DEGENERATIVE DISEASES OF AIITERIAL COATS. 587 



presents an irregular granular appearance, and is destitute of 

 obvious arrangement. 



Chemically, it is composed of the phosphate and carbonate of 

 lime, and animal matter (Lassaigne), and it constitutes one of 

 the various examples of that calcareous degeneration common 

 to old age, which is displayed in the increasing proportions of 

 earthy matters in various parts of the animal body. 



cartilaginous degeneration. 



Cartilaginous deposits are chiefly found in the small arteries, 

 at a considerable distance from the heart, and present themselves 

 in various forms of transparency, consistency, and connection 

 with the inner membrane. 



They are deposits upon the inner membrane, and in some 

 instances are easily peeled off, leaving the membrane entire ; at 

 other times they are firmly adherent to it. " The only changes 

 wliich they seem to undergo, after assuming a cartilaginous con- 

 sistency, is increase of thickness." — (Pirrie.) " They originate 

 in the exudation of arteritis, which is at first of a gelatinous con- 

 sistence, but gradually becomes firmer, and eventually supplants 

 the inner membrane, on the free surface of which it was origi- 

 nally effused." — (Bizot.) 



fatty or atheromatous degeneration. 



Fatty metamorphosis of the arterial coats is rarely met with 

 in comparison to the calcareous fonn, but it may be witnessed 

 in the coronary (cardiac) and in the cerebral arteries of old 

 horses, such as old favourite carriage-horses, which have led a 

 life of ease and good living ; and very lately I met with this 

 condition, along with atrophy and fatty degeneration of the 

 ventricular walls, in the heart of a brewer's horse, which for 

 some years had done little or no work. This form of degenera- 

 tive disease consists of a deposition of fatty granules of a pale 

 yellowish colour, situated between the middle and inner coats of 

 the artery. Later on, the coats of the vessel have a thickened 

 leathery appearance, due to degenerative changes having taken 

 place in all its tissues, by which its power of contractility 

 is more or less destroyed, and if it be cut open, well-marked 



