.

In the following work, which was also begun by Pro-
fessor Nipher, and completed by the writer, an attempt
has been made to compute the total precipitation on the
main body of the United States, exclusive of Alaska, and
the outlying possessions; and also to find the average an-
nual temperature of the same region as a whole. It would
seem that this, or some similar method, is the proper way
of expressing the climate of an entire country, such as
the United States.

Twenty-eight manuscript maps, covering the fourteen
vears 1891-1904, were obtained from the office of the
Weather Bureau at Washington. Half of these indicated
the precipitation in inches per year, and the other four-
teen the mean annual temperature. The figures for these
had been marked on the maps at the points of observa-
tion, and lines passing through points having equal pre-
5^ cipitation, and lines of equal temperature had also been
drawn upon the maps by the weather officials. These

nr.^

'^''' * Read before The Academy of Science of St. Louis, June 5, 1911.
P~, 1 Trans. Acad. Sci. St. Louis. 5:383.

tJj (71)

72 Trans. Acad. Sci. of St. Louis.

lines divided the maps into zones or sections, one zone
comprising, let ns say, the territory whose mean annual
temperature lay between 50" and 55°, the next 55° to 60",
etc.

It was intended at first to find the areas included in
these several zones by the planimeter. Then, knowing
the area over which the mean temperature was 50°, an-
other over which it was 55°, etc., the average of the whole
might easily be computed.

This integration by means of the planimeter was aban-
doned, however, for it was found by Professor Nipher
that the areas of different sections of the map as shown
by the instrument were not proportional to the actual
areas of those sections. It was also difficult to properly
weight the values with respect to areas, unless the areas
between the lines of equal value were subdivided into
smaller areas.

The method actually adopted by Professor Nipher was
to take each state by itself, and for each year average all
the observations recorded, also filling in values by inter-
polation methods, where the reports were thinly scattered
in some portions of the state as compared with other por-
tions, so as to make the observations as evenly distributed
as possible. These interpolated values were estimated by
means of the values on each side of the deficient areas.

As an illustration, Minnesota has naturally a great
many more stations to report from the southern and
southeastern parts of the state than from the northern;
perhaps the lower half of the state would have three-
fourths of the observations. It would be manifestly un-
fair to give the northern half of the state only one-third
the weight of the southern half in determining the rain-
fall or average temperature. In some states no inter-
polation was necessary, in others a great many were
added. Enough observations were on the maps original-
ly, however, so tliat these interpolations could be made
with a tolerable degree of accuracy.

In Missouri in the vear 1896 the number of observa-

Lindsay — Annual Rainfall and Temperature of TJ. S. 73

tions of rainfall, including those interpolated, was 44.
The average of these 44, or the average for the whole
state, was 40.1 inches. If we multiply this 40.1 by the
number of square miles in the state and divide by 63,360
which is the number of inches in a mile, we have the num-
ber of cubic miles of water which fell in the state during
the year; that is, if r is the precipitation in inches and A

tA

the area of the state 7^777^7^ is the number of cubic miles

63360

of water. This for Missouri in the year 1896, just men-
tioned, was 43.9 cubic miles. The total number of cubic
miles of water falling in Missouri in the fourteen years
was 609,3, giving a mean of 43.5 cubic miles per year.
This is at the rate of 203,000 cubic feet per second as com-
pared with 195,800 cubic feet per second found by Profes-
sor Mpher between 1877 and 1887. The maximum was in
1898, 60.9 cubic miles, 40% above the average; the mini-
mum was in 1901, 28.2 cubic miles, 35% below the average.
These two years, however, were very abnormal, the high-
est outside of 1898 being 49.1 cubic miles, and the lowest,
excepting 1901, 34.6 cubic miles.

The 43.9 cubic miles which fell in Missouri in 1896 are
alone enough to make a layer over the whole city of St.
Louis (which has an area of 62^/2 square miles) 0.7 of a
mile deep. If it could all be utilized it would make a
river V2 mile wide, 16 feet deep, and 29,000 miles in
length. If this flowed at the rate of 3 miles per hour, it
would take over a year to pass a given point, so that
enough water falls in Missouri to fill and keep flowing
continuously a river of this crossection, and of the whole
length of the Mississippi, and then enough would be left
over each year to fill a canal of the same section from
New York to San Francisco.

Professor Nipher showed in his paper before referred
to that the total rainfall in cubic miles falling upon the
State of Missouri during the ten years, was within two
per cent equal to the discharge of the I\Iississippi river
at St. Louis during that interval.

74 Trans. Acad. Sci. of St. Louis.

It may thus be seen that most of the water whicli falls
as rain or snow never reaches the sea through the med-
ium of drainage, but is evaporated from the land. If all
of the precipitation were led into the rivers and con-
ducted back to the sea we should have mighty streams of
water which would make our present ones seem as little
brooks.

The discharge of the whole Mississippi system, how-
ever, is considerably greater than the river we have im-
agined. To make it more definite, the discharge of the
Mississippi river at Carrollton, La., was computed for the
fourteen years. A discharge curve of the river at that
station was constructed from simultaneous gauge read-
ings and discharge observations taken from the reports
of the Mississippi Kiver Commission. From this curve a
discharge curve for each year was constructed, and b}^
mechanically integrating the areas under these curves,
the discharge of the river at Carrollton was found for
each year. These yearly discharges ranged from 76.3
cubic miles in 1895 to 154.7 cubic miles in 1903. The aver-
age was 117.0 cubic miles per year, or 545,800 cubic feet
per second. This is less than three times the precipita-
tion on the state of Missouri. It would be interesting to
see what part this discharge is of the whole amount fall-
ing upon the area which drains into the Mississippi above
its mouth.

