FAT AND MITOCHONDRIA IN CARDIAC MUSCLE 27 



One may form some idea of the quantity of the phosphoHpines 

 in the fibers by observing the number and size of the true inter- 

 stitial granules and by taking into consideration also the extent 

 to which they suffer loss of substance when treated with a fat 

 solvent. Estimated in this rough manner the quantity of phos- 

 pholipine in the granules appears to be sufficient to account for 

 the total amount of the one to two per cent bj^ weight of this 

 substance shown by chemical analyses. 



According to Kolliker f'89), Schaffer ('93), Altmann ('94), 

 Wegelin ('13) and others, true interstitial granules, under either 

 pathological or physiological conditions give origin to fat drop- 

 lets either by fatty metamorphosis or by serving as foci under 

 the influence of which neutral fat is deposited or synthesized. 

 All the evidence which I have so far been able to obtain is di- 

 rectly opposed to this view. 



If the true interstitial granules, as I have attempted to show, 

 are composed in part of phosphoHpines the conception that they 

 give rise to neutral fat may be taken, from a chemical stand- 

 point, as equivalent to the formation of neutral fat from phos- 

 phoHpines (lecithine and related compounds). Krehl ('93) and 

 Rubow ('04-'05) after careful chemical analyses of normal and 

 pathological hearts conclude that neutral fat is not formed from 

 lecithine (pHosphoHpine) and their results have met with general 

 acceptance. On the other hand we are certain that the phospho- 

 Hpines of the body are built up from neutral fat. This occurs 

 in the liver and perhaps in other organs (Leathes '10). If, as 

 seems probable, it occurs in the heart one might well suppose that 

 the true interstitial granules are actively concerned in the proc- 

 ess. It is not improbable that a molecular supply of fatty acid, 

 drawn either directly from the blood or from the neutral fat drop- 

 lets of the fibers, furnishes the material from which the phospho- 

 lipine of the granules is formed. 



We know that certain of the phosphoHpines are optically 

 active (Leathes '10). Figure 15 shows that the true interstitial 

 granules of cardiac muscle are found in the anisotropic segment 

 Q. This suggests the possibility that the anisotropic property 

 of segment Q is dependent upon the presence of the phosphoH- 

 pines of the granules. 



