THE CIRCULATORY SYSTEM. 435 



entirely to destroy or conceal the normal striations (Fig. 231). These 

 droplets are soluble in ether, and remain unchanged on treatment with 

 acetic acid. This degeneration is sometimes quite universal, but is more 

 apt to occur in patches, giving the heart muscle a mottled appearance. 

 This mottling may usually be best seen on the papillary muscles. The 

 degenerated areas have a pale yellowish color, and the muscle tissue is 

 soft and flabby ; but when moderate or slight in degree the gross appear- 

 ance may be little changed, and the microscopical examination be neces- 

 sary for its determination. This degeneration may lead to thinning of 

 the walls, or to rupture of the heart, or to inability to fulfil its functions. 

 It is not infrequently the cause of sudden death. 



Fatty degeneration may be secondary to hypertrophy of the heart, to 

 inflammation of the heart muscle, or to pericarditis ; to disturbances of 

 the circulation in the coronary arteries by inflammation, atheroma, etc. 

 It may be due to deteriorated conditions of the blood in wasting diseases, 

 excessive haemorrhages, exhausting fevers, leukaemia, etc., to poisoning 

 with phosphorus and arsenic, and to the toxins of microbic origin de- 

 veloped in infectious diseases, such as diphtheria, scarlatina, typhoid 

 fever, etc. ' It may occur in otherwise apparently healthy persons. 



Fatty Degeneration of the Endocardium, It is not uncommon to find, 

 especially in elderly persons, fatty degeneration occurring in patches, 

 especially on the valves, but also on the general endocardium. It may 

 also occur in ill-nourished and anaemic individuals. Small, or even 

 considerable, areas of fatty degeneration appear, as a rule, to be of lit- 

 tle or no clinical significance. They are at least not inconsistent with 

 perfect health. In these areas of fatty degeneration the connective- 

 tissue cells are more or less completely filled with larger and smaller fat 

 droplets. 



Amyloid Degeneration of the endocardium or the walls of the blood- 

 vessels and iutermuscular connective-tissue septa is a not very infre- 

 quent, but usually not very important lesion. 



Hyalin Degeneration sometimes occurs in the blood-vessels and in the 

 muscle fibres. 



There may be calcification of the products of inflammation in pericar- 

 ditis, or of connective-tissue membranes in chronic pericarditis ; in the 

 latter case the heart may be more or less enclosed by a calcareous shell. 

 The muscle fibres of the heart wall may, though rarely, become densely 

 infiltrated with salts of lime. 



Fatty Infiltration. This lesion, which should be clearly distinguished 

 from fatty degeneration, consists of an unusual accumulation of fat 

 about the heart and between its muscle fibres. 



The subpericardial fat, which may be present in considerable quantity 

 under normal conditions, may be so greatly increased in amount as to 

 form a thick envelope enclosing nearly the entire organ. Sometimes the 

 accumulation of fat extends into the walls of the heart, between the 

 muscles, causing atrophy of the latter, frequently to a very great extent 

 1 Consult Flexner, Johns Hopkins Hospital Bulletin, vol. v., p. 26, 1894. 



