about two and one-half months later. Both were affected with generalized tuberculosis. The object in making guinea-pig injections in this case was the same as in the case of No. 255.

Cow No. 211, about two years old; tested with tuberculin without reaction.

July 19, 1902.—Injected into right jugular 10 c. c. of moderately virulent human tubercle culture.

July 25, 1902.—Gave birth to a healthy calf.

August 6, 1902.—The above injection repeated.

August 8 to 18, 1902.-Suffered from accelerated respiration and loss of appetite. August 19, 1902.-Has grown quite thin, but seems to be in good general health. The reduction in condition is probably due to the milk secreted for her calf, which latter is in excellent health and growing vigorously.

August 20, 1902.-A third injection of moderately virulent human tubercle culture was made (10 e. c.) into right jugular vein.

September 20, 1902.-A fourth injection of 10 c. c. of human tubercle culture was made into right jugular vein.

October 7, 1902.—A fifth injection of 10 c. c. of moderately virulent human tubercle culture was made into right jugular vein. Each of the five injections was followed by an elevation in temperature of from 2° to 4°, which lasted from three to seven days, and by more or less acceleration in respiration.

December 12, 1902.-The calf was weaned.

January 27, 1903.-The cow is quite thin and looks unthrifty. Is producing about I gallon of milk daily. Was tested with tuberculin without reaction, and placed in stable with tubercular cattle and exposed by moving from stall to stall in the same manner as heifer No. 293.

April 3, 1903.-Is thin, but seems to be in perfect health.

June 10, 1903.-Is improving in condition. Still producing milk. June 30, 1903.-Tested with tuberculin without reaction. August 6, 1903.-Killed this date and examined postmortem. Autopsy record follows: The entire lung is sprinkled with minute white nodules about 1 mm. in diameter. The appearance is similar to that observed on several occasions at the Experiment Station after injection of human tubercle culture into the veins of cattle. There are thousands of little nodules present, and a few as much as 2 mm. in diameter. The mediastinal glands contain a number of circular red patches, but no tubercular lesions. The costal and pulmonary pleura show considerable thickening and roughening. The liver contains a number of necrotic areas of parasitic origin. Two guinea pigs were inoculated with fragments from the red circular patches in the mediastinal glands. These guinea pigs were killed two and one-half months later, and were found to be in excellent condition and free from all lesions of disease. Two guinea pigs were inoculated with minute nodules from the lung. One died after two months, affected with generalized tuberculosis, and the other was killed two and one-half months after inoculation and was found to be affected with generalized tuberculosis.

The tubercular character of all doubtful lesions was confirmed either by microscopic examination or guinea-pig injection. An examination of the records of the cattle shows that every one of the 7 healthy animals exposed a little more than six months to tubercular cattle contracted the affection, with the possible exception of cow No. 211.

Cattle Nos. 255 and 261 received each an injection of dead tubercle culture-one human and the other bovine; these injections were made H. Doc. 743, 58-2—5

in connection with another experiment regarding the effects of dead tubercle culture injections on cattle. The 2 cattle were specially selected for the exposure experiment because it was desirable to determine whether the injections received had affected their susceptibility to tuberculosis. It is clear from the results that the dead culture injections made in July, 1902, had no influence on the exposure beginning in January, 1903.

Cow No. 211, which received five intravenous injections of live human tubercle culture, was included in the exposure at the request of Dr. E. A. de Schweinitz, of the Biochemic Division. The injections in this case were made, in connection with the injections of a number of other animals, in an experiment concerning the immunization of cattle to tuberculosis.

The lesions observed on autopsy in cow No. 211 are undoubtedly the result of the intravenous injections received previous to the exposure. This conclusion is drawn from the fact that it is not probable that a simple stable exposure would have caused thousands of independent centers of disease, all of the same age, to develop in the lung, without a single tubercular lesion in any other portion of the body. It is very likely that the germs introduced into the jugular vein passed along the circulation to the right chambers of the heart, and from there to the lung, where they were entirely filtered out of the blood, and caused a tubercular disease. This disease, it is fair to assume, was of a temporary character, and would have ended in complete recovery if the cow had not been killed. The condition found is very significant.

a A case like the following shows the extensive lung disease which may result from an intravenous injection either of an attenuated tubercle culture or a tubercle culture in which the life of the germ has been destroyed: Sheep No. 46, in excellent health, tested with tuberculin without reaction. On July 19, 1902, received an injection into the right jugular vein of 10 c. c. of dead bovine tubercle culture. The culture was killed by exposing it to a temperature of 98° C. for one hour. Several guinea pigs were injected with portions of the culture as a check on its sterility. The guinea pigs were killed three and one-half months later and found to be in excellent condition and free from all lesions of disease. The sheep was killed on January 6, 1903, not quite six months after the injection was made, and the following lesions found: Sprinkled over the entire surface of the lung, immediately under the pleura, are innumerable minute tubercles, all of about the same size, 1 mm. diameter, excepting where several have coalesced. Similar tubercles are found, on section, to be sprinkled throughout the lung tissue. (In every respect these tubercles were like the tubercles found in the lung of cow No. 211.) The minute tubercles were somewhat more numerous in the caudal portion of the principal lobes of the lung than in other portions of the organ. The distance between the tubercles was from one-half to 1 cm., excepting in a few regions, in which areas of the lung about 3 cm. square were thickly beset with very minute necrotic points. The general appearance was that of miliary tuberculosis of the lung. The individual tubercles had the appearance of opaque, pearl-gray points, surrounded by a ring of translucent, glistening tissue. Mediastinal and bronchial glands free from disease, with the exception of a few reddened patches. One of the throat glands was entirely necrotic. All other organs

