INFECTIOUS DISEASES OF CATTLE. 43 & 



enable anyone to determine this point. Frequently the skin is so poor 

 in blood that it may require several incisions to draw a drop or more. 



The changes in the internal organs, as found on post-mortem exami- 

 nations, are briefly as follows: The spleen or inilt is much larger than 

 in healthy animals. It may weigh three or four times as much. When 

 it is incised the contents or pulp is blackish (see Plate XLII, Fig. 1), and 

 may even well out as a disintegrated mass. The markings of the 

 healthy spleen (Fig. 2) are all effaced by the enormous number of blood 

 corpuscles which have collected in the spleen and to which the enlarge- 

 ment is due. Next to the spleen the liver will arouse our attention. 

 (See Plate XLIII, Fig. 2.) It is larger than in the healthy state, has lost 

 its natural brownish color (Fig. 1), and now has on the surface a paler 

 yellowish hue. When it is incised this yellowish tinge or mahogany 

 color, as it has been called by some, is still moro prominent. This is 

 due to the large amount of bile in the finest bile capillaries, and as 

 these are not uniformly filled with it the cut surface has a mere or less 

 mottled appearance. This bile injection causes in many cases a fatty 

 degeneration of the liver cells, which makes the organ appear still 

 lighter in color. 



In all cases the gall bladder should be examined. This is distended 

 with bile, which holds in suspension a large quantity of yellow flakes, 

 so that when it is poured into a tall bottle to settle fully one-half or more 

 of the column of fluid will be occupied by a layer of flakes. If mucus 

 is present at the same time the bile may become so viscid that when it 

 is poured from one glass to another it forms long bauds. The bile in 

 health is a limpid fluid containing no solid particles. 



If the animal has not been observed during life to pass urine colored 

 witli blood or red water, the bladder should be opened. This quite 

 invariably, in acute cases, contains urine which varies in color from a 

 deep port wine to a light claret. In many cases the color is so dense 

 that light will not pass through even a thin layer. (Plate XLIII, Fig. 3.) 

 The kidneys are always found congested in the acute attack. The dis- 

 ease exerts but little effect on the stomach and intestines beyond more 

 or less reddening of the mucous membrane. Hence an examination of 

 these may be safely omitted. The lungs are, as a rule, not diseased. 

 The heart usually shows patches of blood extravasation on the inside 

 (left ventricle), and less markedly on the outer surface. 



We have observed jaundice of the various tissues but very rarely. 

 It has been observed by some quite regularly, however. 



The cattle tick, Ixode* borix (Riley) Boophilu* borix (Curtice), a* the 

 carrier of Texan fever. (Plato XLIV.) The cattle tick is, as its name 

 indicates, a parasite of cattle in the southern part of the United States. 

 It belongs to the group of Artliropoda and to the, genus Ij-odcs (Boo- 

 philit*), which is included in the order Acarina. Its life history is quite 

 simple and easily traced from one generation to another. It is essen- 

 tially a parasite, attaching itself to the skin suul drawing the blood of 

 24097 28 



