blowing sand. All degrees of reclamation by invading vegetation are found. The types and characteristics of the plants are noted and short lists of the more important plants found at the various stages are given. Notes on some Rocky Mountain plants, chiefly of the Arapahoe mountains: L. H. PAMMEL AND R. I. CRATTY. Further notes on the germination of some trees and shrubs and their juvenile forms: L. H. PAMMEL AND CHARLOTTE M. KING. On the occurrence of the giant puff ball: HARRY M. KELLY. The disintegration of certain intracellular bodies: The teaching of plant pathology: W. H. DAVIS. The vegetation of Cape Blanco: MORTON E. PECK. Some Alaska fungi: J. P. ANDERSON. The genus Ceanothus in Iowa: B. SHIMEK, Notes on the distribution of midsummer bee plants in the Mississippi zone of Clayton county: ADA HAYDEN. The growth of foliage leaves: BERYL TAYLOR. Comparison of the absorption occurring in corn stalk tissue and in prepared bicolloids: L. E. YOCUM AND A. L. BAKKE. Mechanical preparation of sweet corn pericarp: R. A. RUDNICK AND A. L. BAKKE. The Orchidacea of Nebraska: T. J. FITZPATRICK. The influence of forest areas in non-forest regions upon evaporation, soil moisture and movement of ground water: I. BODE. The paper includes the results of a series of studies carried on in the northeastern part of Iowa during the summer of 1919. The work covers a comparison of the evaporation and soil moisture conditions obtaining on forested and non-forested sites, and the influence that forested areas have as to the checking of runoff, the absorption of moisture in the soil and the response of various soils at various depths to precipitation. The results and conclusions bring out some very interesting facts relative to the economic values of forest areas of a state like Iowa in conserving soil mois ture, checking evaporation and regulating the flow of smaller streams throughout the state. Chemistry Simplified electrotitration and its use in determin- An apparatus for determining solubilities up to Vacuum tube circuits as a source of power for conductivity measurements: H. A. GEAUQUE. The free energy of dilution and the activity of the ions of sodium bromide: J. N. PEARRE AND H. B. HART Geology Iowa terranes compared with those of adjoining states: CHARLES KEYES. Since geologic phenomena are not restricted by political boundaries many of the missing leaves of Iowa's earth-history are found clearly imprinted in contiguous states. But it is difficult to make very close comparisons because of the diverse conditions and the varied aims under which the terranal schemes are constructed. By reducing to a standard the geological sections of our state and those of surrounding states a classificatory plan is effected which, although perfectly elastic, permits exact stratigraphic parallelism to be instituted. Belated survival of Wernerian nomenclature: CHARLES KEYES. Galena as denominating a notable Ordovicic dolomite is not a geographic name, as is so often supposed. James Hall, who proposed the term, derived it directly from the chief mineral content of the formation. In using the title this author manifestly modified Featherstonough's earlier name "Galeniferous Limestone," which in turn was an alteration of Schoolcraft's usage of "Metalliferous Limestone."' Rectification of Iowa's Cambric section: CHARLES KEYES. Recent critical inspection of the type localities of the Cambric formations of the upper Mississippi basin indicates that there are grave misinterpretations of stratigraphic succession. Thus, some well-known formational titles become synonyms and pass out of use; several names are new; and a number of substitutions appear. Exact parallelism of the upper Mississippi Basin section and that of the Ozarks is thus satisfactorily permitted. The use of the terms flint and chert: W. S. GLOCK. Common usage of these terms may leave such an uncertainty that a word dare not be employed where scientific accuracy is desired. For example, It is a common habit to call any form of quartz interbedded with iron ore "chert" for want of knowledge of the nature of the quartz and of the meaning of the term employed. Detailed reference to the standard English and American textbooks on geology and mineralogy substantiates the confusion which exists and which is presented therein for the instruction of the reader. Neither chert nor flint should be a provoking "catch-all''; fundamentally they are good terms whose use is Justified only where exactness is implied. The fauna of the Independence Shale: A. 0. THOMAS. This interesting fauna, first reported by Dr. Calvin over forty years ago from a