Page images
PDF
EPUB

tify the wholesale injection of cattle with living tubercle bacilli for purely economic purposes, even if the bacilli used are only weakly pathogenic in character.

Some studies have been made on small experiment animals relative to the latency of tubercle bacilli in the tissues of living animals. That tubercle bacilli may enter and remain latent in the bodies of animals for considerable periods of time, and afterwards, for some reasons not well understood, become active and cause tuberculosis, is a belief held by many competent investigators. If this belief should prove true it will have a very important bearing on all measures for the eradication of the disease. The bureau's investigations have not progressed far enough to warrant any conclusions.

As there are many tuberculous cows from which milk is used as food for persons and lower animals, and as the use of properly pasteurized milk from tuberculous cows is generally regarded as safe, an experiment was made to throw more light on this subject. It seemed especially desirable to learn whether the ingestion of milk that contains tubercle bacilli killed by pasteurization will cause either an increased or reduced susceptibility to infection with living tubercle bacilli. As far as this work has gone it indicates that dead tubercle bacilli ingested with pasteurized milk have no harmful effects on guinea pigs, but that living tubercle bacilli ingested with milk, even when they cause no disease, increase the rapidity with which guinea pigs die from subsequent inoculation with tubercle bacilli.

The question of the relative value of raw, pasteurized, and boiled milk as food for young animals has received some attention, but it is too early to report on this work, beyond stating that it clearly shows that the artificial feeding of unweaned animals with milk of an alien species is by no means conducive to their best development, and when small, delicate animals, such as guinea pigs, are used the mortality is very high.

Further investigations relative to the sources from which hogs contract tuberculosis, as far as such investigations are possible at the station, show that the exposure of hogs to the feces of tuberculous cattle is a much more certain cause of their infection than their exposure to milk from tuberculous cows or to hogs affected with tuberculosis. It must not be concluded from this, however, that raw milk from tuberculous cows is a safe food for hogs or that the presence of tuberculous hogs in a hog yard is without serious danger.

A number of samples of commercial tuberculin were tested to determine whether they were of sufficient potency to be reliable for use as diagnostic agents for cattle tuberculosis. It is pleasing to be able to report than all the samples tested were found to be satisfactory.

Å number of tests of the different ways in which different preparations of tuberculin can be applied for diagnostic purposes have been made. These tests prove that the subcutaneous injection of ordinary old tuberculin is by far the most reliable manner in which tuberculin can be used as a diagnostic agent for cattle tuberculosis. Other methods of application as yet hold out no real promise that they may have value as a means for controlling those fraudulent practices which are used by dishonest persons to defeat the power of a subcutaneous injection of tuberculin to cause a reaction in the presence of tuberculosis.

An experiment relative to the derivation of a healthy from a tuberculous herd of cattle is still in progress.

Considerable work has been done with a bacterium which, as far as we are able to determine, has not been described before. The germ is of common occurrence in the samples of commercial milk examined at the station, and there are several cows at the station which secrete it with their milk. It was found to be present in the milk of approximately 10 per cent of a herd of about 150 dairy cows located in the District of Columbia. It reaches the milk of apparently healthy cows before the milk leaves their udders, and it causes in guinea pigs a serious chronic disease, at times closely resembling tuberculosis in its gross pathologic appearance. This bacterium, from our present viewpoint, seems to have been overlooked in the past because it does not grow on ordinary culture media and because it is very chronic in its pathogenic action on guinea pigs, which animals it affects both through inoculation and ingestion. It is a very minute, Gram-positive, nonacid-fast bacillus. We have cultivated it artificially and have not only proven that pure cultures produce its characteristic pathologic lesions in guinea pigs, but have recovered it from the tissues of guinea pigs infected with pure cultures.

Two conditions evidently due to the bacillus are specially noteworthy. One is that it occasionally causes paralysis in guinea pigs, and the other that it at times causes a peculiar disease in or about the bone articulations. Neither the paralysis nor the disease of the articulations has been observed in any of the large number of guinea pigs at the station which have not been infected with the bacillus. The joint disease is particularly interesting because bacteriologically it is associated with a micrococcus, thus foreshadowing the possibility of a microorganism which by itself may be harmless but which in the presence of another microorganism may cause disease of the bones or their articulations. The importance of this bacterium remains an unsolved question which will receive careful attention in the future. Just at present it is important because it proves conclusively that germs, pathogenic for guinea pigs and possibly for other animals, derived directly from the udders of milk cows, which no system of inspection applied to dairy herds, barns, milk utensils, etc., can eliminate, and which an ordinary bacteriological examination of milk would fail to detect, are of fairly common occurrence in milk. The thermal death point of the bacillus is 60° C. (140° F.) maintained 15 minutes.

OTHER WORK.

During the fiscal year facilities were provided at the Experiment Station for the various divisions of the bureau to aid them in their investigations concerning tetanus, Johne's disease, glanders, swamp fever, dourine, blackleg, infectious abortion, lip-and-leg ulceration, sarcoma, hog cholera, caseous lymphadenitis, ringworm, rabies, diamond skin disease, bighead of sheep, Texas fever and cattle ticks, intestinal parasites of sheep, gid, dips for removing external parasites, inbreeding, studies in Mendelian laws of inheritance, selective breeding, the possible effects of inbreeding on susceptibility of disease, etc.

