of stripped stalks increased with the thickness of planting up to a stand of one plant per foot. White Edge Dent corn showed the same variations as the flint variety in sound and soft kernels and leaves due to rate of planting, but while the weight of water-free stalks of the flint variety was greatest with one plant per foot, the weight of water-free stalks of the dent variety was greatest with the thickest planting, or eight plants per foot. The proportion of sound kernels of the flint variety to total water-free corn increased with the thickness of planting up to two stalks per foot, while the proportion of kernels of the dent variety to the total crop was greatest where the stand was one stalk per 2 feet. The proportion of leaves to total dry crop in both varieties was largest where the proportion of sound kernels was smallest.

COST AND PROFIT IN GROWING.

At the Nebraska Station Centennial White corn was grown at a cost of 23.43 cents per bushel, and Leaming, in a different field, at a cost of 14.9 cents. The cost of planting and harvesting Centennial White was $10.17 per acre, and that of Leaming $6.65 in one field and $6.08 in the other; and the corresponding profits per acre were $1.33, $5.16, and $4.72, respectively, the corn being valued at 30 cents per bushel. In observations made at the Pennsylvania Station the cost of growing and ensiling corn was $16.17 per acre as compared with $57.54 for growing, harvesting, and storing sugar beets and mangels. The roots produced 4,615 pounds of air-dry substance and the corn, 6,763 pounds per acre.

An investigation of the expense of raising corn in Illinois was made by the Illinois Station in 1896. Two hundred and seventyfour estimates from farmers throughout the State were used in calculating the cost. The average yield of corn per acre on the farms taken into consideration was 54 bushels, and the cost of production represented the average sum of the expenses on all the processes involved, from the preparation of the soil to the delivery at the elevator, including the wages of the farmer himself. A proper allowance was made for time lost and for maintenance of team during idleness, interest on investment, including rent, and allowance for depreciation of tools and machinery. On this basis the calculated cost of production of corn was 19.5 cents per bushel and $10.59 per acre.

a Nebraska Sta. Bul. 29.

Pennsylvania Sta. Rpt. 1899, p. 104. cIllinois Sta. Bul. 50.

SOME IMPORTANT FOREIGN VETERINARY INVESTIGATIONS.

By E. V. WILCOX, Ph. D., Office of Experiment Stations.

On account of the crowded condition of the population in the greater part of Europe and the necessity of preventing by all possible means losses which may naturally occur in the national economy of different States, the value of domestic animals is very high and the necessity of a thorough understanding of their diseases correspondingly imperative. A large number of investigators of first rank have for years devoted their energies to a solution of the most important veterinary problems, and their efforts have been supported by liberal governmental aid. Recruits for the army of veterinary investigators are being constantly furnished by a large number of trained men, who are annually graduated from veterinary schools. The present article will be confined to a general account of some of the more important results obtained by these investigators in the study of certain animal diseases. Foreign investigators along veterinary lines have given attention to all phases of the problem of preventing animal diseases, but not all of the results thus obtained are equally available for use in the United States. It may be stated as a general rule, however, that the more important animal diseases are almost world-wide in their distribution, and that no country is absolutely safe from infection by these diseases, particularly in view of the facilities which mutual commercial relations offer for the spread of animal plagues.

TUBERCULOSIS.

Among the various diseases which afflict animal life there is none of such transcendent importance as tuberculosis, both from the standpoint of the losses which it causes to animal industry and also from that of the danger to human health. More time has been devoted, especially in recent years, to the study of this disease than to any other animal disease. Tuberculosis may attack all of the domesticated animals as well as man, and it is, therefore, of more general concern to the human race than the diseases which affect only the lower animals. Although considerable difference of opinion had been held concerning the nature of tuberculosis, a general agreement regarding the H. Doc. 421, 58-3--35

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identity of tuberculosis in animals and man had been reached and prevailed until Koch's announcement before the British Medical Congress of 1901. At this congress, as is generally well known, Professor Koch stated his opinion, based on a number of experiments which he and his pupils had carried out, that there are two essentially different forms of tuberculosis, one of which affects man and the other the common domesticated animals. Koch also asserted, as corollaries of this proposition, that the human tubercle bacillus could not be transformed into that which affects cattle, and vice versa. It was, therefore, argued that the presence of tuberculous human attendants constitutes no serious danger to cattle or other domesticated animals, and that no further precautions need be taken regarding the use of the meat and milk of tuberculous cattle. This announcement of Professor Koch's was immediately contradicted by those who were present at the meeting, and has been subsequently combated in an everincreasing number of articles reporting investigations concerning the identity of human and bovine tuberculosis. As a rule, the evidence obtained by these investigations in Europe has been opposed to the assertions of Professor Koch. Numerous experiments, carried out under the most careful observation of all necessary precautions, have shown beyond question that in a certain percentage of cases the tubercle bacilli obtained from human patients may cause a generalized and even fatal form of tuberculosis when inoculated into small laboratory animals or into large domesticated animals. For some time, therefore, it has been quite generally assumed as demonstrated that there is but one form of tuberculosis affecting man and the higher animals. Quite recently, however, announcement has been made from several sources that there may be two forms of tuberculosis, man being susceptible to both forms. Evidence has been presented to show that apparently the two forms of tuberculosis may coexist in the human patient or in one of the domesticated animals. Dr. Nathan Raw," on the basis of numerous post-mortem examinations of children affected with tuberculosis, came to the conclusion that the ordinary pulmonary form of tuberculosis affects primarily the lungs and is due to infection with bacilli of human origin. In other words, the lung form of tuberculosis in man is considered by Doctor Raw as due to infection from other tuberculous human patients and not from animals. The various forms of tuberculosis which appear in the intestines and other internal organs intimately connected with the intestines are apparently of a different nature, and the bacilli obtained from affected parts differ in many respects from those obtained directly from tuberculous lungs in human patients. A study of the differences observed in the bacilli obtained from the lungs and from a British Med. Jour., 1903, No. 2226, pp. 470-474; 1904, No. 2265, pp. 1245, 1246.

