TUBERCULOSIS. 



of 'Koch,' each with a preference for one particular tissue or culture 

 medium." 



We have seen by the evidence given us by these eminent authorities 

 that a medium must first be obtained before the bacillus can form a 

 colony within the animal. Oi course, there are many strong argu- 

 ments used in favour of hereditary taint. Yet, according to Professor 

 Bang's theory " no young animal is born with the disease in its 

 systeim." The most, therefore, that can be said on that po.nt is that 

 the animal is born with a predisposition to the disease, which, under 

 ordinary conditions amounts to the very same thing. If, as Dr. Brush, 

 oif Philadelphia, says, "The cow is the wet nurse of consumption" 

 and shows the connection by the following facts: " Scrofulous 

 females in the human race usually secrete abundance of milk, because 

 in scrofula there is an unusual tendency to grandular enlargements 

 and activity. As the mammary is the highest type of grandular 

 structure, it is stimulated to increased action. A scrofulous cow is 

 usually the largest milker, and the closest kind of consanguineity has 

 been practised by cattle breeders, with the object of producing a 

 scrofulous animal, not because she is scrofulous, but because the par- 

 ticular form she represents are the largest yielders of milk. We find, 

 too, that consanguineous breeding has been alleged as one of the 

 causes of tuberculosis in the human race, where it can never be con- 

 ducted with so close and intimate blood relations as in the dairy 

 animals." 



If in-and-in or consanguineous breeding is a cause of tuberculosi c 

 just to the extent that such breeding produces ani'.nals which will 

 yield large supplies oi milk, one might, if it were profitable, get over 

 the difficulty by keeping scrub cows ; but change of climatic con- 

 ditions will bring about immunity to a great extent. On this im- 

 portant point we have the opinion of a gentleman not unknown to us 

 here in Australia, Dr. Crookshank. He says : " Immunity may be 

 acquired by acclimatisation, for the inhabitants of tropical c'imates 

 are less susceptible to the diseases of the country malarial fever, for 

 instance than strangers." He 'further states : " It is difficult to 

 conceive that the leucocytes in the blood and tissues of field mice are 

 differently constituted from those of the home mouse, so that they 

 form an effectual barrier in the one case, though so readily destroyed 

 in the other." 



Now, without attempting to dive deeply into the cell life in the 

 blood of animals, it may not be out of place to state one's experience 

 in dairy heiiers which were taken from the same mob, and which 

 were bred on the same identical lines with others on the coast, and 

 sent away to the tableland. Those animals left on the coast in the 

 course of time nearly all died from tuberculosis, whereas of those 

 taken to the tableland not 2 per cent, of them suffered from that 

 disease. They were all got by a bull that contracted tuberculosis and 

 died or was otherwise destroyed. The climatic conditions undoubtedly 

 in this instance had the desired effect of alterin"- the condition of the 

 leucoytes, making them more active and vigorous in resisting disease. 



Speaking generally, tuberculosis is a compound name for all the 

 pathological changes caused by tubercle bacilli. It is a contagious 

 disease which occurs both in man arid in the lower animal, pursues 

 its course slowly, and shows itself in the formation O'i a larger or 

 smaller quantity of nodules, called tubercules. Among domestic ani- 

 mals it principally attacks cattle and pigs, more seldom dogs, h rses, 

 and cats, very rarely sheep and goats. The tuberculosis which has 

 been observed at different times in poultrv appears to be of a special 

 kind, inasmuch as the tuberculosis o-f mankind and mammals seems 

 to be only capable with difficulty of being conveyed to poultry, as 

 also that poultry tuberculosis does not attack mammals. Wild animals 

 in a natural state are practically free from the disease, but easily 

 contract it in a state of domestication or captivity. 



265. 