After the precipitation for each state had been com-
puted, they were summed up in five districts; the North-
east, the Southeast, the North Central, the South Cen-
tral, and the Western. The Northeast division comprised
the New England States, New York, New Jersey, and
Pennsylvania. The Southeast division, Delaware, INIary-
land. West Virginia, and the South Atlantic States. The
North Central, Ohio, Indiana, Illinois, Wisconsin, Mich-
igan, Minnesota, Iowa, Missouri, North Dakota, South
Dakota, Nebraska and Kansas. The South Central, Ken-
tucky, Tennessee, Alabama, Mississippi, Arkansas,

Lindsay — Annual Rainfall and Temperature of U. S. 75

Louisiana, Texas and Oklahoma. The Western division
compiised the remaining states to the west.

In the year 1896 the total rainfall on the Northeast
section was 98.9 cubic miles; on the Southeast, 199.7; on
die iSTorth Central, 363.0; on the South Central, 308.8, and
on the Western, 326.0, making a total for the United
States of 1,296.4 cubic miles. This is about thirty times
as much as falls in Missouri in one year. The greatest
annual volume of precipitation during the years consid-
ered was in 1902 when 1,396.9 cubic miles fiell. In 1894,
the year of minimum fall, there was only 1,199.1, a dif-
ference of about 200 cubic miles.

The curve P shows the variation of precipitation from
year to year. The average for these fourteen years is
1,308.0 cubic miles. One cubic mile of water weighs 4.58
xlO^ tons. This great volume of 1,308 cubic miles ap-
pears more gigantic when we think of its weight — 6.00x
10^- tons for the vear. A tremendous amount of work
would be required to lift this mass from the surface of
the earth to the height from which it falls again as rain.
Taking the average height of the raincloud as 3/< mile, it
would require 317x10^^ foot-lbs. of work. 18,270,000 en-
gines of 100 ]i. p. each would be kept in operation day
and night to elevate the water to the clouds as rapidly
as it falls on the surface of the United States. If we
consider the heat required to vaporize it we find it would
require the combustion of 5x10^^ tons of anthracite per
annum to furnish enough to change the water into vapor
at a temperature of 68° F.

The average yearly temperature for the whole coun-
try was obtained as follows: The average for each state
was found, just as in the case of the rainfall, by averag-
ing the values of the several station reports, together
with interpolated values, multiplying the average by the
area of the state, adding these products for all the states,
and dividing the sum by the area of the whole United
States.

This gives for the average temperature of the United

76 Trans. Acad. Sci. of St. Louis.

States for successive years, the values shown in a table
at tlie close of this paper and represented by the curve
T. It will be seen that the values are remarkably con-
stant, the highest in the fourteen years being 54°.4 in
1900 and the lowest 51°.4 in 1894, a difference of only 3°.
The mean for the period being 52°.9, the gTeatest varia-
tion was only 1°.5 above or below this.

AVe m.ay say then, that taking the fourteen years as a
basis, the average annual temperature of the United
States, excluding the outlying parts, is 52°.9 F., and the
annual precipitation is 1,308 cubic miles.

The state having the lowest amount of precipitation in
any year was Arizona in 1894, 5.8 inches; the greatest,
Alabama in 1900, 71.6 inches. The state having the low-
est average temperature was North Dakota in 1893, 35°.5;
the highest, Florida in 1897, 71°.8. These of course are
far from representing the extremes for small areas. The
maximum rainfall for single stations is not in Alabama
at all, but on the North Pacific coast, where in Washing-
ton and Oregon the rainfall is very often more than 100
inches per year, while some areas are of course practical-
ly rainless.

Many attempts have been made to show a periodic
variation of the temperature and rainfall, and to connect
this jDcriod with some celestial phenomenon, as sunspots.
The chart shows both temperature and precipitation
curves together, and also the curve of Wolff's sunspot
numbers. While there seems to be a tendency, esiDCcially
in the first part of the fourteen years, for a minimum tem-
perature and rainfall to occur at a maximum of sunspots,
the latter part of the period covered is erratic in both
temperature and precipitation curves. The fluctuation
is a large fraction of the general periodic change which
coincides fairly well with the sunspot period. A contin-
uation of this work through the next sunspot period may
yield more conclusive results.

Briickner has constructed a table of world tempera-
tures and precipitation from about 1731 to 1885, which

Lindsay — Annual Rainfall and Temperature of TJ. S. 77

he finds, apparently, indicates a period for both of about
thirty-five years. The interval, however, between max-
ima and minima varies from four to thirty years. The
maxima for temperature and rainfall sometimes fall to-
gether and sometimes a maximum of temperature coin-
cides with a minimum of rainfall.

It may be considered then that the most that may be
said is that there are not yet enough data, or perhaps,
better, not enough work has been done on the vast
amount of data already accumulated, to show with any
certainty, or even probability, that any celestial phe-
nomena govern the variation of temperature and precipi-
tation from year to year. The remarkable thing is that
the yearly variation is so small, considering the great
storms and great variations of temperature extending
over short periods. This very uniformity is perhaps
more wonderful than the discovery of some celestial cause
for the variation.

The mtegi'ated values for the entire country evidently
furnish a much more reliable basis for a study of climatic
conditions upon the earth than could ever be obtained
by observations at isolated stations.

EXPLANATION OF PLATES.