If it is preferred to attribute the lesions to the exposure in the stable, the conclusion must be drawn that the tubercle culture injections failed to produce immunity. On the other hand, if the lesions are attributed to the immunizing injections, it is clearly shown, by the death of the guinea pigs injected with fragments of the lung, that living tubercle germs were still present ten months after the last injection was made, a condition which certainly is very objectionable in a method which has for its primary object the prevention of tubercular disease. While there is no desire on the part of the writers to urge or support the views of Doctors Koch and Smith with respect to the difference between the human and the bovine tubercle bacilli, to which we are really opposed, it seems, nevertheless, in the present unsettled state of the question, that we should not make cattle a repository for human tubercle bacilli in order to protect them from bovine tuberculosis.

The rapidity with which tuberculosis spreads in stables occupied by tubercular cattle is shown with particular emphasis by the 2 cattle, Nos. 263 and 257, which became tubercular without actual contact with the tubercular cows, in stalls which were separated from the other stalls by solid partitions 6 feet high. The distribution of the lesions in the several cattle merits some attention, although it is not possible to draw definite conclusions from so small a number of, animals regarding the organs which are more apt to become affected in an exposure of the kind practiced. In a general way, 5 of the 7 cattle showed lesions in the mediastinal lymph glands, 3 in the bronchial glands, 4 in the lungs, 2 in the throat glands, 2 in the mesenteric glands, 1 in the liver and portal glands, 1 in the lymph glands at the brim of the pelvis, and 2 showed disease of the pulmonary surfaces of the lungs and thorax. It would seem from this distribution that the germs of tuberculosis in stall and stable infection are more commonly respired than ingested with food. The importance of this condition. lies in the fact that it points out clearly that cattle can not be protected from tuberculosis in stables with tubercular cattle by restricting carefully each animal to its own individual stall.

Finally, it is interesting to know that 100 guinea pigs were exposed to tubercular infection in this experiment. The guinea pigs were divided into twenty lots, and one lot placed in a wall cage in each stall and one lot in a cage constructed below the manger in each stall. The normal. Three guinea pigs injected with material from the lung, and 3 with material from the throat gland, were killed eight months later, and found to be in excellent condition and free from all lesions of disease. Sections made of the nodules in the lung of the sheep and examined under the microscope showed the presence of innumerable tubercle bacilli. In other words, the dead germs not only caused extensive disease, but were retained in countless numbers in the tissues for very nearly six months. The sheep at no time following the injection showed syriptoms of disease, and remained in excellent condition, and was fat and apparently in perfect health when it was killed.

manger cages were so arranged that a constant sifting of food should occur from the mangers to the guinea-pig cages while the cattle were eating. Among the 100 guinea pigs 2 died early during the exposure as the result of pneumonia. Of the remaining 98, all of which were exposed throughout the entire time of the exposure of the cattle, only 1 guinea pig became affected with tuberculosis. This pig was exposed in one of the manger pens.

During the experiment three cats lived in the stable used for the exposure and were fed the mixed milk of the several tubercular cows. In addition to the milk, the cats received no other feed excepting such rats or mice as they could catch for themselves. The cats were killed and upon careful examination after death were found to be free from lesions of tuberculosis.

SOME OBSERVATIONS ON THE TUBERCULOSIS OF

ANIMALS."

By D. E. SALMON, D. V. M.,

Chief of the Bureau of Animal Industry.

The tuberculosis of animals is a subject of very great importance from more than one point of view. To the agriculturist, the economist, the statesman, it causes, or should cause, anxiety because of the loss of food-producing animals which it occasions and because of its tendency 'to counteract the efforts of breeders to improve the quality of such animals. To the physician and the sanitarian it must be a matter of grave concern because of the possibility of its having an injurious effect upon the public health. To every citizen who possesses the finer feelings developed by civilization, intelligence, and cultivation, it must be a matter of some solicitude as to whether the steak which he eats for his breakfast was cut from the carcass of a steer affected with generalized tuberculosis or whether the milk which he drinks with his luncheon was produced by a cow having tuberculosis of the udder. However, in the remarks which I have the privilege of making before this audience, I shall treat the subject of animal tuberculosis from a medical point of view, with especial reference to the lessons of comparative pathology.

There are two questions of superlative interest before the medical profession at this time relative to animal tuberculosis: First, Is animal tuberculosis communicable to man? Second, In case it is communicable to man, how frequently does such transmission occur? Clinical observation has not been able to give us satisfactory answers to these questions, and experimentation has been forced to approach them by more or less indirect routes, which necessarily has made the evidence obtained somewhat inconclusive and liable to more than one interpretation. It appears, however, that some rays of light are beginning to penetrate the obscurity and that all must soon agree upon the answer to the first of the questions which I have just formulated. The second question can not be answered definitely for a long time to come.

WIDE RANGE OF ANIMAL SPECIES AFFECTED WITH TUBERCULOSIS.

In the whole list of infectious diseases of animals there is probably not one which affects a larger number of species, or species which are a Paper read before the Tuberculosis Exposition, at Baltimore, Md., January 28, 1904.