the intestines of tuberculous human beings thoroughly convinced Doctor Raw that these were distinct species of bacilli, not capable of being transformed into each other. It was announced, therefore, as already stated, that there are two forms of tuberculosis, to both of which man seems to be readily susceptible.

Essentially the same results have quite recently been obtained, according to a preliminary statement by the German Imperial Tuberculosis Commission. On the basis of extensive experiments, it was announced by this commission that two essentially different forms of tuberculosis must be recognized, one of which is characterized as human tuberculosis and normally affects the lungs of man, while the other, or bovine tuberculosis, is represented by the various forms of tuberculosis in cattle and intestinal tuberculosis in man. The intense interest which has existed for several years in the solution of the problem of the unity or duality of tuberculosis is considerably increased by these announcements affirming essential differences between human and bovine tuberculosis. Although according to this view, which appears to rest upon a firm basis at present, one of the essential contentions of Professor Koch is corroborated, the other, and from a sanitary standpoint the more important one, must fall to the ground. Reference is had here to Koch's assertion that on account of the nonidentity of human and bovine tuberculosis no care need be exercised regarding the treatment of meat and milk of tuberculous cattle. The most recent investigations referred to, however, indicate clearly that while there are two different forms of tuberculosis, man is nevertheless susceptible to both, and it is therefore necessary that care be exercised to exclude tuberculous products from the market.

During the past five years more time has perhaps been devoted to the solution of this problem in the study of tuberculosis than to any other phase of the subject. Next in importance, however, in the aspects of the tuberculosis question comes that of the prevention of the disease. Along the line of prevention the greatest strides have been made in the methods of vaccination. The methods thus far proposed have yielded quite satisfactory results and have incidentally led to various controversies regarding priority in their discovery. The question of priority can not be discussed in this connection. Reference may be made briefly to some of the more important results which have been announced in Europe as a result of the studies in the prevention of the disease. Professor von Behring published a preliminary statement of his method of immunizing cattle against tuberculosis in 1902. The method is called jennerization on account of its resemblance in essential details

a British Med. Jour., 1904, No. 2293, pp. 1596, 1597.

Beitr. Expt. Ther., 1902, No. 5, p. 1-90.

to the method of preventing smallpox in man. Von Behring found, as most other investigators had done, that different cultures of tubercle bacilli from man and from animals differ greatly in their virulence. It was demonstrated by laboratory experiments that the virulence of these races of bacilli could be greatly increased by the proper treatment and that likewise it could be attenuated by subjecting the bacilli to unfavorable conditions. During these experiments it was found that human bacilli when maintained in artificial cultures for many generations in the laboratory finally lost their virulence to such an extent that when inoculated into cattle they produced only a mild form of tuberculosis from which the inoculated animals subsequently recover. An examination of the lungs of cattle killed at varying periods after such inoculation showed that the process of the healing of the tubercles in the lungs was slow, but that ultimately the process became complete, at which time no bacilli could be found in the old tubercles. Some of the cattle kept at the Marburg University for experimental purposes were inoculated with these cultures of weak virulence for a number of times, and it was observed that the intensity of the reaction which followed these inoculations gradually diminished. After a number of such inoculations, the treated cattle were inoculated with very virulent cultures of tubercle bacilli obtained from cattle. The bacilli used in the first experiment of Von Behring had been so increased in their virulence that they produced death of untreated cattle within two weeks after inoculation. It was found, however, that the cattle which had been previously inoculated with human tubercle bacilli and had recovered from such inoculation were quite. immune to the disease. No fatal cases of tuberculosis were developed among such animals. In most instances a mild form of the disease was caused, resulting in a slight elevation of temperature and some coughing for a few months, after which, however, the symptoms of tuberculosis disappeared. Such animals when killed and examined showed evidence of tubercles in the lungs, but such tubercles were healed and the bacilli contained in them were entirely disintegrated within a comparatively short time.

The method proposed by von Behring has been tested quite extensively at the Marburg University and among the neighboring herds. The results announced in the preliminary statement have been confirmed, and the latest statement made by Doctor Römer," one of von Behring's associates, is to the effect that the principle underlying von Behring's method of immunization has been definitely established after giving satisfactory results in more than 1,000 cattle. The investigators at the Marburg University state that in the future

a Beitr. Expt. Ther., 1903, No. 6, pp. 1-110; No. 7, pp. 73-109.