Plate VIIT. — "With the time interval 1891-1904 are plotted: (P) The
precipitation, in cubic miles per year, on the entire United States.
(T) The annual temperature of the United States. (S.S.) Wolff's
sunspot numbers.

Issued, June 19, 1912.

78 Trans. Acad. Sci. of St. Louis.

Average Temp. Precipitation

Year. ° F. Cubic miles.

1891 52.6 1352.0

1892 52.5 1362.1

1893 51.9 1277.5

1894 51.4 1199.1

1895 53.2 1249.8

1896 54.1 1296.4

1897 53.0 1340.3

1898 52.9 1366.2

1899 52.8 1298.2

1900 54.4 1352.9

1901 53.5 1254.3

1902 53.3 1396.9

1903 52.1 1345.4

1904 52.4 1235.0

Trans. Acad. Sci. of St. Louis, Vol. XXI.

Plate VIII.

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Transactions of The Academy of Science of St. Louis.

VOIi. XXI. No. 3.

THE NATURE OF ELECTRICAL DISCHARGE
POSITIVE COLUMN EFFECTS IN
A METAL CONDUCTOR.

FRANCIS E. NIPHER.

Issued July 3, 1912.

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Continued on page 3 of Cover,

LIBRARY

NEW VOliK

BOTANICAL

GARDEN

THE NATURE OF ELECTRICAL DISCHARGE-
POSITIVE COLUMN EFFECTS IN A
METAL CONDUCTOR. *

Francis E. Nipher.

In former papers in these Transactions (Vols. XIX No.
1; XIX No. 4; XX No. 1) experimental evidence has
been obtained, which seems to indicate that the positive
column or the positive streamers in electrical discharge
through gases, is a negative inflow to the exhaust or
positive terminal. The molecules of matter in such a
drainage channel are moving in the opposite direction
from that in which the negative fluid is flowing.

The result of recent experiments with solid conductors
seems to justify the conclusion that such a conductor
carrying a discharge, is an aggregation of positive ions,
and that a copper wire under such conditions is urged
in the opposite direction from that of the corpuscular
flow.

A wire 50 centimeters in length and having a diameter
of 0.23 mm. was placed in a glass tube supported at its
middle point in a horizontal position. Tubes of various
internal diameters between one and five mm. have been
used, and all give similar results. The length of the
tube is such that the wire protrudes from it at each end
a distance of about a centimeter.

Two discharge knobs forming the terminals of rods 2.5

meters in length were placed with their centers over the

ends of the glass tube. The rods were supported near

the glass tube by silk cords. The other ends rested on

c^ the discharge rods of an eight-plate influence machine,

S^ driven by an electric motor. The glass tube containing

^ the wire was parallel to the discharge rods of the ma-

r-H chine, and at right angles to the rods leading from the
D-

UJ *Presented June 3, 1912.

^ (79)

80 Trans. Acad. Sci. of St. Louis.

machine. It is necessary that the knobs be placed above
the ends of the tube. The protruding ends of the wire
are slightly lifted just before the sparks occur. This
prevents bending of the wire around the edge of the
glass at the end of the tube, from interfering with the
longitudinal creeping of the wire.

The discharge gaps at the ends of the glass tube were
made equal. The discharge knobs had equal diameter.
The gaps usually had a length of four or five cm. each,
so that discharges could be freely produced, at intervals
varying from half a second to three seconds.

The machine was in a glass case containing a supply
of calcium chloride, and warmed inside by a one-kilowatt
heater. The wire was observed by means of a telescope
magnifying about 27 diameters. No longitudinal motion
of the wire due to a single spark, can be detected by ob-
servation with this telescope, but the summation effects
of three or four sparks is plainly to be seen. The wire
gradually creeps along within the tube in the opposite
direction from that in which the negative discharge
passes through it. In one case the wire was placed
symmetrically in the tube so that each end projected 1.2
cm. The sparks were i)assed into the side of the wire
at the end of the glass tube. A condenser of sheet glass
having on each side a metal plate of al)Out 1,000 sq. cm.
was used. Sparks were passed into the wire for about
three hours, during which time the displacement of the
wire was 1.2 cm. due to about 3,500 discharges. As the
wire was gradually displaced from the position of sym-
metry, sparks at the positive end occasionally entered
the wire at its end. At the close of the operation when
the end of the wire was at the end of the tube, all of the
sparks at this end, entered the wire at its end. It may
be that an end effect due to interaction between the wire
and the air is thus increased. At each end of the wire
there is a point discharge, but these opposing effects on
the wire seem to be greatest when no spark is passing,
and to cease when the spark has passed.

Nipher — The Nature of Electrical Discharge.

81

No creeping of the wire occurs except at the instant
when the sparks occur. The gaps may be made so long
that no sparks can pass. Electrostatic attractions are
then greatest and point effects at the ends of the wire
can be observed in a dark room. The wire does not then
move. The arrangement of the apparatus is shown in
the annexed figure.

©

0

Fig. 1. Apparatus showing the gradual creeping of a wire in a
direction opposite to that of the corpuscular discharge.

It is found that the wire creeps to the right as shown
in the figure, when it is unsymmetrically placed with the
end on the right hand even with the end of the glass
tube. It then projected from the left end of the tube a
distance of 2.4 cm. It would require over 7,000 discharges
with the apparatus used to displace the wire 2.4 cm. into
the position formerly described. The amount of displace-
ment per spark does not seem to depend upon the posi-
tion of the wire between such limits, although no precise
measurements have been made.

