SOUTHERN CATTLE FEVER (TEXAS FEVER, TICK FEVER). 



DESCRIPTION OF PLATES. 



Plate XLIV. Normal spleen and spleen affected by Texas fever. 



Fig. 1. Spleen of an acute, fatal case of Texas fever. The narrow end of 

 the spleen is here represented. 



Fig. 2. Spleen of healthy steer. Though the latter animal weighed one-half 

 more than the former, the weight of the diseased spleen (6| pounds) 

 was nearly three times that of the healthy spleen (2§ pounds). 

 Plate XLV. Texas fever. 



Fig. 1, The cut surface of a healthy liver taken from a steer slaughtered 

 for beef. 



Fig. 2. The cut surface of the liver in Texas fever. 



Fig. 3. Appearance of the urine in an acute, fatal case of Texas fever. 



Fig. 4. Red corpuscles, magnified 1,000 diameters, containing the parasite of 

 Texas fever. This appears as a blue point a near the edge of the 

 corpuscle. The blood was taken from a skin incision. The case was 

 nonfatal and occurred late in the fall. 



Fig. 5. Red corpuscles from the blood of an acute, fatal case, 20 hours be- 

 fore death. The Texas fever microbes a are shown as pear-shaped 

 bodies, stained with methylene blue, within the red corpuscles. The 

 larger body on the right ft is a white blood corpuscle, also stained with 

 methylene blue. (Magnified 1,000 diameters.) 

 Plate XLYI. The cattle tick (Margaropus anmilatus) , the carrier of Texas 

 fever. 



Fig, 1. A series of ticks, natural size, from the smallest, just hatched from 

 the egg, to the mature female, ready to drop off and lay eggs. 



Fig. 2. Eggs, magnified 5 times. 



Fig. 3. The young tick just hatched (magnified 40 times). 



Fig. 4. The male after the last molt (magnified 10 times). 



Fig. 5. The female after the last molt (magnified 10 times). 



Fig. 6, A portion of the skin of the udder, showing the small ticks. From 

 a fatal case of Texas fever produced by placing young ticks on the 

 animal. (Natural size.) 



Fig. 7. A portion of the ear of the same animal, sliowing same full-grown 

 ticks ready to drop off. (Natural size.) 

 Plate XLVII. The cattle tick {Margaropus annulatus). 



Fig. 1. Dorsal view of male. (Greatly enlarged. Original.) 



Fig. 2. Ventral view of male. (Greatly enlarged. Original.) 



Fig. 3. Dorsal view of replete female. (Greatly enlarged. Original.) 



Fig. 4, Ventral view of same, 

 Plate XLVIII, Portion of a steer's hide, showing the Texas fever tick {^[ar^ 



garopus annulatus) . (Natural size. Original.) 

 Plate XLIX. Fig. 1, Tick-infested steer. 



Fig. 2. Dipping cattle to kill ticks. 

 Plate L. Map of the United States, showing region infected with Texas 

 fever of cattle. The heavy line shows the boundary of the tick-infested 

 area at the beginning of the work of tick eradication in 1906. White 

 areas below the line show territory that has been freed from ticks and 

 released from quarantine. Shaded areas remain tick infested and 

 imder quarantine (April 1, 1916)! As a general rule, cattle may not be 

 shipped interstate from the shaded area except for immediate slaughter. 

 As the quarantined area is subject to change at any time, this map 

 should be compared with the latest regulations, which may be obtained 

 at any- time on application to the Secretary of Agriculture. 

 504 