FUTURE WORK.

Besides continuing unfinished work, the following lines of research are contemplated during the coming year and following years: To repeat tests made a few years ago regarding the frequency with which tubercle bacilli occur in butter; to learn if possible whether American oleomargarin (like European, according to European investigators) contains tubercle bacilli in a fairly large percentage of instances; to make additional tests to determine the frequency with which dairy cows eliminate from their bodies the newly discovered bacillus already mentioned; to make additional tests relative to the frequency with which this bacillus occurs in commercial milk; to make additional tests relative to the significance of this bacillus, especially when it occurs in symbiosis with certain other bacilli, and to determine if possible whether the bacillus is associated with some definable condition in the bodies of the cows that eliminate it. It is also desirable to make further tests relative to the persistence of tubercle bacilli in a virulent state in manure heaps from stables containing tuberculous cattle. Some work on the subject was done during the past year, but we were not able to carry it out in a way to obtain satisfactory material for reliable conclusions.

REPORT OF THE CHIEF OF THE BUREAU OF PLANT INDUSTRY.

U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY,
Washington, D. C., September 30,

1911.

SIR: I have the honor to submit herewith a report of the work of the Bureau of Plant Industry for the fiscal year ended June 30, 1911.

Respectfully,

Hon. JAMES WILSON,

Secretary of Agriculture.

B. T. GALLOWAY,

Chief of Bureau.

GENERAL WORK OF THE YEAR.

The total funds appropriated by Congress for the work of the Bureau of Plant Industry for the fiscal year ended June 30, 1911, were $1,758,206, of which $255,270 was for statutory salaries, and $309,590 for the work in connection with the purchase and distribution of seeds, while the remainder, $1,193,346, was apportioned in definite items among the various branches of the bureau conducting scientific or related work.

BUSINESS OPERATIONS.

The volume of correspondence of the bureau during the past year entailed the preparation of replies to about 300,000 letters, covering a wide field of agricultural activity. This number is exclusive of many general inquiries received by the bureau which can be answered through the sending of circular letters or publications.

In connection with the fiscal operations of the bureau, 6,300 requisitions for supplies were issued; 15,700 accounts were received and audited administratively; 176 requests for contracts and leases were made; 1,628 letters of authorization and amendments thereto were drawn; and 1,888 letters of instruction to field investigators were prepared.

CHANGES IN PERSONNEL.

During the year a number of changes have taken place in the personnel of the bureau. On January 1, 1911, Mr. G. Harold Powell, the assistant chief of the bureau, resigned to accept the position of secretary and manager of the California Citrus Protective League.

23165°

-AGR 1911-17

257

Mr. William A. Taylor was made assistant chief in the place made vacant by the resignation of Mr. Powell. Owing to the large amount and constant growth of the administrative work, Dr. Nathan A. Cobb has been designated as acting assistant chief to aid the chief and assistant chief of the bureau in their work.

A change was made necessary in the Office of Grain Standardization by the resignation of Mr. John D. Shanahan. Dr. J. W. T. Duvel was placed in charge, as set forth in another part of this report.

The Farmers' Cooperative Demonstration Work and the field studies in beet-sugar production suffered the loss of the men in charge through the deaths of Dr. S. A. Knapp and Mr. Charles F. Saylor. Mr. Bradford Knapp was appointed to take charge of the Farmers' Cooperative Demonstration Work and the studies of sugar-beet production formerly conducted by Mr. Saylor have been merged with other projects on sugar beets in charge of Mr. W. A. Orton.

From September 1, 1910, to August 31, 1911, the following changes in the personnel of the bureau were made: Resignations, 226; deaths, 7; dismissals, 2; transfers from the bureau, 35; and furloughs and terminations of appointments, 435; making a total of 705 employees dropped from the rolls during that period. There have been made in the same period 1.007 appointments, increasing the total force of the bureau by 302. On September 1, 1911, the numerical strength of the bureau was as follows: In Washington, 686; outside of Washington, 1,096; total, 1,782. The total number of employees in the bureau on the same date a year ago was 1,480.

PUBLICATIONS.

The publications and the job printing work of the bureau have continued in charge of Mr. J. E. Rockwell.

The number of new publications issued during the year was 97, the first editions aggregating 1,596,900 copies. In addition, 7 papers were contributed to the Yearbook of the department for 1910, all of which will be reprinted in due course in separate form for special distribution. The 97 publications mentioned contain 3,588 printed pages, 177 full-page plates, and 559 text figures. The total number of pages of printed text exceeded that of the previous fiscal year by 934, while the plate and text-figure illustrations used were greater by 18 and 197, respectively.

The new publications issued include 34 bulletins of the bureau, 23 numbered circulars of the bureau, and 23 Farmers' Bulletins. The number of publications, exclusive of Farmers' Bulletins, reprinted during the year was 76.

FIELD STATIONS.

It has been found necessary for the bureau to maintain a number of field stations in order to successfully prosecute the numerous and varied lines of work required. The propagation and testing of new plant introductions; the securing of information regarding the best methods of harvesting, handling, storing, and shipping grains, fruits, and other crops; the testing of seeds used by the farmer and gardener; investigations, experiments, and demonstrations to determine the underlying principles governing agriculture in the Great Plains area; and investigations, experiments, and demonstrations for the guidance

« PreviousContinue »