The question arises whether the observed creeping of
the wire is due to a differential action between the ends
of the wire and the air which surrounds these ends, at
the instant when the spark occurs.

This was examined by means of a differential electric
whirl constructed as follows:

Two small hollow spheres of metal were mounted upon
the ends of a thin metal tube about 50 cm. in length.

Curved and pointed wires having a length of 18 cm.

82 Trans. Acad. Sci. of St. Louis.

were mounted around the two spheres in their equatorial
planes. The ends of the wires were 14 cm. from the
axis of the tube, which was along the polar diameters
of the spheres. The wires on the two spheres curved in
opposite directions, so that each group would produce
whirling in an opposite direction. The device was hung
in a vertical position on a bundle of fibers of unspun
silk. From the lower sphere a small weight was hung
on a similar bundle of silk.

One object to be secured was a symmetrical arrange-
ment of matter at the upper and lower ends of the whirl-
ing device.

Vertical discharge rods were placed above and below
the whirl, so that sparks could be sent along the silk
fibres to the two balls. The tube was gently clamped in
a friction brake of hard rubber, the force being applied
by means of a flexible rubber band. This was necessary
by reason of the fact that local clouds of ionized air in
the room produced rotations of the whirl which were
sometimes in one direction and sometimes in the op-
posite direction. This device was much more sensitive
to differential point effects than the wire lying in the
glass tube. The air in the room has occasionally been
in such a condition that the frictional contacts could be
wholly removed, and the device would be in perfect equi-
librium while sparks were passing. Eeversing the dis-
charge gave the same result.

Such stability has been maintained for intervals of
several minutes, and would only be disturbed by move-
ment of the obsem^er, or other causes producing a move-
ment of the air, such for example as gusts of wind.

The apparatus shown in Fig. 1, has been varied in
length from 20 to 50 cm. The ends of the wire have been
tipped with small spheres of solder, in order to diminish
point discharges from the two ends into the surrounding
air. So far as could be observed, the creeping of the
wire was not affected by such changes.

There have been conditions when no creeping of the

Nipher — The Nature of Electrical DiscJiarge. 83

wire was observed. If the wire protrudes too far from
tlie tube at the positive end, it is likely to cause frictional
contact with the glass tube. This is particularly the case
when the wire has been long in use so that its surface
has become irregular from the effects of the discharge.
It is also necessary that the terminal potentials shall be
high, and that the condenser shall be of capacity not
much less than that described.

Apparently the effect here obser\^ed in the creeping
of the wire, is what might have been expected, as a logical
sequence of Rowland's experiment. His results showed
that a wire having upon its outer surface a thin film of
negative suiDcrcharge, when given a longitudinal motion,
produced an external magnetic field. When a thin film
of the wire surface is drained of the negative fluid, and
the wire is moved in the opposite direction the sanio ex-
ternal field is produced. In both cases the external field
is electro-magnetic in character.

The phenomenon here described appears to indicate
that when the external field is imposed upon the wire
from an external source, the negative fluid and the solid
aggregation of positive ions, namely, the copper wire, are
urged in opposite directions.

The ends of the wire were bent at right angles and
dipped into mercur^^ cups. By means of a snap key, the
wire was momentarily connected with terminals of a sep-
arately excited dynamo. The potential difference thus
imposed was 175 volts. In this case very appreciable
expansions could be observed with the unaided eye. The
wire was not appreciably distorted in form, as was the
case in smaller wires through which spark discharges
were sent. Some deceptive results were at one time ob-
served which appeared to be a creeping of the wire along
the tube. They were later traced to contraction effects.
The two ends of the wire were found to be unequally free
to contract after expansion had taken place. There was
no creeping of the wire as a whole under the conditions
last described.

84 Trans. Acad. Sci. of St. Louis.

The field thus impressed upon the wire was deficient
in its electrostatic component, necessary to produce an
apparent recoil of the wire.

Under the conditions in which the creeping of the wire
occurs, we must consider the simultaneous discharge at
the two ends of the wire to be compression and rare-
faction waves traveling in opposite directions through
the wire. There was no visible expansion when the wire
was observed through the telescope. The i^henomena of
the cathode discharge discovered by Crookes, and the
fact that the plates of the influence machine are in con-
tinuous motion, give standing evidence of sudden dis-
placements at each spark discharge. The corpuscular
displacements in the compression and in the rarefaction
waves are in the same direction, namely, in the opposite
direction from that in which the wire creeps. It would
seem that such waves impressed upon the two ends of a
wire might result in the formation of a series of waves
throughout the entire wire. The corpuscular nebula
within an insulated sphere of metal is displaced when a
charged sphere is brought near it. It seems evident that
the conditions which exist on the two halves of such a
spherical surface may exist along a metal wire. They
would somewhat resemble longitudinal waves which might
be produced in a column of water contained in a flexible
i*ubber tube. The two halves of such an electric wave
would attract each other.

A result which appears to give evidence of the existence
of such waves was obtained as follows:

A piece of % ampere fuse wire, having a diameter of
0.115 mm. and a length of about 50 cm. was placed in a
glass tube containing coal-oil. The ends of the fuse wire
were soldered to copper wire of about 0.2 mm. diameter
which protruded through sealing wax with which the
ends of the tube were closed. A single discharge from
the machine to which was connected a condenser of about
4,000 sq. cm. area, gave various results depending upon
the spark-length. In two cases the wire reached the con-

Nipher — The Nature of Electrical Discharge. 85

dition bordering closely on fusion. Some parts were
fused. Fragments of the wire are shown in Plate IX,
Fig. A. At fairly regular intervals of 0.05 cm., the wire
was longitudinally compressed into nodules, shown in
the figure. This result may be due to electrical striae
within the wire. The wire cooled down to a rigid condi-
tion at the instant when it had assumed this form. The
nodules would then represent nodes of compression, and
the points midway between the nodules would be rare-
faction nodes in the electrical waves. Adjoining semi-
waves have alternately a surface super charge and a de-
ficiency of negative corpuscles. These semi-waves attract
each other, and the metal yields for the moment.

