10 H. HAYS BULLARD 



preparations bring out the fact that the fatty fibers are distrib- 

 uted with approximate uniformity throughout the myocardium 

 of both ventricles. This is also true in the cat and doubtless in 

 other animals although I have not studied the question ex- 

 haustively. In the auricles the fat content of the fibers appears 

 normally to parallel that found in the ventricles. Figure 13 

 represents a transverse section of fibers from the right auricle of 

 a dog. Figure 10 at L and D shows cardiac fibers from the inter- 

 ventricular septum of the same heart. The number of fat drop- 

 lets and the distribution of light and dark fibers in the auricle is 

 similar to that in the ventricle. 



OCCURRENCE OF NEUTRAL FAT IN THE HEART MUSCLE OF DIF- 

 FERENT MAMMALS UNDER VARIOUS NUTRITIVE CONDITIONS 



The data upon which this investigation rests are, in part, 

 given below in tabular form. The animals are grouped ac- 

 cording to species and also with respect to character of food. 

 Although in nearly all animals some cardiac fibers hold much more 

 fat than others, the distribution of fatty fibers is so uniform that 

 in any given heart the quantity of fat in sections taken at ran- 

 dom from different parts of the ventricles is approximately the 

 same in all sections. This makes it possible, in any given indi- 

 vidual, to represent fairly accurately the amount of fat in the 

 ventricular fibers by one of the following five designations viz: 

 very large, figure 6; large, figure 4; moderate, figure 3; small, figure 

 2 ; very small, figure 1 . An acquaintance with the literature makes 

 it appear that what is 'very large' to one author is but 'large' 

 to another and ' moderate' to a third. In order to show with some 

 clearness what is here intended to be conveyed by the various 

 designations just given a type drawing is referred to in each case. 

 From the tables it will at once be noted that animals, especially 

 rats, kept for a short time on a fatty diet, have much more fat 

 in the heart muscle than do those which are on a diet of carbo- 

 hydrate and protein with only a small amount of fat. In inani- 

 tion, however, animals show a comparatively small amount of 

 fat in the cardiac fibers. The fat findings here given are based 

 upon preparations stained by Herxheimer's alkalin-alcoholic 



