. 235 



is held between the thumb and finger of the left hand. 

 Dry the smears immediately after making them, and 

 place them in the hot air oven, keeping them there for 

 one and one-half to two hours, at a temperature 110 to 

 120 degrees C. Stain the smears with Loeffler's alkaline 

 methrl blue from one to one and one-half mintites ; wash 

 in wnter and dip for an instant into a one-third per cent, 

 acetic acid solution to remove excess of diffuse stain in 

 the red blood cells; wash in water and mount in water 

 or dry and mount in xyol balsam. Examine with a high 

 power objective. (Smith's method.) 



The CHANGES that OCCUR IN THE BLOOD are very char- 

 acteristic in a case of Texas fever. Red blood cells in 

 great numbers are destroyed by the micro-parasite. 

 This is determined by actual count of the red blood cells 

 in a definite quantity of blood; the test being made be- 

 fore, during and after or following the fever. In 

 nealthy old cattle the average number of red blood cells 

 in a cubic millimeter is about 6,000,000. In healthy 

 young calves the average number of red cells per cmm. 

 may be as high as 8,000,000. In healthy mature or mid- 

 dle-aged cattle the average number may be about 7,000,- 

 0( per cmm. In acute cases of Texas fever the number 

 of red cells in the blood may be reduced 2,000,000 or 

 less per cmm. In mild cases of Texas fever the number 

 of red cells will vary between 3,000,000 and 5,000,000 

 per cmm. 



As associated with, or as a result of the great loss of 

 red blood cells (anaemia) the red cells will vary in size 

 and shape ; some are very much larger than normal red 

 blood cells and when stained with Loeffler's alkaline 

 methyl-blue, become diffusely stained, and some of them 

 contain very small granules. These large red cells are 

 found in some forms of ansemia in man, and are called 

 megalocytes. 



