original functions, retain and store up the accumulated excreta which is discharged only after feeding ceases, when such discharge on the interior of the cell occupied by the larva would not involve contamination of the food. JAS. A. NELSON BUREAU OF ENTOMOLOGY, SPECIAL ARTICLES CONCERNING THE EFFECT OF INGESTED PLACENTA ON THE GROWTH-PROMOTING PROPERTIES OF HUMAN MILK It has been shown that the feeding of desiccated placenta to women during the first eleven days after parturition causes an increase in the protein and lactose per cent. of the milk.1 The present report is concerned with the growth of the infants subsisting upon the milk from the above sources. As a basis for comparison there is used the growth of the infants whose nourishment was derived from the women whose milk production was not subjected to the influence of ingested desiccated pla centa. In the tables at the end of this paper the number assigned to the infant corresponds to the number given to the mother in the previous reports. It should be remembered that all the mothers were receiving the same diet and that to the second set 0.6 gm. of desiccated placenta was fed three times a day throughout the period. Certain definite differences in the progress of growth of the two sets of infants are to be observed. The variation limit per cent. from day to day, and the absolute per cent. variation from day to day is less in degree and tends to take on more of a positive character in those infants whose mothers were fed the desiccated placenta. Also the per cent. variation from the first day, both as regards its limits and its average is at all times less in degree. The general trend of these latter values is towards zero; this is not to be seen with the infants receiving milk from uninfluenced sources. 1 Hammett, F. S., and L. G. McNeile, Jour. Biol. Chem., 1917, XXX.; Hammett, F. S., Jour. Biol. Chem., 1917, XXIX., 381. intra-uterine growth aside from its function tion, it is quite probable that soils in general as a transfer system. FREDERICK S. HAMMETT, LYLE G. MCNEILE COLLEGE OF PHYSICIANS AND Surgeons, UNIVERSITY OF SOUTHERN CALIFORNIA, LOS ANGELES, Calif. THE EFFECT of drAINAGE ON SOIL ACIDITY For the purpose of studying the effect of drainage on soil acidity, samples of soil were taken in October, 1916, from three of the experiment fields of the Purdue Agricultural Experiment Station. These fields are located near Westport, North Vernon and Worthington. The soils of these fields are all heavy silt loam, very low in organic matter and naturally poorly drained and quite acid in reaction. All will tend to become less acid when thoroughly drained, and vice versa; they will tend to become more acid when water-logged and poorly aerated. In testing soil acidity at different seasons of the year the results often vary quite a little in samples from the same plots of soil. These differences can not be attributed alto gether to errors in sampling. The writer believes that at least part of the change of acidity is due to difference in aeration and moisture content of the soil at different seasons. Lipman and Waynick,1 in an investigation of the effect of climate on soil properties, report that Maryland soil, which shows an acid reaction in its original location, when transported to Kansas or to California becomes neutral or better drainage and aeration of the soil when placed under less humid conditions could account very largely for the changes in reaction. of these fields have been thoroughly tile slightly alkaline. It is quite probable that the drained from three to five years. A portion of the Westport field is undrained and there are adjacent undrained, untreated areas alongside the North Vernon and the Worthington fields. Table I. shows the acidity of the soil as determined by the potassium nitrate method. Without entering into a discussion of the merits of different soil acidity methods, it may be said that on these soils, which are low in organic matter, there is no great difference in the degree of acidity shown by this method and the lime water and calcium salt methods. These results are consistent enough to indicate that drainage has a material influence on the acidity of soil of this type. Farmers often refer to wet, poorly drained land as sour. While agricultural writers have placed little or no emphasis on such a correla Considering SiO, an acid-forming oxide, practically all soils except those very high in the basic reacting elements, have a potentially great capacity for developing an acid reaction. The writer believes that the constitution of the silicates of aluminum has more to do with injurious soil acidity than any other single factor. The acidity of aluminum silicates varies both with the relative proportion of SiO, to ALO, and with the amount of combined water in the silicate. The weathering and changing of soil silicates under poorly drained or well-drained conditions would undoubtedly vary the constitution of the silicates and also vary the degree of soil acidity. It is quite true that certain types of well-drained sandy soils are acid. It is true also that a number of other factors besides drainage conditions affect soil acidity, but it is probable that the most acid soils are formed in poorly drained areas. S. D. CONNER INDIANA AGRICultural ExperRIMENT STATION, LAFAYETTE, IND. 1 Lipman, C. B., and Waynick, D. D., Soil Science, Vol. I., No. 1, p. 5, 1916. 