408 DISEASES OF CATTLE. 



them Nocard, still believe that the udder is diseased when the milk is 

 infected, but that the disease escapes observation. However this may 

 be, the fact that the udder may be diseased and the disease not recog- 

 nizable, simply casts suspicion upon all milk from tuberculous animals. 

 The question as it now stands leaves the matter unsettled. We know 

 that the milk of tuberculous cattle may or may not contain tubercle 

 bacilli when the udder is apparently free from disease. But we have 

 no rapid method of determining whether in any given case the milk 

 contains tubercle bacilli or not. Moreover, the bacilli may be absent 

 at one time and present at another in inilk from the same cow. When 

 we consider, therefore, the extent of tuberculosis and the hidden char- 

 acter of the disease, a certain amount of suspicion rests upon all milk. 

 Fortunately tubercle bacilli are readily destroyed by the temperature 

 of boiling water, and hence both meat and milk are made entirely safe, 

 the former by the various processes of cooking, the latter by boiling 

 for a few moments. Until better means of diagnosis are at hand it is 

 incumbent upon all communities to have dairy cows examined or 

 inspected "at least to the extent of finding out whether the udder shows 

 any signs of disease. If this is detected the affected animal should be 

 at once killed, or else all opportunity for the sale of such milk removed 

 by appropriate measures. The dangers from infected milk might by 

 these means be very materially lessened. 



TUBERCULOSIS. 



[Description of plates.] 



PLATE XXXIV. Tuberculosis of the lungs. The upper figures represent a large 

 cheesy mass, surrounded lay a capsule of connective tissue, the whole embedded in 

 healthy lung tissue. The lower figure illustrates in section a mass of tubercles 

 which have undergone cheesy degeneration, and some of which are embedded in dense 

 connective tissue. 



PLATE XXXV. Tuberculosis of the liver. A large portion of the lobe represented 

 in the plate has undergone tuberculous changes. The whitish, very fine, newly 

 formed connective tissue contains the yellowish, partly cheesy, partly gritty masses 

 characteristic of advanced tuberculous degeneration. This large mass projected 

 above the surface of the liver. In the plate the diseased mass is shown cut through 

 its central portion with the cut surface presented. 



PLATE XXXVI. A lymph gland from the region of the thorax behind or above 

 the oesophagus or gullet (posterior or dorsal mediastinum). The gland is shown cut 

 through and laid open. It is very much enlarged, and the yellowish cheesy masses 

 surrounded by dense connective tissue are well shown on the cut surface. 



PLATE XXXVII. Represents the omentum or caul of a tuberculous cow. The 

 preparation had been in alcohol for some time. The projecting masses are the 

 tubercles, whence the name "pearly disease," for that form of the malady in which 

 these tubercles are present. They are mainly restricted to the lining membrane of 

 the thorax and abdomen. 



PLATE XXXVIII. Fig. 1. Lymphatic gland of the mesentery (the fold of mem- 

 brane to which the small intestines are attached) cut open. The gland is very 

 much enlarged. The yellowish portions represent tissue which has undergone 

 tuberculous changes. 



Fig. 2. Omentum or caul resting upon the paunch. The reddish nodules with 

 which the membrane is beset are tubercles, the product of the disease. Both speci- 

 mens are from the same animal, a Jersey cow. 