In one case the discharge was slightly greater, so that
the nodules separated, and further change in form was
arrested at the instant when they had an almost per-
fectly spherical form. There were about 1,000 of these
minute spheres distributed over a length of 50 cm. Those
at the ends of the tube were somewhat larger than those
along the main body of the tube, and were slightly dis-
torted. In cases where the discharge was greater, the
fragments of the wire were distorted into irregular forms.

A sample of the fuse wire which is in its natural form
is also shown in Fig. A. The effect shown by the other
fragments in this figure were due to a single discharge.
' In Fig. B is shown a few cuttings from a copper wire
having a diameter of 0.09 mm., through which about 50
discharges were sent. This wire gradually buckles into
irregular wave forms, as was first observed by Plante.
Two wires, three meters in length were suspended in a
horizontal position on thirty-one fine silk threads at reg-
ular intervals. The threads were about two meters in
length. The wires terminated in somewhat larger wires
which show no such effects, which were bent downwards
into metal vessels containing a salt solution. A slight
expansion of the wire could be observed at each end when
a spark was sent through the wire. No recoil of the
wire as a whole could be observed, and summation effects

86 Trans. Acad. Sci. of St. Louis.

were not obtained, sueli as were obtained by the arrange-
ment first described, and which was used later.

One end of each wire was then fixed to a glass tube by
means of sealing wax. Switching connections were so
made that alternate and equal discharges from either
terminal could be sent into one wire at the free, and the
other wire at the fixed end, and thence to ground. The
other teniiinal of the machine was gi'ounded on a separate
earth connection.

Precisely the same buckling effects were obtained as in
the former arrangement. These effects were alike from
end to end of each wire. The last half-centimeter at the
fixed end showed the same effects as the last half-centi-
meter at the free end. This also points to balanced longi-
tudinal stresses within the wire as the cause of this buck-
ling effect. The irregularity in form may be due to va-
riations in structure and foiTa of the drawn wire. In a
previous paper, such waves in a fine platinum wire were
described, and their form was much more nearly uniform.
That some differences in the length and form of striae
in a vacuum tube are observed, is well known.

Added June 17, 1912.

After this paper was in type, a simple method sug-
gested itself, of practically eliminating opposing end
thrusts due to point discharges from the ends of the wire
in the device of Fig. 1. About 1 cm. of the wire at each
end was bent downwards at right angles to the wire.
This results in applying these end thrusts at right angles
to the direction in which the wire creeps. This effect is
thus also utilized in diminishing frictional contact be-
tween the wire and the edge of the glass at the ends of
the tube. The ends of the wire rise slightly as the con-
ditions for the disruptive discharge are approached. The
effect of thus directing the ends of the wire downwards,
is to slightly increase this upward lifting of the wire at
its ends. It does not appear to materially increase the

Nipher — The Nature of Electrical Discharge. 87

creeping effect, if tlie wire is not in contact with the edge
of the tube. In all cases the ends of the wire drop
slightly, at the instant when the discharge passes.

The fact that the creeping of the wire occurs under
these conditions, shows very conclusively that this result
is not due to a difTerential end thrust resulting from
point discharges from the ends of the wire into the air.

The only rational explanation which suggests itself is,
that it is a reversal of the Rowland effect referred to in
the body of this paper. This also involves the assump-
tion that a wire having a positive charge is one from
which negative cori^uscles have been drained. The creep-
ing wire is a solid aggregation of positive ions. It is
a positive column. Like the positive column of the Geiss-
ler tube it may have in it striations. Here, however,
these striations are waves in the corpuscular nebula
which pervades the conducting column.

88 Trans. Acad. Sci. of St. Louis.

EXPLANATION OF THE PLATE.

Plate IX. — Fig. A. Nodules in a fuse wire, giving evidence of striations
in the corpuscular nebula within the wire.

Fig. B. Buckling of a fine wire due to balanced forces in electric
waves.

Issued July 3, 1912.

Trans. Acad. Sci. of St. Louis, Vol. XX.

Plate IX.

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Transactions of The Academy of Science of St. Louis.

VOL. XXI. No. 4.

TITLE-PAGE, PREFATORY MATTER AND INDEX.
RECORD FROM JAN. 1, 1912, TO DEC. 31, 1912.

Issued May 5, 1913.

List of Authors. 89

LIST OF AUTHOKS.

Abbott, J. F., xl, xlvii

Bostwick, A. E., xxxix

Ewing, A. E., xxv, 1
Ewing, H. E., 1

Gill, C. M., xl

Hard, M. E., xlvi
Harris, D. L., xlix
Hecker, F., xl
Hus, H. T. A., xxxii

James, G. O., xxvii, xxxv, xlii, xlv

Langsdorf, A. S., xxv, xxxvi
Lindsay, G. A., 71

McMaster, L., 1

Nipher, F. E., xxxiii, xxxv, xli, xlvi,
79

Pearse, A. S., xli

Rau, Phil, xli

Roever, W. H., xl, xlviii

Terry, R. J., xxxiii, xli

Todd, C. A., xxxi

Turner, C. H., xxx, xxxvii, xlvii

Van Ornum, J. L., xxxv, xli

Waldo, C. A., xxxiv, xxxvi
Whelpley, H. M., xxxi, xxxiv, xlviii

90

Trans. Acad. Sci. of St. Louis.

