610 
and transverse striations. The borders of the cells show regular round 
elevations with sharply marked depressions between. The eleva- 
tions correspond the “disques epais” of voluntary muscle, while the 
line between represents the “disque mince”. According to RANVIER 
the contractile element of the heart is the fibril, which is made up of 
successive segments having the same structure as voluntary muscle. 
The substance surrounding the nucleus in the centre sends out pro- 
cesses which enclose the fibril bundles in thin sheaths. 
STéHR !) gives a somewhat similar description representing the 
fibril bundles as flat columns placed in a radial fashion around the 
periphery, with smaller cylindrical bundles more centrally situated. 
These fibril bundles are surrounded by processes from the central 
undifferentiated sarcoplasm, which contains many granules. v. KoEL- 
LIKER ?) describes the heart muscle as consisting of anastomosing 
cells which contain elements entirely like those of voluntary muscle, 
that is, fibrils and sarcoplasm with interstitial granules in the sarco- 
plasm. According to him, the fibrils are grouped in columns or 
Muskelsäulchen, which, around the periphery, are in the form of flat 
bands arranged radially. 
SCHIEFFERDECKER’S ?) description is essentially the same. Accord- 
ing to him the muscle consists of branching cells containing rela- 
tively much sarcoplasm, which is collected principally around the 
centrally placed nucleus. At the poles of the nucleus granular yellow- 
ish brown pigment is present in human heart muscle after the tenth 
year. As age advances the pigment increases in quantity, and the 
granules become larger in size and of a deeper color. According to 
Maass the pigment is of fatty origin. The whole muscle forms a 
network of cells united by cement substance. 
Methods and Material. 
In the work of which the following is a report, the tissues used 
were mainly from mammals. The adult tissue was taken from the 
ventricles of the human subject, dog, pig, cat, rabbit and mouse. The 
heart muscle of birds and the frog was also examined. The embryonic 
tissues were derived mainly from pig embryo varying in length from 
10 mm to 100 mm, a series having been studied consisting of hearts 
1) P. Stöur, Lehrbuch der Histologie, Jena 1896, 7. Aufl., p. 71. 
2) A. v. Korrzıker, Handbuch der Gewebelehre des Menschen, Leipzig 
1889, 6. Aufl, p. 142. 
3) SCHIEFFERDECKER und KossEL, Gewebelehre, Braunschweig 1891, 
1. Abt., p. 121. 
