THE MICROSCOPE IN DIAGNOSIS. 297 



and covered with a flat glass cover. As soon as the cor- 

 puscles have settled to the bottom, the number in a defi- 

 nite area is counted. If the area chosen is one-fifth of a 

 square millimeter, we have, of course, one-fifth of a cubic 

 millimeter of diluted blood ready for enumeration by aid 

 of the ocular micrometer divided into squares as before. 



Changes in the appearance of the globules, white or 

 red, should be noted, even though such changes are due 

 to physical causes, as crenated margins, not running to- 

 gether in rouleaux, etc. Minute particles of bioplasm (mi- 

 crocy tesl are sometimes seen, appearing as granular debris, 

 whose significance is unknown. In pernicious anaemia 

 globular cells, deeper in color and smaller than ordinary 

 red globules, have been observed. In a case reported by 

 Dr. Mackenzie the number of red disks was but 18.6 per 

 cent, or 930,000 to the cubic millimeter, instead of 5,000- 

 000 (page 187). 



In the disease known as malignant pustule, splenic 

 fever, anthrax, etc., a short, straight, motionless rod, 

 about as long as the width of a blood-corpuscle, has been 

 found in the blood, and is definitely related to the activity 

 of the virus. It is called Bacillus anthracis, and resembles 

 a common and harmless one found in infusions of hay, 

 etc., the Bacillus subtilis, although the latter is endowed 

 with motion. 



In relapsing fever, during the paroxysm and relapse, 

 but not in the interval, Spirilla are found in the blood. 

 They are minute spirals of great tenuity, and are from 

 two to six times the breadth of a blood-corpuscle. 



The Filaria sanguinis hominis is found in the blood and 

 urine of persons affected with a certain form of chyluria. 

 It is about the breadth of a blood-cell, and ^ 5 th of an 

 inch in length. It exhibits active wriggling movements.* 



* Finlayson's Clinical Diagnosis. 