2 Conner, S. D., "Acid Soils and the Effect of Acid Phosphate and Other Fertilizers upon Them," Jour. Ind. and Eng. Chem., Vol. VII., No. 1, p. 35, 1916. The First Two The Third Year The Fourth Year Course is clinical. Students spend the entire forenoon throughout the year as clinical clerks in hospitals under careful supervision. The clinical clerk takes the history, makes the physical examination and the laboratory examinations, arrives at a diagnosis which he must defend, outlines the treatment under his instructor and observes and records the result. In case of operation or of autopsy he follows the specimen and identifies its pathological nature. Two general hospitals, one of which is owned and controlled by the University, one special hospital and the municipal hospitals and laboratories are open to our students. The afternoons are spent in the College Dispensary and in clinical work in medical and surgical specialties and in conferences. Summer School-A summer course in pathology covering a period of six weeks during June and July will be given in case there is a sufficient number of applicants. Address the Secretary of the College, 307 Orange Street COLLEGE OF MEDICINE (Established in 1834) School of Medicine— Admission: One year of college work in the sciences and a modern foreign language. After January 1, 1918, all students entering the Freshman Class will be required to present credits for two years of college work, which must include Biology, Chemistry and Physics, with their laboratories, and one year in German or French. Graduate School of Medicine— A school for physicians desiring practical clinical opportunities, review, laboratory technic or cadaverio work in surgery or gynecology. Excellent facilities offered in all special branches. School of Hygiene and Tropical Medicine, including Preventive Medicine Systematic courses offered, leading to certificates in Public Health, diploma in Tropical Medicine, and to the degree of Dr. P. H. Laboratory, Clinic and Field Work. School of Pharmacy Admission: Three years of high school work, or 12 units. Two years for Ph.G. degree. Three years for Ph.C.degree. 1765 School of Medicine of the University of Pennsylvania 1917 The One Hundred Fifty-second Annual Session of this institution will open September 28, 1917, and continue until June 19, 1918. The first and second year classes are limited to one hundred students, and application for admission should be in the hands of the Dean before July 1st. REQUIREMENTS FOR ADMISSION: Candidates must have successfully completed the work prescribed for the Freshman and Sophomore Classes in colleges recognized by this University, which must include at least one year of college work in Physics, General Biology or Zoology and Chemistry (Qualitative Analysis is required; Organic Chemistry is recommended, and in 1919 will be required), together with appropriate laboratory exercises in each of these subjects, and either French or German of more than elementary grade. For detailed information send for catalogue. UNDERGRADUATE COURSE: The course of instruction extends over four annual sessions, the work so graded that the first and second years are largely occupied by the fundamental medical subjects. The third and fourth years are largely devoted to the practical branches, prominence being given to clinical instruction, and the classes sub-divided into small groups so that the individual students are brought into particularly close and personal relations with the instructors and with the patients at the bedside and in the operating room. After graduation further hospital work is undertaken by the members of the class; and more than 90 per cent. attain by competitive examination or by appoint ment positions as internes in hospitals in this city or elsewhere. The Pennsylvania Bureau of Medical Education and Licensure requires of applicants for license a year spent in an approved hospital. POST GRADUATE WORK: (1) Any graduate possessing a baccalaureate degree may pursue work in Anatomy, Physiology, Physiological-Chemistry, Bacteriology, Pathology, Pharmacology, Research Medicine and Mental Diseases with view of obtaining the higher degrees of Master of Arts or Science and of Doctor of Philosophy in the Graduate School of the University. For information address Dean of Graduate School, University of Pennsylvania. (2) Courses in Public Health (inaugurated in 1906) leading to diploma (Doctor of Public Hygiene, Dr. P.H.), are