TEXAS FEVEK. 



[Descrii>tlon of plates.] 



Plate XLVI. Fig. 1. Spleen of an acute fatal case of Texas fever. The nar- 

 row 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 (6J pounds) was nearly three times that of the healthy 

 spleen (2f pounds). 



Plate XLVII. 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, maguilied 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 occui-red late in 

 fall. Fig. 5. Red corpuscles from the blood of an acute fatal case, 20 hoiirs 

 before death. The Texas fever microbes u are showu as pear-shaped bo<lies, 

 stained with methylene blue, within the red corpusc-les. The larger body on the 

 right 6 is a white blood coi-puscle, also stained with methylene blue. Magnified 

 1,000 diameters. 



Plate XLA'III. The cattle tick, 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 i)ortion 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, showing same full-grown ticks ready to drop off. Natural size. 



Plate XI^IX. Portion of a steer's hide, showing the Texas fever tick (Mur- 

 garopus annulatus) of the United States. Natural size. Original. 



Plate L. Fig. 1. Dorsal view of male Murgaropus anmilatus of the United 

 States, greatly enlarged. Original. Fig. 2. Ventral view of male Margaropus 

 anmilatus of the United States, greatly enlarged. Original. Fig. 3. Dorsal 

 view of replete female Margaropus annulatus, greatly enlarged. Original. Fig. 

 4. Ventral view of same. 



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

 fever. The shaded and black portions show the area quarantined on account of 

 this disease. As a general rule, cattle may not be shipped interstate from the 

 shaded area except for immediate slaughter. In the black areas the infection 

 is slight, as a result of the work being done for the extermination of the cattle 

 ticks, and cattle oflicially inspectetl and found free from infection may be 

 shipped interstate therefrom for any purpose. 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. 



484 



