58 



PATHOLOGY. 



Fig. 1. — Fatty degeneration of 

 muscular tissue. External matter 

 replaced by oil particles. 



minute granules within the cells of the tissues. A muscular 

 fibre thus affected shows that the sarcous elements, the real 



contractile tissue, within the sarco- 

 lemma, are replaced by shining oil 

 particles, so that the contractile 

 power of such fibre is destroyed. 

 These oil granules, when examined 

 microscopically, present a sharp 

 contour, a dark colour, and strongly 

 refract light. They are soluble in 

 ether ; and as they increase, they, 

 by coalescence, sometimes form 

 distinct drops of fat, but usually they retain their granular form. 

 The cells, however, which contain them increase in size and 

 become globular in shape, the nucleus and cell wall are destroyed, 

 and the cell transformed into a mass of fat. The destruction of 

 the cell is an essential element in fatty degeneration, and distin- 

 guishes it from fatty infiltration, where the cells, within which 

 the fat accumulates, still remain. 



This pathological process is very similar to some of the 

 physiological ones. Thus, in the formation of milk, the cells lining 

 the lobuli of the mammary gland multiply abundantly, and are 

 converted into fat; then they break vip, and constitute the 

 creamy particles (corpuscles) of the milk. The corpuscles thus 

 formed are pushed forward in the ducts by the formation of 

 new cells, which in their turn undergo the degenerative process, 

 and in this manner a continuous formation and destruction of 

 cells take place. 



Fatty degeneration is clearly a kind of atro]Dhy, but is not 

 identical with the simple form, for it may be seen, in degenera- 

 tion of the heart more particularly, that the muscular fibres may 

 be atrophied with loss of their transverse striae, and yet contain 

 not a single drop of oil. 



When much tissue is affected, the change can be readily dis- 

 tinguished with the naked eye by the yellowish white appearance, 

 and by a diminution in consistence and elasticity. 



The parts most commonly affected by the fatty metamorphosis 

 in the horse are the laryngeal muscles — producing the disease 

 which is so well known by the term " roaring," — the voluntary 

 muscles, particularly those of the shoulder, the coats of the 



