THE MICROSCOPE IN PATHOLOGY AND MEDICINE. 231 



and in arcus senilis. Of vascular organs, the muscular 

 tissue of the heart is most liable to it. 



The cheesy degeneration of Virchow is a variety of 

 fatty degeneration. It is a yellowish, compact, friable, 

 or smeary mass, like cheese. It was formerly believed to 

 be the product of tuberculosis, and regarded as. the sepa- 

 ration of morbid matter (crude tubercle) from diseased 

 blood. It is now regarded as a fatty degeneration prod- 

 uct, with less water present than usual. Sometimes salts 

 of lime are infiltrated in such masses. Real tubercle is a 

 gray, translucent, compact nodule, about the size of a 

 millet-seed (miliary), found in great numbers together. 

 Cheesy inflammation and miliary tuberculosis are often 

 found side by side, and Oohnheim, etc., have shown that 

 inoculation with cheesy detritus will produce tubercle. 

 Tubercle is found in many organs, especially the lungs. 

 Its structure consists of: 1. Large rounded cells of finely 

 granular substance, and small strongly-shining nucleus 

 or nuclei. 2. Small cells, with shining, darkly-contoured 

 nuclei. 3. Mother-cells, with 'clear areas round the small 

 ones. 4. A fine fibrous network (Plate XXV, Fig. 182). 



(2.) Mucoid softening. Mucus is a colloid substance, 

 capable of swelling by imbibition, but of little capacity 

 for diffusion. It is a local production from epithelia of 

 mucous membrane, yet is a structural element in many 

 tumors. In the foetus, the entire subcutaneous cellular 

 tissue is mucous tissue. The fibrinous pseudo-membranes 

 of the respiratory organs soften by mucoid metamorpho- 

 sis, and in cartilage the intercellular substance dissolves 

 in the same way, producing fibres near the surface. 



(3.) Colloid degeneration. This is similar to the last, 

 but differs in having peculiar cells, colloid globules, begin- 

 ning in a normal cell by a change in its bioplasm, while 

 mucoid softening occurs between the fibres of connective 

 tissue. Like mucus, colloid enlarges by imbibition, and 

 ends in soda albuminate. more soluble than common albu- 



