2 H. HAYS BULLARD 



and Winckler ('02), Rubow ('04-'05), Erlandsen ('07), Rosen- 

 bloom ('13 a) and others who have analyzed portions of the myo- 

 cardium which had been carefully freed from adipose tissue. The 

 work of the biochemists just mentioned indicates that from two 

 to four per cent of the weight of the undried substance of the 

 myocardium is fat, half of which is present as phospholipines 

 while the other half is mainly neutral fat. The entire fat con- 

 tent of normal cardiac muscle is commonly supposed to be 

 'invisible,' that is, in such a form that it cannot be micro- 

 scopically demonstrated. A few investigators would appear to 

 make the total fat content not only 'invisible' but 'combined' 

 or 'masked;' others would limit the latter terms to the compara- 

 tively small fraction of the total fats which can be extracted 

 only after protein digestion. According to Leathes ('10) there 

 is not sufficient evidence to justify us in assuming the existence 

 of a chemical combination of fat and protein. FA)m Rosen- 

 bloom's ('13 b) recent review of the literature of the subject 

 one is impressed by the vague character of the information as 

 yet vouchsafed concerning this supposed fat-protein compound. 

 Virchow ('47) taught that visible fat appears in cardiac muscle 

 only as the result of a pronounced retrogressive process, the de- 

 generation of cell protein into fat. By many clinicians, 'fatty 

 degeneration' in the heart was thought to lead to serious disturb- 

 ances of function of the organ with death as the inevitable out- 

 come. Welch ('88) demonstrated that this extreme view is not 

 tenable. He observed that rabbits kept for some time at a high 

 temperature and therefore known to possess fatty cardiac muscle, 

 show no symptoms of cardiac derangement either at the time of 

 the experiment or thereafter. He also found that cardiac fibers 

 which are crowded with fat will nevertheless contract rhythmic- 

 ally. Flexner ('94-95) showed that fat in the heart muscle 

 appears more frequently in certain infections than in others. He 

 pointed out that many clinical conditions formerly supposed to be 

 due to fatty degeneration of the heart are now known to be due 

 to other causes. Hasenfeld and Fenyvessy ('99) demonstrated 

 that even when cardiac muscle is extremely fatty, following phos- 

 phorus poisoning, the heart action is apparentl}^ unimpaired. 



c 



