332 BACTERIOLOGY. 



are employed for the description of the microscopic 

 appearance of these nodules, yet it is very rarely that 

 any condition other than that due to the fusion of 

 several of these minute foci can be detected by the 

 naked eye. 



The miliary tubercles are of a pale gray color, with a 

 white centre, are slightly elevated above the surface of 

 the tissue in which they are located, and, as stated, vary 

 considerably in dimensions, usually appearing as points 

 which range in size from that of a pin-point to that of 

 a pin-head. They are not only located upon the surface 

 of the organs, but are distributed through the depths of 

 the tissues. To the touch they sometimes present noth- 

 ing characteristic, but when closely packed together in 

 large numbers they usually give a mealy or sandy sen- 

 sation to the hand passed over them. Stained sections 

 of miliary tubercles present a distinctly characteristic 

 appearance, and the disease may be diagnosticated by 

 these histological changes alone, though the crucial test 

 in the diagnosis is the demonstration of tubercle bacilli 

 Yvfithin the nodules. 



Microscopic Appearance of Miliary Tuber- 

 cles. — A miliary tubercle under a low magnifying 

 power of the microscope presents somewhat the follow- 

 ing appearance : there is a central pale area, evidently 

 composed of necrotic tissue because of its incapacity 

 for taking up the nuclear stains commonly employed. 

 Scattered through this necrotic area may be seen granular 

 masses irregular in size and shape ; they take up the stains 

 employed and are evidently fragments of cell-nuclei in 

 course of destruction. Througli the necrotic area may 

 here and there be seen irregular lines, bands, or ridges, the 

 remains of tissues not yet completely destroyed by the 