GENERAL INDEX.

Acarina, Origin and significance of

parasitism in 1
Active members vii
Animal membranes, Permeability

of xlvii
Annual rainfall and temperature of

United States 71
Anti-rabio immunity, Experimental

work on the etiology of rabies

and the mechanism of xlix
Ants, Homing of xxxvii
Arrows, Miniature flint xxxiv
Atomic theories of energy xxxix
Axes and celts, Indian xlviii

Baskets, Miniature Indian xxxi
Bees, Experimental study of color

vision and pattern vision of xxx
Borers which infest peach tree

roots XXV
Buckley, E. R., Death of xxx

Celts, Indian miniature axes and
xlviii

Charter xviii

Chemical origin of life 1

Coal exhaustion xxxiv

Cole, J. J., Death of xli

Color vision and pattern vision of
bees xxx

Coloi'ado, Problematical geological
phenomenon in xxxi

Colorado, Recreation studies in
Estes Park xl

Concrete, Effect of fatigue tests of
moisture upon elasticity of xli

Concrete, Permeability and imper-
meability of XXXV

Conductors, Electric waves in solid
xli

Conductors, Geissler tube effects in
solid xlvi

Conductors, Nature of electrical dis-
charge in metal 79

Contingence of physical theory and
problem of geologic past xlii

Corpuscles, Sudden drainage of neg-
ative xxxiii

Crabs, Fiddler xli, xlvii

Cranium in mammals. Develop-
ment of xli

Cupples, Samuel, Death of xxvii

Curators report lii

Curculio, Plum 1

Devil-horse, Life history of xli
Drainage of negative corpuscles.
Sudden xxxiii

Elasticity of concrete. Effects of
fatigue tests of moisture upon
xli
Electric discharge. Nature of 79
Electric waves in solid conductors

xli
Electrical motors. Graphical meth-
ods for constructing character-
istic curves of xxv
Electrical phenomena. Transient

xxxvi
Energy, Atomic theories of xxxix
Estes Park, Recreation studies in xl
Etiology of rabies and the mechan-
ism of anti-rabio immunity xlix
Exchanges xxi

Fatigue tests of moisture upon elas-
ticity of concrete xli
Fiddler crabs xli, xlvii
Flight, Mechanical xxvii
Flint arrows. Miniature xxxiv
Force, Mechanism for illustrating
lines of xl, xlviii

Geissler tube effects in solid con-
ductors xlvi

Geologic past, Contingence of phys-
ical theory and problem of xlii

Geological phenomenon in Colo-
rado, Problematical xxxi

Grove of deformed trees xxxiii

General Index.

91

History xviii

Homing of ants xxxvii

Honorary members vi

Immunity, Experimental work on
etiology of rabies and the
mechanism of anti-rabio xlix
Impermeability of concrete xxxv
Indian baskets, Miniature xxxi
Indian miniature axes and celts

xlviii
Inheritance in Capsella xxxii

Librarian, Report of lii
Library xxi

Life, Chemical origin of 1
Lines of force. Mechanism for illus-
trating xl, xlviii

Mammals, Development of cranium
in xli

Management xix

McGee, WJ, Death of xlvi

Mechanical flight xxvii

Meetings xx

Members vi

Membership xix

Membranes, Permeability of animal
xlvii

Mercury, Application of relativity
law of gravitation to motion of
perihelion of xxxv

Metal conductors. Nature of elec-
tric discharge in 79

Microscopic studies of living organ-
isms and rate of growth xl

Miniature axes and celts, Indian
xlviii

Miniature flint arrows xxxiv

Miniature Indian baskets xxxi

Moisture upon elasticity of con-
crete. Fatigue tests of xli

Museum xxi

Mushrooms in vicinity of St. Louis
xlvi

Nature of electric discharge 79

Necrology

Buckley, E. R. xxx
Cole, J. J. xli
Cupples, Samuel xxvii
McGee, WJ xlvii
Poincare, Henri xlv
Sander, Enno xxxi, xxxiii

Objects xviii
Officers v, xix
Organization xviii
Origin and significance of parasit-
ism in Acarina 1

Paper-making wasp. History of or-
phan colony of xlvii

Parasitism in Acarina, Origin and
significance of 1

Patrons vi

Pattern vision of bees. Experimental
study of color and xxx

Peach tree root borers xxv

Permeability of animal membranes
xlvii

Permeability of concrete and meth-
ods of securing impermeability
xxxv

Physical theory and the problem of
geologic past, Contingence of
xlii

Plum curculio 1

Poincare, Henri, Death of xlv

Problem of coal exhaustion xxxiv

Problematical geological phenome-
non in Colorado xxxi

Program xxii

Publications xxi

Rabies and the mechanism of anti-
rabio immunity. Experimental
work on the etiology of xlix

Rainfall and temperature in United
States, Annual 71

Relativity law of gravitation to the
motion of perihelion of Mer-
cury, Application of xxxv

92

Trans. Acad. Sci. of St. Louis.

