THE RELATION BETWEEN THE CYTO-RETICULUM AND 
THE FIBRIL BUNDLES IN THE HEART MUSCLE CELL 
OF THE CHICK. 
BY 
HARRY LEWIS WIEMAN. 
From the Biological Laboratory of the University of Cincinnati. 
WirH 2 DIAGRAMS AND 17 FIGURES. 
In the great mass of literature that has appeared on the subject of 
the striated muscle, no account apparently exists of the histogenesis of 
the heart muscle cell of the chick. This seems rather strange in face 
of the fact that the chick always has been the classic subject for embryo- 
logical research. The present study was undertaken for the purpose of 
determining the structures existing in the heart muscle cell of the chick, 
especially for comparison with results of similar work that has already 
been done on other vertebrate forms. 
The particular phase of the histogenesis treated in this paper is the 
relation between the cyto-reticulum of the embryonic cell and the fibril 
bundles as found in the adult muscle tissue. To avoid any possible con- 
fusion or misunderstanding, a definition of terms here at the outset will 
perhaps not be amiss. 
By cyto-reticulum, the writer means the deeply staining network found 
traversing the cytoplasm of early embryonic cells. The fibril bundles, 
corresponding to the “ Muskelsiulchen ” of Koelliker, 02, are the striated 
longitudinally disposed masses running the length of the adult cell. 
Each fibril bundle is composed of more elementary parts called fibrils. 
On account of the abundance of material and the ease with which 
the various stages in the development of the cell can be secured, the 
chick is very well adapted to a study of this kind. The one serious ob- 
jection is that the various structures of the cell are not as well differ- - 
entiated as in some other forms. 
To Professor Guyer, at whose suggestion this work was taken up, the 
writer is much indebted for valuable assistance. 
AMERICAN JOURNAL OF ANATOMY.—VoOL. VI. 
