At the end of the fiscal year the personnel consisted of the director, assistant director, professor of zoology, professor of chemistry, professor of pharmacology, 11 commissioned medical officers, 2 pharmacists, 6 technical assistants, an artist, 2 sanitary chemists, 5 sanitary bacteriologists, 1 sanitary engineer, 1 organic chemist, 4 laboratory aids, and 31 attendants.

Buildings and grounds.-The equipment of the animal house and disinfection rooms has been practically completed. Metal cages have been provided for the supply of animals used in the laboratory investigations.

Demonstrations and exhibits.-Several demonstrations of service work were made at the laboratory to delegates in attendance upon scientific meetings in Washington. The lines of work were so arranged as to give the visitors grasp of the essentials within the short time at their disposal.

Considerable material for a safety-first exhibit held in the National Museum and for the service exhibit on the safety-first train which toured the country was prepared at the laboratory.

The laboratory was thrown open to the American Society of Tropical Medicine during the society's meeting in May. The library was used for holding the sessions, and the use of a lantern and operator was provided. The members of the society were shown the various activities of the laboratory.

Course of instruction.-The course in laboratory technic given service officers was somewhat enlarged upon during the last semester. The course, in immediate charge of Passed Asst. Surg. Hasseltine, began on November 1, 1915, and closed March 1, 1916. In addition to attending lectures and receiving laboratory instruction, each officer was assigned a special problem for study, upon which he prepared a thesis. All branches of the laboratory were called upon for cooperation, members of the staff giving lectures and demonstrations. Lectures were also given the class by several members of the Army and Navy Medical Services, by members of the advisory board, and by various service officers stationed at the bureau and away from Washington.

The class consisted of 10 student officers. In addition, five other public-health workers were extended the facilities of the laboratory for purposes of instruction at various times during the year, as follows: Dr. H. M. Mills and Dr. C. M. Ausley, of the Florida State Board of Health; Dr. C. R. Stingily, of the Mississippi State Board of Health; Dr. Ira C. Ayer, of the Philadelphia Board of Health; and Dr. Frank W. Schofield, of the Provincial Board of Health, Toronto, Canada. It has been a pleasure to offer the facilities of the laboratory to these representatives of public-health organizations. Assistance to field investigations.-During the year various members of field parties were supplied temporarily with laboratory and office facilities in their studies of sewage disposal, trade wastes, pellagra, rural sanitation, and school hygiene.

AID TO OTHER BRANCHES OF GOVERNMENT.

In a number of instances the laboratory was of aid to several other branches of the Government service during the past year. Aside from the many inquiries and conferences of a routine nature that

arise through the interrelation of the Government bureaus, the following may be mentioned:

(Sewer department of District of Columbia.-The sewer department of the District government has found it desirable to accumulate data in regard to the pollution of streams in the District of Columbia. As a consequence, the laboratory has examined 288 specimens of water from these streams, many of them being found highly contaminated with the colon organism.

Bureau of Animal Industry.-In connection with an outbreak of foot-and-mouth disease in 1915, the laboratory was called upon to make examinations of several lots of hog-cholera serum, under suspicion of disseminating the infection. The tests were carried out on calves and hogs provided by the Bureau of Animal Industry and covered a period of three weeks.

Post Office Department.-A number of substances were submitted to ascertain whether they were of a poisonous or otherwise dangerous nature. Tests were made in each case and reports submitted to the proper office.

Marine Corps.-A number of disinfectants were tested for the phenol coefficient, as a preliminary to placing a contract for supplies. Panama Canal.-A standing arrangement has been made whereby the laboratory supplies the first half of one antirabic treatment every month for emergency use on the Isthmus. In addition, several specimens of disinfectants were tested for their phenol coefficients with a view to placing contracts.

Commissioner of Internal Revenue.-Many conferences were held, and opinions rendered, in relation to the enforcement of the narcotic law.

Civil Service Commission.-Members of the laboratory staff, as heretofore, have assisted the Civil Service Commission in providing questions and rating papers in certain examinations for scientific positions.

Army Medical School.-A member of the laboratory staff delivered two lectures before the class of officers of the Army Medical School.

Naval Medical School.-Several lectures and demonstrations were given to members of the Naval Medical School.

Office of Indian Affairs.-Several lots of antityphoid vaccine were supplied for use on various Indian reservations. (See also p. 58.)

AID FROM OTHER BRANCHES OF THE GOVERNMENT.

Aside from matters of merely routine interest, several branches of the Government have extended aid to the laboratory. Among these may be mentioned the Bureau of Standards, the Bureau of Chemistry, the Coast and Geodetic Survey, the Census Bureau, the Geological Survey, the Patent Office library, the Library of Congress, the library of the Surgeon General's Office, United States Army, the Naval Medical School and Hospital, the Smithsonian Institution, and the library of the Department of Agriculture. Particular mention is made of the assistance rendered by the Zoological Park in caring temporarily for monkeys in the intervals between investigations.