open to graduates in medicine who have had a preliminary education similar to that required for admission to the Medical School. The subjects comprehended in the course are: Bacteriology, Medical Protozoology and Entomology, Chemistry, Sanitary Engineering, Sanitary Architecture, Meat and Milk Inspection, School Inspection, Vital Statistics, Sanitary Legislation, and Personal and General Hygiene. The full course extends over one academic year. Special subjects in the course may be taken by any one possessing suitable preliminary qualifications. For details address Director of Laboratory of Hygiene. (3) From the opening of each term to about February 1 courses in Tropical Medicine are open to graduates in Medicine comprehending instruction in Medical Climatology and Geography, Hygiene of Tropics and of Ships, Tropical Medicine, Bacteriology, Protozoology, Entomology, Helminthology, and General Medical Zoology, Pathology, Skin Diseases, Eye Diseases, and Surgery of Tropical Affections. (4) During the academic session special courses in any of the branches of the medical curriculum are open to graduates of this or other regular schools of Medicine, both in the clinical subjects and in laboratory studies. The excellent hospital facilities offered by the University Hospital, the neighboring Philadelphia General Hospital and other institutions with which the members of the staff of instruction are connected, guarantee exceptional opportunities for clinical observation. TUITION FEE: Undergraduate study, $200 annually; fees for special courses on application. For detailed information or catalogue address DEAN OF SCHOOL OF MEDICINE University of Pennsylvania University of Alabama School of Medicine Mobile, Alabama The satisfactory completion of two years of study, in an institution of collegiate grade, to include Biology, Chemistry, Physics, and a reading knowledge of French or German. In addition to four year High School diploma. Combined Course The Combined Course which is now offered by the University in connection with its Medical Department gives to the student the opportunity of obtaining the B.S. and M. D. degrees in six years This course is recommended to all intending students. The equipment of the school is complete. The clinical facilities ample. Eight full time teachers. For catalog and any desired information, address Tucker H. Frazer, M.D., Dean St. Anthony and Lawrence Sts., Philadelphia, Pa. University of Georgia MEDICAL DEPARTMENT The eighty-sixth session begins September 12, 1917; ENTRANCE REQUIREMENTS Candidates for entrance this session must have completed one full year of work in an approved college in addition to four years of high school. The college work must have included Physics, Chemistry, Biology and French or German. Beginning in 1918 two years of college work will be required. INSTRUCTION The course of instruction occupies four years. The first two years are devoted to the fundamental sciences, and the third and fourth to practical clinic instruction in medicine and surgery. All the organized medical and surgical charities of the city of Augusta and Richmond County, including the hospitals, are under the entire control of the Board of Trustees of the University. This arrangement affords a large number and variety of patients which are used in the clinical teaching. Especial emphasis is laid upon practical work both in the laboratory and clinical departments. TUITION The charge for tuition is $150.00 a year except for residents of the State of Georgia, to whom tuition is free. For further information and catalogue address, The Medical Department, University of Georgia AUGUSTA, GEORGIA SCIENCE RADIATION AND MATTER1 WE must congratulate ourselves upon the fact that we have been able to listen to such clear, concise and accurate presentations of the most fundamental problems that lie before pure science to-day. I would like, also, to extend to the speakers our sincere thanks for their efforts in giving us such interesting expositions of these abstruse theories. It is my privilege to open the discussion on radiation and the structure of matter. Modern theories of radiation are largely concerned with Planck's conception of the radiation of energy in quanta, and with the extraordinary action constant usually denoted by the letter "h." I would like to present for your discussion some ideas on the relations between the high frequency vibrations which we observe in general Xradiation, and the forces holding the electrons and atoms together, including a physical conception of what this constant "h" really means. Instead of basing the discussion on the conceptions of entropy, and thermo-dynamic probability, I shall start from our recent experiments on general X-radiation. Before we learned from experiments that X-rays had definite wave-lengths, people supposed that they had, and that we could calculate their frequencies by the formula kinetic energy equals hv. |