510 Tuberculosis. 



is not excessive (not more than 4 eg.) . The ingestion of such material will 

 produce local changes only in the mesenteric glands. 



Kossel, Weber & Heuss, who experimented with 38 differeut strains of the 

 human type and with 27 strains of the bovine type, included in their experiments 

 a large number of cattle. Subcutaneous inoculation of .05 g. of culture produced 

 at first au inflanunatory swelling at the point of inoculation which developed into 

 abscesses that broke and discharged their contents. This was followed by enlarge- 

 ment of the prescapular glands. When the bacillus of the human type was used 

 this swelling attained the size of a goose egg but was considerably larger in cases 

 where the bacillus of the bovine type was used, sometimes as large as a man's 

 head. When the bacillus of the human type was used the process stopped at this 

 point and was followed by retrogressive changes. After seven months all bacilli 

 were destroyed. On the other hand the bacilli of the bovine type continued their 

 work of destruction and produced a progressive tuberculosis which, in 30% of 

 all cases ended in death in the course of 8 or 10 weeks. Feeding experiments 

 demonstrated that one feeding of bacilli of the bovine type sufficed to infect calves. 

 Of eight animals some of which were given one treatment, others repeated treat- 

 ments, four died in from 79 to 115 days. Post-mortem examination showed severe 

 lesions in the intestines and the regional mesenteric glands. On the other hand 

 all calves fed with glycerin bouillon cultures of the human type remained alive. 

 The bacilli which had been introduced into the intestinal canal were lodged partly 

 in the mesenteric glands where they gave rise to the formation of small yellow 

 calcified foci which had not caused any reaction in the otherwise normal tissue. 

 In the course of inhalation experiments it was shown that bacilli of the bovine 

 type introduced in this manner were exceedingly virulent. One mg. of bacilli was 

 sufficient to kill a calf four months old within 48 days. Following a period of 

 incubation of 12 to 14 days the animals were attacked with a high fever ami 

 difficult respiration. Four died in the course of 26 to 62 days with caseous pneumonia. 

 Four others were affected in the course of 110 to 174 days with pulmonary tuber- 

 culosis and tuberculosis of the adjacent lymph glands and serous membranes. On 

 the other hand the bacilli of the human type in these experiments produced no 

 tuberculous disease. 



TJie difference in virulence is observed also where injections are made into 

 the rtiilk ducts of cattle and goats. Thus tubercle bacilli of human origin produced 

 only a slight reddening lasting a few days, and attended with moderate sensitiveness 

 and swelling of the affected quarter. On the other hand the bovine liacilli produced 

 a pronounced tuberculosis of the udder and mammary glands and, in addition, 

 probabh' as a result of an intoxication, rapid emaciation ending in death (Nocard, 

 Meyer, Calmette & Guerin, Zwick). 



The differences in results referred to above apply only to charac- 

 teristic pure cultures. Since both types occur in man, inoculation ex- 

 periments with crude material, such as sputum, tuberculous tissue, etc., 

 give varying results. However, these results correspond with the fact 

 that the human type is most frequently present in man, while the bovine 

 t.vpe is almost exclusively present in cattle. (For further information 

 on this subject refer to the chapter on the Relationship between Human 

 Tuberculosis and Bovine Tuberculosis.) 



Results of experimental inoculations of other animals with morbid 

 secretions or tissue show, in general, that swine are readily infected 

 with either of the two types of bacilli, that sheep and goats are most 

 readily infected with material containing the bovine type and that dogs 

 may be infected with large doses of either the human or the bovine 

 type of bacillus (Titze & Weidanz). Other mammals possess a con- 

 siderable power of resistance to infection. Again, all avian species 

 with the exception of house birds (parrots), possess considerable resist- 

 ing power against infection with the bacilli of the mammalian types. 



Infectious Secretions and Products. In the bodies of tuber- 

 culous animals the bacilli are, with the exception of miliary 

 tuberculosis, found usually only in the affected organs, and in 