very limited exposure, has recently become better known due to the discovery of several fossiliferous outcrops of the shale as reported before the academy a year ago. Among the additions to the fauna is a species of the crinoid Arthracantha, hitherto known only from the Devonian of the region of Lake Ontario. There is also a species of Spirifer akin to 8. disjunctus, a new Chonetes, and a fine specimen of Hypothyridina cuboides. A few of the species of the Independence shale recur in the Lime Creek shale at the top of the Iowa Devonian but none of the forms just mentioned are known to occur in the later formation. Nortonechinus, a Devonian sea urchin: A. O. THOMAS. This is a highly specialized genus known only from dissociated plates, spines, and parts of the lantern. The test of the living animal was doubtless very flexible and was well protected by the covering afforded by the broadly expanded distal ends of the spines as in modern Colobocentrotus. Two other genera of echinoids also found in the Lime Creek shales will be briefly discussed. The corals of the Hopkinton stage, Iowa Silurian: A. O. THOMAS AND BERYL TAYLOR. The Iowa Silurian affords a rich and interesting assemblage of corals most of which are highly silicified. The Calvin Collections from the typical localities together with those made by various field classes and by the writers, furnish a large series in which some of the genera are very well represented. Strombodes, for example, has no less than ten species, Favosites, seven, Zaphrentis, six, and Heliolites, four. The reefs furnish upwards of seventy species, many of which are new. The conservation of underground water: JAMES H. LEES. The paper discusses the importance of water, its source and distribution, its relation to the rock strata and its use by plants. The need for better conservation is emphasized and the effect of population increase and of agriculture is discussed. Certain post-Pliocene deposits in Missouri: B. SHIMEK. On the occurrence of charcoal in an interglacial peat bed in Union county: RALPH W. CHANEY. A sink hole in northeast Iowa: E. J. CABLE. A field of eskers in Iowa: JOHN E. SMITH. The Palisades of the Cedar: Wм. H. NORTON. Physics The Hall effect and the specific resistance of thin silver films: G. R. WAIT. The dependence of the resistance of silver films LETT. The perception of binaural phase difference not caused by an intensity effect: G. W. STewart. The frequency limits of the binaural phase difference and intensity effects: G. W. STEWART. Note on the principle of similitude: I. MAIZLISH. blowing sand. All degrees of reclamation by invading vegetation are found. The types and characteristics of the plants are noted and short lists of the more important plants found at the various stages are given. Notes on some Rocky Mountain plants, chiefly of the Arapahoe mountains: L. H. PAMMEL AND R. I. CRATTY. Further notes on the germination of some trees and shrubs and their juvenile forms: L. H. PAMMEL AND CHARLOTTE M. KING. On the occurrence of the giant puff ball: HARRY M. KELLY. The disintegration of certain intracellular bodies: The teaching of plant pathology: W. H. Davis. The vegetation of Cape Blanco: MORTON E. PECK. Some Alaska fungi: J. P. ANDERSON. The genus Ceanothus in Iowa: B. SHIMEK, Notes on the distribution of midsummer bee plants in the Mississippi zone of Clayton county: ADA HAYDEN. The growth of foliage leaves: BERYL TAYLOR. Comparison of the absorption occurring in corn stalk tissue and in prepared bicolloids: L. E. YOCUM AND A. L. BAKKE. Mechanical preparation of sweet corn pericarp: R. A. RUDNICK AND A. L. BAKKE. The Orchidacea of Nebraska: T. J. FITZPATRICK. The influence of forest areas in non-forest regions upon evaporation, soil moisture and movement of ground water: I. BODE. The paper includes the results of a series of studies carried on in the northeastern part of Iowa during the summer of 1919. The work covers a comparison of the evaporation and soil moisture conditions obtaining on forested and non-forested sites, and the influence that forested areas have as to the checking of runoff, the absorption of moisture in the soil and the response of various soils at various depths to precipitation. The results and conclusions bring out some very interesting facts relative to the economic values of forest areas of a state like Iowa in conserving soil mois ture, checking evaporation and regulating the flow of smaller streams throughout the state. Chemistry Simplified electrotitration and its use in determin- An apparatus for determining solubilities up to Vacuum tube circuits as a source of