FIRST CENTURY OF DAIRYING IN NEW SOUTH WALES. 



take place, a predisposition on the part of the individual attacked is 

 necessary, without which tubercular disease does not occur. This 

 predisposition may be either general or local. In general terms, any- 

 thing which reduces vitality may operate as a general predisposing 

 cause of tubercle. But, in this connection, there are two inherited 

 diachctic conditions which are of especial importance. The one, 

 diathesis (scrofulous or strumous), is characterised by slow nutrition 

 and general feeble powers of resistance on the part of the tissues. 

 The second diathetic condition (sometimes called tubercular) is 

 characterised by premature rapid growth, out of proportion to nutri- 

 tion, and associated with a special instability of the body tissues. As 

 a local predisposition it would appear that any antecedent disease may 

 act in this way, in so far as it lowers the standard of nutrition of a 

 part." 



Speaking of the cause of tuberculosis, Dr. Sims Woodhead, M.D., 

 Edin., says : " There seems in most cases to be, first, a weakened 

 condition, an impaired power of resistance of the epithelial cells lin- 

 ing the small bronchi ; the smaller air passages, and the air vesicles 

 making up the spongy tissue of the lung ; the bacilli in the air and 

 dust then finding their way to a surface already weakened and spe- 

 cially prepared, as it were, for their reception, recommence their 

 parasitic life, multiply and make their way further into the tissues, 

 whence they set up the change associated with tubercular disease. It 

 is evident from all this, therefore, that much work still lies ready to 

 our hand in connection with the spread of tubercules, and that if we 

 could only persuade people to look upon tubercle as an infectious 

 disease similar in character to scarlet fever, though not so rapidly 

 developed, much would have been done to prevent its spread, and a 

 great advance in preventive medicine would have been made." 



It is plain enough, from the foregoing remarks, that what is most 

 necessary as a means of prevention in the case of animal tuberculosis 

 are as follows : Cleanliness, good food, and plenty of fresh air. Now, 

 under all the conditions of city life, it does not seem possib.e to place 

 a large percentage of the children raised in cities in a favourable con- 

 dition to resist disease ; hence it is that the country milk supply is 

 held up to the world as the cause of all the ills the flesh is heir to 

 on this mundane sphere ; whereas it is traceable to other causes. 



Shumway says : " The slower process of tuberculosis as compared 

 with other infectious diseases has aided in the general indifference with 

 which it has been regarded. In its acute form it often runs its course 

 ;n a few weeks, but its usual manifestation is of a chronic and 

 dilatory character, often lasting for years. The disease attacks many 

 of the organs of the body, and it often makes considerable progress 

 in one organ before others are involved. This results in great diffi- 

 culty in recognising its presence in its earlier stages, or in identifying 

 it where some difficulty or disease is indicated. It is in such cases 

 that the : tuberculin test' is so pronounced and cert'iin. Unfortunately, 

 however, we have no guarantee that the tuberculin poison, once in the 

 system, does not remain there, much to the detriment of the animal. 

 Few scientists, one might venture to say, would care to eat the flesh 

 of a beast after the tuberculin has been injected, whether it reacted or 

 not, owing to the suspicious nature of tuberculin." 



Nocard says : " From a clinical point in" view two threat division- 

 are pulmonary tuberculosis and abdominal tuberculous. From 

 an anatomical point of view three chief divisions are made : (i) 

 Tuberculosis of the organs; (2) tuberculo.-is of the serous membranes; 

 (3) tuberculosis of the lymphatic glands. In most cases, undoubted y, 

 these three forms co-exist in the same subject, but still it is quite 

 common to see animals succumb, either to intense glandular tuber- 

 culosis or to enormous tuberculous growths of the pleura or peri- 

 toneum, without the process having attacked the neighbouring viscera. 

 It would almost seem as if there were three varieties of the bacillus 



264. 



