Throughout the chapter and also in later chapters we are given clearly to understand that the enemy submarine campaign was the gravest peril which ever threatened Great Britain.

Chapter III. tells of Anti-Submarine Operations; and while the volume lacks a dramatic climax, like Jutland, the reader whose blood runs faster because of heroic deeds, can find in this chapter stirring records of courage and defiance to the end, by the officers and men on decoy ships, drifters, trawlers and mine

sweepers.

Chapter IV. describes the Introduction of the Convoy System. There were not enough destroyers to give adequate protection. Requests for protection came from every quarter, but "the vessels wanted did not exist." At the end of February, 1917, the enemy had 130 submarines of all types in home waters and 20 in the Mediterranean.

A very serious situation followed the sinking of so many tankers or fuel oil ships. These vessels of great length and slow speed presented the easiest of targets for a torpedo from a submerged submarine. The reserve of oil became so perilously low that directions were issued limiting the speed of warships burning oil.

Other chapters describe the effect of the entry of the United States, the Patrol Craft and Minesweeping, Production at the Admiralty-and the Future.

The impression left on the reader is that the big fleets, big guns and big ships were to a certain degree side-tracked; and that the smaller units did most of the work and were the effective factors in winning the war. The Admiral clearly indicates this in an eloquent passage on page 188.

I regret very deeply that in spite of a strong desire to undertake the task, I have neither the information nor the literary ability to do justice to the many deeds of individual gallantry, selfsacrifice and resource performed by the splendid officers and men who manned the small craft. No words of mine can adequately convey the intense admiration which I felt and which I know was shared by the whole Navy for the manner in which

their arduous and perilous work was carried out. These fine seamen though quite strange to the hazardous work which they were called upon to undertake quickly accustomed themselves to their new duties; and the Nation should ever be full of gratitude that it bred such a race of hardy, skilful and courageous men as these who took so great a part in defeating the greatest menace with which the Empire has ever been faced.

The references to the American Navy, and in particular to Admiral Sims, are most complimentary. The laying of the mine barrage from Scotland to Norway indicates how far modern warfare at sea has changed since the days when Captain Mahan wrote his treatise on Sea Power."

In the future, the seaplane, greatly developed of course from its present stage, will be the effective unit, both in offense and defense. With perhaps more truth the words of the Admiral regarding specialized training will hold for officers of the Air Service.

ALEXANDER MOADIE

Diseases of Economic Plants. By F. L. STEVENS. New York, The Macmillan Com

pany.

This is a revised edition of a former work under the same title by Stevens and Hall. It will be welcomed not only by the professional botanists, but also by a very large number of teachers, county farm demonstrators and others who are finding plant pathology a subject of increasing interest and importance. The importance of plant diseases and the very rapid progress of plant pathology makes frequent revision of a work of this kind imperative. The general plan of the work is very similar to the original edition but is somewhat enlarged and has been brought up to date. The author pays a pleasing tribute to our American workers by inserting the pictures of Farlow, Burrill, Halsted, Bessey, Atkinson and E. F. Smith, who are so well known to all students of mycology and plant pathology.

The discussions are arranged with reference to the crops on which the diseases occur. The diseases are grouped mostly with reference to

the crops on which they occur and are subdivided into diseases of major and minor importance. This arrangement is especially serviceable to those who are not specialists on plant diseases. The descriptions of the symptoms are brief, clear and very readable. There is no attempt whatever to discuss the organisms which are the causes of these diseases but references are given to some of the more important publications. Each disease is designated by its common name; the scientific name for both the imperfect and the perfect stages, where known, are placed in parenthesis. The book also contains chapters on the history of the subject, damages due to plant diseases, prevention and cure, general diseases which attack a large number of crops, fungicides and soil disinfection. The chapter on cost of spraying which was in the first edition is very properly omitted since this is a varying factor dependent on cost of materials and labor.

The work is intended primarily as a textbook and it will prove of great service to all teachers of plant pathology. Possibly its greatest value lies in the brief, clear descriptions which are of such great importance in making diagnoses of diseases in the field. The student of mycology will also find it an important supplement for his work on economic forms. The horticulturists, nurserymen, county farm demonstrators, progressive farmers and in fact all others who are interested in the applications of agriculture will find it an extremely useful reference book.

The mechanical make-up of the work is good except for the crowded arrangement of the bibliography which would lead any one who uses it to fear that the supply of paper is exhausted.

NEW JERSEY AGRICULTURAL EXPERIMENT STATION

MEL T. COOK

SPECIAL ARTICLES

THE Y-CHROMOSOME IN MAMMALS

THE majority of workers on mammalian spermatogenesis have described the sex-chro

1

mosome as being of the X-O type but recent investigations in this field by the author indicate that the X-Y type of chromosome may be more common than is generally thought. In the opossum, an animal for which the X-O type of sex-chromosome has been described, the writer finds a typical X-Y sexchromosome complex. Both the X and Y components may be recognized in spermatogonial and somatic divisions because of their distinctive size. In the first maturation division the X and Y elements segregate apart to opposite poles of the cell, and in the second maturation division both divide equationally. Hence half of the sperm carry an X and half carry a Y chromosome.

