INTRODUCTION. 



19 



is considered to be generally a retrospective change, 

 whereby the primitive characters of the tissues are 

 resumed ; it occurs especially in connective tissues and 

 cartilages, affecting generally the intercellular substance. 



Colloid Degeneration depends upon the conversion of 

 the protoplasmic contents of cells into a tenacious jelly- 

 like material. The cells are burst by accumulation of 

 this matter, and considerable lumps of gelatinous material 

 are produced. The thyroid body is the most frequent 

 seat of this change, but both mucoid and colloid changes 

 may occur in tumours, whether of a malignant or non- 

 malignant type. Neither of these has any bearing of 

 importance upon cattle pathology, though we shall find it 

 occasionally necessary to allude to them. 



Fatty Degeneration is extremely liable to occur in 

 organs which have nerve or blood supply interfered with, 

 for it is a retrograde process resulting from deficient 

 supply or appropriation of nutritive matter. It is a 

 conversion of the contents of the cells of a tissue into fat, 

 which may accumulate so considerably as to burst the 

 cell-walls, whereby a secondary process of diseased action 



Mil 



Fig. 2. — Fatty degeneration of the Heart. 

 After Harley and Brown. 



200 diameters. 



occurs. It affects especially the muscles, as also the 

 lining membranes of arteries and the bowels (in which case 

 the epithelial cells are involved) . This process is of very 

 considerable importance, for it occurs often when a 

 morbid product is to be absorbed and passed into the 

 blood. Sometimes caseous change supervenes upon this 



