DISEASES OF THE OX AND SHEEP. 



215 



These tubercle-bacilli require a temperature as high as 38° C, 

 and hence they cannot thrive in the outside world, as some 

 disease-producing organisms do. Dr. Klein, one of the greatest 

 authorities on all questions relating to germs, states that the 

 bacilli of human tuberculosis are larger than those found in 

 cases of bovine tuberculosis, and in many instances they seem 

 to be more regularly granular. The bacilli found in human 

 tubercular sputum are at least one third as large again as those 

 found in the caseous masses of the lungs of cattle. Moreover, 

 the tubercle-bacilli of oxen are always contained in the cells, and 

 only when these disintegrate, as they do sooner or later, do the 



Fig. 23. 



From a section through a tubercle of the lung from a case of Acute Miliary 

 Tuberculosis in a Child. Several Alveoli are seen filled -with debris, in the 

 centre of which are seen numerous nuclei, and amongst them the tubercle- 

 bacilli. Magnifying power about 350. (Klein.) 



bacilli become free in groups. In this respect they are like the 

 bacilli found in leprosy. In man the tubercle-bacilli are 

 always scattered between the cells. 



It will doubtless be remembered that fowls seem to be not 

 readily infected with bovine tuberculosis, possibly because they, 

 being so much mixed up with oxen, have become thoroughly 

 used to the disease, so that the virus has lost its poisonous 

 properties. On the other hand they do take human tuber- 

 culosis, though in a mild form. Guinea-pigs, on the contrary, 

 are more liable to suffer from being fed with bovine tuber- 

 cular matter than they are from being fed either with human 