Report of Curators lii

Librarian lii

Treasurer lii
Russian peasants, Multiplication of

two quantities by xxxvi

Saint Louis, Mushrooms in vicinity

of xlvi
Sander, Enno, Death of xxxi, xxxiii
Stream lines. Mechanism for illus-
trating certain systems of lines
of force and xlviii

Temperature in United States. An-
nual rainfall and 71
Theories of energy. Atomic xxxix

Transient electrical phenomena

xxxvi
Treasurer, Report of lii
Trees, Grove of deformed xxxiii
Trelease, William, Honorary mem-
ber xl

United States, Annual rainfall and
temperature of 71

Vision of bees. Experimental study
of color and pattern xxx

Wasp, History of orphan colony of
paper making xlvii

Water-boatmen, an unexplored cor-
ner of insect world xl

Index to Genera.

93

INDEX TO GENERA.

Acanthis 38
Accentor 36, 38
Accipitor 33
Acer 45
Acridium 25
Acrocephalus 36, 39
Aepypodius 33-34
Aesculus 46
Aglaeactis 36
Ajuga 45
Alauda 24, 39
Alca 38
Allanalges 38
Alloptes 38
Allothrombidium 25
Alnus 44
Alyssum 44
Aniblyomma 29
Araelanchier 45
Analges 36, 57, 70
Anas 32, 35
Anorrhirus 35-36
Anser 32

Antennophorus 10, 19, 59
Anthracoceros 34, 35, 37
Anthus 38-39
Antilope 42
Anystis 10
Aphis 25
Apus 34
Aquila 34, 38
Ara 32, 34
Arenaria 34
Argas 27
Arphia 50
Artemisia 46
Arvicola 23, 30-31
Asio 36
Atax 10, 61-62
Aulacorhamphus 35
Avena 44, 46

Barbatula 36
Bassaris 29
Bdellorhynchus 35

Berteroa 44
Betula 44
Bombycilla 38
Boophilus 67
Bos 28, 42
Botaurus 33
Bracliypteracias 34
Bracon xxvii
Bromus 44, 46
Brotogerys 37
Bryobia 10
Buceros 34, 36
Buteo 33

Caccabis 33-35

Caeculus 10

Caica 37

Calcopsitta 34

Caligonus 10

Caloenas 35

Calornis 36

Camelina 44

Camelus 42

Campanula 45

Canis 28, 43

Capito 33

Capra, 28, 42

Capsella, 44, xxxii

Carex xxxi

Carpophaga 35

Castor 31

Celaenopsis 10

Centaurea 46

Ceratixodes 28

Cereus 27

Cervus 28

Charadrius 33, 35

Chelidonaria 36-37, 39

Chen 32

Cheyletiella 10, 12, 19, 60

Cheyletus 10, 12, 16, 68

Chiloceras 35

Chrysolampis 39

Chrysotis 35

Ciconia 32

94

Trans. Acad. Sci. of St. Louis.

Cilliba 11, 59-61
Cillibano 59
Circaetus 33
Circus 33
Clematis 46
Clivicola 36-38
Cnemidocopus 42, 68
Coccothraustes 24
Columba 37
Colymbus 34
Conurus 33-35, 37
Corvultur 33
Corvus 33, 36
Corylus 46
Cotile 28
Cotoneaster 45
Coturnix 35, 37
Cranorrhinus 33, 37
Crossopus 25
Crataegus 45
Cuculus 33
Cyanocorax 35, 39
Cyanolesbia 38-39
Cygnus 32
Cytisus 46
Cytoleichus 59

Dactylis 44, 46
Demodex 14, 59, 69
Dendrocopus 37, 39
Dendroecia 37
Dermacentor 29
Dermanyssus 20, 48-49, 67
Dermogyphus 35
Dichoceros 37
Dinychus 11
Diomedea 32
Disosteira 50
Disparipes 11
Docophorus 48
Dorycnium 45
Dromas 36

Echinomegistus 59
Eclectus 36
Elainea 37-38
Emberiza 38-39
Empoasca 16, 70
Eos 34
Ephippiorhynchus 32

Epicrius 10
Epitrimerus 46
Equus 28, 42-43
Erinaceus 28
Eriophyes 44-46, 70
Erismatura 35
Erithacus 39
Ervum 45
Erysimum 44
Erythraeus 10
Eulampis 36, 39
Eurylaemus 39
Eutoxeres 35, 38
Eutrygon 35
Euxenura 32

Falco 37
Falculifer 35
Felis 28-29, 43
Fratercula 38
Fraxinus 45
Freyana 32
Fringilla 38
Fulica 33
Fuligula 32

Galium 45-46
Gallinago 35, 39
Gallinula 37
Gallus 35, 42
Gamasus 11, 48-49, 67
Garrulus 39
Gekobia 10, 60-63
Genetta 28
Genista 45
Geranium 45
Giraffa 42
Glossopsittacus 34
Glycyphagus 21
Glyphopsis 11
Goura 25, 35
Greeniella 10
Grus 32
Gryllotalpa 25

Haemaphysalis 29
Haematopus 38
Haemogamasus 10, 59
Haliaetus 34
Haliastur 34

Index to Genera.