power for conductivity measurements: H. A. GEAUQUE. The free energy of dilution and the activity of the ions of sodium bromide: J. N. PEARRE AND H. B. HART Geology Iowa terranes compared with those of adjoining states: CHARLES KEYES. Since geologic phenomena are not restricted by political boundaries many of the missing leaves of Iowa's earth-history are found clearly imprinted in contiguous states. But it is difficult to make very close comparisons because of the diverse conditions and the varied aims under which the terranal schemes are constructed. By reducing to a standard the geological sections of our state and those of surrounding states a classificatory plan is effected which, although perfectly elastic, permits exact stratigraphic parallelism to be instituted. Belated survival of Wernerian nomenclature: CHARLES KEYES. Galena as denominating a notable Ordovicic dolomite is not a geographic name, as is so often supposed. James Hall, who proposed the term, derived it directly from the chief mineral content of the formation. In using the title this author manifestly modified Featherstonough's earlier name "Galeniferous Limestone," which in turn was an alteration of Schoolcraft's usage of "Metalliferous Limestone."' Rectification of Iowa's Cambric section: CHARLES KEYES. Recent critical inspection of the type localities of the Cambric formations of the upper Mississippi basin indicates that there are grave misinterpretations of stratigraphic succession. Thus, some well-known formational titles become synonyms and pass out of use; several names are new; and a number of substitutions appear. Exact parallelism of the upper Mississippi Basin section and that of the Ozarks is thus satisfactorily permitted. The use of the terms flint and chert: W. S. GLOCK. Common usage of these terms may leave such an uncertainty that a word dare not be employed where scientific accuracy is desired. For example, It is a common habit to call any form of quartz interbedded with iron ore "chert" for want of knowledge of the nature of the quartz and of the meaning of the term employed. Detailed reference to the standard English and American textbooks on geology and mineralogy substantiates the confusion which exists and which is presented therein for the instruction of the reader. Neither chert nor flint should be a provoking "catch-all''; fundamentally they are good terms whose use is Justified only where exactness is implied. The fauna of the Independence Shale: A. O. THOMAS. This interesting fauna, first reported by Dr. Calvin over forty years ago from a very limited exposure, has recently become better known due to the discovery of several fossiliferous outcrops of the shale as reported before the academy a year ago. Among the additions to the fauna is a species of the crinoid Arthracantha, hitherto known only from the Devonian of the region of Lake Ontario. There is also a species of Spirifer akin to B. disjunctus, a new Chonetes, and a fine specimen of Hypothyridina cuboides. A few of the species of the Independence shale recur in the Lime Creek shale at the top of the Iowa Devonian but none of the forms just mentioned are known to occur in the later formation. Nortonechinus, a Devonian sea urchin: A. O. THOMAS. This is a highly specialized genus known only from dissociated plates, spines, and parts of the lantern. The test of the living animal was doubtless very flexible and was well protected by the covering afforded by the broadly expanded distal ends of the spines as in modern Colobocentrotus. Two other genera of echinoids also found in the Lime Creek shales will be briefly discussed. The corals of the Hopkinton stage, Iowa Silurian: A. O. THOMAS AND BERYL TAYLOR. The Iowa Silurian affords a rich and interesting assemblage of corals most of which are highly silicified. The Calvin Collections from the typical localities together with those made by various field classes and by the writers, furnish a large series in which some of the genera are very well represented. Strombodes, for example, has no less than ten species, Favosites, seven, Zaphrentis, six, and Heliolites, four. The reefs furnish upwards of seventy species, many of which are new. The conservation of underground water: JAMES H. LEES. The paper discusses the importance of water, its source and distribution, its relation to the rock strata and its use by plants. The need for better conservation is emphasized and the effect of popu lation increase and of agriculture is discussed. Certain post-Pliocene deposits in Missouri: B. SHIMEK. On the occurrence of charcoal in an interglacial peat bed in Union county: