62 PATHOLOGY. 



commonly occurs in parts wliicli come in contact with the air." 

 — (Green.) The caseous mass is converted into a thin puriform 

 fluid containing curd-like matter, composed of animal debris, fat, 

 and cholesterine crystals, which, if not absorbed or discharged, 

 may ultimately dry and become calcified. 



THE MUCOID AND COLLOID DEGENERATIONS 



Are conditions wliich are rarely met with in the lower animals. 

 The reader is therefore referred to works upon human pathology, 

 more particularly to Green's Pathology and Moi^hid Anatomy. 



PIGMENTARY DEGENERATION. 



In this process pigment takes the place of the tissue elements, 

 in the same manner as fat or earthy salts in the fatty and 

 calcareous degeneration. 



I have witnessed this form of deposit in the lungs of horses. 

 It is, however, of little importance, and I shall merely refer the 

 reader to authorities upon the subject, amongst whom may be 

 mentioned Aitken, Bennett, Virchow, and Green. 



AMYLOID DEGENERATION. 



This morbid process consists in the transformation of the 

 tissues into a peculiar homogeneous substance, having a relation 

 in some respects to the chemical characters of cellulose or starch. 



Tliis degeneration has been long known by medical men under 

 a variety of names, such as the lardaceous, waxy, hacon-lihe, and 

 albuminoid degeneration. I have met with several cases which 

 presented the physical appearance of this form of disease both in 

 the liver and in the kidneys ; but I have only satisfied myself 

 in one instance of the character of the morbid product. For an 

 account of the method by which this disease has been investi- 

 gated, I take the liberty of making the following quotation from 

 Aitken, who, after mentioning a number of names by which the 

 disease has been known, proceeds to say that " Chemistry and 

 micro-chemical investigation have modified the views regarding 

 the nature of the disease, and now and then have led to modiii- 

 cations in the nomenclature. Under this kind of inquisitive 