95

Harpactes 38

Harpyrhynchus 10, 18, 24, 59, 61-63,

68
Helianthemum 44
Hemisarcoptes 11, 13, 21, 59-60, 62,

68
Heteropsorus 39
Hirundo 25

Histiostoma 11, 13, 59, 62
Homo 25, 28-29, 42
Hydrocorax 34-35

Iphiopis 10
Ixodes 28-30

Labidocarpus 56, 69
Lagopus 34
Lama 42
Laminosioptes 59
Lamprocolius 39
Lamprotornis 36
Lanius 38
Larus 36, 38
Lepidium 44
Lepus 28, 30
Limosa 33, 38
Liroaspis 11
Listrophorus 30, 56
Lobivanellus 32
Lophoceros 34
Lophophaps 35
Lophornis 39
Loriculus 34
Lorius 34, 37
Lotus 45
Loxia 24
Loxigilla 38
Lutra 28
Lycium 45
Lysimachia 45

Macrocheles 10, 19, 70
Mainatus 36
Mallophaga 48
Malva 45
Mantis 25
Margaropus 29
Medicago 45
Megapodius 33-34
Megisthanus 10

Megninia 37, 41, 69

Melanophus 50

Meleagris 35, 37

Meles 28

Mergus 32

Microglossus 34

Microlichus 39

Microsarcops 33

Microtrombidium 26-27, 48, 50, 70

Milvus 34

Monieziella 20-21, 67

Motacilla 36

Mus 23, 28, 30-31, 42, 49-50

Musca 25, 49-50

Muscicapa 36

Mustela 23, 28, 30

Mycoptes 31, 57

Myobia 10, 23-25, 30, 49, 59, 61-63

Myopotamus 28

Myoxus 28

Neophyllobius 10

Neotoma 28

Nestor 34

Nettapus 32

Nirmus 48-49

Notoedres 42-43, 48, 50, 68

Numenius 33

Numida 35

Nymphicus 34

Oncideres xxxiii-xxxiv
Ononis 45
Oolaelaps 20, 59
Opilioacarus 8
Oribata 63
Orlava 45
Ornithodoros 28
Orthygometra 37, 39
Ortholophus 34, 37
Ostinops 39
Otodectes 43
Ovis 28, 42
Oxypleurites 46

Pachylichus 39
Paludicola 30, 42
Panurus 36
Paradisea 39
Parus 36

96

Trans. Acad. Sci. of St. Louis.

Passer 36, 38-39
Pediculoides 11, 22, 59, 62
Penelopides 34-35
Perdix 33-35
Pernis 33
Petasophora 36
Peucedanum 45
Pezoporus 34
Phaethon 37-38
Phaethornis 35, 38
Phyllocoptes 46
Phyllorhina 23
Phoenopepla 23
Picobia 10, 23-24, 56, 61-63
Picus 36-37
Pigmeophorus 11
Pimelia 54
Pimelobia 60
Pipra 38
Pirus 45-46
Platalea 37
Platycercus 34, 37
Plecotus 25
Plegadis 37
Podapolipus 11
Podocinum 11
Poeocephalus 34
Pogonorhynchus 36
Polistes xlvii
Polyaspis 11
Polygala 45
Poocaetes 39
Populus 44, 46
Porphyrio 33
Potentilla 45
Procellaria 36
Protophyllodes 38, 41, 48-49
Procyon 29
Prosopodectes 42
Protalges 36-37
Prunus 45-46
Psephotus 34
Psoralges 43

Psorergates 10, 23-24, 61-63
Psoroptes 43, 70
Pteralloptes 37
Pterodectes 39, 70
Pteroglossus 33, 36
Pterolichus 32-35, 42
Pteronyssus 36

Pterophagus 39
Pterophanes 36
Puffinus 36
Pyrrhula, 32, 34-35
Pyrrhulopsis 34
Pyrrhura 37

Quercus 44

Raillietia 10, 59
Rallus 37
Raphignathus 10
Rhagida 8
Rhamphastus 33
Rhea 33, 35
Rhinolophus 23, 42
Rhipicephalus 29
Rhizoglyphus 69
Rhododendron 45
Rhyncholophus 63, 69-70
Rhytidoceros 33-36
Ribes 45

Sacculina 64

Salix 44, 46, xxxi

Salvia 45

Sambucus 46

Sanninoidea xxv-xxvii

Sarcoptes 42-43, 68-69

Sarothamnus 45

Saxifraga 45

Sayornis 39

Schizocarpus 31

Schizoris 33

Sciurus 28

Seius 11

Sericulus 39

Serinus 35, 37

Seseli 45

Sesia xxvii

Siphonaptera 48

Sisymbrium 44

Sieteroptes 11

Smaris 63

Sorbus 45

Spermophilus 25, 28, 43, 49-50

Sphaerogastra 36

Stagmomantis xli

Steganura 33

Stercorarius 38

Index to Genera.

97

sterna 35-36, 38

Stigmaeodes 10

Stigmaeus 10

Stnithio 33, 35

Sturnus 36

Sula 32

Sus 28

Sylvia 36, 39

Symphemia 33

Synotus 23

Syringophilus 10, 23-24, 56, 61-63, 69

Talegallus 34
Talpa 25, 28
Tamandua 43
Tamias 28
Tarsonemus 11, 22
Tauracus 33
Tenuipalpus 10
Tetranychus 10
Thecarthra 35
Thesium 45
TUia 45
Topaza 39
Torilis 45-46
Totanus 33-34, 36, 38-39

Trichoecius 31
Trichoglossus 34, 36
Trifolium 45
Tringa 33-34, 36, 38-39
Trinia 45
Trogon 38

Trombidium 25-26, 50
Tronessartia 38
Tyroglyphus 68

Uca xlvii
Uria 38
Urinator 34
Uropoda 11, 60
Uroseius 11

Vanellus 37
Veronica 45
Vesperugo 23, 25, 42

Xanthura 39
Xolalges 37
Xoloptes 35

Zaitha 50
Zercon 11

New York Botanical Garden Librai

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