The diploid chromosome number for both the male and female opossum is 22, and not 17 or 24 as concluded by previous investigators.

In the testes of both the white man and the negro I have found in the first spermatocytes a chromosome pair which is similar in appearance and behavior to the X-Y chromosome of the opossum. The two members of this pair, in the human, representing the X and Y components, are unequal in size; they segregate apart in the first maturation division just as in the case of the opossum.

It will be of general interest to biologists to know that the diploid number of chromosomes for man is very close to the number (47) given by Winiwarter.2 In my own material the counts range from 45 to 48 apparent chromosomes, although in the clearest equatorial plates so far studied only 46 chromosomes have been found. Before a final conclusion is made on the exact number it is desired to make a careful study of a large number of division plates. There can be absolutely no question, however, but that the diploid number of chromosomes for both the white man and the negro falls between 45 and 48. With the X-Y type of sex-chromosome we 1 The writer's work now in press.

2 Winiwarter, H. von, 1912, Arch. de Biol., Vol. 27.

may expect an even number, that is, either 46 or 48.

My material to date includes the testes of one white man and of two negroes. All individuals were castrated because of self abuse, at one of the Texas state institutions. The testes were removed with the use of local anæsthetics and immediately preserved in Bouin's fluid, to which chromic acid and urea had been added. In less than a minute after removal from the body the germ-cells were being bathed in the fixing fluid. The preservation thus obtained is very satisfactory.

In view of the uncertainty which has existed regarding the chromosome number in man, the author will gladly send samples of this human material to any experienced cytologist in order that the latter may verify for himself the correctness of the chromosome counts given. The complete spermatogenesis of man is being, reworked by the writer at the present time and his results will be published in the near future.

THEOPHILUS S. PAINTER

THE ROCHESTER MEETING OF THE AMERICAN CHEMICAL SOCIETY

THE sixty-first general meeting of the American Chemical Society was held at Rochester, N. Y., from April 25 to April 29, inclusive. The council meeting was held on April 25, the general meeting on the morning and afternoon of the twenty-sixth, divisional meetings all day Wednesday and Thursday, and excursions on Friday. Full details of the meeting and program will be found in the May issue of the Journal of Industrial and Engineering Chemistry. The registration was 1,139, and 1,270 sat down to dinner at the good fellowship meeting.

eral business meeting held Tuesday morning, April 26, Charles F. Chandler and William H. Nichols were unanimously elected honorary members of the society. The chief public address was given at Convention Hall on Wednesday evening, April 27, by Charles F. Chandler, on "Chemistry in the United States." At the general meeting on Tuesday afternoon, the following general papers were presented:

"Ammono carbonic acids," by E. C. Franklin. "The measurement of color,'' by C. E. K. Mees.

"Blue eyes and blue feathers,' " by W. D. Bancroft.

"Surface Films as Plastic Solids," by R. E. Wilson.

"The relation between the stability and the structure of molecules," by Irving Langmuir. "Ionization of electrolytes," by G. N. Lewis.

The following divisions and sections met: Divisions of Agricultural and Food Chemistry, Biological Chemistry, Chemistry of Medicinal Products, Dye Chemistry, Industrial and Engineering Chemistry, Organic Chemistry, Physical and Inorganic Chemistry, Rubber Chemistry, and Water, Sewage and Sanitation; Sections of Cellulose Chemistry, Petroleum Chemistry and Sugar Chemistry and Technology. Further details of their meetings will be found in the May issue of the Journal of Industrial and Engineering Chemistry.

Tuesday evening was given up to dinners and gatherings of various colleges and fraternities. On Thursday evening the good fellowship meeting, complimentary to the members of the Rochester Section, consisted of a dinner in the Bausch and Lomb dining hall, followed by a varied and interesting program consisting of music, vaudeville entertainment, motion pictures of the convention itself and prominent members thereof, and a film shown for the first time, picturing the operations of the Eastman Kodak Company. The scientific program was the most extensive ever presented before a meeting of the American Chemical Society and consisted of 280 papers.

CHARLES L. PARSONS,
Secretary

Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction, including laboratory work, in Chemistry, and one year each in physics and biology, together with evidence of a reading knowledge of French and German.

Each class is limited to 90 students, men and women being admitted on the same terms. Except in unusual circumstances, applications for admission will not be considered after July 1st. If vacancies occur, students from other institutions desiring advanced standing may be admitted to the second or third year provided they fulfill all of our requirements and present exceptional qualifications.

The charge for tuition is $250 per annum, payable in three instalments. There are no extra fees except for rental of microscope, certain expensive supplies, and laboratory breakage.

The annual announcement and application blanks may be obtained by addressing the

Dean of the Johns Hopkins Medical School Washington and Monument Sts. BALTIMORE, MD

SUMMER WORK FOR GRADUATES
IN MEDICINE

Beginning Tuesday, June 6th, and ending Thursday, July 16th, a course in medical diagnosis, including laboratory exercises in clinical pathology and demonstrations in pathological anatomy, will be offered. The course will be limited to twenty students, fee $100. Applications should be made to the Dean's Office.

