IOWA STATE COLLEGE JOURNAL OF SCIENCE Published on the first day of October, January, April, and July EDITORIAL BOARD EDITOR-IN-CHIEF, Joseph c. Gilman. AssISTANT EDITOR, H. E. Ingle. CONSULTING EDITORS: R. E. Buchanan, C. J. Drake, I. E. Melhus, E. A. Benbrook, P. Mabel Nelson, V. E. Nelson, C. H. Brown, Jay W. Woodrow. From Sigma Xi: E. W. Lindstrom, D. L. Holl, B. W. Hammer. All manuscripts submitted should be addressed to J. C. Gilman, Botany Hall, Iowa State College, Ames, Iowa. All remittances should be addressed to Collegiate Press, Inc., Iowa State College, Ames, Iowa. Single Copies: One Dollar. Annual Subscription: Three Dollars; in Can­ ada, Three Dollars and Twenty-Five Cents; Foreign, Three Dollars and Fifty Cents. Entered as second-class .:me«Eir '~~~ 1~;. :t935.- Qt. the postoffice at Ames, Iowa, under the,..... ae,t . .df. ?,JEO:'cn 3, 11119.: :. .',: . .:. .: ..: ... .. .... .... .. ... .. .. : .. ·... ···.. ·.. · .. ::·::··.. .. ·. .. .. ·: . .· .: .. .. .. :. ·.... · .. .. :. : : .: : . .. : .. ·: .: ·. ..·... ··::.:: .. : ·:·.·.: ....... ABSTRACTS OF DOCTORAL THESES1 CONTENTS Serial correlation in the analysis of time series. RICHARD L. ANDERSON 3 Relative reactivities of some organometallic compounds. LESTER D. APPERSON................................................................................ 7 The physiologic and economic efficiency of rations containing differ­ ent amounts of grain when fed to dairy cattle. KENNETH MAXWELL AUTREY.................................................................. 10 Fermentative utilization of cassava. JULIAN R. BANZON........................ 15 Chemical engineering applications of a modified archimedean screw. HERBERT TEMPLETON BATES.................................................................. 19 The theory and application of tensor analysis. ROBERT EDWIN BEAM.... 21 Ionic exchange materials and their uses. RICHARD ERNEST BENSON.... 28 Unsymmetrical organolead compounds. ERNEST BINDSCHADLER............ 33 Fractionation of starch. CARLYLE G. CALDWELL........................................ 37 Errors in the approximations of functions by the use of functionals. RoY HERBERT CooK .... ............................................................................ 41 The absorption of radiant energy in plants. JACOB E. DINGER................ 44 Meat in nutrition. XVIII. Glycogen in maternal and fetal livers of rats fed a diet containing dried autoclaved pork muscle. HELEN ELIZABETH FARRANKOP................................................................ 46 An analysis of group differences arising from a Poisson distribution of observations obtained from irradiation experiments. HoLLY CLAm FRYER ................................................................................ 49 The polarographic method in the investigation of several Aceto­ bacter suboxydans fermentation products. EAKIN M. GLYMPH.... 52 Mineral acids and mold amylase as saccharifying agents for produc­ tion of fermentable sugars from starch. KENNETH JUSTIN GOERING 55 Effects of pH and of various concentrations of sodium, potassium, and calcium chloride on motility of the isolated crop of Peri- planeta americana. JAMES T. GRIFFITHS, JR. .................................... 57 Effects of dietary modifications on the tapeworm Hymenolepis diminuta. ANNA HAGER.......................................................................... 60 The effect of controlled pH upon the production of chemicals in several fermentations. RICHARD JAMES HICKEY................................ 63 The host relation of the cotton flea hopper. EPHRIAM HIXSON................ 66 Meat in Nutrition. XVII. Concentration of sugar in blood of pregnant rats fed a diet containing dried autoclaved pork muscle. FLORENCE PEN Ho...................................................................................... 69 Soil-inhabiting fungi attacking the roots of maize. WEN-CHUN Ho...... 72 Distribution of salt in butter and its effect on bacterial action. WESLEY HENRY HOECKER........................................................................ 75 Relationship of the lipolytic and proteolytic activities of various peni­ cillia to the ripening of blue cheese. CHRISTIAN JENSEN................ 77 A micromorphological approach to the study of soils. JOSEPH REX JOHNSTON ................ ······ .......................................... ······· ... .. 80 The effect of insect control on the yield and quality of cotton prema­ turely killed by cotton root rot. S. E. JONES.................................... 