TUBERCLE BACILLUS 63 



intra- uterine or placenta! infection does occasionally occur. 

 Although human semen may contain tubercle bacilli. 

 Jordan considers that transmission by the male parent 

 is very unlikely to occur, and there is only one recorded 

 case of an infected ovum. A ' tendency ' to the disease may 

 be inherited, but it is more logical to attribute the occur- 

 rence of the disease in a family to the intimacy of family 

 relations allowing abundant opportunity for infection. 



The lesions produced in tuberculosis have more or less 

 similarity to those of leprosy. The little yellowish 

 nodules or tubercles (to which anatomists first applied the 

 term ' tuberculosis ') are non- vascular, and vary in size 

 from that of a pin's head up. They consist of vast 

 aggregates of cells (hence the term ' Granulomata '). In 

 the centre of a young tubercle a mass or masses of pro- 

 toplasm are found (' giant cells '). (Giant cells are much 

 less common in leprosy.) In the giant cell is a ring of 

 tubercle bacilli, and around this zone and arranged round 

 the periphery is a ring of nuclei. Around the giant cells 

 epithelioid cells with large nuclei are found, and around 

 these a collection of lymphoid cells. 



Although tuberculosis is best known as a pulmonary 

 disease, the glands, skin, bones, peritoneum, urinary 

 organs, meninges, etc., are also frequently attacked. 

 Widely diverse findings are recorded of the frequency with 

 which the tubercle bacillus occurs or is found in the 

 blood. Minchin assumes tubercle bacilli in the host to 

 be suspended in ' shut-away fluid ' which protects them 

 from the influence of germicides and sera. 



Bovine Tuberculosis. Cattle, particularly those kept 

 in insanitary sheds, are very liable to tuberculosis. The 

 bovine organism may reach others than those in contact 

 with the animal, through the medium of the milk or 

 flesh. When the udder is affected, the bacilli will prob- 

 ably be found in the milk, but even when the udder is 

 free from tuberculosis, the bacilli may find their way 

 into the milk, from the faeces, uterine secretion, or sputum, 

 according to the locality of the infection, unless precau- 

 tions are taken during milking. The bovine bacillus is. 

 shorter, thicker, and less readily cultivated than the 

 human one. These considerations, with others, led Koch 

 in 1901 to question the communicabiiity of the bovine 

 tubercle to man. A Royal Commission was appointed in 