Louisiana

SCHOOL OF MEDICINE

(Established in 1834)

ADMISSION: All students entering the Freshman Class will be required to present credits for two years of college work, which must include Chemistry (General and Organic), Physics and Biology, with their laboratories, and at least one year in English and one year in a modern foreign language.

COMBINED COURSES: Premedical course of two years is offered in the College of Arts and Sciences, which provides for systematic work leading to the B.S. degree at the end of the second year in the medical course.

School of Pharmacy, School of Dentistry and Graduate School of Medicine also.

Women admitted to all Schools of the College of Medicine

For bulletins and all other information, address

Tulane College of Medicine

P. O. Box 770

New Orleans, Le.

Rush Medical College

IN AFFILIATION WITH

The University of Chicago

Curriculum.-The fundamental branches (Anatomy, Physiol ogy, Bacteriology, etc.) are taught in the Departments of Science at the hull Biological and the Ricketts Laboratories, University of Chicago. The courses of the three clinical years are given in Rush Medical College and in the Presbyterian, the Cook County Hospital, the Home for Destitute Crippled Children, and other hospitals.

Classes Limited.-The number of students admitted to each class is limited, selection of those to be admitted is made on the basis of merit.

Hospital Year.-The Fifth Year, consisting of service as an interne under supervision in an approved hospital, or of advanced work in one of the departments is prerequisite for graduation.

Summer Quarter.-The college year is divided into four quarters, three of which constitute an annual session. The summer quarter, in the climate of Chicage is advantageous for work. Students are admitted to begin the medical courses only in the Autumn and Spring quarters. Elective System.-A considerable freedom of choice of courses and instructors is open to the student. Graduate Courses. Advanced and research courses are offered in all departments. Students by attending summer quarters and prolonging their residence at the University of Chicago in advanced work may secure the degree of A.M., S.M., or Ph.D. from the University.

Prize Scholarship.-Six prize scholarships-three in the first two years and three in the last two (clinical) years-are awarded to college graduates for theses embodying original research.

The Spring quarter commences March 28, 1921. TUITION-$75.00 per quarter, no laboratory fees. Complete and detailed information may be secured by addressing THE MEDICAL DEAN The University of Chicago

CHICAGO, ILL.

Yale University

SCHOOL OF MEDICINE Affiliated with the New Haven Hospital and New Haven Dispensary

109th Session

Reorganized on a full-time basis Entrance Requirements: A minimum of two years (or its equivalent) of college including general biology, physics, general and organic chemistry, physical chemistry or laboratory physics, and either French or German.

ALL OF THE GENERAL FACILITIES OF THE UNIVERSITY ARE AVAILABLE TO MEDICAL STUDENTS

As the number admitted to each class is limited, applications must be made before July 1.

Dean, Yale University School of Medicine NEW HAVEN, CONN.

Marine Biological Laboratory

Woods Hole, Mass.

INVESTIGATION

Entire Year

INSTRUCTION

June 29 to August 9 1921

SUPPLY DEPARTMENT Open the Entire Year

Facilities for research in Zoology, Embryology, Physiology, and Botany. Eighty-four private labora tories, $100 each for not over three months. Thirty tables are available for beginners in research who desire to work under the direction of members of the staff. The fee for such a table is $50.00.

Courses of laboratory instruction with lectures are offered in Invertebrate Zoology, Protozoology, Embryology, Physiology and Morphology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $75. A lecture course on the Philosophical Aspects of Biology and Allied Selences is also offered.

Animals and plants, preserved, living, and in embryonic stages. Preserved material of all types of animals and of Algae, Fungi, Liverworts and Mosses furnished for classwork, or for the museum. Liv

ing material furnished in season as ordered. Microscopic slides in Zoology, Botany, Histology, Bacteriology. Price lists of Zoological and Botanical material and Microscopic Slides sent on application. State which is desired. For price lists and all information regarding material, address

GEO. M. GRAY, Curator, Woods Hole, Mass. The annual announcement will be sent on application to The Director, Marine Biological Laboratory, Woods Hole, Mass.

Publications of

The Philippine Bureau of Science

VEGETATION OF PHILIPPINE MOUNTAINS. The relation between the environment and physical types at different altitudes. By William H. Brown, 434 pages, 41 plates, and 30 text figures; postpaid $2.50, U. S. currency.

INDEX то THE GENERA OF BIRDS. By Richard C. McGregor. 185 pages; postpaid $1.00, U. S. currency.

SPECIES BLANCOANAE. A critical revision of the Philippine species of plants described by Blanco and by Llanos. By E. D. Merrill. 424 pages; postpaid $2.25, Ŭ. S. currency.

PHILIPPINE WATER SUPPLIES. By G. W. Helse and A. S. Behrman. 218 pages, 19 plates; postpaid $1.75, U. S. currency.

AN INTERPRETATION OF RUMPHIUS'S HERBARIUM AMBOINENSE. By E. D. Merrill. 596 pages, 2 maps; postpaid $3.00, U. S. cur