82 1 Complete copies of these theses may be consulted at the Library, Iowa State College, Ames, Iowa. [1] Effect of the presence of salts on the hydrogen overvoltage of solu- tions. JoHN NELSON JUDY...................................................................... 85 Analysis of continuous space frames by three-dimensional moment­ distribution and slope-deflection methods. SHIH-CHING Lo............ 88 The ecology and management of the redhead, Nyroca americana (Eyton), in Iowa. JESSOP BUDGE Low................................................ 90 Ecology and management of the mourning dove, Zenaidura macroura (Linn.), in southwest Iowa. H. ELLIOTT McCLURE............................ 93 Bionornics and morphology of the black onion fly, Tritoxa flexa (Wied.) (Diptera, Ortalidae). HUBERT CLYDE MANIS.................... 96 Condensation of mercaptans with chloral in the gaseous phase. FRANCIS B. MOORE........ ............................................................................ 99 Relationship between the electron-sharing ability of radicals and the ionizing power of non-aqueous solvents. FRANK J . MooRE ............ 103 Some metal-metal interconversions with organolithium compounds. FRED wARREN MOORE ................................................................................ 106 The concentration, characterization, and properties of soybean amy- lase. J . MARSHALL NEWTON .................................................................... 108 Quantitative volumetric titration of heavy metals. HOWARD FREDERIC NICOLAYSEN .............................................................. 111 Interreflection of light between parallel planes. FRANK NOAKES...... ...... 114 Lateral organoalkali compounds. HENRY ALEXANDER PACEVITZ............ 117 Properties of compounds produced by the action of Acetobacter suboxydans upon i-inositol. WALTER H. PITCHER .............................. 120 Production of chemicals by the fermentation of the acid hydrolyzate of oat hulls. MORTON M. RAYMAN ........................................................ 122 Fluorescence associated with proteins. WENDELL REEDER .................... 125 The dielectric constant of gases at ultra-high frequencies. ALDEN HOOVER RYAN ................................................................................ 128 A chemical investigation of American veratrum. EDWIN J. SEIFERLE .... 130 Effect of carbon dioxide and acids on survival of micro-organisms. CLIFFORD ALLEN SHILLINGLAW ............ ........................ ........... ....... ........ 132 Some metallic oxides as promoters for copper oxide catalysts in the hydrogenation of furfural. MEREDITH MARVIN STEWART ................ 134 A microscopic method for measuring soil pore space and for charac- terizing soil structure. C. LOYAL W. SWANSON ................................ 137 The approximate solution of linear differential equations by the use of functionals. CHARLES J. THORNE ...................................................... 140 Monograph of the Psyllinae and Triozinae (Psyllidae: Homoptera) in America North of Mexico. LEONARD D. TuTHILL .............................. 145 Some internal effects of dinitrophenols on insects. GETULIO B. VIADO .................................................................................... 146 The effect of soybeans and soybean oil on milk and butterfat produc­ tion and on the quality of the butterfat. NEIL KENNETH WILLIAMS 148 Action of mold inhibitors on dairy products. JUDDIE JOHNSON WILLINGHAM ................................................................ 152 Unsymmetrical organobismuth compounds. HARRY Lours YABLUNKY 155 Nutritional status of Iowa State College women. VI. Factors contrib­ uting to variability in basal metabolism. CHARLOTTE MARIE YOUNG 158 [2] SERIAL CORRELATION IN THE ANALYSIS OF TIME SERIES1 RICHARD L. ANDERSON From the Department of Mathematics, Iowa State College Received June 10, 1941 The problem of serial correlation was first introduced by Yule (8), who stated that the standard error test of significance was invalidated if our observations were not independent of one another. Yule adopted the term lagged serial correlation to denote the relationship between successive values of some variable x. If we have a set of n ordered ob­ servations, x 1 , •••. , x 0 , with mean 0, we will define the sereal correlation coefficient for lag L to be CL X1XL+l + X2XL+2 + ..... + XNXL RL = - = ------------- v ::Sx1 2 The writer was first introduced to this problem in a recent study of the harmonic components of the cyclical deviations of agricultural prices (1). The ordinary tests of significance of the harmonic terms derived by Walker (2) and Fisher (4) could not be used directly. The most obvious difficulty was the determination of the proper number of degrees of freedom in the price series. A tentative solution suggested by E. B. Wilson was adopted at that time (6). Wilson proposed that a sequence of the serial correlation coefficients, R 1, R 2 , •••• , be computed