RALPH W. CHANEY. A sink hole in northeast Iowa: E. J. CABLE. A field of eskers in Iowa: JOHN E. SMITH. The Palisades of the Cedar: WM. H. NORTON. Physics The Hall effect and the specific resistance of thin silver films: G. R. WAIT. The dependence of the resistance of silver films LETT. The perception of binaural phase difference not caused by an intensity effect: G. W. STEWART. The frequency limits of the binaural phase differ. ence and intensity effects: G. W. STEWART. Note on the principle of similitude: I. MAIZLISH. A table of the total number of stroboscopic velocity curves for any of the natural numbers from 1 to 500 inclusive taken as a limiting value of n and m: L. E. DODD. On finding the equation of the characteristic blackening curve of a photographic plate: P. S. HEL MICK. The overtones of air columns: L. B. SPINNEY. The stereoscope in teaching physics and geometry: LEROY D. WELD. The stereoscope has usually been considered a mere toy. In this paper, however, is given a method whereby stereoscopic drawings of any simple figure in space can be easily prepared and duplicated for use in the study of any subject requiring three-dimensional figures, such as solid geometry, crystal structure, analytic mechanics, optics, etc. Psychology Symposium: Some Results of Current Research in the Psychological Laboratory of the State University. Introduced by C. E. Seashore. The talent survey in our music school: ESTHER ALLEN GAW. The Iowa pitch range audiometer: C. C. BUNCH. The normal curve of acuity in hearing: PAUL B. ANDERSON. The localization of sound by wave phase in the open ear: HENRY M. HALVERSON. What constitutes voice: CARL I. ERICKSON. The application of the Mendelian law to talent in music: HAZEL M. STANTON. The personal equation in motor capacities: MARTIN L. REYMERT. Serial action as a basic measure of motor capaci ties: C. F. HANSEN. The measurement of motility in children: LILLIAN Tow. The selection of talent for stenography and typing: B. W. ROBINSON. A measure of capacity for acquiring skill in coordination of eye and hand: WILHELMINE KOERTH. A standardized measure of motility: MERRILL J. REAM. Zoology Some Iowa records of Lepidoptera: A. W. LINDSEY. A biological reconnaisance of Okefinokee swamp, Georgia. The fishes: E. L. PALMER AND A. H. WRIGHT. The Okefinokee swamp in its fish fauna is decidedly fluviatile. Like that of Florida its fish fauna may be held to have "originated from the north and is thus not tropical." The swamp has twenty-three less fresh water species than the whole state of Florida and in number of forms is not comparable to the better known Everglades of Florida. Twenty-eight species are known from the swamp and twenty-two of these are included in the collection upon which this paper is based. Sixtythree specimens of the rare Lucania ommata (Jordan) were taken. The southern limit of the range of Umbra limi (Kirtland) is increased from North Carolina to southern Georgia. In addition the material supports contentions that Umbra pygmæa DeKay is a synonym of Umbra limi (Kirtland); Esox vermiculatus Le Sueur, of Esox americanus (Gmelin.); Enneacanthus gloriosus (Holbrook), of Enneacanthus obesus Baird; and Copelandellus quiescens (Jordan), of Boleichthys fusiformis Girard. Bird records of the season 1919–1920 in the vicinity of Iowa City: DAYTON STONER. Cladocera of the Okoboji and Spirit Lake regions: FRANK A. STROMSTEN. Copepoda of the Okoboji region: FRANK A. STROMSTEN. Rotatoria of the Okoboji region: DWIGHT C. ENSIGN. Similarities between the lateral-line systems of elasmobranchs and amphibians: H. W. NORRIS. Naked neuromasts in amphibians correspond to pit-organs and canal-organs in the elasmobranch fishes. The mandibular series of neuromasts of amphibians is distinctly double, oral, and gular. Similarly in elasmobranchs the mandibular and hyomandibular canal organs correspond to the oral series and a mandibular row of pit-organs to the gular series of neuromasts of amphibians. The vaguely defined occipital group of neuromasts of amphibians corresponds to the sense-organ of the supratemporal canal. Three lines of neuromasts occur on the trunk of the body in amphibians, innervated by three distinct nerve rami. Three series of lateral-line organs are to be found on the trunk in elasmobranchs. Susceptible and resistant phases of the dividing sea-urchin egg when subjected to various concentrations of lipoid-soluble substances, especially the higher alcohols: FRANCIS MARSH BALDWIN. When subjected to suitable concentrations of various lipoid-soluble substances the developing seaurchin egg shows unmistakable rhythms of sus |