312 STATE BOARD OF AtJHlCULTURE. 



That human tuberculosis may be transmitted lo tlie bovine sju-eies, we have the 

 work of Bollinger, Baumgarten, Sidney Martin, Smith, Frothinghara and Dinwiddie 

 to testify. Each has demonstrated that the tubercle bacillus found in man is capable 

 of setting up tuberculosis in cattle, both by inoculation and by feeding. It is a 

 difhcult matter to decide whether the tubercle bacilli coming from the human subject 

 are less virulent upon the bovine subject than tubercle bacilli coming from the bovine 

 species; yet the inoculations of human tuberculous material act in most cases somewhat 

 tardily upon cattle. On the other hand, tubercle bacilli taken from the bovine source is 

 exceedingly variable in its virulence, if we may draw such a conclusion from two experi- 

 ments carried on here at the college. These experiments have two purposes, first to 

 show the transmissibility of bovine tuberculosis to ])igs, which has been repeatedly 

 shown by other workers, as Gerlach, Ernst, Dinwiddie, Thomassen and others, and 

 to show the difference in the virulence of material employed. Six pigs, three weeks 

 old, and all fronj the same litter, were divided into two lots, three in each lot. To 

 one lot was fed in milk for four days, tuberculous material taken from a cow which 

 had run down very rapidly l)efore she was tested with tuberculin and killed. The 

 lungs of this animal were highly alTected with tuberculosis. These were chopped 

 fine and the tissue fluids extracted by means of a meat press. About one pint of this 

 fluid was added to one hundred pounds of milk. One c. c. of this milk introduced 

 into the abdominal cavity of guinea pigs caused their death from tuberculosis in eight 

 weeks. The one lot of three pigs received this greatly diluted tuberculous material 

 for four days. After the first day, however, the milk was sour, notwithstanding it 

 was kept constantly in a refrigerator at 15° C. As soon as this milk was 

 consumed the feeding was the same as the controlling lot of three pigs which were fed 

 on heated milk and meal. At the end of six months all of these pigs were killed. 

 The controlling three were free from disease as would be expected. They had had no 

 tuberculous material and their food was carefully watched against infection, as was also 

 the food of the three which received the tuberculously infected milk. Wlien the pigs 

 which had eaten the infected, milk were opened, although the outward ap])earances 

 were such as to indicate the animals in the best of health and flesh, the glands and 

 organs contained numerous tubercles. There is no need of entering into a detailed 

 description of the post-mortem appearances: suffice it to say that the mesenteric, 

 portal, mediastinal and pharyngeal glands were thoroughly t\iberculous. The liver, 

 lungs and spleen were more or less invaded with tubercles. In tliis instance every 

 animal fed with tuberculously infected milk became infected witli the disease, while 

 each check animal was entirely free from any trace of it. From the great dilution 

 and from the action of the material upon the pigs, as well as guinea pigs, also from 

 the^rapid decadence of the cow, it may be justifiable to conclude that the tubercle 

 bacilli were of a high degree of virulence. Our next experiment might be considered 

 a jump to the other extreme. In this experiment were eight pigs and four calves. The 

 pigs were obtained from the same litter and were placed in four separate pens -with 

 two in each pen. The calves were arranged with only one in each pen. The pigs 

 were labeled pens one. two, three and four, and the calves, one. two. three and four. 

 The tuberculous material was obtained from cattle whicli had previously reacted several 

 times to tuberculin, but from ante-mortem and post-mortem appearances were holding 

 their own, and so far as is knoAvn and as suspected at the time miglit have been 

 recovering. [These animals will be considered later. — Author.] The material was 

 chopped fine, as in the preceding experiment, and the tissue fluids extracted by means 

 of a meat press. The material was more abundant than in the preceding test and 

 much larger quantities of the fluid extracted were used with smaller amounts of 

 milk. A pint of this material was mixed with twelve quarts of pasteurized milk. The 

 pigs in pen one received four feedings (all they could drink) of this infected milk: pigs 

 in pen three received only one feeding of this milk : pigs in pens two and four acted 

 as controls or checks. After the feeding of the pens one and three with infected milk, 

 all the pigs received pasteurized milk and meal only. Calf one received four feedings 

 of this same tuberculously infected milk and calf two one feeding only. Calves three 

 and four acted as controls or checks. Calves one and two. after the feeding of the 

 infected milk, received the same as the checks or controls, pasteurized milk, with meal 

 and hay. Six months from the beginning of the above experiment all the above ani- 

 mals were killed and nothing of a tuberculous nature could be positively demonstrated 

 in any of the animals. It can now be added that guinea pigs inoculated with this 

 material were slow in succumbing to tuberculosis and half of the number did not 

 contract the disease at all. This experiment seems to indicate that it is possiljle for 

 tuberculosis to reach a latent condition in whieli the tubercle bacilli are ]iractically 