LIBRARY.

The total number of bound volumes in the library at the close of the fiscal year was 6,633 and the total number received during the fiscal year 885, including 50 books received from the Carnegie Institution of Washington. Four hundred and twenty-one volumes were received from the Copyright Office, under section 59 of the copyright law of March 4, 1909.

Through the courtesy of the Journal of the American Medical Association and the New York Medical Journal, the library has received over a thousand reprints. A number of doctoral theses have been received from universities.

In addition to the constant use of books and periodicals in the library, 1,947 volumes were issued to borrowers, of which 762 belonged to this library and 1,185 were borrowed from other libraries. Fifty volumes were loaned to other libraries. In several instances, books belonging to the library were forwarded to workers in the field.

During the year, 4,327 printed cards were received from the Library of Congress and incorporated in the card catalogues, making a total of 14,592 printed cards received to date. In addition to the printed cards, typewritten cards have been prepared for reprints and for an index of important articles appearing in the current literature. A record is also kept of important new works bearing upon the activities of the laboratory.

Through a circular letter issued to the health departments, both in the United States and Canada, an effort has been made to secure both the regular reports and the incidental literature issued by these departments. This has met with a very generous response.

DIVISION OF PATHOLOGY AND BACTERIOLOGY.

Both research and routine work of a varied nature have been conducted through this division.

Scarlet fever.-Epidemiological studies on scarlet fever, begun in the spring of 1915 in cooperation with the health officer of the District of Columbia, were continued and a total of more than 600 cases studied. It was observed that, upon the close of the District schools for the summer vacation a marked diminution in the number of cases occurred. Shortly after the opening of the schools in the autumn the number of cases increased. A large amount of data of an epidemiological nature was gathered and the tabulation begun.

Rocky Mountain spotted fever.-As a result of field investigations conducted by Surg. Fricks in the West, notably in Montana, in the spring and summer of 1915 (see p. 266) considerable data and material were collected and brought to the laboratory for study. A strain of the virus was kept running through animals, and studies were made. The results of these observations have been published in the Public Health Reports and issued as Reprint No. 327.

Diphtheria studies.-In connection with the routine examination of diphtheria cultures an opportunity was presented of determining the relative value of pure and mixed cultures in virulence tests. This work indicates that mixed cultures may be used with results that compare favorably with those obtained when pure cultures are

employed. A second point demonstrated was the fact that transmission by mail, causing a delay of 24 hours prior to incubation, makes no material difference in the results secured.

Toxicity of preservatives.-A considerable number of experiments have been made to determine the toxicity for mice of various preservatives used in the preparation of serums, etc. Glycerin, alcohol, phenol, and trikresol have been tried separately and in combination with and without serum, but the results thus far obtained are not sufficiently definite to permit of summarization. The fact seems clear, however, that glycerin and alcohol do not reduce the toxicity of phenol.

Researches on tubercle bacillus antigens.-Studies on the reactions. produced by tubercle bacillus antigens introduced into rabbits have been instituted. These investigations, which are being conducted by Assistant Director A. M. Stimson, are designed to throw light on immunity processes and variations in this disease.

Examination of specimens.—The past fiscal year has seen a great increase in the number of specimens submitted to the laboratory for examination. The following shows the number and kind of specimens received:

Cultures furnished.-From July 1, 1915, to June 30, 1916, 178 cultures were sent to various workers on their request. A large proportion of these cultures were B. typhosus, the Hopkins strain of this organism being used in the testing of disinfectants and the Rawling strain in the manufacture of antityphoid vaccine. Cultures of organisms are given out only to persons or to institutions known to be reliable and actually engaged in scientific investigations.

The laboratory endeavors to keep a stock of the more common organisms, not only for use in the laboratory, but to be supplied to various individuals and institutions engaged in public-health work. Diphtheria. An epidemic of diphtheria occurring in Martinsburg, W. Va., late in 1915 (see p. 16), the laboratory was called upon to examine throat cultures of the school children in that city. The cultures were shipped by express and by mail to the laboratory. Telegraphic reports were made of the positive cases.

An outbreak of diphtheria also occurred at the National Training School for Boys and examinations were made of cultures from the throats of the inmates of that institution.

In addition, a number of cultures and swabs were submitted by local health officers in the vicinity of Washington. In all of these cases prompt reports were made.

As a result of the above epidemics, 992 examinations of throat cultures were made at the laboratory during the fiscal year.

Pasteur treatment.-Thirty-six persons received antirabic treatment at the Hygienic Laboratory, and 1,738 complete treatments were cent to State health authorities, as compared with 1,864 in the preceding year. The geographic distribution of the virus is shown in the following table: